Articles de revues : « REFRIGERANT COUPLE »

1

Xu, Lei, Yan Long Jiang, Nian Yong Zhou et Jun Li. « Study on the Performance of an Open Loop Cycle CO₂ Refrigeration System in the Extreme Limit Condition ». Advanced Materials Research 1025-1026 (septembre 2014) : 178–82. http://dx.doi.org/10.4028/www.scientific.net/amr.1025-1026.178.

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As a result of the strict restrictions on the use of power supply under the mine disaster, the Open loop cycle CO2 refrigeration system is used in the Mine Rescue Cabin. Traditional system have got a couple of equipment malfunctions frequently, such as the Ice-block in Cold-start, Cold-frost and Overheating. In this paper, a new type of refrigeration system is designed after the Thermodynamic analysis of extreme limit condition. The new system avoids the Ice-block and the cold-frost by limit the refrigerant flow, it also can improve the capability of the evaporator. It has a important reference value to the research and application of the open loop cycle CO2 refrigeration system in the extreme condition.

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Martinazzoli, Gianni, Daniele Pasinelli, Adriano Maria Lezzi et Mariagrazia Pilotelli. « Design of a 5th Generation District Heating Substation Prototype for a Real Case Study ». Sustainability 15, n^o 4 (7 février 2023) : 2972. http://dx.doi.org/10.3390/su15042972.

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The evolution of district heating networks is moving toward low temperatures in heat distribution with so called 4th generation networks. However, the lowest heat transfer fluid temperatures in district heating are achieved through ultra-low temperature networks, referred to as 5th generation district heating networks (5GDHNs). Low temperatures in heat distribution results in an extremely different configuration of 5GDHN compared to traditional district heating network, especially in the grid substation due to the inability to directly couple the grid with the buildings. This paper presents a detailed design of a 5th generation substation prototype, which is carried out to verify the proper operation and monitor the performance of this type of substation in a real case study. The prototype is fed by low-temperature waste heat, currently dissipated through evaporative towers, and will be built in the city of Brescia, Italy. The layout of the substation prototype, consisting of a bidirectional pumping system, a reversible water-to-water heat pump, an inertial thermal energy storage and a heat exchanger, is presented. An analysis is performed to figure out which refrigerant offers the best performance of the heat pump. In addition, fixed the refrigerant, the performance of the grid connected heat pump is found to be increased from 29.5% to 55.5% for both heating and cooling compared with a stand-alone air-to-water heat pump solution. Finally, the process flow diagram and the piping and instrumentation diagram of the substation are presented and commented.

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Aprea, Ciro, Adriana Greco, Angelo Maiorino et Claudia Masselli. « Enhancing the Heat Transfer in an Active Barocaloric Cooling System Using Ethylene-Glycol Based Nanofluids as Secondary Medium ». Energies 12, n^o 15 (28 juillet 2019) : 2902. http://dx.doi.org/10.3390/en12152902.

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Barocaloric cooling is classified as environmentally friendly because of the employment of solid-state materials as refrigerants. The reference and well-established processes are based on the active barocaloric regenerative refrigeration cycle, where the solid-state material acts both as refrigerant and regenerator; an auxiliary fluid (generally water of water/glycol mixtures) is used to transfer the heat fluxes with the final purpose of subtracting heat from the cold heat exchanger coupled with the cold cell. In this paper, we numerically investigate the effect on heat transfer of working with nanofluids as auxiliary fluids in an active barocaloric refrigerator operating with a vulcanizing rubber. The results reveal that, as a general trend, adding 10% of copper nanoparticles in the water/ethylene-glycol mixture carries to +30% as medium heat transfer enhancement.

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Kunert, Anna T., Mark Lamneck, Frank Helleis, Ulrich Pöschl, Mira L. Pöhlker et Janine Fröhlich-Nowoisky. « Twin-plate Ice Nucleation Assay (TINA) with infrared detection for high-throughput droplet freezing experiments with biological ice nuclei in laboratory and field samples ». Atmospheric Measurement Techniques 11, n^o 11 (23 novembre 2018) : 6327–37. http://dx.doi.org/10.5194/amt-11-6327-2018.

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Abstract. For efficient analysis and characterization of biological ice nuclei under immersion freezing conditions, we developed the Twin-plate Ice Nucleation Assay (TINA) for high-throughput droplet freezing experiments, in which the temperature profile and freezing of each droplet is tracked by an infrared detector. In the fully automated setup, a couple of independently cooled aluminum blocks carrying two 96-well plates and two 384-well plates, respectively, are available to study ice nucleation and freezing events simultaneously in hundreds of microliter-range droplets (0.1–40 µL). A cooling system with two refrigerant circulation loops is used for high-precision temperature control (uncertainty <0.2 K), enabling measurements over a wide range of temperatures (∼ 272–233 K) at variable cooling rates (up to 10 K min−1). The TINA instrument was tested and characterized in experiments with bacterial and fungal ice nuclei (IN) from Pseudomonas syringae (Snomax®) and Mortierella alpina, exhibiting freezing curves in good agreement with literature data. Moreover, TINA was applied to investigate the influence of chemical processing on the activity of biological IN, in particular the effects of oxidation and nitration reactions. Upon exposure of Snomax® to O3 and NO2, the cumulative number of IN active at 270–266 K decreased by more than 1 order of magnitude. Furthermore, TINA was used to study aqueous extracts of atmospheric aerosols, simultaneously investigating a multitude of samples that were pre-treated in different ways to distinguish different kinds of IN. For example, heat treatment and filtration indicated that most biological IN were larger than 5 µm. The results confirm that TINA is suitable for high-throughput experiments and efficient analysis of biological IN in laboratory and field samples.

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Rony, Rajib, Huojun Yang, Sumathy Krishnan et Jongchul Song. « Recent Advances in Transcritical CO2 (R744) Heat Pump System : A Review ». Energies 12, n^o 3 (31 janvier 2019) : 457. http://dx.doi.org/10.3390/en12030457.

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Heat pump (HP) is one of the most energy efficient tools for address heating and possibly cooling needs in buildings. Growing environmental concerns over conventional HP refrigerants, chlorofluorocarbons (CFCs), and hydrofluorocarbons (HFCs) have forced legislators and researchers to look for alternatives. As such, carbon dioxide (R744/CO2) has come to light due to its low global warming potential (GWP) and zero ozone depleting characteristics. Even though CO2 is environmentally benign, the performance of CO2 HP has been of concern since its inception. To improve the performance of CO2 HP, research has been playing a pivotal role in developing functional designs of heat exchangers, expansion devices, and compressors to suit the CO2 transcritical cycle. Different CO2 HP cycles coupled with auxiliary components, hybrid systems, and refrigerant mixtures along with advanced control strategies have been applied and tested. This paper presents a complete overview of the most recent developments of transcritical CO2 HPs, their components, and applications.

