Journal articles on the topic 'Rate of cooling (heating) system'
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1
Wicaksono, Nugroho Budi, and Sukma Meganova Effendi. "Heating and Cooling Rate Study on Water Cooling Thermal Cycler using Aluminium Block Sample." Journal of Electronics, Electromedical Engineering, and Medical Informatics 4, no. 2 (March 4, 2022): 55–61. http://dx.doi.org/10.35882/jeeemi.v4i2.1.
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Temperature measurement has many applications in medical devices. In recent days, body temperature become the main screening procedure to justify people infected by SARS-CoV-2. Related to pandemic situation due to SARS-Cov-2, Polymerase Chain Reaction (PCR) method become the most accurate and reliable detection method. This method employs a device named PCR machine or Thermal Cycler. In this research, we focus to build a Thermal Cycler using a low-cost material such as aluminium and using a liquid coolant as the cooling system. We use 2 types of coolant solution: mineral water and generic liquid coolant. Peltier device in thermal cycler serves as heating and cooling element. In heating rate experiments, generic liquid coolant shows a better result than using mineral water due to specific heat capacity and thermal conductivity of water. In the cooling rate experiments, the water pump is activated to stream the liquid solution, the flow rate of liquid solution is influenced by viscosity of the liquid. Generic liquid coolant has approx. 4,5 times greater viscosity than water. The higher flow rate means better performance for cooling rate. Using 2 pieces of 60-Watt heaters and a 60-Watt chiller and aluminium material as block sample, our research shows a heating and cooling rate up to approx. 0,1°C/s. Compared to commercially thermal cycler, our thermal cycler has a lower wattage; this lower wattage performance has been tradeoff with lower ramping rate. Some factors are suspected become the source of contributors of lower ramping rate.
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Zhang, Wei, Xianzhao Yang, Tao Wang, Xueyuan Peng, and Xiaolin Wang. "Experimental Study of a Gas Engine-driven Heat Pump System for Space Heating and Cooling." Civil Engineering Journal 5, no. 10 (October 21, 2019): 2282–95. http://dx.doi.org/10.28991/cej-2019-03091411.
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In this paper, the performance of a gas engine-driven heat pump (GEHP) was experimentally studied for space heating and cooling. An experimental test facility was developed for this purpose. The effect of key parameters on system performance was investigated under both cooling and heating modes. The results showed that as the engine speed increased from 1400 to 2000 rpm, the cooling and heating capacities increased by 23% and 28.5%, respectively while the GEHP system Primary Energy Ratio (PER) decreased by 13.5% and 11.7% in the cooling and heating modes, respectively. The system PER in the cooling mode was found lower than that in the heating mode. This indicated that heat recovery from the engine cylinder and exhaust gas was very important for improving the GEHP system performance. In the heating mode, the ambient temperature and condenser water flow rate had a large effect on the system heating capacity and PER, and insignificant effect on the gas energy input. In the cooling mode, the chilled water inlet temperature showed a large effect on both cooling capacity and gas energy input while the chilled water flow rate had a large effect on cooling capacity and insignificant effect on the gas energy input.
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Joubert, G. D., and R. T. Dobson. "Modelling and testing a passive night-sky radiation system." Journal of Energy in Southern Africa 28, no. 1 (March 23, 2017): 76. http://dx.doi.org/10.17159/2413-3051/2017/v28i1a1550.
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The as-built and tested passive night-sky radiation cooling/heating system considered in this investigation consists of a radiation panel, a cold water storage tank, a hot water storage tank, a room and the interconnecting pipework. The stored cold water can be used to cool a room during the day, particularly in summer. A theoretical time-dependent thermal performance model was also developed and compared with the experimental results and it is shown that the theoretical simulation model captures the experimental system performance to within a reasonable degree of accuracy. A natural circulation experimental set-up was constructed and subsequently used to show that under local (Stellenbosch, South Africa) conditions the typical heat-removal rate from the water in the tank is 55 W/m2 of radiating panel during the night; during the day the water in the hot water-storage tank was heated from 24 °C to 62 °C at a rate of 96 W/m2. The system was also able to cool the room at a rate of 120 W/m3. The results thus confirmed that it is entirely plausible to design an entirely passive system, that is, without the use of any moving mechanical equipment such as pumps and active controls, for both room-cooling and water-heating. It is thus concluded that a passive night-sky radiation cooling/heating system is a viable energy-saving option and that the theoretical simulation, as presented, can be used with confidence as an energy-saving system design and evaluation tool. Keywords: passive cooling and heating, buoyancy-driven fluid flow, theoretical simulation, experimental verification Highlights:Passively driven renewable energy heating and cooling systems are considered.Time-dependent mathematical simulation model is presented.Experimental buoyancy-driven heating and cooling system built and tested.Experimental results demonstrate the applicability of the theoretical simulation model.Saving and evaluation design tool.
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Xu, Aixiang, Mengjin Xu, Nan Xie, Yawen Xiong, Junze Huang, Yingjie Cai, Zhiqiang Liu, and Sheng Yang. "Thermodynamic Analysis of a Hybrid System Coupled Cooling, Heating and Liquid Dehumidification Powered by Geothermal Energy." Energies 14, no. 19 (September 24, 2021): 6084. http://dx.doi.org/10.3390/en14196084.
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The utilization of geothermal energy is favorable for the improvement of energy efficiency. A hybrid system consisting of a seasonal heating and cooling cycle, an absorption refrigeration cycle and a liquid dehumidification cycle is proposed to meet dehumidification, space cooling and space heating demands. Geothermal energy is utilized effectively in a cascade approach. Six performance indicators, including humidity efficiency, enthalpy efficiency, moisture removal rate, coefficient of performance, cooling capacity, and heating capacity, are developed to analyze the proposed system. The effect of key design parameters in terms of desiccant concentration, air humidity, air temperature, refrigeration temperature and segment temperature on the performance indicators are investigated. The simulation results indicated that the increase of the desiccant concentration makes the enthalpy efficiency, the coefficient of performance, the moisture removal rate and the cooling capacity increase and makes the humidity efficiency decrease. With the increase of air humidity, the humidity efficiency and moisture removal rate for the segment temperatures from 100 to 130 °C are approximately invariant. The decreasing rates of the humidity efficiency and the moisture removal rate with the segment temperature of 140 °C increases respectively. Six indicators, except the cooling capacity and heating capacity, decrease with an increase of air temperature. The heating capacity decreases by 49.88% with the reinjection temperature increasing from 70 to 80 °C. This work proposed a potential system to utilize geothermal for the dehumidification, space cooling and space heating effectively.
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Mushtaq I. Hasan and Dhay Mohammed Muter. "Numerical Investigation of The Air Flow Rate Effect Performance of Earth to Air Heat Exchanger Used for Cooling of Poultry Houses." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 84, no. 2 (July 24, 2021): 167–84. http://dx.doi.org/10.37934/arfmts.84.2.167184.
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Usually, poultry houses are located in a remote area where there is no electricity, and where there is electricity, it is expensive, so resorting to these solutions is considered important solutions to save electrical energy and provide free cooling. The main part of generated energy is consumed by cooling and heating systems. One of the well-known approaches to implemented heating and cooling system is earth to air heat exchanger (EAHE) system. This system is effective passive heating and cooling systems which can be used with poultry houses and building. This research studies numerically the effect of mass flow rate on the overall performance of earth to air HE for poultry houses. Four parameters (mass flow rate, required rate, required cooling load and pipe lengths) are selected under environment of Nasiriyah city (a city located in the south of Iraq). The study is conducted using PVC material. The study has been done during summer season. The suggested numerical model has been tested and validated using existing approaches selected from literature review papers. This test shows good agreement with results of selected papers. Moreover, validation and simulation results showed that the required cooling load increased with increasing mass flow rate. Also, with the increasing length of pipe of EAHE, the inflow temperature compared to the space temperature is decreased. However, the overall performance factor of EAHEs decreases by the increase of length of pipe and mass flow rate. Which indicate the possibility of using the earth to air heat exchanger for cooling and heating poultry houses and reduce the use of electrical energy.
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Bass, Mark, and Rolf R. de Swardt. "Laboratory Heat Transfer Experiments on a 155mm Compound Gun Tube With Full Length Integral Mid-Wall Cooling Channels." Journal of Pressure Vessel Technology 128, no. 2 (January 17, 2006): 279–84. http://dx.doi.org/10.1115/1.2179434.
