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Artykuły w czasopismach na temat "Low head pumps"
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Bunt, E. A., B. Parsons i F. Holtzhausen. "Role of Dissipation Characteristics in Predicting Flow from Dissimilar Centrifugal Pumps". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 208, nr 4 (listopad 1994): 285–94. http://dx.doi.org/10.1243/pime_proc_1994_208_049_02.
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Examination of flows in a particular case of dissimilar pumps coupled in series or in parallel (without check valves) showed that the ‘classical’ graphical solution of combined characteristics in the [+H, +Q] quadrant did not accord with the output field in certain regions. To predict the full flow fields, it was necessary to take into account dissipative flow characteristics in two other quadrants: for low-output parallel flow (when there is still flow available from the pump of higher head when the ‘weaker’ pump's flow has been reduced to zero), that in the [+H, –Q] quadrant; and for high series flow (after the output head of the pump of lower maximum flow has been reduced to zero), that in the [–H, +Q] quadrant. This problem does not arise when the pumps have identical characteristics.
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Howey, D. A., i K. R. Pullen. "Hydraulic air pumps for low-head hydropower". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 223, nr 2 (9.01.2009): 115–25. http://dx.doi.org/10.1243/09576509jpe645.
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Choi, Young-Do, Junichi Kurokawa i Jun Matsui. "Performance and Internal Flow Characteristics of a Very Low Specific Speed Centrifugal Pump". Journal of Fluids Engineering 128, nr 2 (5.09.2005): 341–49. http://dx.doi.org/10.1115/1.2169815.
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In very low specific speed range (ns<0.25), the efficiency of the centrifugal pump designed by the conventional method becomes remarkably low. Therefore, positive-displacement pumps have been widely used for long. However, the positive-displacement pumps remain associated with problems such as noise and vibration and they require high manufacturing precision. Since the recently used centrifugal pumps are becoming higher in rotational speed and smaller in size, there appear to be many expectations to develop a new centrifugal pump with high performance in the very low specific speed range. The purpose of this study is to investigate the internal flow characteristics and its influence on the performance of a very low specific speed centrifugal pump. The results show that large reverse flow at the semi-open impeller outlet decreases absolute tangential velocity considerably which in turn decreases the pumping head.
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Zhang, Li, Hui Li, Hong Xu, Weidong Shi, Yang Yang, Wanhong Wang i Ling Zhou. "Experimental and Numerical Investigation of Pressure Fluctuation in a Low-Specific-Speed Centrifugal Pump with a Gap Drainage Impeller". Shock and Vibration 2021 (30.06.2021): 1–14. http://dx.doi.org/10.1155/2021/5571178.
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In order to analyze the effect of impeller with different slot widths on the performance of the low-specific-speed centrifugal pumps, based on the impeller of a single-stage pump with the specific speed of 21, two gap drainage schemes with slot widths of 1.5 mm and 6.0 mm, slot diameter of 180 mm, and lap length of 5 mm were designed. Both experimental and numerical simulation methods were applied to compare the steady performance, which includes the head, efficiency, and the internal flow field distribution, and the unsteady pressure pulsation performance between new designed pumps and the original pump. The results show that gap drainage would cause a certain degree of head reduction, but a smaller slot width could achieve higher efficiency. Meanwhile, a reasonable open seam scheme can reduce the development of pressure pulsation, which provides experience and reference for the stable operation of low-specific-speed centrifugal pumps.
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Meakhail, T., i S. O. Park. "An improved theory for regenerative pump performance". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 219, nr 3 (1.05.2005): 213–22. http://dx.doi.org/10.1243/095765005x7565.
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Owing to their low specific speed, regenerative pumps allow high heads with small flow rates and have performance curves with very stable features. This kind of pump is also smaller and simpler to construct than the other equivalent volumetric pumps, although it has fairly low efficiency. Over the past few years, regenerative pumps have been subject to more interest in various industrial applications. Previous mathematical models do not describe the flow characteristics very well as they are based on simplified assumptions. An improved model is proposed in this paper for the pump performance. The model can handle one inlet angle and two exit angles for the impeller blades and it can be used for the design of twisted blades that would increase the pump head and efficiency. A new feature of the pump characteristics based on the proposed model is discussed. It is shown that the proposed model yield results that are in good agreements with the experimental results. The new model also shows that the side-blade exit angle has a major effect on the performance of regenerative pump, which has not been accounted for in the previous theory.
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Xue, Rong, Xinyi Lin, Beile Zhang, Hong Zhou, Tianwei Lai i Yu Hou. "CFD and Energy Loss Model Analysis of High-Speed Centrifugal Pump with Low Specific Speed". Applied Sciences 12, nr 15 (24.07.2022): 7435. http://dx.doi.org/10.3390/app12157435.
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High-speed centrifugal pumps with low specific speed have the characteristics of a small flowrate, a high head, and being compact and light weight, making them promising candidates for applications in the thermal management of aerospace and electronic devices. The energy loss in the low specific speed pump is critical and complex due to the large impeller diameter, the narrow and long flow channel, and the small outlet width. In this paper, an analysis method based on an energy loss model and computational fluid dynamics simulations (ELM/CFD) is proposed to analyze the performance of the low specific speed pump with a fully sealed structure. Experiments were carried out under variable water flowrates. The results show that the empirical correlation method failed to accurately predict the performance of high-speed centrifugal pumps, because the bearing clearance leakage and motor channel leakage are ignored. Moreover, the volume loss and hydraulic loss are calculated based on the empirical parameters of commonly used pumps that are different from the high-speed pump with the low specific speed in the complex flow channel structure. The ELM/CFD method calculates various loss power based on the simulation results and can predict the head and efficiency with deviations less than 2% and 5%, respectively. ELM/CFD can accurately analyze the optimization direction of the pump. The hydraulic loss and the volume loss of the impeller are the dominant factors that restrict the pump efficiency under the lower flowrates, while the hydraulic loss of subsequent flow channels becomes important under the larger flowrates.
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Wang, Xiaohui, Junhu Yang, Zhengting Xia, Yan Hao i Xiaorui Cheng. "Effect of Velocity Slip on Head Prediction for Centrifugal Pumps as Turbines". Mathematical Problems in Engineering 2019 (24.03.2019): 1–10. http://dx.doi.org/10.1155/2019/5431047.
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The application of pumps as turbines (PAT) has been developed in several applications for energy recovery schemes. Therefore, establishing a performance correlation between pump mode and turbine mode is essential for selecting the proper machine. However, slip phenomenon is the challenges of head prediction for PAT. In this paper, the slip phenomenon of pump and PAT was revealed, and the slip factor was studied using CFD. The effect of slip on head prediction for PAT was analyzed, and a theoretical prediction model was presented considering slip factors. In order to validate the head prediction model, six centrifugal pumps with specific speed (ns) from 9 to 54.8 were tested as turbines. Results showed that the predicted head by the proposed method was in good agreement with the experimental data, and it is more accurate than Stepanoff, Alatorre-Frenk, Sharma, and Derakhshan models. This method can be applied in head prediction for low specific speed PAT ( ns <60).
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Wan, Stephen, Jason Leong, Te Ba, Arthur Lim i Chang Wei Kang. "Numerical Characterization of the Performance of Fluid Pumps Based on a Wankel Geometry". Journal of Fluids 2014 (30.09.2014): 1–7. http://dx.doi.org/10.1155/2014/241010.
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The performance of fluid pumps based on Wankel-type geometry, taking the shape of a double-lobed limaçon, is characterized. To the authors’ knowledge, this is the first time such an attempt has been made. To this end, numerous simulations for three different pump sizes were carried out and the results were understood in terms of the usual scaling coefficients. The results show that such pumps operate as low efficiency (<30%) valveless positive displacements pumps, with pump flow-rate noticeably falling at the onset of internal leakage. Also, for such pumps, the mechanical efficiency varies linearly with the head coefficient, and, within the onset of internal leakage, the capacity coefficient holds steady even across pump efficiency. Simulation of the flow field reveals a structure rich in three-dimensional vortices even in the laminar regime, including Taylor-like counterrotating vortex pairs, pointing towards the utility of these pumps in microfluidic applications. Given the planar geometry of such pumps, their applications as microreactors and micromixers are recommended.