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Fouad, Wael A., et Lourdes F. Vega. « The phase and interfacial properties of azeotropic refrigerants : the prediction of aneotropes from molecular theory ». Physical Chemistry Chemical Physics 19, n^o 13 (2017) : 8977–88. http://dx.doi.org/10.1039/c6cp08031f.

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He, Dazhuang, Yangfan Liu et Davide Ziviani. « Numerical modeling of noise and vibration due to discharge in hermetic compressors ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 264, n^o 1 (24 juin 2022) : 362–77. http://dx.doi.org/10.3397/nc-2022-741.

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The pulsive and intermittent nature of the operation of a hermetic refrigeration compressor leads to the generation of noise and vibration during the operation. Specifically, in hermetic compressors, gas pulsation induced by refrigerant discharge is a major source of NVH effects. The generation of noise and vibration due to refrigerant gas discharge is a process that involves thermo-mechanical operation within compressor cylinder, cavity acoustic resonance, valve opening/closing, hermetic shell vibration, and exterior sound radiation. In the presented study, a numerical simulation model was developed to address the multi-physical process of noise generation due to refrigerant gas discharge. The thermodynamics aspects of the compression process and the vibro-acoustics aspects are coupled together. The thermo-mechanical submodel is based on a compressor mechanistic model based on control volume analysis with lumped parameters. The vibro-acoustics submodel is based on finite element analysis, and it describes the two-way coupled interaction of compressor cavity acoustic resonances and hermetic shell vibration. Meanwhile, the acoustics response in the cavity is coupled with the thermodynamics submodel through proper modeling dynamics of discharge valves. Numerical simulations were conducted to demonstrate how simulation models work and how they can potentially help compressor manufacturers to gain a better understanding of the physical reasons behind NVH effects of compressors.

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Mohammadi, Kasra, et Kody M. Powell. « Thermoeconomic Evaluation and Optimization of Using Different Environmentally Friendly Refrigerant Pairs for a Dual-Evaporator Cascade Refrigeration System ». Processes 9, n^o 10 (19 octobre 2021) : 1855. http://dx.doi.org/10.3390/pr9101855.

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Applications of dual-evaporator refrigeration systems have recently gained much attention both in academia and industry due to their multiple benefits. In this study, a comprehensive thermodynamic and economic analysis is conducted to evaluate the potential of using several environmentally friendly refrigerant couples and identifies the most suitable one yielding the best economic results. To achieve this goal, a detailed parametric study is conducted, and an optimization process is performed using a particle swarm optimization (PSO) approach to minimize the unit production cost of cooling (UPCC) of the cascade refrigeration system. The results showed that among all selected 18 refrigerant pairs and for all ranges of examined operating parameters, the R170-R161 pair and R1150-R1234yf pair are identified as the best and worst pairs, respectively, from both thermodynamic and economic viewpoints. The results also confirm that R170-R161 pair has an improvement over R717-R744, used as a typical refrigerant pair of cascade refrigeration cycles. For a base case analysis, the COP of R170-R161 and R1150-R1234yf pairs is determined as 1.727 and 1.552, respectively, while their UPCC is found to be $0.395/ton-hr and $0.419/ton-hr, respectively, showing the influence of proper selection of refrigerant pairs on the cascade cycle’s performance. Overall, this study offers a useful thermodynamic and economic insight regarding the selection of proper refrigerant pairs for a dual-evaporator cascade vapor compression refrigeration system.

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Lee, Sangheon, Chulung Cheong et Jinhyung Park. « Development of flow-vibroacoustic coupled numerical methods for prediction of noise radiation due to flow-born vibration of compressor discharge piping system ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, n^o 1 (1 février 2023) : 6032–39. http://dx.doi.org/10.3397/in_2022_0896.

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The compressor and fan in air conditioner outdoor unit are the core component which deter-mines noise performance as well as cooling or heating performance. Among these, the com-pressor has larger contribution to the noise of outdoor units. For high efficiency air condition-er, the size and operating speed of compressor are smaller and faster. The high-speed com-pressor causes loud noise which is complaints for the customer. Traditionally, it is well-known that the vibration of compressor and connected duct is main noise source. However, as the compressor speed increases, the refrigerant flow in the compressor discharge duct also emerged as a major noise source. To reduce the compressor noise operating at high speed, it is necessary to analyze vibrational and acoustic characteristics of compressor discharge duct. This duct noise has the two-types source: structure born noise and flow induced noise. The structure born noise is generated by the duct vibration caused by compressor movement. For the flow induced noise, the static pressure field of refrigerant flow in the duct is vibrational source. In this paper, the compressor discharge duct noise considering two mechanisms was investigated. The refrigerant flow is solved using CFD and duct vibration and noise radiation are computed by FE-BE method.

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Ibarra-Bahena, Jonathan, Eduardo Venegas-Reyes, Yuridiana R. Galindo-Luna, Wilfrido Rivera, Rosenberg J. Romero, Antonio Rodríguez-Martínez et Ulises Dehesa-Carrasco. « Feasibility Analysis of a Membrane Desorber Powered by Thermal Solar Energy for Absorption Cooling Systems ». Applied Sciences 10, n^o 3 (7 février 2020) : 1110. http://dx.doi.org/10.3390/app10031110.

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In absorption cooling systems, the desorber is a component that separates the refrigerant fluid from the liquid working mixture, most commonly completed by boiling separation; however, the operation temperature of boiling desorbers is generally higher than the low-enthalpy energy, such as solar, geothermal, or waste heat. In this study, we used a hydrophobic membrane desorber to separate water vapor from an aqueous LiBr solution. Influencing factors, such as the H2O/LiBr solution and cooling water temperatures, were tested and analyzed. With the experimental data, a solar collector system was simulated on a larger scale, considering a 1 m2 membrane. The membrane desorber evaluation shows that the desorption rate of water vapor increased as the LiBr solution temperature increased and the cooling water temperature decreased. Based on the experimental data from the membrane desorber/condenser, a theoretical heat load was calculated to size a solar system. Meteorological data from Emiliano Zapata in Mexico were considered. According to the numerical result, nine solar collectors with a total area of 37.4 m2 provide a solar fraction of 0.797. The membrane desorber/condenser coupled to the solar system can provide an average of 16.8 kg/day of refrigerant fluid that can be used to produce a cooling effect in an absorption refrigerant system.