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A 155 mm compound gun barrel with full-length integral mid-wall cooling channels was manufactured and connected to a purpose built heat exchanger. Laboratory testing of this system was carried out using electrical heating jackets applied to the outer surface of the barrel and an internal electrical chamber heater to heat the barrel as uniformly as possible along its length. A series of tests were then carried out consisting of first heating the barrel to a uniform temperature of approximately 80°C followed by switching on the heat exchanger and monitoring the rate at which the barrel cooled. The purpose of these tests was to determine the optimum cooling characteristics of the system by studying the effect of different coolant flow rates combined with one or both radiators functioning and also the effect of using different cooling fluid solutions. Having derived the optimum flow rate and coolant solution combination a further cooling test was carried out with the heat exchanger configured to these optimum values and with the barrel heaters operating at maximum capacity. Finally a natural cooling test was undertaken where the barrel was uniformly heated to 160°C, the heating jackets removed and the barrel left to cool overnight. The results from these tests prove that natural cooling is dramatically slower than forced mid-wall cooling.
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Kim, Il Ho, Won Sik Lee, Se Hyun Ko, Jin Man Jang, and Ho Sung Kim. "Charge and Discharge Properties of Hydrogen in the Alloy Hydride System with Open Cell Al Foam." Materials Science Forum 569 (January 2008): 301–4. http://dx.doi.org/10.4028/www.scientific.net/msf.569.301.
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The effects of use of open cell Al foam and thermoelectric element in a hydrogen storage system were investigated. Extremely different heat conductivities were observed in two storage systems with or without open cell Al foam. By applying the open cell Al in this hydrogen storage system, the reaction sensitivity of the temperature and equilibrium pressure was far rapidly increased than that without the open cell Al foam. During increasing the temperature by heating element, heating rate of hydride powders was very fast in the storage system including Al foam, while temperature of powders was almost not changed in system without foam. Also, in case of using thermoelectric element, heating and cooling rate was very sensitive in the system with Al foam and heating-cooling cyclic behavior within the system controlled by thermoelectric element is seemed to be satisfied for some applications in industry.
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Xu, Shanglong, Weijie Wang, Zongkun Guo, Xinglong Hu, and Wei Guo. "A multi-channel cooling system for multiple heat source." Thermal Science 20, no. 6 (2016): 1991–2000. http://dx.doi.org/10.2298/tsci140313123x.
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High-power electronic devices with multiple heating elements often require temperature uniformity and operating within their functional temperature range for optimal performance. A multi-channel cooling experiment apparatus is developed for studying heat removal inside an electronic device with multiple heat sources. It mainly consists of a computer-controlled pump, a multi-channel heat sink for multi-zone cooling and the apparatus for measuring the temperature and pressure drop. The experimental results show the system and the designed multi-channel heat sink structure can control temperature distribution of electronic device with multiple heat sources by altering coolant flow rate.
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Seebacher, F., and C. E. Franklin. "Control of heart rate during thermoregulation in the heliothermic lizard Pogona barbata: importance of cholinergic and adrenergic mechanisms." Journal of Experimental Biology 204, no. 24 (December 15, 2001): 4361–66. http://dx.doi.org/10.1242/jeb.204.24.4361.
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SUMMARY During thermoregulation in the bearded dragon Pogona barbata, heart rate when heating is significantly faster than when cooling at any given body temperature (heart rate hysteresis), resulting in faster rates of heating than cooling. However, the mechanisms that control heart rate during heating and cooling are unknown. The aim of this study was to test the hypothesis that changes in cholinergic and adrenergic tone on the heart are responsible for the heart rate hysteresis during heating and cooling in P. barbata. Heating and cooling trials were conducted before and after the administration of atropine, a muscarinic antagonist, and sotalol, a β-adrenergic antagonist. Cholinergic and β-adrenergic blockade did not abolish the heart rate hysteresis, as the heart rate during heating was significantly faster than during cooling in all cases. Adrenergic tone was extremely high (92.3 %) at the commencement of heating, and decreased to 30.7 % at the end of the cooling period. Moreover, in four lizards there was an instantaneous drop in heart rate (up to 15 beats min–1) as the heat source was switched off, and this drop in heart rate coincided with either a drop in β-adrenergic tone or an increase in cholinergic tone. Rates of heating were significantly faster during the cholinergic blockade, and least with a combined cholinergic and β-adrenergic blockade. The results showed that cholinergic and β-adrenergic systems are not the only control mechanisms acting on the heart during heating and cooling, but they do have a significant effect on heart rate and on rates of heating and cooling.
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Tan, Jiahui, Mu Chai, Kuanfang He, and Yong Chen. "Numerical Simulation on Heating Effects during Hydrogen Absorption in Metal Hydride Systems for Hydrogen Storage." Energies 15, no. 7 (April 6, 2022): 2673. http://dx.doi.org/10.3390/en15072673.
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A 2-D numerical simulation model was established based on a small-sized metal hydride storage tank, and the model was validated by the existing experiments. An external cooling bath was equipped to simulate the heating effects of hydrogen absorption reactions. Furthermore, both the type and the flow rate of the cooling fluids in the cooling bath were altered, so that changes in temperature and hydrogen storage capacity in the hydrogen storage model could be analyzed. It is demonstrated that the reaction rate in the center of the hydrogen storage tank gradually becomes lower than that at the wall surface. When the flow rate of the fluid is small, significant differences can be found in the cooling liquid temperature at the inlet and the outlet cooling bath. In areas adjacent to its inlet, the reaction rate is higher than that at the outlet, and a better cooling effect is produced by water. As the flow rate increases, the total time consumed by hydrogen adsorption reaction is gradually reduced to a constant value. At the same flow rate, the wall surface of the tank shows a reaction rate insignificantly different from that in its center, provided that cooling water or oil coolant is replaced with air.
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Gong, Xiao, Fan Li, Bo Sun, and Dong Liu. "Collaborative Optimization of Multi-Energy Complementary Combined Cooling, Heating, and Power Systems Considering Schedulable Loads." Energies 13, no. 4 (February 18, 2020): 918. http://dx.doi.org/10.3390/en13040918.
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Combined cooling, heating, and power (CCHP) systems are a promising energy-efficient and environment-friendly technology. However, their performance in terms of energy, economy, and environment factors depends on the operation strategy. This paper proposes a multi-energy complementary CCHP system integrating renewable energy sources and schedulable heating, cooling, and electrical loads. The system uses schedulable loads instead of energy storage, at the same time, a collaborative optimization scheduling strategy, which integrates energy supply and load demand into a unified optimization framework to achieve the optimal system performance, is presented. Schedulable cooling and heating load models are formulated using the relationship between indoor and outdoor house temperatures. A genetic algorithm is employed to optimize the overall performance of energy, economy, and environment factors and obtain optimal day-ahead scheduling scheme. Case studies are conducted to verify the efficiency of the proposed method. Compared with a system involving thermal energy storage and demand response (DR), the proposed method exhibits a higher primary energy saving rate, greenhouse gas emission reduction rate, and operation costs saving rate of 7.44%, 6.59%, and 4.73%, respectively, for a typical summer day, thereby demonstrating the feasibility and superiority of the proposed approach.
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Fahdiran, Riser, Iwan Sugihartono, Mutia Delina, Teguh Budi Prayitno, Sunaryo, and Esmar Budi. "Influence of heating and cooling rates on thermodynamic properties of aluminum thin film from 300 to 1100 K." Journal of Physics: Conference Series 2193, no. 1 (February 1, 2022): 012027. http://dx.doi.org/10.1088/1742-6596/2193/1/012027.
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Abstract Temperature and pressure evolution due to heating and cooling in the range of 300 to 1100 K of Aluminum thin film with thickness 10 nm were investigated based on Molecular Dynamics (MD) simulation. Pressure evolution shows that heating and cooling rates with comparison of 3:2:1 provides significant contribution on melting and recrystallization of the system. The oscillation of the pressure is the strongest at the highest heating rate which indicate that the system collapses stronger than the lower rate. It is responsible for the destruction of the structure correlated to the elevation of the temperature. While for recrystallization, the analysis on pressure oscillations confirmed the influence of the rates. Analysis based on local crystal structure indicated that at T = 1100 K, all the systems are melted.