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Kim, Changhyun, Semi Kim, Chang-Ho Choi i Jehyun Baek. "Effects of inducer tip clearance on the performance and flow characteristics of a pump in a turbopump". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 231, nr 5 (2.05.2017): 398–414. http://dx.doi.org/10.1177/0957650917707656.
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A turbopump is used to pressurize propellants to gain high thrust in a projectile and consists of two pumps and a turbine. The pumps usually employ an inducer upstream to prevent performance deterioration by lowering net positive suction head required of the main impeller. However, several types of cavitation and instabilities take place in the flow field. Therefore, numerous experiments and CFD analysis for turbopumps have been conducted. Especially, there were some previous studies on inducer tip clearance, but they were limited to inducer regions due to the complexity of simulating the entire pump. In this study, the flow through an oxidizer pump in a turbopump was numerically investigated with four different sizes of inducer tip clearances. ANSYS CFX 13.0 with Rayleigh–Plesset equation was used to test flows in both non-cavitating and cavitating conditions. In the non-cavitating condition, the pump with the largest inducer tip clearance showed the worst head rise, efficiency and huge size of backflow arose near inducer casing. Also, the vortex was generated between the inducer blades in the case of large inducer tip clearance due to weak tip leakage flow. In the cavitating condition, the inducer with large tip clearance was found to be vulnerable to low suction pressure and floating cavity was observed between the inducer blades. However, the heads of the pumps with different inducer tip clearances were broken down at similar cavitation numbers due to the blade cavitation near the impeller throat. In addition, the transferred cavity from the inducer region also induced head breakdown of the pump.
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Jiang, Linglin, Houlin Liu, Yong Wang, Yanhong Mao, Runze Zhou i Jianbin Gu. "Experimental Study on the Effect of Gas Volume Fraction on the Cavitation Performance of a Low-Specific-Speed Centrifugal Pump". Water 14, nr 5 (3.03.2022): 798. http://dx.doi.org/10.3390/w14050798.
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In order to study the cavitation performance of centrifugal pumps with low specific speeds under the condition of gas–liquid two-phase flow, a cavitation test rig for pumping gas–liquid two-phase flow was set up. The cavitation performance of the pump with a specific speed of 32 was studied. The variation of the head, pressure pulsation intensity, and vibration intensity with the cavitation allowance NPSHa (Net Positive Suction Head available) of the centrifugal pump were obtained at different inlet gas volume fraction (IGVF) conditions of 0, 1%, 2%, and 3%. The results show that the cavitation performance of a low-specific-speed centrifugal pump can be improved obviously in a certain liquid flow range when the IGVF is 1%, especially at a low liquid flow rate. When cavitation did not occur or the degree of cavitation was low, a lower IGVF can reduce pressure pulsation intensity at the pump outlet and the vibration intensity at the pump inlet under design flow rate and high flow rate conditions. Additionally, all performances of the low-specific-speed pump are more sensitive to gas when the liquid flow rate is low. The results can provide a reference for improving the cavitation performance of low-specific-speed pumps for transporting gas–liquid two-phase flow and single-phase liquids.
Rozprawy doktorskie na temat "Low head pumps"
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Toal, B. R. H. "The application of heat pumps to low temperature drying". Thesis, University of Ulster, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378669.
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Vivian, Jacopo. "Direct Use of Low Temperature Heat in District Heating Networks with Booster Heat Pumps". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3422669.
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Buildings are responsible for over one third of the energy demand in Europe. Thus, reducing their energy consumption, increasing energy efficiency and integrating low carbon energy sources have become primary goals in the transition towards a sustainable society. District heating and cooling (DHC) systems play a key role to achieve these targets, as they allow any available source of heat to be exploited, including waste heat and renewable heat sources such as geothermal or solar heat. Nowadays, state-of-the-art DH networks have sup-ply temperatures of 70°C in winter and 55°C in summer. Due to their top-down structure, today’s networks are not well-suited for decentralized heat supply. The present thesis explores the potential of a new generation of DHC systems, that distribute heat at lower temperature (from 15°C to 45°C) and use booster heat pumps in the customers substations to raise the temperature level according to the needs of the building served. This concept brings several advantages over conventional networks, such as the abatement of thermal losses, the extension of the temperature range of recoverable heat sources and the potential decentralization of heat supply. In a preliminary analysis, the implementation of the system was investigated for a small town in the North-East of Italy with a large amount of available wastewater in a tem-perature range between 45 and 55°C. In this case-study, the DH system with booster heat pumps reduced the primary energy consumption of about 70% compared to a heat supply sce-nario based on individual gas boilers and of 30% compared to a traditional DH system with a central heat pump and an auxiliary gas boiler. Such improvement occurs also because the dis-tributed heat pumps can be adapted to the supplied buildings: this is particularly relevant con-sidering the heterogeneneity of the building stock in the urban environment. The optimal de-sign and management of this kind of networks is a new topic in the scientific literature. There-fore, the first part of the work tries to answer the following general question:
“What are the most critical aspects in the system design?”
The thesis analyses the effect of some critical design parameters on the cost of heat for the final user, using the payback time for the DH utility as a fixed constraint. It emerges that a higher supply temperature leads to two positive effects: the heat sales increase and the ex-penditure for electrical energy is reduced. The levelized cost of energy of the system drops by 17% when the network supply temperature goes from 40°C to 20°C, provided that the heat can be recovered at the same price. Moreover, the network temperature difference plays an important role in the design phase. Depending on the business model adopted by the DH utili-ty to purchase the heat and on the specific energy consumption of the considered building stock, an optimal temperature difference may arise from the trade-off between low initial in-vestment and low operational costs. The decentralized structure of these networks also intro-duces new challenges in the control strategies. Indeed, if the utility purchases and/or produces the electricity needed by the heat pumps, the control strategy should possibly take into ac-count the price and/or the production cost of electricity. Secondly, the control system of the network manager must be able to react on increasing shares of decentralized heat supply from the prosumers. These issues can be summarized by the following research question:
“How can the network manager control its heat supply units in a smart way?”