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Sami, Samuel. « Modeling and Simulation of a Novel Combined Solar Photovoltaic-Thermal Panel and Heat Pump Hybrid System ». Clean Technologies 1, n^o 1 (13 août 2018) : 89–113. http://dx.doi.org/10.3390/cleantechnol1010007.

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A numerical simulation model for a novel concept of a hybrid composed of photovoltaic-thermal solar panels and a heat pump is presented. This concept was developed to assess the performance and energy conversion efficiency of the hybrid system used to produce domestic hot water and electricity. A two-dimensional heat transfer and fluid flow dynamic model was developed to describe the behavior of the hybrid system under different solar irradiance, heat pump boundary conditions and different refrigerants. The model is based on dynamic mass and energy equations coupled with the heat transfer coefficients, and the thermodynamic properties of refrigerants as well as material properties. The model compared fairly to experimental data.

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Sözen, Adnan, Mehmet Özalp et Erol Arcaklioğlu. « Investigation of thermodynamic properties of refrigerant/absorbent couples using artificial neural networks ». Chemical Engineering and Processing : Process Intensification 43, n^o 10 (octobre 2004) : 1253–64. http://dx.doi.org/10.1016/j.cep.2003.12.008.

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DİKMEN, Erkan, et Arzu ŞENCAN ŞAHİN. « Comparative exergy analysis of the cascade cooling system for alternative refrigerant couples ». International Journal of Energy Applications and Technologies 7, n^o 4 (31 décembre 2020) : 115–19. http://dx.doi.org/10.31593/ijeat.772180.

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Şencan, Arzu. « Modeling of thermodynamic properties of refrigerant/absorbent couples using data mining process ». Energy Conversion and Management 48, n^o 2 (février 2007) : 470–80. http://dx.doi.org/10.1016/j.enconman.2006.06.018.

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Kilicarslan, A., et M. Hosoz. « Energy and irreversibility analysis of a cascade refrigeration system for various refrigerant couples ». Energy Conversion and Management 51, n^o 12 (décembre 2010) : 2947–54. http://dx.doi.org/10.1016/j.enconman.2010.06.037.

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KAUFMANN, Christof. « LOW TEMPERATURE HEAT TO POWER COUPLER ». INNOVATIONS IN THE SCIENTIFIC, TECHNICAL AND SOCIAL ECOSYSTEMS 1, n^o 6 (19 mai 2023) : 66–81. http://dx.doi.org/10.56378/asch020230516.

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The Purpose of the Study is to substantiate the possibility of a real connection of thermal energy, where heat generates energy (electricity) for low temperatures (below 120 °C). The Research Methodology: Methods of analysis, modeling, description and generalization of the data of the studied problem of low temperature heat to power coupler. The Scientific Novelty lies in the fact that for the first time, technical extensions of the well-known steam technology have been investigated, which, in combination with the newly chosen environment, make possible the innovative implementation of the technology. The Conclusion. The method is able to provide large amounts of energy, free of charge and indefinitely, because the energy reservoir “Earth” provides energy indefinitely and 24 hours a day. Of course, the application of low-temperature combined heat and power is not limited to geothermal energy. Hot industrial exhaust gases can also be considered if the volume flow is sufficiently high. The grade of efficiency of the system is infinitely large, since the effort = 0. Remaining task: finding the right turbine. At least as a first approach, the pentanes appear to solve the problem of selecting a refrigerant for energy transfer. As far as the turbine or piston machine is concerned, a solution is being sought that can reasonably drive a generator with pressures of 5−12 bar, with the power ultimately being adjusted via the volume flow.

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Xu, Yan Sheng. « Model Investigation on Coupled Throttling Flow Characteristic of Stepped Capillary Tube with R22 ». Advanced Materials Research 960-961 (juin 2014) : 648–53. http://dx.doi.org/10.4028/www.scientific.net/amr.960-961.648.

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In order to calculate the structure size of stepped capillary tube, the experiments of flow characteristic of it were performed. The experience benchmark model of flow characteristics of R22 was set up through experimental method in specific reference conditions based on the impedance calculation method. The variable working condition model suitable for a range of conditions was obtained through fixing the condition based on the reference model. The mass flow rate of refrigerant R22 in two stepped capillary tubes with different size was tested. The experimental results show that the stepped capillary tube model has a high precision and working condition of certain flexibility. The deviation of cooling and heating flow between the calculated values and measured values are less than±10%. The model can meet the need of matching for stepped capillary tube on the heat pump type air conditioner with R22.

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Sözen, Adnan, Erol Arcakliogˇlu et Mehmet Özalp. « Formulation based on artificial neural network of thermodynamic properties of ozone friendly refrigerant/absorbent couples ». Applied Thermal Engineering 25, n^o 11-12 (août 2005) : 1808–20. http://dx.doi.org/10.1016/j.applthermaleng.2004.11.003.

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Ho ejowska, Sylwia. « Determining 2D temperature field in flow boiling with the use of Trefftz functions ». EPJ Web of Conferences 213 (2019) : 02026. http://dx.doi.org/10.1051/epjconf/201921302026.

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The paper proposes the use of Trefftz method to solve the triple coupled heat conduction problem in flow boiling of refrigerant in an asymmetrically heated minichannel. A mathematical model of heat transfer in a rectangular minichannel is suggested. Two sets of Trefftz functions were used to determine 2D temperature fields at a fluid flow in the minichannel tilted at a known angle. The procedure for the calculation of the liquid temperature was coupled with the process of determining temperature fields in two adjacent elements of the experimental stand with the minichannel, i.e. in the glass pane and the heating foil. Heat transfer in the glass, foil and liquid is described using various 2D differential equations with an adequate set of boundary conditions. Solving those equations led to the solving of the triple coupled heat conduction problem made up of one direct and two subsequent inverse problems. The results are presented as: (1) 2D temperature of the glass pane, the heating foil, the flowing liquid, (2) mean square errors between temperature approximations and selected boundary conditions, (3) the heat transfer coefficient versus the distance from the minichannel inlet.

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Dongellini, Matteo, Christian Natale, Claudia Naldi, Eugenia Rossi di Schio, Paolo Valdiserri et Gian Luca Morini. « Energy and Environmental Performance Comparison of Heat Pump Systems Working with Alternative Refrigerants ». Applied Sciences 13, n^o 12 (17 juin 2023) : 7238. http://dx.doi.org/10.3390/app13127238.