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Kiil, Martin, Raimo Simson, Martin Thalfeldt, and Jarek Kurnitski. "A Comparative Study on Cooling Period Thermal Comfort Assessment in Modern Open Office Landscape in Estonia." Atmosphere 11, no. 2 (January 23, 2020): 127. http://dx.doi.org/10.3390/atmos11020127.
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Local thermal comfort and draught rate has been studied widely. There has been more meaningful research performed in controlled boundary condition situations than in actual work environments involving occupants. Thermal comfort conditions in office buildings in Estonia have been barely investigated in the past. In this paper, the results of thermal comfort and draught rate assessment in five office buildings in Tallinn are presented and discussed. Studied office landscapes vary in heating, ventilation and cooling system parameters, room units, and elements. All sample buildings were less than six years old, equipped with dedicated outdoor air ventilation system and room conditioning units. The on-site measurements consisted of thermal comfort and draught rate assessment with indoor climate questionnaire. The purpose of the survey is to assess the correspondence between heating, ventilation and cooling system design, and the actual situation. Results show, whether and in what extent the standard-based criteria for thermal comfort is suitable for actual usage of the occupants. Preferring one room conditioning unit type or system may not guarantee better thermal environment without draught. Although some heating, ventilation and cooling systems observed in this study should create the prerequisites for ensuring more comfort, results show that this is not the case for all buildings in this study.
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Zhou, Yuekuan, Siqian Zheng, Hao Chen, and Guoqiang Zhang. "Thermal performance and optimized thickness of active shape-stabilized PCM boards for side-wall cooling and under-floor heating system." Indoor and Built Environment 25, no. 8 (October 5, 2016): 1279–95. http://dx.doi.org/10.1177/1420326x16671983.
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Phase change materials (PCMs) have the potential to maintain thermal comfort of occupants while reducing the energy consumption due to their high energy storage capacity. In this paper, thermal performance of active heat conduction–enhanced shape-stabilized phase change material (HCE-SSPCM) encapsulated boards, fitted with active hot/chilled water pipes were investigated for side-wall cooling and for incorporation in an under-floor heating system. Numerical model based on finite difference method was developed to study the effect of HCE-SSPCM on annual heating/cooling energy consumption saving and indoor air relative temperature fluctuation rate reduction. Our study shows that there exists an optimal location for HCE-SSPCM according to thermal resistance value of each layer and ambient conditions. The recommended thickness and thermal conductivity of HCE-SSPCM wallboard were 30–60 mm and 1–1.5 W·m−1·K−1. Compared to the room without HCE-SSPCM boards, the maximum annual heating energy consumption saving would be 16.2%. Indoor air relative temperature fluctuation rate for heating would be reduced by 41.3%. The maximum annual cooling energy consumption saving would be 4.53%. Indoor air relative temperature fluctuation rate for cooling would be reduced by 56.2%. Our research provided scientific evidences for application of PCMs to reduce energy consumption in residential buildings without sacrificing indoor thermal comfort.
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CHOI, JONGMIN, HYUN JOON CHOUNG, YOUNGJU JOO, HOON KANG, and YONGCHAN KIM. "PERFORMANCE CHARACTERISTICS OF A SIMULTANEOUS HEATING AND COOLING HEAT PUMP IN THE HEAT RECOVERY MODE." International Journal of Air-Conditioning and Refrigeration 18, no. 03 (September 2010): 237–45. http://dx.doi.org/10.1142/s2010132510000162.
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The cooling load in winter is significant in buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. Hence, the development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the performance of a simultaneous heating and cooling heat pump was investigated in the heat recovery mode (HR mode). The system adopted a variable speed compressor using R-410A with four indoor units and one outdoor unit. In the HR mode, the capacity and COP were improved as compared with those in the cooling or heating mode because the waste heat in the outdoor unit was utilized as useful heat in the indoor units. However, energy imbalance between heating and cooling capacities of each indoor unit was observed in the 2H–1C HR mode. Therefore, the performance of the system in the 2H–1C HR mode was enhanced by controlling refrigerant flow rate through the outdoor unit.
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Leist, U., A. Winkler, J. Büssow, and K. Al-Shamery. "Mobile sample holder applying multiple heating systems with a variable heating and cooling rate." Review of Scientific Instruments 74, no. 11 (November 2003): 4772–78. http://dx.doi.org/10.1063/1.1614413.
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Blank, D. A., and C. Wu. "Cooling and heating rate limits of a reversed reciprocating ericsson cycle at steady state." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 214, no. 1 (February 1, 2000): 75–85. http://dx.doi.org/10.1243/0957650001537877.
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The optimal cooling and heating rates for the reversed reciprocating Ericsson cycle with ideal regeneration are determined for heat pump operations. These limiting rates are based on the upper and lower thermal reservoir temperature bounds and are obtained using time and entropy minimization procedures from irreversible thermodynamics. Use is made of time symmetry (a second law constraint) to minimize cycle time. This optimally allocates the thermal capacitances of the cycle and minimizes internal cycle entropy generation. Although primarily a theoretical work, a very practical and extensive parametric study using several environmentally friendly working fluids (neon, nitrogen and helium) is included. This study evaluates the relative contributions of various system parameters to rate-optimized design. The coefficient of performance (COP), and thus the quantity of cooling or heating for a given energy input, is the traditional focus; instead this work aims at the rate of cooling or heating in heat pumps under steady state conditions and using ideal gases as their working substances. The results obtained provide additional criteria for use in the study, design and performance evaluation of employing Ericsson cycles in refrigeration, air conditioning and heat pump applications. They give direct insight into what is required in designing a reversed Ericsson heat pump to achieve maximum heating and cooling rates. The choices of working fluids and pressure ratios were found to be very significant design parameters, together with selection of regenerator and source—sink heat transfer parameters. The parameter most influencing both the heating and cooling mode COPs and the heat transfer rates was found to be the heat conductance of the thermal sink.
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Abd-Elhady, M. S., E. Bishara, and M. A. Halim. "Increasing the Cooling Rate of the Vapor Compression Cycle by Heating." International Journal of Air-Conditioning and Refrigeration 29, no. 01 (March 2021): 2150009. http://dx.doi.org/10.1142/s2010132521500097.
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Refrigeration and air conditioning cycles consume a large amount of electrical energy and the shortage in traditional sources of energy is the main reasons for governments to use renewable energy. The most power consuming part in the Vapor Compression Cycle (VCC) is the gas compressor. Therefore, the objective of this research is to increase the cooling rate of the VCC using the same compressor, and that is done by heating the refrigerant coming out from the compressor. The proposed cycle is similar to the VCC except that the compression processes is done in two stages, the first stage via a gas compressor and in the second stage by heating the refrigerant under constant volume. The heating process can be done using solar energy. An experimental setup has been developed to study the influence of heating the refrigerant on the cooling rate of the VCC. The heating process is performed after the compressor, and it is done under constant volume in order to increase the pressure of the refrigerant. Four experiments have been performed; the first experiment is a normal VCC, i.e., without heating, while in the second, third and fourth experiments, the refrigerant has been heated to 50∘C, 100∘C and 150∘C, respectively. It has been found that the cooling power increases with the heating temperature. Heating increases the pressure of the refrigerant in VCC, and consequently increases the mass flow rate of the refrigerant that results in an increase in the refrigeration power for the same compressor power. However, the disadvantage of heating the refrigerant is that it increases the evaporator temperature, which limits the possibility of the VCC to be used in freezing applications.
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Guo, You Dan. "Critical Cooling Rate and Design of Mould Cooling System for Hot Forming of High-Strength Sheet." Advanced Materials Research 295-297 (July 2011): 1474–78. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.1474.