This part of the thesis was developed within the H2020 Project FLEXYNETS. In order to minimize the operational cost for the network manager, an intelligent control method based on MILP optimization was developed and tested via computer simulations. The proposed control system proved capable of self-adapting to the current situation of heat demand, waste heat availability and electricity price, such as to increase the share of electricity self-consumption and the share of low-grade heat recovered from the remote prosumers. During two simulated winter months, the advanced control strategy was able to reduce operational costs by 11% compared to a conventional rule-based control. The receding horizon scheme makes the sys-tem potentially feasible for real-time applications. The novelty of this work consists not only in the aforementioned findings per se, but also in the methodological framework that led to those results. In fact, the developed models allowed to integrate the whole energy system (buildings, substations, district heating network and heat supply stations) into a unique simulation environment.Gli edifici sono responsabili di oltre un terzo della domanda di energia in Europa. Ridurre il consumo di energia, aumentare l’efficienza energetica ed integrare fonti di energia a basso impatto ambientale sono diventati obiettivi fondamentali nella transizione verso un futuro sostenibile. Le reti di teleriscaldamento e teleraffrescamento hanno un ruolo fondamen-tale nel raggiungimento di questi obiettivi, in quanto permettono di recuperare ed utilizzare il calore da qualsiasi fonte sia disponibile a livello locale: dal calore di scarto al calore di fonti rinnovabili come il geotermico e il solare. Oggi le reti di teleriscaldamento più efficienti hanno temperature di mandata pari a circa 70°C in inverno e 55°C d’estate. A causa della loro struttura centralizzata, le reti di oggi non sono predisposte per la generazione distribuita del calore. Questa tesi analizza il potenziale di una nuova generazione di reti, che distribuiscono il calore ad una temperatura più bassa (in generale tra 15°C e 45°C) e usano pompe di calore di rilancio nelle sottostazioni d’utenza per fornire calore alla temperatura desiderata da ogni sin-golo edificio. Questa nuova filosofia progettuale porta diversi benefici rispetto alle reti tradi-zionali, come l’abbattimento delle perdite di calore, la possibilità di integrare fonti a più bassa temperatura e la decentralizzazione del sistema. In una analisi preliminare, l’implementazione del sistema proposto è stata studiata per una cittadina italiana in cui è presente un’ingente quantità di acqua di risulta tra i 45°C e i 55°C. In questo caso studio, la rete di teleriscalda-mento con le pompe di calore distribuite riduce il consumo di energia primaria e le emissioni di anidride carbonica di circa il 70% rispetto allo sceanrio costituito da caldaie autonome e del 30% rispetto ad una rete tradizionale con pompa di calore centralizzata e caldaia a gas di inte-grazione. Questo miglioramento si verifica anche perché ogni pompa di calore viene adattata all’edificio, il che assume notevole importanza in virtù dell’eterogeneità del parco edilizio normalmente presente nel contesto urbano. La progettazione e la gestione di questo tipo di reti è un argomento nuovo nella letteratura scientifica. La prima parte della Tesi cerca perciò di rispondere ad una domanda di carattere generale: “Quali sono gli aspetti più importanti nella progettazione del sistema?” La tesi analizza gli effetti di alcuni parametri di progetto sul costo dell’energia all’utente fina-le, mantenendo fisso il tempo di rientro dell’utility. Ne è emerso che una elevata temperatura di mandata porta a due benefici: (a) aumentano le vendite di calore da parte dell’utility e (b) si riduce il consumo di energia elettrica delle pompe di calore. Come conseguenza, passando da 40°C a 20°C ato dell’energia si abbassa del 17% a parità di costo del calore che alimenta la rete. In più, anche la differenza di temperatura tra mandata e ritorno ha un ruolo importante nella fase di progetto della rete. Il compromesso che nasce per contenere da un lato l’investimento iniziale e dall’altro i costi operativi può portare ad una differenza di temperatu-ra ottimale tra mandata e ritorno. La struttura decentralizzata di queste reti inoltre fa nascere la necessità di studiare nuove strategie di controllo. Infatti, se l’utility compra e/o produce l’energia elettrica di cui le pompe di calore necessitano, la strategia di controllo deve tenere in considerazione anche il prezzo e/o il costo di produzione dell’energia elettrica. Inoltre, il si-stema di controllo del gestore della rete deve essere in grado di far fronte a quantità ingenti di calore fornito dai prosumers. Questi problemi possono essere riassunti nel seguente quesito: “In che modo il gestore di rete può controllare i suoi impianti?” Questa parte della tesi è stata sviluppata nell’ambito del progetto H2020 FLEXYNETS. Al fine di minimizzare il costo operativo per il gestore di rete è stato sviluppato e successivamente testato attraverso simulazioni un metodo di controllo intelligente basato su ottimizzazione MILP. Col metodo proposto il sistema è stato in grado di adattarsi alla situazione di domanda di calore, disponibilità di energia da parte dei prosumers e prezzo dell’elettricità in modo tale da aumentare la quota di autoconsumo e aumentare la quota di energia recuperata dai prosu-mers. Durante i due mesi di simulazione, la strategia di controllo è stata in grado di ridurre i costi operativi dell’11% rispetto ad un sistema di controllo convenzionale. Lo schema “rece-ding horizon” rende il metodo potenzialmente fruibile in applicazioni real-time. Il contributo della tesi non è solamente relativo ai risultati in quanto tali, ma anche alla metodologia utiliz-zata per raggiungerli. Infatti i modelli sviluppati hanno permesso di studiare il sistema energe-tico nel suo insieme.
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Mateu, Royo Carlos. "Development of High Temperature Heat Pumps for Industrial Waste Heat Recovery". Doctoral thesis, Universitat Jaume I, 2021. http://dx.doi.org/10.6035/14107.2021.744033.
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One of the major challenges of this decade is developing more sustainable energy systems that contribute to environmental concern, especially climate change mitigation. Extending the operating conditions of the heat pump technology to higher temperatures will allow decarbonising the industrial sector from two slopes: recovering heat from waste heat sources that currently is being rejected to the ambient and produce heat at the required industrial thermal levels that become useful for the industrial processes. Both challenges will make possible reduce the equivalent CO2 emissions of the industrial sector and operate at high temperatures that conventional heat pumps. This thesis deals with the development of high temperature heat pumps through a comprehensive theoretical and experimental analysis to overcome different technology challenge: architecture, refrigerants, experimental prototype, advanced applications and system integration, providing new knowledge that represents a step forward in high temperature heat pump technology.Uno de los mayores desafíos de esta década recae en el desarrollo de sistemas energéticos más sostenibles que contribuyan a la preocupación medioambiental, especialmente la mitigación del cambio climático. Extender las condiciones de funcionamiento de la tecnología de bomba de calor a temperaturas más elevadas permitirá descarbonizar el sector industrial desde dos vertientes: recuperando calor de fuentes de calor residual, actualmente disipado al ambiente y producir calor a los niveles térmicos requeridos, útiles para los procesos industriales, reduciendo así las emisiones de CO2 equivalentes del sector industrial y contribuyendo al desarrollo sostenible. Esta tesis pretende abordar el desarrollo de bombas de calor de alta temperatura a través de un análisis teórico y experimental, para abordar diferentes desafíos tecnológicos: arquitectura, refrigerantes, prototipo experimental, aplicaciones avanzadas e integración de sistemas, generando nuevos conocimientos que representan un paso adelante en la tecnología de bombas de calor de alta temperatura.
Programa de Doctorat en Tecnologies Industrials i Materials
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Mempouo, B. "Investigations of novel heat pump systems for low carbon homes". Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12043/.
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The European standard EN15450 states that the Coefficient of Performance (COP) target range for a Ground Source Heat Pump (GSHP) installation should lie within the range of 3.5 to 4.5; when used for heating a building, and a typical Air-Source Heat Pump (ASHP) has a COP of 2.0 to 3.0 at the beginning of the heating season and then decrease gradually as the ambient air becomes cooler, whereas a typical GSHP is in the range of 3.5 –4.0, also at the beginning of the heating season and then decrease gradually as heat is drawn from the ground. For these reasons, in the middle of winter, when the COP drop, the heat pumps can generally only be considered as a ‘pre-heating’ method for producing higher temperature heat such as domestic hot water. In addition soil presents certain difficulties, due to the high cost of drilling to position coils in the ground compare to air source, although frost formation on the evaporator in winter limits also limit the use of air source. Though technology advances or are needed to overcome those issues. The aims of this project, therefore, were firstly to reduce the drilling length of the ground heat exchanger of the ground source heat pumps and to maintain high COPs of the air and ground source heat pumps from beginning to the end of the heating season; and secondly to develop a viable alternative evaporator for air source heat pumps to reduce frost formation during winter. These were achieved; the first aim through the combination of ground loops with solar-air panels or solar roof/collectors roof to ground heat exchangers loops to reduce the length of the boreholes, and to reduce the freezing effects around the boreholes, hence increase or maintain a constant temperature during heating season. The second aim was also achieved through development and validation of novel air source heat pump evaporator, using Direct Expansion (DX) black flat plate absorber or/and vacuum tubes for frost reduction. In this thesis, in order to achieve the above aims; four aspects of investigations have been independently investigated as following: 1- Preliminary investigation on Direct Expansion (DX) Solar Source Heat Pump system. 2- Investigation on the performance of the DX- PV/heat pipe heat pump system to reduce frost and enhance the COP of the air source heat pumps, 3- A small scale testing on the heat injection on energy piles for residential buildings for earth charging by means of solar roof/collectors 4- A field trial testing of the performance of the combination of solar-air thermal collectors with conventional GSHP with shorter ground heat exchangers (48m deep) to charge the ground and reduce freezing effects around the piles after heating cycle. From the simulation results, the novel PV/hp-HP system has a COP ranging from 4.65 to 6.16 with an average of 5.35. The condenser capacity ranging from 33 to 174 W would provide the heat source for space heating and domestic hot water. The energy performance of the novel PV/hp-heat pump was not as good as expected due to the low solar radiation. It should be much better in some low latitude locations with better solar radiation. The results of this thesis have shown that the length of ground source boreholes could be considerably reduce by about 60% compare to conventional boreholes using a combination of solar-air collectors with the GSHP and the average COP of 3.7 was achieved.
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Zubair, Syed M. "Solar assisted heat pump : a thermoeconomic design based on second law". Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/17573.
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Thygesen, Richard. "Low energy buildings equipped with heat pumps for high self-consumption of photovoltaic electricity". Doctoral thesis, Mälardalens högskola, Framtidens energi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-31314.