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The European Parliament has imposed to reduce by 2030 whole HFC emissions by at least two-thirds with respect to 2014 levels. With the aim of contributing to determine the energy and environmental advantages of refrigerants alternative to R-410A, this paper reports the results of a numerical study focused on an HVAC system coupled to a residential building and based on a reversible electric heat pump. In particular, two heat pump typologies are considered: an air-source and a ground-source heat pump, both operating with the two refrigerants R-410A and R-454B. The environmental performance of the studied system is assessed by means of the TEWI (total equivalent warming impact) index. The adoption of R-454B involves a slight decrease (2–3%) in the overall annual energy performance of the system with respect to the use of R-410A. On the other hand, the working fluid R-454B guarantees a marked decrease in the TEWI indicator. Indeed, considering the current Italian emission factor of electricity taken from the grid, the total emissions over the entire heat pump operating life drop by about 25% and can decrease by up to 89% in perspective, following the current reduction trend of the emission factor.

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Shao, Suola, Huan Zhang, Shijun You, Wandong Zheng et Lingfei Jiang. « Thermal performance analysis of a new refrigerant-heated radiator coupled with air-source heat pump heating system ». Applied Energy 247 (août 2019) : 78–88. http://dx.doi.org/10.1016/j.apenergy.2019.04.032.

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Li, Zhengfei, Jianming Tan, Shaobin Li, Jiangyan Liu, Huanxin Chen, Jiaqin Shen, Ronggeng Huang et Jiahui Liu. « An efficient online wkNN diagnostic strategy for variable refrigerant flow system based on coupled feature selection method ». Energy and Buildings 183 (janvier 2019) : 222–37. http://dx.doi.org/10.1016/j.enbuild.2018.11.020.

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Xu, Ying, Zhiqiang Wang, Zhaoqing Ke, Bozhen Lai, Ying Zhang et Xingyuan Huang. « Experimental and Simulation Research on Heat Pipe Thermal Management System Coupled with Battery Thermo-Electric Model ». Processes 11, n^o 4 (13 avril 2023) : 1204. http://dx.doi.org/10.3390/pr11041204.

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The lithium-ion battery is widely used in the power system of pure electric vehicles and hybrid electric vehicles due to its high energy density. However, the chemical and electrochemical reactions generate a lot of heat. If the heat is not transferred through some refrigeration methods in time, it will lead to a rapid rise in the temperature of the battery. In this paper, an electric–thermal coupling model of a cylindrical Panasonic 21700 battery was proposed by using offline parameter identification method. Based on this model, a battery thermal management system using a heat pipe was established. The experimental results show that the model can simulate the actual performance of battery well. When the ambient temperature is 25 °C, the battery parameters change little and battery performance is better. The heat pipe battery thermal management system performs better than the non-heat pipe battery system in the discharge process, and can control the battery temperature well at low and high temperatures. Changing the refrigerant temperature can achieve a better thermal management effect under suitable ambient temperature conditions.

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Sun, Zhili, Youcai Liang, Shengchun Liu, Weichuan Ji, Runqing Zang, Rongzhen Liang et Zhikai Guo. « Comparative analysis of thermodynamic performance of a cascade refrigeration system for refrigerant couples R41/R404A and R23/R404A ». Applied Energy 184 (décembre 2016) : 19–25. http://dx.doi.org/10.1016/j.apenergy.2016.10.014.

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Shao, Suola, Huan Zhang, Lingfei Jiang, Shijun You et Wandong Zheng. « Numerical Investigation and Thermal Analysis of a Refrigerant-heated Radiator Heating System coupled with Air Source Heat Pump ». Energy Procedia 158 (février 2019) : 2158–63. http://dx.doi.org/10.1016/j.egypro.2019.01.614.

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Zhang, Huan, Lingfei Jiang, Wandong Zheng, Shijun You, Tingting Jiang, Suola Shao et Xingming Zhu. « Experimental study on a novel thermal storage refrigerant-heated radiator coupled with air source heat pump heating system ». Building and Environment 164 (octobre 2019) : 106341. http://dx.doi.org/10.1016/j.buildenv.2019.106341.

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Santos, Rubens Souza. « On the starting and operational transients at the core of the RMB based on 2D multigroup diffusion ». Brazilian Journal of Radiation Sciences 10, n^o 3B (Suppl.) (31 juillet 2023) : 01–27. http://dx.doi.org/10.15392/2319-0612.2022.1993.

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RMB is a multipurpose reactor to be built by CNEN. As a multipurpose facility, unlike a nuclear power plant, some operations may result in transients, whether during the movement of materials from remote irradiation, extraction of neutrons through beam holes, reactor starting up, control rod accident, etc. For that, a methodology to visualize some variables like neutron fluxes, temperatures, power, etc., was developed. In this one present some preliminary results based on multigroup diffusion theory, thermal hydraulics feedbacks, and numerical methods, systematized in the DINUCLE code. DINUCLE couples a numerical code of multigroup spatial kinetics, for calculations of the flux of neutrons in the core of reactors, with a numerical code for the analysis of thermo hydraulic transients in rods and plates, considering the refrigerant always single-phase. Use was made of a programming in VBA (Visual Basic for Applications) from Excel, for data visualization in the transient.

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Kumar, Ranganathan, Thomas A. Trabold et Charles C. Maneri. « Experiments and Modeling in Bubbly Flows at Elevated Pressures ». Journal of Fluids Engineering 125, n^o 3 (1 mai 2003) : 469–78. http://dx.doi.org/10.1115/1.1567308.

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Measurements of local void fraction, rise velocity, and bubble diameter have been obtained for cocurrent, wall-heated, upward bubbly flows in a pressurized refrigerant. The instrumentation used are the gamma densitometer and the hot-film anemometer. Departure bubble size is correlated in terms of liquid subcooling and bulk bubble size in terms of void fraction. Flow visualization techniques have also been used to understand the two-phase flow structure and the behavior of the bubbly flow for different bubble shapes and sizes, and to obtain the bubble diameter and rise velocity. The lift model is provided explicitly in terms of Eotvos number which is changed by changing the system pressure. In general, Eotvos number plays a strong role in determining both bubbly lift and drag. Such insight coupled with quantitative local and averaged data on void fraction and bubble size at different pressures has aided in developing bubbly flow models applicable to heated two-phase flows at high pressure.

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Yin, Xiang, Anci Wang, Jianmin Fang, Feng Cao et Xiaolin Wang. « Coupled effect of operation conditions and refrigerant charge on the performance of a transcritical CO2 automotive air conditioning system ». International Journal of Refrigeration 123 (mars 2021) : 72–80. http://dx.doi.org/10.1016/j.ijrefrig.2020.10.031.