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High-strength sheet including 2MnB5 Boron and magnesium alloy sheet is the material commonly used in modern machinery, which is easy to induce problems such as excessive rebound, cracking, forming force increase, easy mould wear and the like. The heat analysis of 2MnB5 Boron and magnesium alloy sheet hot stamping forming process and experiments indicate that the transition process from Austenite to Martensite by controlling the sheet heating and cooling temperature is the foundation of heat forming. Only when the cooling rate reaches or surpasses the critical cooling rate, Austenite can be transformed to Martensite directly. Critical cooling rate of sheet is related to the elements of critical water flow rate, mould cooling system design, cooling medium, dented mould medium and the like. Under the condition that the elements of mould structure, cooling system, cooling medium and the like are defined, critical cooling rate is a constant value. As a result, through controlling critical water flow rate, hot forming transition process and hot forming requirements can be guaranteed to overcome the excessive rebound, cracking, forming force increase, easy mould wear and the like in hot forming process.
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Zhang, Gui Chen. "Energy Performance Simulation Study on VAV Air Condition System at SPSU Campus Office Building with EnergyPlus." Applied Mechanics and Materials 361-363 (August 2013): 249–52. http://dx.doi.org/10.4028/www.scientific.net/amm.361-363.249.
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Based on the air condition systems theorem, by EnergyPlus7.0 the office building models were built up with the variable air volume (VAV) and constant air volume (CAV) systems separately at SPSU campus in the USA. The weather datum from Department of Energy US were used to simulate the energy consumption performance both daily and annually. Results show that the VAV system saves the sensible cooling rate 19.25% compared with the CAV one in the hottest day. The VAV system saves the sensible cooling rate 8.95% and reduces the outdoor infiltration sensible heat gain about 35.06% yearly. The VAV terminal-damper position doesnt change linearly as the outdoor climate temperature for the complex system in heating, ventilating, and air-conditioning (HVAC). Though the outdoor temperature is the same, the system sensible cooling rate is greatly different in autumn and spring day.
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Sarkar, Jahar, and Souvik Bhattacharyya. "Operating characteristics of transcritical CO2 heat pump for simultaneous water cooling and heating." Archives of Thermodynamics 33, no. 4 (November 1, 2011): 23–40. http://dx.doi.org/10.2478/v10173-012-0026-8.
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Abstract The effects of water-side operating conditions (mass flow rates and inlet temperatures) of both evaporator and gas cooler on the experimental as well as simulated performances (cooling and heating capacities, system coefficient of performance (COP) and water outlet temperatures) of the transcritical CO2 heat pump for simultaneous water cooling and heating the are studied and revised. Study shows that both the water mass flow rate and inlet temperature have significant effect on the system performances. Test results show that the effect of evaporator water mass flow rate on the system performances and water outlet temperatures is more pronounced (COP increases by 0.6 for 1 kg/min) compared to that of gas cooler water mass flow rate (COP increases by 0.4 for 1 kg/min) and the effect of gas cooler water inlet temperature is more significant (COP decreases by 0.48 for given range) compared to that of evaporator water inlet temperature (COP increases by 0.43 for given range). Comparisons of experimental values with simulated results show the maximum deviation of 5% for cooling capacity, 10% for heating capacity and 16% for system COP.
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Borushchak, L. O., I. O. Shuliar, N. V. Ilkiv, and S. V. Okrepkyi. "Computer optimization of cooling systems 91 for thermoplastics molding." Scientific Bulletin of Ivano-Frankivsk National Technical University of Oil and Gas, no. 2(49) (December 30, 2020): 91–105. http://dx.doi.org/10.31471/1993-9965-2020-2(49)-91-105.
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The work analyses the problem of high-quality cooling of molds for obtaining castings from thermoplastics, which are characterized by significant coefficients of volumetric and linear thermal expansion, the ability to compact in the molten state. The change in the volume of the thermoplastic melt and, accordingly, product quality characteristics primarily depend on the mold temperature mode. The latter provides for the required temperature, heating rate and cooling rate of the mold. In turn, these parameters partially determine the pressure of the thermoplastic in the working volume. The heating rate and cooling rate of the mold are primarily determined by the dimensions and configuration of the channels of the mold cooling system. Experimental improvement of the design of the cooling system channels requires significant expenditures of materials, time and money. The authors of the article proposed a method for optimizing the design of a mold cooling system using computer technologies for 3D modeling in the Solid Works environment and thermodynamic studies using the finite element method in the ANSYS program. In the first part of the work, several versions of virtual models of the main structural parts of a mold for casting a thin-walled real product from a thermoplastic were created: dies, punches and mounting plates. At the same time, the main structural dimensions of the mold were maintained and necessary structural simplifications were made (inscriptions, stamps were removed) in order to save resources when performing thermodynamic studies. The differences between the models were in the different configurations of the water cooling channels - straight, V- and W-shaped. These studies were carried out in the Transient Thermal package. The main task of these studies was to determine the nature of the propagation of thermal fields in the volume of the matrix. Initial data for research - mold temperature, temperature and volumetric supply of coolant in all experiments are the same. The results of computer studies have shown that in a cooling system with W-shaped channels, the cooling of a thermoplastic casting occurs most uniformly, as evidenced by the configuration of thermal fields in the die and the punch. Based on research materials, a mold was made. Test results have confirmed efficiency of computer research in plastic molding technologies.
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Mei, V. C., F. C. Chen, and B. Mathiprakasam. "Comparison of Thermoelectric and Vapor Cycle Technologies for Groundwater Heat Pump Application." Journal of Solar Energy Engineering 111, no. 4 (November 1, 1989): 353–57. http://dx.doi.org/10.1115/1.3268334.
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The performance of a groundwater thermoelectric (TE) heat pump system, based on today’s state-of-the-art TE materials, was calculated and compared with that of a conventional groundwater heat pump under the same water inlet temperature and flow rate. It was found that the TE system was competitive for cooling, particularly for groundwater temperatures below 18° C (64° F). The TE system performed poorly for heating mode operation. A cooling coefficient of performance (COP) of 6.4 could be realized by a properly designed TE system at a groundwater temperature of 13° C (55° F), compared with a COP of 4.35 for a conventional heat pump. For heating mode operation at the same water temperature, the TE system achieved a COP of 1.72, while the conventional heat pump performed at a COP of 3.72. Use of TE systems should be considered in areas where year-round cooling load dominates.
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Ivanov, N. A., D. V. Otmakhov, S. P. Zakharychev, and O. V. Kazannikov. "Development of the design of an internal combustion engine cooling system with a pre-starting heating function." Traktory i sel'hozmashiny 1, no. 1 (2021): 51–56. http://dx.doi.org/10.31992/0321-4443-2021-1-51-56.
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The main topic of the article is the development of an effective design for a pre-starting heating system for an internal combustion engine for conditions of limited power supply. The work to im-prove the design of light wheeled all-terrain vehicles on low pressure pneumatics is done at Pacific National University. Prototypes of light wheeled off-road vehicles are used mainly in agriculture and for forestry production. There are prerequisites for their use in oil and gas fields in the Far North conditions. This vehicle is operated all year round, in the absence of power supply, it is stored in the open air, so the problem of starting a cold engine is quite important, and the topic of creating a design for a pre-starting heating system for an internal combustion engine under conditions of limited or com-plete absence of power supply is relevant. The purpose of the work is to develop and study the efficiency of the pre-starting heating system for an internal combustion engine with liquid cooling for conditions of limited power supply. Our own design of the cooling system with a pre-starting heating function based on a gasoline burner was developed. To assess the efficiency of the engine warm-up process, the circuit was as-sembled on a light wheeled all-terrain vehicle. The experimental studies were carried out to deter-mine the regularity of changes in the temperature of the engine coolant during pre-starting heating at different ambient temperatures. The results of the experiment indicate the high efficiency of the developed system based on a gasoline burner. The average heating rate of the engine coolant during the warm-up process was 2.1 - 2.8 оС per minute, which indicates an intensive pace of pre-starting heating.
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GORDON, GOREN, NOAM EREZ, and GERSHON KURIZKI. "ZENO HEATING AND ANTI-ZENO COOLING BY FREQUENT QUANTUM MEASUREMENTS." International Journal of Quantum Information 07, supp01 (January 2009): 49–62. http://dx.doi.org/10.1142/s021974990900475x.
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We study disturbances of thermal equilibrium between two-level systems (TLS) and a bath by frequent and brief quantum measurements of the TLS energy-states. If the measurements induce either the Zeno or the anti-Zeno regime, namely, the slowdown or speedup of the TLS relaxation, then the resulting entropy and temperature of both the system and the bath are found to be completely determined by the measurement rate, and unrelated to what is expected by standard thermodynamical rules that hold for markovian baths. These anomalies allow for very fast control heating, cooling and state-purification (entropy reduction) of quantum systems much sooner than their thermal equilibration time.