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The building sector is a prioritized area in the European Unions (EU) ambition to reduce the total final energy use by 20 %; lower the emission of greenhouse gases by 20 % and using energy 20 % more efficient by 2020. The residential sector in the European Union accounts for 27% of the un-ion’s final energy use and the EU views decentralized energy generation and heat pumps as important measures in reducing the energy demand in the building sector. In recent years a rapid decrease in photovoltaic system prices has led to a growing popularity in Sweden. This fact in combination with a large in-crease of heat pump systems in residential buildings the last decade makes a combination of heat pumps and solar energy systems an interesting sys-tem configuration to analyze. In addition, the electricity price structure in Sweden and the uncertainty of the sustainability of the Swedish solar energy support schemes makes the topic of self-consumption an important research area. Different solar energy systems for residential buildings and two different storage technologies, batteries and hot water storage tanks, have been analyzed with regards to profitability, solar energy fraction and self-consumption levels. The results suggest that the system with a heat pump in combination with a photovoltaic system can be profitable and have high solar energy fractions and high levels of self-consumption and that the systems with storage are not profitable but give high levels of self-consumption and relatively high solar energy fractions. The hot water storage gives almost as high level of self-consumption as batteries but have half of the batteries levelized cost of electricity. A system with a ground source heat pump and a solar thermal system are ineffective, unprofitable and give low solar energy fractions. A system with a weather forecast controller gives a small increase in self-consumption and is unprofitable. The proposed near energy zero building definition proposed by the Swedish National Board of Housing, Building and Planning in 2015 is unclear in terms of what electrical load the PV electricity reduces in the building. This has a fairly large impact on the building specific energy demand.
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Navarro, Espinosa Alejandro. "Low carbon technologies in low voltage distribution networks : probabilistic assessment of impacts and solutions". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/low-carbon-technologies-in-low-voltage-distribution-networks-probabilistic-assessment-of-impacts-and-solutions(cc5c77df-54fe-4c1c-a599-3bbea8fbd0c1).html.
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The main outcome of this research is the development of a Probabilistic Impact Assessment methodology to comprehensively understand the effects of low carbon technologies (LCTs) in low voltage (LV) distribution networks and the potential solutions available to increase their adoption. The adoption of LCTs by domestic customers is an alternative to decreasing carbon emissions. Given that these customers are connected to LV distribution networks, these assets are likely to face the first impacts of LCTs. Thus, to quantify these problems a Monte Carlo-based Probabilistic Impact Assessment methodology is proposed in this Thesis. This methodology embeds the uncertainties related to four LCTs (PV, EHPs, µCHP and EVs). Penetration levels as a percentage of houses with a particular LCT, ranging from 0 to 100% in steps of 10%, are investigated. Five minute time-series profiles and three-phase four-wire LV networks are adopted. Performance metrics related to voltage and congestion are computed for each of the 100 simulations per penetration level. Given the probabilistic nature of the approach, results can be used by decision makers to determine the occurrence of problems according to an acceptable probability of technical issues. To implement the proposed methodology, electrical models of real LV networks and high resolution profiles for loads and LCTs are also developed. Due to the historic passive nature of LV circuits, many Distribution Network Operators (DNOs) have no model for them. In most cases, the information is limited to Geographic Information Systems (GIS) typically produced for asset management purposes and sometimes with connectivity issues. Hence, this Thesis develops a methodology to transform GIS data into suitable computer-based models. In addition, thousands of residential load, PV, µCHP, EHP and EV profiles are created. These daily profiles have a resolution of five minutes. To understand the average behaviour of LCTs and their relationship with load profiles, the average peak demand is calculated for different numbers of loads with and without each LCT.The Probabilistic Impact Assessment methodology is applied over 25 UK LV networks (i.e., 128 feeders) for the four LCTs under analysis. Findings show that about half of the studied feeders are capable of having 100% of the houses with a given LCT. A regression analysis is carried out per LCT, to identify the relationships between the first occurrence of problems and key feeder parameters (length, number of customers, etc.). These results can be translated into lookup tables that can help DNOs produce preliminary and quick estimates of the LCT impacts on a particular feeder without performing detailed studies. To increase the adoption of LCTs in the feeders with problems, four solutions are investigated: feeder reinforcement, three-phase connection of LCTs, loop connection of LV feeders and implementation of OLTCs (on-load tap changers) in LV networks. All these solutions are embedded in the Probabilistic Impact Assessment. The technical and economic benefits of each of the solutions are quantified for the 25 networks implemented.
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TADDIA, GLENDA. "Low Enthalpy Geothermal Open Loop Heat Pumps: a suitable tool for thermal energy supply in urban areas". Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2617565.
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Geothermal heat pumps represent an interesting technology that is expected to
contribute significantly to the reduction of primary energy use for heating and
cooling and meet the targets set by the European Union. Additional benefits of this
technology are related to the integration with discontinuous energy resources, in
particular wind, combining heat and power.
The replacement of conventional heating systems such as boilers, with heat pump
systems allows the de-localization of emissions of micropollutants from urban
centers to the sites in which thermal power stations are operating. This also
enhances emissions monitoring and control. Furthermore, the use of distributed
production systems based on the use of renewable sources reduces also CO2
emissions. (Lo Russo et al., 2011)
In this general context, the increasing implementation in several areas of the world
of the open-loop groundwater heat pumps technology which discharge into the
aquifer for cooling and heating buildings could potentially cause, even in the short
term, a significant environmental impact associated with thermal interference with
groundwater, particularly in the shallow aquifers.
The discharge of water at different temperatures compared to baseline (warmer in
summer and colder in winter) poses a number of problems in relation to the
potential functionality of many existing situations of use of the groundwater
(drinking water wells, agricultural, industrial, etc.). In addition, there may be cases
of interference between systems, especially in the more densely urbanized. This
means that the alteration of the temperature of the groundwater determined by a
plant may affect the installations located downstream, with significant alterations
of the performances of the systems themselves. These issues highlight how it is
crucial for the compatible development of the technology of groundwater heat
pumps discharging into aquifers that it shall be a fair assessment and technically
effective both for cooling and heating plants and pumping and injection systems in
ground.
The current legislation related to withdrawals and discharges into aquifers design a
framework suitable for the protection of groundwater and permit to decide the
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best configuration of the plant with a case by case approach. Appropriate
specialized hydrogeological investigations should be performed for the
characterization of the main hydrogeological parameters of the subsoil at the
considered site.
In this thesis some important aspects related to the development of open-loop heat
pumps have been explored in a typical urban contest (Torino city, NW Italy).
The results of the work have allowed to define several fundamental aspects in order
to optimize the design choices of GroundWater Heat Pump (GWHP) systems.
After a general description of the low enthalpy geothermal heat pumps
technologies (Chapter 1), the analysis and comparison of the current hydrogeology
problems in urban area are described, considering the impact of groundwater heat
pump system in a urban contest (Chapter 2). Urban and industrial development can
impose major stresses on groundwater resources. The conceptual model for the
groundwater flow system, the schematization of the aquifer boundaries and the
estimation of basic hydrogeological parameters are among the main issues which
should be investigated in the development of open-loop heat pumps plants. In
particular, some characteristics of urban elements require particular attention if
compared to less anthropized areas.
In Chapter 3 the geological and hydro-stratigraphical characteristics of the Torino
test site have been described. This chapter includes a complete description of the
GWHP system plant and monitoring system that has been installed in the
Politecnico di Torino and the illustration of the fundamentals of the numerical
modelling we performed using a specific commercial code (FEFLOW® Diersch,
2010).
In Chapter 4 the relative significance of the different subsurface parameters that
mostly characterize the developed thermal plume is determined through a detailed
sensitivity analysis under different simulation conditions. In Chapter 5 we explore
the importance of the compliance between real and simulated variable input flow
data (discharge and injection temperatures) to obtain reliable simulation results.
In the following Chapter (6) we explore the potential alternative to Finite Element
Modeling (FEM) tools in the spatial and temporal prediction of the thermal plume
development by considering the use of Artificial Neural Networks (ANNs). Finally, in
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Chapter 7, we consider the potential alternatives to traditional vertical drilled wells
to disperse the thermal energy in the aquifer comparing such technology with the
alternative use of gabions draining.
The results highlighted some important aspects that should be considered in the
modeling of the open-loop heat pumps that are summarized in the Conclusions.