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Ust, Yasin, et A. Sinan Karakurt. « Analysis of a Cascade Refrigeration System (CRS) by Using Different Refrigerant Couples Based on the Exergetic Performance Coefficient (EPC) Criterion ». Arabian Journal for Science and Engineering 39, n^o 11 (2 septembre 2014) : 8147–56. http://dx.doi.org/10.1007/s13369-014-1335-9.

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Lorenzini, Giulio, et Cesare Biserni. « A Vapotron Effect Application for Electronic Equipment Cooling ». Journal of Electronic Packaging 125, n^o 4 (1 décembre 2003) : 475–79. http://dx.doi.org/10.1115/1.1615796.

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This research is aimed at investigating by experimental means a possible use of the Vapotron Effect for the cooling of electronic devices. The problem deals with a particular kind of subcooled boiling which is able to enhance heat exchange between a non-isothermal finned surface, simulating the packaging of an electronic component, and a refrigerant fluid (water in the case here presented) flowing on it. The experimental set up is first described in detail then employed to perform a number of tests aiming at a full characterization of the pulsatile nature of the phenomenon; the average heat transfer coefficient for the Vapotron Effect in a state of forced convection has been experimentally determined. The experimental tests have shown the existence of a relation that couples temperature trend of water in the cavities between the fins and cycle of events characterising the phenomenon. These results will be applied in the future to the study of more dynamic phenomena. A comparative analysis concerning the thermal performances of the Vapotron Effect concludes the paper.

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Rehman, Omais Abdur, Valeria Palomba, Andrea Frazzica, Antonios Charalampidis, Sotirios Karellas et Luisa F. Cabeza. « Numerical and Experimental Analysis of a Low-GWP Heat Pump Coupled to Electrical and Thermal Energy Storage to Increase the Share of Renewables across Europe ». Sustainability 15, n^o 6 (10 mars 2023) : 4973. http://dx.doi.org/10.3390/su15064973.

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In order to reduce the dependence on fossil fuels in the residential sector, low-carbon-footprint technologies such as heat pumps should be used. To fully exploit solar-assisted heat pumps, an effective control strategy is required. This study employs a low-global-warming-potential (GWP) refrigerant for a water-to-water reversible heat pump, which is assisted by a thermal energy storage tank, photovoltaic (PV) installation, and battery storage system using a dedicated control strategy. The heat pump’s operation is validated against the experimental data. Simulations are carried out for three different climates to analyze the performance of reversible heat pumps across Europe. The reversible heat pump fully meets the summer cooling demand in all three climates, while the heating demand is covered with the help of a backup source. An economic analysis is carried out for three different PV sizes and the results are compared with the reference energy systems. The inclusion of a battery storage system results in high payback times but increases overall flexibility and self-sufficiency.

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Zhang, Gangan, Dehui Du, Le Zhang, Yanlong Xiang, Wei Li, Jiapei Zhang, Jincai Du et David J. Kukulka. « A Modified Correlative Model for Condensation Heat Transfer in Horizontal Enhanced Tubes with R32 and R410A Refrigerants ». Energies 16, n^o 13 (22 juin 2023) : 4883. http://dx.doi.org/10.3390/en16134883.

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An experimental study was performed that compared tube side condensation heat transfer characteristics of enhanced tubes (hydrophobic surface tubes (HYD), herringbone micro fin tube (HB), and a composite hydrophobic/herringbone (micro fin) tube (HYD/HB)) to the performance of a smooth tube (ST). The condensation heat transfer coefficient (HTC) was calculated from data that were recorded for smooth and enhanced tubes that had an outer diameter (OD) of 12.7 mm. Data were collected (as a function of mass flow rate) using a couple of refrigerants (R410A and R32), for saturated temperatures of 35 °C and 45 °C, with vapor qualities that ranged from 0.8 to 0.2. Several previously reported smooth tube HTC models were used to calculate values that could be compared to experimentally obtained HTC values. The correlation model that demonstrated the best accuracy (for the conditions considered) was then modified for use with the enhanced tubes from this study. Results from the modified correlation show differences with experimental values that ranged from −10% to +17%; the new modified correlation demonstrates high prediction accuracy. An accurate correlation allows the evaluation of enhanced heat transfer tubes for use in high-efficiency heat exchanger systems. The development of this new model is significant in the study of enhanced heat transfer.

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Yan, Fengyuan, Jinliang Geng, Guangxin Rong, Heng Sun, Lei Zhang et Jinxu Li. « Optimization and Analysis of an Integrated Liquefaction Process for Hydrogen and Natural Gas Utilizing Mixed Refrigerant Pre-Cooling ». Energies 16, n^o 10 (22 mai 2023) : 4239. http://dx.doi.org/10.3390/en16104239.

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Liquefying hydrogen is an efficient way to store and transport hydrogen. However, the hydrogen liquefaction process is energy intensive. Therefore, an integrated liquefaction process of hydrogen and natural gas utilizing the mixed refrigerant cycle and the hydrogen Claude cycle is proposed. The process not only couples a steam methane reforming process to produce hydrogen and a carbon dioxide refrigeration cycle to assist in pre-cooling, but also employs a solar energy absorption refrigeration system to enhance energy efficiency. The proposed process is simulated and optimized using HYSYS and the particle swarm optimization algorithm, and energy, exergy, and economic analyses are performed. The energy analysis shows that the specific energy consumption of the proposed process is 5.2201 kWh/kg, a reduction of 10.67% compared to the base case. The exergy loss and exergy efficiency are 64,904 kW and 62.21%, which are 13.63% and 6.63% lower than the base case, respectively. The economic analysis shows that the total annualized cost of the process is USD 28.6 million per year. The proposed integrated liquefaction process not only realizes the high efficiency of energy utilization but also follows the development trend of integrated energy systems.

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Obersteiner, Florian, Harald Bönisch, Timo Keber, Simon O'Doherty et Andreas Engel. « A versatile, refrigerant- and cryogen-free cryofocusing–thermodesorption unit for preconcentration of traces gases in air ». Atmospheric Measurement Techniques 9, n^o 11 (31 octobre 2016) : 5265–79. http://dx.doi.org/10.5194/amt-9-5265-2016.