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Arunwattana, Weerawoot. "Heat Pump Design for Simultaneous Cooling Space and Heating Water Coupled with Earth-Tube Heat Exchanger as Secondary Heat Sink." Trends in Sciences 19, no. 6 (February 25, 2022): 2899. http://dx.doi.org/10.48048/tis.2022.2899.
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A heat pump for simultaneous heating and cooling (HPS) is more efficient in energy and beneficial
in use than a reversible heat pump which works in either direction to provide heating or cooling. A HPS is usually coupled with a thermal storage tank for possibly operating in 3 modes: heating mode, cooling mode, and simultaneous heating and cooling mode. To improve the HPS performance in heating mode or cooling mode, the HPS should be installed an auxiliary equipment in order to reject overheat in the system or to absorb supplemental heat into the system. This paper proposed a design of a HPS for cooling space and hot water production coupled with a horizontally shallow earth-tube heat exchanger as secondary heat sink for Thai residences in which the main components in the design are composed of the condenser and the earth tube heat exchanger. The coefficients of performance (COP) of the HPS were evaluated by the experiments. The results showed that it could work the best performance when it worked in simultaneous cooling and heating mode at the water flow rate of 6.0 L/min with the coefficient of performance (COP) of 6.3±3.1 %. The HPS had high efficiency and it worked continuously in cooling mode when it operated in the nighttime with the average COP of 4.3±14.5 %. However, an efficiency of the HPS was declined when heat gain in the conditioned room is significantly increased by high intensity of solar radiation in the daytime with the average COP of 2.5±14.5 %.
HIGHLIGHTS
Energy used for cooling or heating systems such as air-conditioning and hot water production is predominantly effect to total energy use in residential sector in many countries including Thailand
A heat pump for simultaneous heating and cooling (HPS) for cooling space and hot water production coupled with thermal storage tank and a horizontally shallow earth-tube heat exchanger as secondary heat sink were designed for Thai residences
This HPS could work the best performance when it worked in simultaneous cooling and heating mode
For only cooling mode, this HPS worked continuously with high performance when it operated in the nighttime but in the daytime it still worked continuously with lower performance
GRAPHICAL ABSTRACT
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Wells, G. D., A. S. Rodger, R. J. Moffett, G. J. Bailey, and T. J. Fuller-Rowell. "The effects of nitric oxide cooling and the photodissociation of molecular oxygen on the thermosphere/ionosphere system over the Argentine Islands." Annales Geophysicae 15, no. 3 (March 31, 1997): 355–65. http://dx.doi.org/10.1007/s00585-997-0355-0.
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Abstract. In the past the global, fully coupled, time-dependent mathematical model of the Earth's thermosphere/ionosphere/plasmasphere (CTIP) has been unable to reproduce accurately observed values of the maximum plasma frequency, foF2, at extreme geophysical locations such as the Argentine Islands during the summer solstice where the ionosphere remains in sunlight throughout the day. This is probably because the seasonal dependence of thermospheric cooling by 5.3 µm nitric oxide has been neglected and the photodissociation of O2 and heating rate calculations have been over-simplified. Now we have included an up-to-date calculation of the solar EUV and UV thermospheric heating rate, coupled with a new calculation of a diurnally varying O2 photodissociation rate, in the model. Seasonally dependent 5.3 µm nitric oxide cooling is also included. With these important improvements, it is found that model values of foF2 are in substantially better agreement with observation. The height of the F2-peak is reduced throughout the day, but remains within acceptable limits of values derived from observation, except at around 0600 h LT. We also carry out two studies of the sensitivity of the upper atmosphere to changes in the magnitude of nitric oxide cooling and photodissociation rates. We find that hmF2 increases with increased heating, whilst foF2 falls. The converse is true for an increase in the cooling rate. Similarly increasing the photodissociation rate increases both hmF2 and foF2. These changes are explained in terms of changes in the neutral temperature, composition and neutral wind.
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Hung, San Shan, Hsing Cheng Chang, and Chan Ming Liang. "Design of the Liquid-Cooling System for High Power LED Modules Using Taguchi Analysis." Advanced Materials Research 383-390 (November 2011): 6416–21. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.6416.
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To optimize thermal dissipation efficiency for cooling high power LED modules is studied and analyzed using ANSYS CFX software and Taguchi method. In liquid-cooling system, four control factors are tested and compared in order to find the best cooling arrangement that are pump flow rate, fan power, cooling liquid type and k- value of thermal compound. The experimental results show that the importance of these cooling parameters applied to high power LED module are k-value of thermal compound, fan power, liquid type and pump flow rate in sequence. For a constant heating power of 90W from an LED lighting module, an optimal thermal resistance of 0.563K/W is obtained that shows a significant improved result then the conventional LED module’s. It has high potential in future high power LED applications.
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Yam, Ke San, Raja Wahiduzzaman Bin Raja Ismail, Vincent Chieng Chen Lee, and Hyung Chul Jung. "Performance Comparison of Organic Rankine Cycle and Vapour Compression Cycle Hybrid Cooling-Heating System using Subcritical or Supercritical Working Fluid." MATEC Web of Conferences 202 (2018): 02008. http://dx.doi.org/10.1051/matecconf/201820202008.
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This paper presents a mathematical modelling on the evaluation of cooling, heating and power performance of a hybrid system of Organic Rankine Cycle and Vapour Compression Cycle. The system is assumed to be powered through solar parabolic trough collector and is able to generate a cooling power of 10 kW. Refrigerants R134a or R245fa are chosen as the working fluid of the system. The system is constructed using commercial energy modelling tool AspenPlus. Analysis is performed to determine the effect of changing the mass flow rate split ratio on the energy output. The effect of using subcritical and supercritical working fluid is also compared. Particular attention is paid toward the condition where the power output is equivalent to the energy consumption in view of creating a self-powered cooling and heating system. The result shows that the coefficient of performance for system using R245fa is higher compared to that using R134a. However, the system using R134a allows a self-powered cooling and heating system to be achieved to be achieve at a much higher mass split ratio, resulting the system to be 35% more efficient in the performance.
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Chan, Hoy Yen, Saffa Riffat, and Jie Zhu. "Solar Façade for a Combined Heating and Cooling System in London." Applied Mechanics and Materials 284-287 (January 2013): 1409–15. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.1409.
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A combined heating and cooling system was developed and the system performance was simulated by a mathematical model. This is a building integrated system whereby the facade is used as a solar collector. The system consists of two cavities, i.e. the air is heated throughout the Cavity 1 whereas the air in Cavity 2 is cooled via indirect evaporative cooling. The simulation study used weather conditions of London for a south-facing façade with plate area of 40m2; and followed by a simple economic analysis for the system. Space heating is needed for most of the months, however cooling is more favorable for the months of June, July and August. It is estimated that present system is able to give an annual energy saving of 10,877kWh, which is equivalent to 5,874kgCO2/year of emission avoidance. Moreover, it is cheaper compared to the conventional solar flat plate air heaters. For a discount rate of 5% and 30 years of lifetime, the economic analysis found that the total system cost is approximately £4,952, which gives a payback period for less than a year.
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Kowalski, Gregory J., and Mansour Zenouzi. "Selection of Distributed Power-Generating Systems Based on Electric, Heating, and Cooling Loads." Journal of Energy Resources Technology 128, no. 3 (March 8, 2006): 168–78. http://dx.doi.org/10.1115/1.2213275.
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A generalized thermodynamic model is developed to describe combined cooling, heating, and power generating systems. This model is based on reversible power generation and refrigeration devices with practical, irreversible heat exchanger processes. It provides information on a system’s performance and allows easy comparisons among different systems at different loading conditions. Using both the first and second laws as well as the carbon dioxide production rate allows one to make a first-order system assessment of its energy usage and environment impact. The consistency of the exergy destruction rate and the first law performance ensures that the thermodynamic system boundaries are correctly and completely defined. The importance of the total thermal load to the required power ratio (HLRP) as a scaling parameter is demonstrated. A number of trends for limited conditions can be delineated even though the reported results confirmed that generalized trends are not identifiable because of the systems’ complexities. The results demonstrate that the combined vapor compression∕absorption refrigeration has higher first law utilization factors and lower carbon dioxide production rate for systems with high refrigeration to total thermal load ratios for all HLRP values. Fuel cell systems outperform engine systems for large refrigeration load applications. An illustration of combining these results to an economic analysis is presented.