The research individuated some important aspects and reached important results
but, as clearly highlighted, several aspects of the analysis of these kind of
technology should be further investigated by research and practical monitoring
observations in the future. However, even taking into account all the limitations of
the open-loop heat pumps technology, we believe that these systems represent one
of the most promising potential clean energy source especially in the urban areas
under transformation in order to reach the important goal of greenhouse-gas
emission reduction of the future Smart liveable Cities.
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Worall, Mark. "An investigation of a jet-pump thermal (ice) storage system powered by low-grade heat". Thesis, University of Nottingham, 2001. http://eprints.nottingham.ac.uk/11111/.
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This thesis investigates a novel combination of a jet-pump refrigeration cycle and a thermal (ice) storage (TIS) system that could substantially reduce the electrical energy requirements attributable to comfort cooling.Two methods of TIS were identified; spray ice TIS would use evaporative freezing to store ice on a vertical surface,and encapsulated ice TIS would freeze a bed of encapsulated elements by sublimation freezing.Thestudy also investigates jet-pump refrigeration at partload and a convergent-divergent design manufactured from a thermoset plastic to make recommendations for performance enhancement for a system that has a low COP. An experimental rig was built to investigate the novel concepts in the laboratory. Encapsulated ice TIS was superior to spray ice TIS because, for the same nominal secondary flow, sublimation freezing causes an increase in coolth storage rate of about 10 % compared to evaporative freezing. Encapsulated ice stores experience difficulties in fully discharging their coolth (approximately 6% in this case), but spray ice TIS can be used to produce an ice/brine slurry enabling all of the ice to be used, and so may be more suitable if the unmelted ice represents a large proportion of the cooling capacity. Approximately 85 % to 90 % of the ice formed on the vertical surface during spray ice TIS testing was formed by evaporative freezing from a falling film. At high saturation conditions, heat is transferred mainly by conduction across the falling film. Both the growth of an ice layer on a vertical surface and freezing of encapsulated elements were found to be successful, but a large data spread was observed during spray ice TIS testing. It was thought that a variation in the steady-state saturation conditions in the evaporator/ice store was caused by variability of droplet size distribution from the spray nozzle flow, which may make a full-scale system unreliable. The COP of the spray ice TIS system was approximately 0.15 compared to a COP of approximately 0.25 found during encapsulated ice TIS testing. The difference was because of the use of an over-expanded primary nozzle, which restricted secondary flow and increased momentum losses. A primary nozzle that expands close to the design evaporator saturation conditions should be used to maximise entrainment ratio. The COP of a jet-pump TIS is low, but a system designed to operate at off-peak periods could increase the COP to about 0.8 by taking advantage of the lower ambient conditions. The measurement of entrainment ratio was used successfully to determine ice storage rate and COP. This was valid because of the assumption that the saturation conditions in the evaporator/ice store approached steady-state. However, over longer periods that would be found in large-scale systems, the ice storage rate and entrainment ratio may fall substantially. The steady-state assumption could still be used to observe the change in evaporator conditions by sampling over short time intervals (30 minutes). At part-load, increases in evaporator saturation temperature could increase entrainment ratio substantially (50 % increase) for only a small reduction in critical pressure lift ratio Ns *(15 % reduction). A variation in chilled water temperature could be used to boost entrainment ratio at the peak demand. The variation in Ns* is too small to use this strategy to control the jet-pump with respect to condenser operating conditions. The entrainment ratio is approximately proportional to the diff-user to primary nozzle area ratio. A doubling of entrainment ratio was attained for only a 15% reduction in Ns*. The change in geometry from a constant area throat to a convergent-divergent design caused the flow through the jet-pump to vary with outlet conditions indicating that secondary flow was not choked. Higher entrainment ratios and pressure lift ratios were observed, but the entrainment ratio varied with outlet conditions in the form of peaks and troughs, making its operation unpredictable. This was thought to be caused by the restriction in secondary flow area due to the interaction of the primary jet and the curved wall. The convergent-divergent design manufactured from a thermoset plastic was successfully tested, showing that a plastic material can be used as a material of construction. In principle, a large number of jet-pump units could be manufactured from a single mould, reducing the first cost. The investigation proved the concept of jet-pump TIS. Waste-heat could be utilised over 24 hours and year round, increasing the efficiency of the process. The use of a convergent-divergent throat design, multiple geometry jet-pumps and operation at off-peak periods can maximise the performance over a cooling season, and be competitive with other TIS and chiller systems. The mass production of jet-pumps using injection moulding techniques could reduce substantially the capital cost of a system. All of these factors should encourage the development of such systems, so that the harmful emissions caused by the use of air conditioning systems can be minimised.
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Jenicek, David P. (David Pierre). "Design of low-power permanent-magnet synchronous motor for use in high-density heat pump". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/66427.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 63).
An analytical model for the functionality of a permanent-magnet synchronous motor is developed. Taking as input a specific geometry, it predicts steady-state losses of a design at an average rate of 0.85 seconds per analysis, orders of magnitude faster than existing finite-element methods. A wide design space is analyzed and, based on the necessary motor profile and manufacturing limits, an optimal design is selected. Subsequently, this motor was fabricated and integrated with a prototype design of a high-density heat pump. This application requires an unusually low motor profile - with the motor width being much (~ 10 x ) larger than its thickness - which has not been explored by other researchers. Furthermore, the design metrics specify a tight upper bound of 33.3 W on available power. Electrical characteristics are modeled and tested to determine optimal phase-excitation waveforms. Finally, power electronics with a sensorless control scheme are designed and incorporated using a custom-designed printed circuit board at an all-inclusive cost of under $50, which is well below the price of typical development control boards used to test prototype motors. Speeds of up to 7000 RPM were observed. At the design point of 5000 RPM, the motor delivered 35 mN-m of torque and drew 23.8 W of power, significantly below the available power budget.
by David P. Jenicek.
M.Eng.
Książki na temat "Low head pumps"
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Toal, Bernard Robert Hugh. The application of heat pumps to low temperature drying. [S.l: The Author], 1985.
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Matthias, Gottmann, i United States. National Aeronautics and Space Administration., red. Thermal control systems for low-temperature heat rejection on a lunar base: Semiannual status report for grant NAG5-1572. Tucson, AZ: Dept. of Aerospace and Mechanical Engineering, University of Arizona, 1992.
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Matthias, Gottmann, Nanjundan Ashok i Goddard Space Flight Center, red. Thermal control systems for low-temperature heat rejection on a lunar base: Annual progress report for grant NAG5-1572 (MOD). [Tucson, Ariz.?]: Aerospace and Mechanical Engineering, University of Arizona, 1993.
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Matthias, Gottmann, Nanjundan Ashok i Goddard Space Flight Center, red. Thermal control systems for low-temperature heat rejection on a lunar base: Annual progress report for grant NAG5-1572 (MOD). [Tucson, Ariz.?]: Aerospace and Mechanical Engineering, University of Arizona, 1993.
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United Nations Environment Programme. Refrigeration, Air Conditioning, and Heat Pumps Technical Options Committee. 2006 report of the Refrigeration, Air Conditioning, and Heat Pumps Technical Options Committee: 2006 assessment. [Nairobi, Kenya: United Nations Environment Programme, Ozone Secretariat, 2003.
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United Nations Environment Programme. Refrigeration, Air Conditioning, and Heat Pumps Technical Options Committee. 2002 report of the Refrigeration, Air Conditioning, and Heat Pumps Technical Options Committee: 2002 assessment. [Nairobi, Kenya: United Nations Environment Programme, Ozone Secretariat, 2003.
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Sherwood, Dennis, i Paul Dalby. Clausius, Kelvin, Planck, Carathéodory and Carnot. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198782957.003.0010.
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A chapter that draws together, and compares and contrasts, the principal alternative formulations of the Second Law – The Clausius statement, the Kelvin-Planck statement, the Carathéodory statement, and the Carnot cycle. This includes a discussion of heat engines and heat pumps, and of the efficiency of devices that transform heat into work.
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Hyysalo, Sampsa, i Jouni K. Juntunen. User Innovation and Peer Assistance in Small-Scale Renewable Energy Technologies. Redaktorzy Debra J. Davidson i Matthias Gross. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780190633851.013.22.