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Abstract. We present a compact and versatile cryofocusing–thermodesorption unit, which we developed for quantitative analysis of halogenated trace gases in ambient air. Possible applications include aircraft-based in situ measurements, in situ monitoring and laboratory operation for the analysis of flask samples. Analytes are trapped on adsorptive material cooled by a Stirling cooler to low temperatures (e.g. −80 °C) and subsequently desorbed by rapid heating of the adsorptive material (e.g. +200 °C). The set-up involves neither the exchange of adsorption tubes nor any further condensation or refocusing steps. No moving parts are used that would require vacuum insulation. This allows for a simple and robust design. Reliable operation is ensured by the Stirling cooler, which neither contains a liquid refrigerant nor requires refilling a cryogen. At the same time, it allows for significantly lower adsorption temperatures compared to commonly used Peltier elements. We use gas chromatography – mass spectrometry (GC–MS) for separation and detection of the preconcentrated analytes after splitless injection. A substance boiling point range of approximately −80 to +150 °C and a substance mixing ratio range of less than 1 ppt (pmol mol−1) to more than 500 ppt in preconcentrated sample volumes of 0.1 to 10 L of ambient air is covered, depending on the application and its analytical demands. We present the instrumental design of the preconcentration unit and demonstrate capabilities and performance through the examination of analyte breakthrough during adsorption, repeatability of desorption and analyte residues in blank tests. Examples of application are taken from the analysis of flask samples collected at Mace Head Atmospheric Research Station in Ireland using our laboratory GC–MS instruments and by data obtained during a research flight with our in situ aircraft instrument GhOST-MS (Gas chromatograph for the Observation of Tracers – coupled with a Mass Spectrometer).

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Yao, Mengliang, Yunhua Gan, Jialin Liang, Daowei Dong, Li Ma, Jinlong Liu, Qiliang Luo et Yong Li. « Performance simulation of a heat pipe and refrigerant-based lithium-ion battery thermal management system coupled with electric vehicle air-conditioning ». Applied Thermal Engineering 191 (juin 2021) : 116878. http://dx.doi.org/10.1016/j.applthermaleng.2021.116878.

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Jiang, Jun, Tong Chen et Ximing Xu. « Simultaneous Determination of 16 Phthalate Esters in Suet Oil by GC–EIMS Coupled with Refrigerant Centrifugation and Ethylenediamine-N-propylsilane Depuration ». Chromatographia 82, n^o 11 (20 août 2019) : 1721–32. http://dx.doi.org/10.1007/s10337-019-03789-8.

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Chen, Hong Bing, et Ping Wei. « Investigation of a Hybrid Photovoltaic Thermal Heat Pump System ». Advanced Materials Research 512-515 (mai 2012) : 78–83. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.78.

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The decrease of photovoltaic (PV) cell temperature by 10 °C is expected to improve the PV electrical efficiency by 0.6-0.7% based on the reference efficiency of 15%. Different cooling liquids like air and water have been introduced to pass across the PVs to reduce the cell temperature, and thus increase the electrical efficiency. In this paper, the refrigerant R134a was used as the cooling liquid and a PV/thermal (PV/T) collector was coupled with a heat pump system acting as the evaporator, which was expected to achieve a better cooling effect and energy performance due to its low boiling temperature. A hybrid PV/T collector, made of 6 glass vacuum tube – PV module – aluminum sheet – cooper tube sandwiches connected in series, worked as the evaporator of the heat pump system. Numerical steady models were established for each component of the heat pump system and part of the PV/T collector/evaporator for predicting their energy performance under the weather data of January 14th at Tibet, China. The results showed that the maximum COP could reach up to 7.6. The daily average thermal efficiency and electrical efficiency were 0.764 and 0.104, respectively.

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Alva, Luis H., et Jorge E. Gonza´lez. « Simulation of an Air-Cooled Solar-Assisted Absorption Air Conditioning System ». Journal of Solar Energy Engineering 124, n^o 3 (1 août 2002) : 276–82. http://dx.doi.org/10.1115/1.1487885.

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This paper investigates the technical feasibility of using a compact, air-cooled, solar-assisted, absorption air conditioning system in Puerto Rico and similar regions. Computer simulations were conducted to evaluate the system’s performance when subjected to dynamic cooling loads. Within the computer model, heat and mass balances are conducted on each component of the system, including the solar collectors, thermal storage tank, the air-cooled condenser, and the air-cooled absorber. Guidance on component design and insight into the effects of such operating factors as ambient air temperature were gained from exercizing the simulation model. Comparisons are made with an absorption air conditioning system that uses a cooling tower instead of air-cooled components. The particular absorption system of study is one that uses lithium bromide and water as the absorbent and refrigerant, respectively. The heat input to the absorption system generator is provided by an array of flat plate collectors that are coupled to a thermal storage tank. Systems having nominal cooling capacities of 10.5, 14, and 17.5 kW were considered. Useful information about the number of collectors needed, storage tank volume, and efficiency of the overall system is presented.

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Strąk, Kinga, Beata Maciejewska et Magdalena Piasecka. « The heat transfer coefficient determination with the use of the Beck-Trefftz method in flow boiling in a minichannel ». EPJ Web of Conferences 180 (2018) : 02099. http://dx.doi.org/10.1051/epjconf/201818002099.

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In this paper, the solution of the two-dimensional inverse heat transfer problem with the use of the Beck method coupled with the Trefftz method is proposed. This method was applied for solving an inverse heat conduction problem. The aim of the calculation was to determine the boiling heat transfer coefficient on the basis of temperature measurements taken by infrared thermography. The experimental data of flow boiling heat transfer in a single vertical minichannel of 1.7 mm depth, heated asymmetrically, were used in calculations. The heating element for two refrigerants (FC-72 and HFE-7100, 3M) flowing in the minichannel was the plate enhanced on the side contacting with the fluid. The analysis of the results was performed on the basis of experimental series obtained for the same heat flux and two different mass flow velocities. The results were presented as infrared thermographs, heated wall temperature and heat transfer coefficient as a function of the distance from the minichannel inlet. The results was discussed for the subcooled and saturated boiling regions separately.

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Al-Sakini, Sahar. « Design and Implementation of Low Power Thermoelectric Refrigerator ». Journal of Al-Rafidain University College For Sciences ( Print ISSN : 1681-6870 ,Online ISSN : 2790-2293 ), n^o 2 (9 octobre 2021) : 260–81. http://dx.doi.org/10.55562/jrucs.v40i2.203.

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The Objective of this study is to design a prototype of thermoelectric Refrigerator using Peltier effect on thermoelectric refrigerate or to achieve and protect a specific temperature, to be maintained a selected temperature at acceptable range. The Interior volume of the thermoelectric refrigerator is 6.8 Liter. The design requirements are to cool the volume (6.8Liter) to a suitable temperature within a short time, low power and low cost. The Thermo electrical refrigeration is a new ersatz because it can change waste electricity power to useful cooling, so it's increasing demand desired at the field of food preservation, vaccine storages, cooling of electronic devices and medical services. The system consists of the thermoelectric chamber, heat sink, thermo couple, fan, insulator material and D.C. Source. The Results of this work show that the reduced energy needed for thermoelectric refrigerator is about 60 Watt, which is less than the power for the traditional refrigerator. In this study foam insulator is used of thicknesses (20mm, 40mm) and the heat load (Qc) which obtained is (31W, 23W) respectively .