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Chen, Xiu Wen, Pu Yan Zheng, Yan Zhou Yuan, and Guo Xu Chai. "Study on Thermodynamic Evaluation Index of Combined Cooling Heating and Power (CCHP) System." Advanced Materials Research 614-615 (December 2012): 36–40. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.36.
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Combined cooling, heating and power ( CCHP ) system provides three different energy level products. This paper presents four thermodynamic evaluation indexes, such as primary energy rate, exergy efficiency, energy saving rate and energy cascade utilization efficiency. These thermodynamic evaluation indexes are adopted to evaluate four redesign system schemes based on an actual hospital in this paper. Analysis results show that exergy efficiency and energy cascade utilization efficiency, which take exergy value into account, are more reasonable than the others.the others.
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Khaled, Mahmoud, Samer Ali, Hassan Jaber, Jalal Faraj, Rabih Murr, and Thierry Lemenand. "Heating/Cooling Fresh Air Using Hot/Cold Exhaust Air of Heating, Ventilating, and Air Conditioning Systems." Energies 15, no. 5 (March 3, 2022): 1877. http://dx.doi.org/10.3390/en15051877.
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This paper suggests a heat recovery concept that is based on preheating/precooling the cold/hot fresh outside air by means of the relatively hot/cold exhaust air in winter/summer weather conditions. To investigate the feasibility of such a concept, an experimental setup is established to simulate conditions similar to an All-Air HVAC system. The prototype consists of a 6.7-m3 air-conditioned chamber by means of a split unit of 5.3-kW capacity. The heat recovery module consists of a duct system that is used to reroute the exhaust air from a conditioned chamber to flow through the fin side of a fin-and-tube heat exchanger of crossflow type. At the same time, outside, fresh air is flowing through the tube side of the fin-and-tube heat exchanger. A parametric study is performed to assess the amount of heat that can be recovered by varying the mass flow rates on both the duct and heat exchanger sides. The results show that up to 200 W of power can be saved for an exhaust flow rate of 0.1 kg/s and a fresh, outdoor air flow rate of 0.05 kg/s. Environmentally speaking, this leads to a reduction in production of about 1 tons of CO2 per year when the system operates 24 h/day. From an economic point of view, the system is able to return its price after 1.5 years when it is used 24 h per day during hot days at 196-W thermal recovery, whereas it requires at least 6.3 years when it is used during cold days at a 60-W thermal recovery rate, which, in both cases, represents a duration less than the lifespan of an air conditioner.
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Kashif, Muhammad, Muhammad Sultan, and Zahid Mahmood Khan. "Alternative Air-Conditioning Options for Developing Countries." European Journal of Engineering Research and Science 2, no. 1 (January 31, 2017): 76. http://dx.doi.org/10.24018/ejers.2017.2.1.261.
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This study assesses the potential selection of efficient air-conditioning (AC) and cooling systems in order to avoid excess power consumption, mitigation of harmful refrigerants generated by the existing AC systems. Several varieties of active and passive air-conditioning systems i.e. heating ventilating air-conditioning (HVAC), vapor compression air-conditioning (VCAC) conventional direct evaporative cooling (DEC) and indirect evaporative cooling (IEC) and desiccant air-conditioning (DAC) systems are under practice for the cooling and dehumidification. The storage of agricultural products mainly based on product individual characteristics i.e. respiration rate, transpiration rate and moisture content of that product. Variant ambient air conditions and the type of application are the main parameters for the choice of air-conditioning system to get optimum performance. The DAC system subsidize the coefficient of performance (COP) in humid regions, coastal ranges of developing countries e.g. Karachi and Gawadar (Pakistan) with hot humid climatic conditions. In similar way, hottest regions of the country such as Sibbi, Jacobabad and Multan perform better results when incorporates with M-cycle evaporative cooling system. Variation in ambient air conditions directly affect the cooling load and the choice of sustainable air-conditioning system
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Kashif, Muhammad, Muhammad Sultan, and Zahid Mahmood Khan. "Alternative Air-Conditioning Options for Developing Countries." European Journal of Engineering and Technology Research 2, no. 1 (January 31, 2017): 76–79. http://dx.doi.org/10.24018/ejeng.2017.2.1.261.
Full textAbstract:
This study assesses the potential selection of efficient air-conditioning (AC) and cooling systems in order to avoid excess power consumption, mitigation of harmful refrigerants generated by the existing AC systems. Several varieties of active and passive air-conditioning systems i.e. heating ventilating air-conditioning (HVAC), vapor compression air-conditioning (VCAC) conventional direct evaporative cooling (DEC) and indirect evaporative cooling (IEC) and desiccant air-conditioning (DAC) systems are under practice for the cooling and dehumidification. The storage of agricultural products mainly based on product individual characteristics i.e. respiration rate, transpiration rate and moisture content of that product. Variant ambient air conditions and the type of application are the main parameters for the choice of air-conditioning system to get optimum performance. The DAC system subsidize the coefficient of performance (COP) in humid regions, coastal ranges of developing countries e.g. Karachi and Gawadar (Pakistan) with hot humid climatic conditions. In similar way, hottest regions of the country such as Sibbi, Jacobabad and Multan perform better results when incorporates with M-cycle evaporative cooling system. Variation in ambient air conditions directly affect the cooling load and the choice of sustainable air-conditioning system
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Todorov, Oleg, Kari Alanne, Markku Virtanen, and Risto Kosonen. "Aquifer Thermal Energy Storage (ATES) for District Heating and Cooling: A Novel Modeling Approach Applied in a Case Study of a Finnish Urban District." Energies 13, no. 10 (May 14, 2020): 2478. http://dx.doi.org/10.3390/en13102478.
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Aquifer thermal energy storage (ATES) combined with ground-source heat pumps (GSHP) offer an attractive technology to match supply and demand by efficiently recycling heating and cooling loads. This study analyses the integration of the ATES–GSHP system in both district heating and cooling networks of an urban district in southwestern Finland, in terms of technoeconomic feasibility, efficiency, and impact on the aquifer area. A novel mathematical modeling for GSHP operation and energy system management is proposed and demonstrated, using hourly data for heating and cooling demand. Hydrogeological and geographic data from different Finnish data sources is retrieved in order to calibrate and validate a groundwater model. Two different scenarios for ATES operation are investigated, limited by the maximum pumping flow rate of the groundwater area. The additional precooling exchanger in the second scenario resulted in an important advantage, since it increased the heating and cooling demand covered by ATES by 13% and 15%, respectively, and decreased the energy production cost by 5.2%. It is concluded that dispatching heating and cooling loads in a single operation, with annually balanced ATES management in terms of energy and pumping flows resulted in a low long-term environmental impact and is economically feasible (energy production cost below 30 €/MWh).
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Lee, Moo-Yeon, Kunal Sandip Garud, Han-Byeol Jeon, and Ho-Seong Lee. "A Study on Performance Characteristics of a Heat Pump System with High-Pressure Side Chiller for Light-Duty Commercial Electric Vehicles." Symmetry 12, no. 8 (July 27, 2020): 1237. http://dx.doi.org/10.3390/sym12081237.
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One of barriers for the present heat pump system’s application in an electric vehicle was decreased performance under cold ambient conditions due to the lack of evaporating heat source. In order to improve the heat pump’s performance, a high-pressure side chiller was additionally installed, and the tested heat pump system was modified with respect to refrigerant flow direction along with operating modes. In the present work, the performance characteristics of the heat pump system with a high-pressure side chiller for light-duty commercial electric vehicles were studied experimentally under hot and cold ambient conditions, reflecting real road driving. The high-pressure side chiller was located after the electric compressor so that the highest refrigerant temperature transferred the heat to the coolant. The controlled coolant with discharged refrigerant from the electric compressor was used to heat up the cabin, transferring heat to the inlet air like the internal combustion engine vehicle’s heating system, except with unused engine waste heat. In the cooling mode, for the exterior air temperature of 35 °C and interior air temperature of 25 °C, cooling performance along with the compressor speed showed that the system efficiency decreased by 16.4% on average, the cooling capacity increased by 8.0% on average and the compressor work increased by 27% on average. In heating mode, at the exterior and interior air temperature of −6.7 °C, compressor speed and coolant temperature variation with steady conditions were tested with respect to heating performance. In transient mode, to increase coolant temperature with a closed loop from −6.7 °C, tested system characteristics were studied along the compressor speed with respect to heating up the cabin. As the inlet air of the HVAC was maintained at −6.7 °C, even though the heat-up rate of the cabin room was a little slow, the cabin temperature reached 20 °C within 50 min and the temperature difference with the ambient air attained 28.7 °C.