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There have been many attempts to include citizens as more active players in the proliferation of renewable energy technologies. However, the roles that citizen users play in renewables proliferation are not limited to adoption, but include technological domestication, innovation, and market creation. This chapter first reviews innovation by citizen users in the early phases of small-scale renewable energy technologies (S-RET) technology development in wind turbines, solar collectors, and low-energy housing. It then examines user innovation and peer assistance in the later phases of diffusion in air-source and ground-source heat pumps, pellet-burning systems, and solar collectors. It reviews research user motivations, diffusion pathways, and peer intermediation, and pays particular attention to how the forms of innovative citizen energy communities are changing from locality-based community energy initiatives to distributed and Internet-mediated energy communities. The chapter concludes by drawing policy implications regarding user innovation and peer assistance in the transformation of energy systems.
Części książek na temat "Low head pumps"
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Aprianti, Tine, Kandadai Srinivasan i Hui Tong Chua. "Low-Enthalpy Geothermal Applications". W Geothermal Heat Pump Systems, 19–65. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-24524-4_2.
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Wu, Wei, Xianting Li i Tian You. "Low Evaporation Temperature Absorption Heat Pump". W Absorption Heating Technologies, 75–108. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-15-0470-9_3.
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Vasiliev, L. L., D. A. Mishkinis, A. A. Antukh, A. G. Kulakov i L. L. Vasiliev. "Multisalt-Carbon Portable Resorption Heat Pump". W Low Temperature and Cryogenic Refrigeration, 387–400. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0099-4_22.
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Mota-Babiloni, Adrián, Carlos Mateu-Royo i Joaquín Navarro-Esbrí. "High-Temperature Heat Pumps for Sustainable Industry". W Emerging Research in Sustainable Energy and Buildings for a Low-Carbon Future, 287–97. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-8775-7_17.
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Minea, Vasile. "Ground-Source Heat Pump Systems for Low-Energy Buildings". W Heating and Cooling with Ground-Source Heat Pumps in Cold and Moderate Climates, 331–64. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9780367466589-14.
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Liu, Changliang, Sheng Meiling, Jingmeng Qiu i Wenhong He. "Calculation and Analysis of Cavitation for Low-Head Safety Injection Pump". W Proceedings of The 20th Pacific Basin Nuclear Conference, 85–92. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-2314-9_7.
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Leontiev, A. I., i I. V. Derevich. "Numerical Simulation of Heat and Mass Transfer in Heat Pump Working on Supercritical R-744". W Low Temperature and Cryogenic Refrigeration, 165–80. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0099-4_10.
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Kharchenko, V. V., A. O. Sychov i G. N. Uzakov. "Innovative Instruments for Extraction of Low-Grade Heat from Surface Watercourses for Heating Systems with Heat Pump". W Innovative Computing Trends and Applications, 59–68. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-03898-4_7.
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Kim, Young-Sang, i Ba Huu Dinh. "Development and Characterization of Controlled Low-strength Materials as a Heat Transfer Medium for Horizontal Ground-Source Heat Pump System". W Proceedings of the 4th International Conference on Sustainability in Civil Engineering, 23–34. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2345-8_2.
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Sychov, A., V. Kharchenko, P. Vasant i G. Uzakov. "Application of Various Computer Tools for the Optimization of the Heat Pump Heating Systems with Extraction of Low-Grade Heat from Surface Watercourses". W Intelligent Computing & Optimization, 310–19. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-00979-3_32.
Pełny tekst źródłaStreszczenia konferencji na temat "Low head pumps"
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Yuan, Jianping, Hongqin He, Zhixia He i Shouqi Yuan. "Numerical Analysis of Unsteady Flow in Centrifugal Pumps With Impellers Based on Different Hydraulic Design Principles". W ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30441.
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The centrifugal pump is one of the most widely used pumps. Lower efficiency, worse cavitation performance and stronger unsteady flow are three main problems for the low-specific-speed centrifugal pumps. Due to unsteady flow within pumps, pressure is fluctuant, which further induces vibration and noise. For a centrifugal pump with different impellers, its characteristics of unsteady flow are also different. In this paper, five different impellers were designed adopting low-specific-speed design method, splitter-blades design method and velocity-coefficient method with a set of performance parameters (Q = 25m3/h, H = 10m, n = 1450r/min). 3D unsteady turbulent flow field within the centrifugal pump was simulated. The periodic fluctuation phenomenon and the unsteady flow characteristics were investigated. The static pressure fluctuation in the volute and at the volute outlet and the instantaneous head changes were showed for the pumps with five different impellers operated at design and off-design conditions. The pressure fluctuation is the strongest near the tongue and is slighter at the volute outlet section. The transient head fluctuation increases with the flow rate. The transient head fluctuation of the pump with the low-specific-speed designed impeller is the biggest, while that of the pump with the normal-designed impeller is the smallest. Among the three splitter-blade impellers, the transient head fluctuation of the impeller with splitter blades leaned to the corresponding suction side of the long blades is the smallest. Eventually, the different design schemes were evaluated using the unsteady flow analysis. These conclusions from this paper can supply some references for the design of low-specific-speed centrifugal pumps considering its pressure fluctuation and flow-induced vibration and noise.
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Makarachi, Peymaan, i Mohammad Pourgol-Mohammad. "Optimization of Failure Rate of Centrifugal Pumps Using Genetic Algorithm". W ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87633.
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Centrifugal pumps are the most common type of kinetic pumps, and are used most often in applications with moderate to high flow and low head. In order to increase the reliability of the pumps, researches have been conducted on pump design and maintenance approaches in recent years in order to reduce their failure rates. In this article, Genetic Algorithm (GA) is used to find the optimum value for the total failure rate of a centrifugal pump. The total failure rate of the pump is modeled here as a combination of the failure rates of its individual components such as pump seals, shaft, bearings, casing and fluid driver ( by a weakest link model). Considering that all failure modes are statistically independent and any component failure breaks down the pump, the pump total failure rate is the sum of the components’ failure rates. The failure rate function of seals, shaft, bearings, casing, and fluid driver components which are given in [1], are used as objective functions in the optimization problem. Finally, the optimized parameters and failure rate value of the pump’s specific components are obtained.
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Jin, Yan, Chao Liu, Fangping Tang, Jiren Zhou i Li Cheng. "Analysis of the Influence of Passage Components on the Efficiency of Bulb Tubular Pumps". W ASME 2008 Fluids Engineering Division Summer Meeting collocated with the Heat Transfer, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/fedsm2008-55234.
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For large discharge and low lift head, it is especially suitable to use tubular pumps for their economic characteristics. Tubular pumps have high efficiency, small hydraulic loss, compact unit structure, simple construction arrangement and low cost both for construction and running. Recently, in the east route of South to North Water Diversion Project in China, there are many low head and large discharge pump stations using tubular pumps. It is important to analyze the flow characteristics and performance of tubular pump. In this paper CFD method is used to simulate the whole flow passage in a bulb tubular pump which includes inlet passage, outlet passage, guide vane, bulb unit and supportings. Based on the RNG k–ε turbulent model with Wall-Function Law, the SIMPLE algorithm is applied for the solution of the discrete governing equations. The results of the calculation indicate that all of the flow passage components influence the efficiency of the tubular pump, especially the parts of guide vane unit and bulb section. The shape of the bulb and relative position of guide vanes and bulb supportings have important effects on total hydraulic losses of the pump. Reasonable supportings not only improve the turbulent flow, but also reduce circumference velocity. The efficiency of the pump after improving can be increased about 6%.
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Wong, C. Channy, Jeb H. Flemming, Douglas R. Adkins i Michael A. Plowman. "Evaluation of Mini/Micro-Pumps for Micro-Chem-Lab™". W ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33674.
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The performance of a selective group of mini and micro-pumps has been evaluated for use in gas phase detection for the Micro-Chem-Lab™. Our major assessment criteria are: flow rate, pressure drop across the pump, and electrical current drawn by the pump. Two pumping configurations have been investigated: (1) upstream pumping to build up pressure head and (2) downstream pumping to draw vacuum. Four mini-pumps (T-Square, SP 250 EC, SP 135 FZ-4, and KNF Neuberger) have been studied. Each of these pumps has been tested to determine whether they meet our requirements of high head pressure, high flow rate, and low power consumption. We have also assessed different mechanisms for pumping gas in micro-domains — specifically, a valveless diffuser/nozzle micro-pump, a LIGA diaphragm micro-pump and a micro drag pump. However our preliminary findings reveal that these micro-pumps do not meet our minimal requirements for use in the μChemLab™.