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Ghosh, Subrata, Saheli Samanta, J. Sridhar Mohanty, Jayee Sinha et Kalyan Mandal. « Giant room temperature magnetocaloric response in a (MnNiSi)_1−x(FeNiGa)_x system ». Journal of Applied Physics 132, n^o 4 (28 juillet 2022) : 045001. http://dx.doi.org/10.1063/5.0098679.

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The coincidence of magnetic and structural transitions near room temperature is observed in (MnNiSi)1− x(FeNiGa) x ( x = 0.16 and 0.17) systems, which leads to a coupled magnetostructural transition (MST) from a high-temperature paramagnetic Ni2In-type hexagonal phase to a low-temperature ferromagnetic TiNiSi-type orthorhombic phase associated with a substantial change in magnetization and a large change in structural unit cell volume, and thus, across MST, a giant magnetocaloric effect is obtained in these systems. The alloys with x = 0.16 and 0.17 are observed to show a giant isothermal magnetic entropy change (ΔSM) of about −26.2 and −63.2 J kg−1 K−1, accompanied with a large relative cooling power of about 220.1 and 264.5 J/kg, respectively, due to a magnetic field change ( μ0Δ H) of 5 T only. Moreover, the material with x = 0.16 and 0.17 shows a large temperature average magnetic entropy change of about −21.64 and −34.4 J kg−1 K−1 over a temperature span of 10 K due to μ0Δ H ∼ 5 T. Thus, these low-cost materials with giant magnetocaloric responses are highly suitable to be used as magnetic refrigerants for room temperature solid-state-based cooling technology.

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Sales, Brian C. « Electron Crystals and Phonon Glasses : A New Path to Improved Thermoelectric Materials ». MRS Bulletin 23, n^o 1 (janvier 1998) : 15–21. http://dx.doi.org/10.1557/s0883769400031419.

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In materials that conduct both electricity and heat, the thermal and electrical currents are coupled. This thermoelectric coupling can be used to construct devices that act as temperature sensors, heat pumps, refrigerators, or power generators. A temperature difference ΔT across any electrical conductor will generate a corresponding voltage difference ΔV The ratio ΔV/ΔT is defined as the Seebeck coefficient S after Thomas See-beck who first discovered the effect in 1823. Probably the most familiar use of this effect is the thermocouple in which the union of two dissimilar metals generates a voltage in response to an imposed temperature difference. Interestingly an electrical current I passing through the junction of two dissimilar conductors results in the absorption or release of heat in the vicinity of the junction depending on the direction of the current. The ability to heat or cool in this manner was first discovered by Peltier and explained by Lord Kelvin. The latter showed that the amount of heat produced (or absorbed) near the junction is given by ΠI = STI where Π is called the Peltier coefficient and T is the temperature. It is primarily this effect that makes thermoelectric (Peltier) refrigeration possible. Thermoelectric refrigerators and power generators are attractive for many applications as they have no moving parts (except electrons and holes), use no liquid refrigerant, and last indefinitely.

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Chen, Hong Bing, et Ping Wei. « Comparative Study on Hybrid PV/T Heat Pump Systems Using Different PV Panels ». Advanced Materials Research 446-449 (janvier 2012) : 2888–94. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2888.

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Many studies have found that the photovoltaic (PV) cell temperature plays an important impact on the solar-to-electricity conversion efficiency. Different cooling liquids like air and water have been introduced to pass across the PVs to reduce the cell temperature, and thus increase the electrical efficiency. In this paper, the refrigerant R134a is used as the cooling liquid and the PV/thermal (PV/T) panel is coupled with a heat pump system acting as the evaporator, which is expected to achieve a better cooling effect and energy performance due to its low boiling temperature. Two different kinds of PV/T panels, glass vacuum tube (GVT) type and flat plate (FP) type, are proposed for the study on the energy performance comparison. The results show that the GVT PV/T panel has an average thermal efficiency of 0.775 and an average electrical efficiency of 0.089 (based on the reference efficiency of 0.12), which is 73.4% and 1.1% higher than that of the FP PV/T panel respectively, with the solar radiation varying from 200 W/m2to 1000 W/m2. The GVT PV/T heat pump system has an average COP of 5.6, 9.8% higher the FP PV/T heat pump system. The GVT PV/T heat pump system has a better energy performance than the FP PV/T heat pump system.

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Wang, Jun, Lin Ruan et Ruiwei Li. « Parametric Investigation on the Electrical-Thermal Performance of Battery Modules with a Pumped Two-Phase Cooling System ». Energies 15, n^o 21 (25 octobre 2022) : 7897. http://dx.doi.org/10.3390/en15217897.

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The pumped two-phase cooling method is a practical way to dissipate heat from the battery module. The operating parameters of the cooling system should be investigated thoroughly to improve the performance of the battery thermal management system (BTMS). However, the previous BTMS designs only explored the thermal performance and ignored the electrical performance in the battery module. This study designed a pumped two-phase cooling BTMS with the refrigerant of R1233zd. An electrothermal coupled model was established for a series-connected battery module to predict thermal and electrical behavior. The results showed that the pumped two-phase cooling system could obtain excellent cooling performance with low system pressure under 2C discharging condition. The average temperature of the module and the temperature difference among cells could be maintained under 40 °C and 5 K under a 2C discharging rate. A lower saturation temperature, higher mass flux, and higher subcooling degree could enhance heat dissipation for the cooling system based on R1233zd. An increase in the saturation temperature and a decrease in the subcooling degree could enhance the temperature uniformity within the module. The battery consistency was mainly dominated by the temperature difference and deteriorated with a lower average temperature in the pack. The research outcome of this paper can guide the design and optimization of the pumped two-phase cooling BTMS.

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Qin, Yanbin, Nanxi Li, Hua Zhang et Baolin Liu. « Thermodynamic performance of a modified −150 °C refrigeration system coupled with Linde-Hampson and three-stage auto-cascade using low-GWP refrigerants ». Energy Conversion and Management 236 (mai 2021) : 114093. http://dx.doi.org/10.1016/j.enconman.2021.114093.