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Fu, Jin Xiang, Xin Chun Zhang, and Peng Fei Yu. "Study on Shortcut and Simultaneous Nitrification and Denitrification under Low Temperatures." Advanced Materials Research 610-613 (December 2012): 2047–52. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.2047.
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This paper studies the impact of cooling and warming on shortcut and simultaneous nitrification and denitrification under low temperature. The results show that the effluent concentration of NH4+-N and TN gradually increased, the nitrite accumulation rate decreased when DO was 0.3~0.5 mg•L-1, sludge return ratio was 300%, PH was 7.5~8.5, temperature dropped from 15 °Cto 8°C. From 10°C to 8°C in cooling, the average nitrite accumulation rate was 58.17% in A (HRT=24h) reactor. During the system heating process, treatment effect of the system gradually changed for the better. From 12°C to 15°Cin heating process, the average nitrite accumulation rate was 74.39% in B (HRT=48h) reactor. The system treatment effect in B reactor was better by contrasting A and B reactors, therefore, we can increase HRT to reduce the adverse effects on the system due to the temperature decreases to enhance TN removal effect of system.
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Cammarata, G., A. Fichera, L. Mammino, and L. Marletta. "Exergonomic Optimization of an Air-Conditioning System." Journal of Energy Resources Technology 119, no. 1 (March 1, 1997): 62–69. http://dx.doi.org/10.1115/1.2794224.
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In this paper, exergonomic theory is applied to an air-conditioning system for optimization purposes. The investigation is addressed to an all-air system with air recirculation, The thermodynamic cycle includes a mixing plenum, a cooling and heating coil, chiller, and heater. The thermodynamic model is stated according to recent formulations of exergy for moist air streams, while the economic model is based on cost balance equations and real cost data for mechanical equipment. The objective function to minimize includes the following decision variables: fresh to total air rate, coefficient of performance for the chiller, inlet temperature of water for the cooling and the heating coils, temperature difference of the same streams. For the exergonomic optimization, the authors followed the approach proposed by Tsatsaronis (1984). The optimum configuration is obtained through an iterative procedure aimed at the design improvement. The results show that there is considerable room for improvement with respect to a system based on typical design parameters.
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Sarkar, Jahar, Souvik Bhattacharyya, and Mudali Ramgopal. "Experimental investigation of transcritical CO2 heat pump for simultaneous water cooling and heating." Thermal Science 14, no. 1 (2010): 57–64. http://dx.doi.org/10.2298/tsci1001057s.
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This paper presents the experimental performances of a transcritical CO2 heat pump prototype for simultaneous water cooling and heating applications. System behavior and performances such as cooling capacity, heating capacity, and system coefficient of performance (COP) have been studied experimentally for various operating parameters such as water mass flow rate, water inlet temperature for both evaporator and gas cooler, and expansion valve opening. Performance is also compared with previous test data. Test indicates that the expansion valve opening has a significant effect as well near the full valve closing condition (up to 20?). Study shows that both the water mass flow rate and inlet temperature have significant effect on system performances. Test results show that, at gas cooler pressure of 90 bar, the effect of evaporator water mass flow rate on the system performances is more pronounced (COP increases 0.6 for 1 kg/min.) compared to the gas cooler water mass flow rate (COP increases 0.4 for 1 kg/min.) and the effect of gas cooler water inlet temperature is more significant (COP decreases 0.48 for given ranges) compared to the evaporator water inlet temperature (COP increases 0.43 for given ranges).
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Eswiasi, Adel, and Phalguni Mukhopadhyaya. "Critical Review on Efficiency of Ground Heat Exchangers in Heat Pump Systems." Clean Technologies 2, no. 2 (June 19, 2020): 204–24. http://dx.doi.org/10.3390/cleantechnol2020014.
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Use of ground source heat pumps has increased significantly in recent years for space heating and cooling of residential houses and commercial buildings, in both heating (i.e., cold region) and cooling (i.e., warm region) dominated climates, due to its low carbon footprint. Ground source heat pumps exploit the passive energy storage capacity of the ground for heating and cooling of buildings. The main focus of this paper is to critically review how different construction and operation parameters (e.g., pipe configuration, pipe diameter, grout, heat injection rate, and volumetric flow rate) have an impact on the thermal efficiency of the vertical ground heat exchanger (VGHE) in a ground source heat pump (GSHP) system. The published literatures indicate that thermal performance of VGHEs increases with an increase of borehole diameter and/or pipe diameter. These literatures show that the borehole thermal resistance of VGHEs decreases within a range of 9% to 52% due to pipe configurations and grout materials. Furthermore, this paper also identifies the scope to increase the thermal efficiency of VGHE. The authors conclude that in order to enhance the heat transfer rate in VGHE, any attempt to increase the surface area of the pipe configuration would likely be an effective solution.
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Fang, Yile, Haoran Liu, Yue Wang, Xiangyi Su, Lian Jin, Yanqi Wu, Yan Deng, et al. "Fast and Accurate Control Strategy for Portable Nucleic Acid Detection (PNAD) System Based on Magnetic Nanoparticles." Journal of Biomedical Nanotechnology 17, no. 3 (March 1, 2021): 407–15. http://dx.doi.org/10.1166/jbn.2021.3028.
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Portable nucleic acid detection (PNAD) systems are performed for sample processing, amplification and detection automatically in an individual device realizing "sample in, answer out." For this goal, numerous function modules should be integrated in a diminutive device, in which temperature controller is one of the most important modules. In a nucleic acid detection process, both sample processing and polymerase chain reaction (PCR) require fast and accurate temperature control to increase concentration and purity of the extraction product and to improve amplification efficiency. In this paper, a dual-channel temperature controller for PNAD systems is developed, which contains a printed circuit board (PCB) and an integrated control program with a fast and accurate control strategy. According to the principle of nucleic acid detection based on magnetic nanoparticles, the controller can work in different modes such as high-precision heating control for nucleic acid extraction, rapid thermal cycle control for PCR, and rate adjustable constant heating/cooling control for melting curve. Evaluatively, the average heating/cooling rate of the module can exceed about 6 C/s, while the temperature fluctuation was less than ± 0.1°C, which can meet the demands of PNAD systems very well.
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Ceglia, Francesca, Adriano Macaluso, Elisa Marrasso, Carlo Roselli, and Laura Vanoli. "Energy, Environmental, and Economic Analyses of Geothermal Polygeneration System Using Dynamic Simulations." Energies 13, no. 18 (September 4, 2020): 4603. http://dx.doi.org/10.3390/en13184603.
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This paper presents a thermodynamic, economic, and environmental analysis of a renewable polygeneration system connected to a district heating and cooling network. The system, fed by geothermal energy, provides thermal energy for heating and cooling, and domestic hot water for a residential district located in the metropolitan city of Naples (South of Italy). The produced electricity is partly used for auxiliaries of the thermal district and partly sold to the power grid. A calibration control strategy was implemented by considering manufacturer data matching the appropriate operating temperature levels in each component. The cooling and thermal demands of the connected users were calculated using suitable building dynamic simulation models. An energy network dedicated to heating and cooling loads was designed and simulated by considering the variable ground temperature throughout the year, as well as the accurate heat transfer coefficients and pressure losses of the network pipes. The results were based on a 1-year dynamic simulation and were analyzed on a daily, monthly, and yearly basis. The performance was evaluated by means of the main economic and environmental aspects. Two parametric analyses were performed by varying geothermal well depth, to consider the uncertainty in the geofluid temperature as a function of the depth, and by varying the time of operation of the district heating and cooling network. Additionally, the economic analysis was performed by considering two different scenarios with and without feed-in tariffs. Based on the assumptions made, the system is economically feasible only if feed-in tariffs are considered: the minimum Simple Pay Back period is 7.00 years, corresponding to a Discounted Pay Back period of 8.84 years, and the maximum Net Present Value is 6.11 M€, corresponding to a Profit Index of 77.9% and a maximum Internal Rate of Return of 13.0%. The system allows avoiding exploitation of 27.2 GWh of primary energy yearly, corresponding to 5.49∙103 tons of CO2 avoided emissions. The increase of the time of the operation increases the economic profitability.