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Leishear, Robert A., William M. Bennett i Jackie Cooper. "Design and Application of Low Flow Steam Siphon Jet Pumps". W ASME 2016 Power Conference collocated with the ASME 2016 10th International Conference on Energy Sustainability and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/power2016-59748.
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Low flow steam siphon jet pumps are referred to as rate jets, since these pumps have the ability to control flow rates by varying the steam pressure applied to the jet. The jet pump design consists of several components. Steam inlet piping is connected to a steam nozzle that directs steam into the jet body to provide energy to lift a liquid, or feed. Feed is lifted up through the suction lift piping, where the condensing steam forces the liquid into a diffuser and out of the jet discharge piping. Closed form equations cannot model these jets, and commercial computer models to describe jet performance are still in a state of development. In general, experimental data is required to determine the performance characteristics of this type of jet design. Numerous tests were performed on different jet designs to evaluate the effects of motive steam pressures, suction lift, discharge head, jet dimensions, and the specific gravity of the fluid that is lifted and pumped by the jet. Additionally, the system installation significantly affects the performance of siphon jets, and one such installation was studied.
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Chattha, Javed A., i Mohammad S. Khan. "Experimental Study to Test an Axial Flow Pump as a Turbine and Development of Performance Characteristics for Micro-Hydro Power Plant". W ASME 2007 Power Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/power2007-22142.
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Standard centrifugal pumps are manufactured in a large number of sizes in order to cover a wide range of heads and flow rates. Conventional turbines, however, are not mass produced since they are custom designed and manufactured. Therefore, pumps are available in the market at comparatively lower cost and shorter delivery periods. In this paper an experimental study is presented in which the use of pumps as turbine (PAT) is explored for micro-hydro power generation. The objective of the study is to explore cheap alternate sources of energy production in remote locations of Pakistan. Extensive research has been carried out by Williams [1] in the field of using pumps as turbines. Only centrifugal pumps were studied to explore their use as turbines in that work. Since then quite a bit of advancement in this sector of technology has taken place. However, to the best of our knowledge, axial flow pumps have never been tested as turbines. The site conditions for micro-hydro power station usually find axial flow pumps to be more appropriate compared cross flow and pelton turbines. A commercially available axial flow pump was selected and test rig was designed and constructed in order to determine the performance characteristics of using the pump as a turbine. The test bed has a provision of simulating various head and flow rate conditions and dynamometer to measure the power output in order to determine the performance of the turbine. The simulated head and flow rates were varied for various typical conditions. Some minor modifications in the basic pump unit were made to accomplish these tests. The experimental study resulted in generating data for which head was varied from 4 to 12 m and flow rate from 700 to 900 m3/hr. For these conditions power developed ranged from 5–20 kW with a maximum efficiency of 70% corresponding to a head of 6.8 m and a flow rate of 800 m3/hr. Pump affinity laws and the data collected in this experimental study were then used to select a Kaplan turbine. This information was then used to choose a commercially available pump for typical low head and high flow rate conditions in Pakistan to generate about 100 kW of electric power, when running in turbine mode. This paper discusses the design and construction of the test rig to carry out experiments for testing pumps as turbines. Details of experimental procedure and results to determine performance characteristics are also presented. Finally selection procedure of a pump for a specific head and flow condition are also discussed in this paper.
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Al-badawi, Muhamed, I. G. Adam, Sherif Haddara i Ahmed H. M. El Sherif. "Influence of Blade Shape Geometry on Very Low Specific Speed Centrifugal Pump Performance". W ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87119.
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Direct or inverse design methods for centrifugal pumps play an important role in investigating their performance. In this paper, a very low specific speed centrifugal pump impeller of ns = 9.5 (metric), three blades and 222° wrap angle. This pump was investigated using the direct design method to achieve the blade shape geometry and examine the blade angle distribution. As the blade angle progression affects the pump performance, four models with different blade angle distribution were used to perform the hydrodynamic and suction performance of the pump. The linear and non-linear derived correlation models were designed firstly using ANSYS-BladeGen module then studied numerically using ANSYS-CFX module to solve the three-dimensional Navier-Stokes equations. Validation of the numerical simulation of the investigated centrifugal pump was done using experimental data. Numerical results show that the change in the blade angle distribution has an influence on the blade wrap angle. Consequently, the variation in the blade wrap angle affects the pump head and the relative velocity distribution. The pressure gradient varies in the pump with changing the blade length. Using the velocity streamline and the velocity vector, the eddies existence and distribution in the blade suction side affect the relative velocity distribution and the pump performance. It was found that the blade with the smallest length decreases the pump head and have best velocity distribution.
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Goodwin, Gabriel B., Jesse R. Maxwell i Triem T. Hoang. "Computational Model Development and Failure Mode Investigation for a Magnetically-Driven Bearingless Micro-Pump". W ASME 2017 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fedsm2017-69065.
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As the electronics systems aboard air and spacecraft grow in scale and complexity, so too does the heat generated by those systems. A high-heat flux, compact, maintenance-free cooling system is required to meet the increased demand for heat removal. Loop heat pipes are robust and effective thermal management systems that are long-life and maintenance-free, making them ideal for use in unmanned spacecraft. Integrating a mechanical pump into a loop heat pipe system can drastically improve the system’s heat removal capacity through increased mass flowrate. Like loop heat pipes, magnetically-driven bearingless pumps are also maintenance-free, which is a necessity in the space environment. This work details the modeling of a low-flowrate, magnetically-driven bearingless centrifugal pump and a computational fluid dynamics study of the pump’s operation and performance under a range of conditions that are typical to the demands of a satellite thermal management system. The purpose of this computational study is to investigate the failure mechanism of a bench-test unit that was unable to generate a pressure head with its intended working fluid of ammonia. Model development, validation, and pump performance with multiple working fluids are discussed. The cause of the pump’s failure is investigated.
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Occari, Matteo, Enrico Munari, Valentina Mazzanti, Michele Pinelli, Francesco Mollica i Alessio Suman. "Experimental Tests With Centrifugal Pumps: Degradation of Performance, Instability and Dynamic Phenomena With Non-Newtonian Suspensions of Kaolin in Water". W ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-4939.
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Abstract The performance of pumps when working with non-Newtonian fluids significantly change with respect to water. In several experimental tests with non-Newtonian fluids, significant deration of head and the presence of head instability were observed. The present work aims to better understand this phenomenon since the reasons that originate it are not clear. Two small size centrifugal pumps were experimentally tested with different mixtures of kaolin-in-water, which showed a verified non-Newtonian behavior. The rheology of the mixtures and the particle size distribution of kaolin powder were measured to characterize the fluids. Similar to previous tests, a strong reduction of head and the appearance of instability were observed at low flow rates and, in some cases, also at higher flow rates. This behavior was related to the presence of air trapped into the fluid that, within the pump, generated a phenomenon known as gas-locking, which in literature it has been studied in detail with water but not with non-Newtonian fluids. Moreover, in some working conditions, non-stable time-varying phenomena are observed and their consequence on performance commented. Comparing the two pumps, characterized by a similar specific speed but by a different geometry, the head drop manifested itself with different intensity.
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Fleder, Sebastian, Frank Hassert, Martin Böhle i Beate Zientek-Strietz. "Influence of Gas-Liquid Multiphase-Flow on Acoustic Behavior and Performance of Side Channel Pumps". W ASME 2017 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fedsm2017-69094.