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Verma, Abhishek, S. C. Kaushik et S. K. Tyagi. « Thermodynamic Analysis of a Combined Single Effect Vapour Absorption System and tc-CO2 Compression Refrigeration System ». HighTech and Innovation Journal 2, n^o 2 (1 juin 2021) : 87–98. http://dx.doi.org/10.28991/hij-2021-02-02-02.

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Transcritical CO2 refrigeration system is coupled with the single effect vapour absorption with LiBr-water as a working pair having an objective to enhance the performance of low temperature transcritical refrigeration system while using natural working pair and to reduce the electricity consumption to produce low temperature refrigeration. The high grade waste heat rejected in the gas cooler of tc-CO2 compression refrigeration system (TCRS) is utilized to run the single effect vapour absorption system (SEVAR) to enhance the energy efficiency of the system. The gas cooler in the transcritical CO2 system is having heat energy at high temperature and pressure, which is utilized to run the vapour absorption system, while the other refrigerant heat exchanger provides subcooling to further enhance the performance. The combined cycle can provide refrigeration temperature at different levels, to use it for different applications. Energetic and exergetic analysis have been done to analyze the combined system to compute the performance parameters and the irreversibilities occurring in different components to further increase the performance. The combined system is optimized for various heat rejection and refrigeration temperatures. The COP of the combined system has been enhanced by to 24.88% while the enhancement in exergetic efficiency (ηex) is observed as 10.14% respectively over tradition transcritical CO2 compression refrigeration system, with -10°C as an evaporation (TCRS cooling) temperature and exit temperature of gas cooler T4 being 40°C. Doi: 10.28991/HIJ-2021-02-02-02 Full Text: PDF

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Unterluggauer, Julian, Verena Sulzgruber, Clemens Kroiss, Johannes Riedl, Reinhard Jentsch et Reinhard Willinger. « Design for a Heat Pump with Sink Temperatures of 200 °C Using a Radial Compressor ». Energies 16, n^o 13 (24 juin 2023) : 4916. http://dx.doi.org/10.3390/en16134916.

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To reduce CO2 emissions in the industrial sector, high-temperature heat pumps are a key technology. This work presents an approach to design such an industrial heat pump system capable of supplying 200 °C sink temperature and a capacity of approximately 1 MW. Today’s market-available heat pumps using displacement compressors are not suitable for reaching that high sink temperatures as they need lubricating oil, which is not temperature resistant enough. As a consequence, in this study a transcritical heat pump cycle using a two-stage oil-free radial compressor is investigated. Based on preliminary studies, R1233zd(E) is chosen as a refrigerant. The procedure couples 1D thermodynamic cycle simulations with a radial compressor mean-line design model. A preliminary geometry for a compressor with and without inlet guide vanes is presented, and compressor maps including the compressors behaviour in off-design are calculated. The compressor design is then imported into a 1D simulation to analysis the performance of the heat pump in the whole operating range. In the analysis, the application of a fixed inlet is evaluated, and an improvement of approximately 21% and 16% of the isentropic efficiency is achieved. The thermodynamic simulations showed a maximum COP of approximately 2.8 and a possible operating range of 0.5 to 1.3 MW thermal power. Furthermore, a techno-economical analysis by means of a deep-fryer use case showed reasonable payback times of between 2 and 10 years, depending on the electricity to gas price ratio.

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Majeed, Khaliq, Muhammad Abdul Qyyum, Alam Nawaz, Ashfaq Ahmad, Muhammad Naqvi, Tianbiao He et Moonyong Lee. « Shuffled Complex Evolution-Based Performance Enhancement and Analysis of Cascade Liquefaction Process for Large-Scale LNG Production ». Energies 13, n^o 10 (15 mai 2020) : 2511. http://dx.doi.org/10.3390/en13102511.

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Among all large-scale natural gas (NG) liquefaction processes, the mixed fluid cascade (MFC) process is recognized as a best-alternative option for the LNG production, mainly due its competitive performance. However, from a thermodynamic point of view, the MFC process is still far from its potential maximum energy efficiency due to non-optimal execution of design variables. Therefore, the energy efficiency enhancement of the MFC process remains an ongoing issue. The design optimization after fixing the main configuration of the process is one of the most economic, but challenging exercises during the design stages. In this study, shuffled complex evolution (SCE) is studied to find the optimal design of the MFC process corresponding to minimal energy consumption in refrigeration cycles. The MFC process is simulated using Aspen Hysys® v10 and then coupled with the SCE approach, which is coded in MATLAB® 2019a. The refrigerant composition and operating pressures for each cycle of the MFC process were optimized considering the approach temperature inside the LNG heat exchanger as a constraint. The resulting optimal MFC process saved 19.76% overall compression power and reduced the exergy destruction up to 28.76%. The thermodynamic efficiency (figure of merit) of the SCE-optimized process was 25% higher than that of the published base case. Furthermore, the optimization results also imply that there is a trade-off between the thermodynamic performance improvement and the computational cost (no. of iterations). In conclusion, SCE exhibited potential to improve the performance of highly nonlinear and complex processes such as LNG processes.

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Artuso, Paolo, Giacomo Tosato, Antonio Rossetti, Sergio Marinetti, Armin Hafner, Krzysztof Banasiak et Silvia Minetto. « Dynamic Modelling and Validation of an Air-to-Water Reversible R744 Heat Pump for High Energy Demand Buildings ». Energies 14, n^o 24 (7 décembre 2021) : 8238. http://dx.doi.org/10.3390/en14248238.

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This paper presents a reversible heat pump based on CO2 as the refrigerant, able to provide heating, cooling, and domestic hot water to high energy demand buildings. The unit was developed and tested under the EU H2020 project MultiPACK, which has the main goal of assuring the market about the feasibility, reliability, and energy efficiency of CO2 integrated systems for heating and cooling and promoting a fast transition to low environmental impact solutions. Within the project, the confidence raising was performed by installation and monitoring of fully integrated state-of-the art CO2 systems in the Southern European Climate. With the aim of predicting the unit behaviour under variable load and boundary conditions, a dynamic model of the entire unit was developed with commercial software, considering actual components and the implemented control system and it was validated with experimental data, collected at the factory’s lab before commissioning. The validation against experimental data collected during operation as a heat pump demonstrated a maximum percentage difference between the experimental and predicted value of gas–cooler heat flow rate equal to +5.0%. A preliminary comparison with the experimental data in chiller configuration is reported, however further development was required to achieve a satisfactory validation. Lastly, the numerical model was utilized to simulate a typical operation in heat pump configuration with the system coupled with a hot water tank storage for the production of domestic hot water and space heating; the model predicts higher COP when operating in domestic hot water operation due to the lower water inlet temperature.

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