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Side-channel pumps (SCP) are a niche product, able to deliver relatively high heads at low flow rates, which corresponds in a low specific speed. They are closing the gap between classical radial centrifugal pumps and positive displacement pumps, combining the advantages of both without having all the negative effects. The hydraulic efficiency of SCP seems low at first sight. But classical centrifugal pumps are often working under part load conditions, when working at this volume flow and specific speed range, which means they are not able to perform at their BEP. This reduces the efficiency of centrifugal pumps and creates a major benefit of SCP, which are able to work in their BEP. The acoustic behavior and the characteristic pulsations and vibrations of a side channel pump are measured with various measurement methods, such as vibrometry, sound level measurement and sound cartography using an acoustic camera. The characteristic vibrations are shown and compared to the characteristic pressure-pulsations of the working fluid. The two-phase liquid-gas flow has, beside the effects on the characteristic curves such as head drop and efficiency reduction, many side effects on the behavior of the pump. This could be acoustical and vibrational effects. When gas is present in the working fluid, the emitted noise from the pump reduces significantly. This effect is shown by sound intensity measurements as well as measurements with an acoustic camera and laser vibrometry and compared to the results for single-phase flow. The maximum amount of gas for the test pump is measured at different rotational speeds. Some theories to improve the maximum amount of gas in the working fluid are presented and the modifications are tested on a test rig. These modifications consist of the idea that a pump without NPSH-impeller could process higher amounts of gas in multiphase-flow conditions. An additional gas outlet hole is added to the pump to allow a phase separation and therefore a better two-phase flow handling of the pump. The effect of these changes on the maximum amount of gas are presented and evaluated.
Raporty organizacyjne na temat "Low head pumps"
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Johra, Hicham. Performance overview of caloric heat pumps: magnetocaloric, elastocaloric, electrocaloric and barocaloric systems. Department of the Built Environment, Aalborg University, styczeń 2022. http://dx.doi.org/10.54337/aau467469997.
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Heat pumps are an excellent solution to supply heating and cooling for indoor space conditioning and domestic hot water production. Conventional heat pumps are typically electrically driven and operate with a vapour-compression thermodynamic cycle of refrigerant fluid to transfer heat from a cold source to a warmer sink. This mature technology is cost-effective and achieves appreciable coefficients of performance (COP). The heat pump market demand is driven up by the urge to improve the energy efficiency of building heating systems coupled with the increase of global cooling needs for air-conditioning. Unfortunately, the refrigerants used in current conventional heat pumps can have a large greenhouse or ozone-depletion effect. Alternative gaseous refrigerants have been identified but they present some issues regarding toxicity, flammability, explosivity, low energy efficiency or high cost. However, several non-vapour-compression heat pump technologies have been invented and could be promising alternatives to conventional systems, with potential for higher COP and without the aforementioned refrigerant drawbacks. Among those, the systems based on the so-called “caloric effects” of solid-state refrigerants are gaining large attention. These caloric effects are characterized by a phase transition varying entropy in the material, resulting in a large adiabatic temperature change. This phase transition is induced by a variation of a specific external field applied to the solid refrigerant. Therefore, the magnetocaloric, elastocaloric, electrocaloric and barocaloric effects are adiabatic temperature changes in specific materials when varying the magnetic field, uniaxial mechanical stress, electrical field or hydrostatic pressure, respectively. Heat pump cycle can be built from these caloric effects and several heating/cooling prototypes were developed and tested over the last few decades. Although not a mature technology yet, some of these caloric systems are well suited to become new efficient and sustainable solutions for indoor space conditioning and domestic hot water production. This technical report (and the paper to which this report is supplementary materials) aims to raise awareness in the building community about these innovative caloric systems. It sheds some light on the recent progress in that field and compares the performance of caloric systems with that of conventional vapour-compression heat pumps for building applications.
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Fyfe, Caroline, Arthur Grimes, Shannon Minehan i Phoebe Taptiklis. Evaluation of the Warmer Kiwis Homes Programme: Full Report including Cost Benefit Analysis. Motu Economic and Public Policy Research, grudzień 2022. http://dx.doi.org/10.29310/wp.2022.14.
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We evaluate the heat pump component of New Zealand’s Warmer Kiwi Homes (WKH) programme. The programme includes provision of heat pumps in living areas for eligible households (based on neighbourhood or income) that do not have suitable heating. It also includes installation of retrofitted insulation for houses with insufficient insulation. Staggered installation enables difference-in-difference estimates of impacts. Heat pump outcomes on which we focus include warmth and dryness of the living area, personal comfort and wellbeing, and electricity consumption. We combine the heat pump findings with prior findings related to insulation and heating to provide a set of cost benefit analyses of WKH. We find that household members overwhelmingly report increases in warmth, comfort and satisfaction with their home, and report decreases in condensation, damp and having to restrict heating due to cost. Some increase in life satisfaction is reported. Living areas of treated houses experience increases in temperature which are most pronounced around breakfast and evening times, and when outdoor temperatures are low. Houses also experience reduced humidity. Households that use the heat pump as an air conditioner experience reduced summer temperatures when outdoor temperatures are high. Winter electricity use falls in a house fitted with a heat pump relative to houses without a heat pump; savings are negligible at night and increase through the day, peaking at 5-9pm. No increase in electricity consumption is detected in summer. Benefit cost ratios (BCRs) are calculated using both wellbeing metrics and conventional health and energy components. The wellbeing-based BCR for the heat pump component (which places a high value on living in a warm home) is estimated at 7.49 while the more conventionally calculated (but overly conservative) BCR is 2.15. For the full WKH programme, the corresponding BCRs are calculated as 4.36 and 1.89.
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Fyfe, Caroline, Arthur Grimes, Shannon Minehan i Phoebe Taptiklis. Evaluation of the Warmer Kiwis Homes Programme: Summary Report including Cost Benefit Analysis. Motu Economic and Public Policy Research, grudzień 2022. http://dx.doi.org/10.29310/wp.2022.13.
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We evaluate the heat pump component of New Zealand’s Warmer Kiwi Homes (WKH) programme. The programme includes provision of heat pumps in living areas for eligible households (based on neighbourhood or income) that do not have such heating. It also includes installation of retrofitted insulation for houses with insufficient insulation. Staggered installation enables difference-in-difference estimates of impacts. Heat pump outcomes on which we focus include warmth and dryness of the living area, personal comfort and wellbeing, and electricity consumption. We combine the heat pump findings with prior findings related to insulation and heating to provide a set of cost benefit analyses of WKH. We find that household members overwhelmingly report increases in warmth, comfort and satisfaction with their home, and report decreases in condensation, damp and having to restrict heating due to cost. Some increase in life satisfaction is reported. Living areas of treated houses experience increases in temperature which are most pronounced around breakfast and evening times, and when outdoor temperatures are low. Houses also experience reduced humidity. Households that use the heat pump as an air conditioner experience reduced summer temperatures when outdoor temperatures are high. Winter electricity use falls in a house fitted with a heat pump relative to houses without a heat pump; savings are negligible at night and increase through the day, peaking at 5-9pm. No increase in electricity consumption is detected in summer. Benefit cost ratios (BCRs) are calculated using both wellbeing metrics and conventional health and energy components. The wellbeing-based BCR for the heat pump component (which places a high value on living in a warm home) is estimated at 7.49 while the more conventionally calculated (but overly conservative) BCR is 2.15. For the full WKH programme, the corresponding BCRs are calculated as 4.36 and 1.89. Complete details of each element of the evaluation are presented in the Full Report available as Motu Working Paper WP 22-14.
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Backman, C., A. German, B. Dakin i D. Springer. Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes. Office of Scientific and Technical Information (OSTI), grudzień 2013. http://dx.doi.org/10.2172/1115792.
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Backman, C., A. German, B. Dakin i D. Springer. Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes. Office of Scientific and Technical Information (OSTI), grudzień 2013. http://dx.doi.org/10.2172/1220914.
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Garrabrant, Michael, i Christopher Keinath. Low-Cost Gas Heat Pump for Building Space Heating. Office of Scientific and Technical Information (OSTI), październik 2016. http://dx.doi.org/10.2172/1328433.
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Booten, Charles, Jonathan Winkler i Ramin Faramarzi. Assessment of Low-Cost Minisplit Heat Pump Connection System. Office of Scientific and Technical Information (OSTI), sierpień 2022. http://dx.doi.org/10.2172/1922100.
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Johnson, R. K. Measured Performance of a Low Temperature Air Source Heat Pump. Office of Scientific and Technical Information (OSTI), wrzesień 2013. http://dx.doi.org/10.2172/1260317.
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Mei, V. C., i J. J. Tomlinson. Development of a Low Cost Heat Pump Water Heater - First Prototype. Office of Scientific and Technical Information (OSTI), wrzesień 2007. http://dx.doi.org/10.2172/984745.
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Mei, V. C., i William G. Craddick. Development of a Low Cost Heat Pump Water Heater - Second Prototype. Office of Scientific and Technical Information (OSTI), wrzesień 2007. http://dx.doi.org/10.2172/984746.
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