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No, Sang Tae, and Jae Yeob Kim. "A Study on the Thermal Load Saving of an University Office Building with Passive Items." Applied Mechanics and Materials 302 (February 2013): 457–61. http://dx.doi.org/10.4028/www.scientific.net/amm.302.457.
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Curtain wall system shows good performance for daylighting and openness, but it also causes deterioration of thermal comfort because it brings too much solar irradiation to interior space. So in this study, to reduce heating and cooling loads, some passive items, such as window-wall ratio, air exchange rate, outdoor louver, and composition of window glass were adopted to a university office building and the monthly heating-cooling loads were evaluated by EnergyPlus simulation. The actual energy usages were compared to loads of simulation data to verify simulation accuracy and real data and simulation result showed good match. As a result, air exchange rate and interior setpoint temperature influenced on thermal loads more than the other passive items.
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Henini, Ghania, Fatiha Souahi, and Ykhlef Laidani. "Development of a Simulation Model for Controlling and Improving the Productivity of Batch Reactors." Polish Journal of Chemical Technology 15, no. 1 (March 1, 2013): 78–87. http://dx.doi.org/10.2478/pjct-2013-0014.
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This paper describes the development of a dynamic simulator model for a jacketed batch reactor equipped with a mono-fluid heating/cooling system. The Mono-fluid flows at constant flow-rate through the jacketed reactor. The heating and cooling are assured respectively by electrical resistance and two plate heat exchangers. A detailed description of the equations leading to the development of simulation model is presented. The model is based on writing the equations of the mass balance and the heat balance for the reactor and the thermal loop in unsteady state. To validate the simulation model, we first studied the thermal behavior of the reaction mixture during heating and cooling, using water as the reaction mixture. We then considered the consecutive chemical reaction of the synthesis of cyclopentanediol from cyclopentadiene by studying the yield of this reaction. The results show that heating the reaction mixture increases significantly the yield of this synthesis reaction.
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Hu, Xian Fang, Yu Yun Li, Yong Ma, Gui Hua Hu, and Qian Tang. "Analysis of Energy and Environmental Benefits about Ground-Source Heat Pump under Heating Conditions in Wuhan Region." Advanced Materials Research 608-609 (December 2012): 974–78. http://dx.doi.org/10.4028/www.scientific.net/amr.608-609.974.
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Based on the heating season testing of ground-source heat pump system (GSHP) in Wuhan, the article discussed the energy efficiency ratio of ground-source heat pump system under the heating conditions. By comparison with conventional chillers & coal-fired boiler system, the system energy savings, environmental benefits and incremental payback period are analysized. There comes to the conclusion that the energy saving rate of the heating season is about 19.74% higher than that of the cooling season, reducing 18.35 kg carbon dioxide emissions, 0.15kg of sulfur dioxide and 0.0743 kg of dust per unit construction area each year. Also this article concludes the annual energy saving rate of ground-source heat pump system equals to that of water-source heat pump, with the payback period 22% longer and the cost-effective ratio 32% higher.
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Mukhtar, Mustapha, Bismark Ameyaw, Nasser Yimen, Quixin Zhang, Olusola Bamisile, Humphrey Adun, and Mustafa Dagbasi. "Building Retrofit and Energy Conservation/Efficiency Review: A Techno-Environ-Economic Assessment of Heat Pump System Retrofit in Housing Stock." Sustainability 13, no. 2 (January 19, 2021): 983. http://dx.doi.org/10.3390/su13020983.
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The world has not been able to achieve minimum greenhouse gas emissions in buildings’ energy consumptions because the energy and emissions optimization techniques have not been fully utilized. Thermal comfort is one of the most important issues for both residential and commercial buildings. Out of the 40% of global energy consumed by buildings, a large fraction is used to maintain their thermal comfort. In this study, a comprehensive review of the recent advancements in building energy conservation and efficiency application is presented based on existing high-quality research papers. Additionally, the retrofit of the heating/cooling and hot water system for an entire community in Cyprus is presented. This study aims to analyze the technical and environmental benefits of replacing existing electric heaters for hot water with heat pump water heating systems and the use of heat pump air conditioners for thermal comfort in place of the existing ordinary air conditioners for space heating and cooling. One administrative building, 86 apartments (including residential and commercial) buildings, and a restaurant building is retrofitted, and the feasibility of the project is determined based on three economic indicators, namely; simple payback period (SPP), internal rate of return (IRR), and net present value (NPV). The electrical energy required by the hot water systems and the heating/cooling system is reduced by 263,564 kWh/yr and 144,825 kWh/yr, respectively. Additionally, the retrofit project will reduce Cyprus’ CO2 emission by 121,592.8 kg yearly. The SPP, IRR, and NPV for the project show that the retrofit is economically feasible.
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Seo, P. K., and Chung Gil Kang. "Microstructural Characterization of Rheology Material Fabricated by Rotational Barrel Type." Materials Science Forum 475-479 (January 2005): 397–400. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.397.
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The new rheology fabrication process has been developed to rheo die casting and rheo forming process. The barrel type equipment, which could continuously fabricate the rheology material, was specially designed to have a function to control cooling rate, shear rate and temperature. During the continuous rotation of barrel with a constant temperature, the shear rate is controlled with the rotation speed. The barrel surface has both the induction heating system and the cooling system to control the temperature of molten metal. By using this system, the effect of the rotation speed and the rotation time on the microstructure was widely examined. The possibility for the rheoforming process was investigated with microstructural characteristic.
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Zhai, Yue, Yubai Li, Yan Li, Wenqi Jiang, and Xuyang Liu. "Research on the Impact Loading and Energy Dissipation of Concrete after Elevated Temperature under Different Heating Gradients and Cooling Methods." Materials 11, no. 9 (September 7, 2018): 1651. http://dx.doi.org/10.3390/ma11091651.
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To provide theoretical basis for fire rescue, post-disaster safety evaluation, and reinforcement of concrete structures, C35 concrete materials are treated with high-temperature heating (200 °C, 400 °C, 600 °C, 800 °C) under two different heating gradients. After natural cooling and water cooling to normal temperature, an impact compression test was carried out at different loading rates using a Split Hopkinson Pressure Bar (SHPB) system with a diameter of 100 mm, and finally the crushed specimens were subjected to a sieving test. The effects of elevated temperatures, cooling methods, heating gradients, and loading rates on the fragment size distribution, fractal characteristics, and energy dissipation of impact-compressed concrete specimens were studied. The results show that with the increase of the loading rate and the rise of the heating temperature, the crushing degree of concrete specimens gradually increases, the average fragment size decreases, and the mass distribution of the fragments move from the coarse end to the fine end. The fragment size distribution of the specimen has obvious fractal characteristics. In addition, its fractal dimension increases with the increase of loading rate and heating temperature, the average size of the specimen fragments decreases correspondingly, and the fracture of the specimen becomes more serious. When the different heating gradients were compared, it was found that the fractal dimension of the specimens subjected to rapid heating treatment was larger than that of the slow heating treatment specimens, and the crushing degree of the specimens with different cooling methods was discrete. By analyzing the energy dissipation of the specimen under different conditions, it is shown that both the fractal dimension and the peak stress increase with the increase of the fragmentation energy dissipation density. It shows that there is a close correlation between the change of fractal dimension and its macroscopic dynamic mechanical properties.
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Wu, Jun W., Eric J. Hu, and Mark J. Biggs. "Low Energy Adsorption Desalination Technology." Advanced Materials Research 347-353 (October 2011): 601–6. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.601.
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Adsorption-based desalination (AD) is attracting increasing attention because of its ability to use low-grade thermal energy to co-generate fresh water and cooling. In this paper, the working principle of the AD technology and the possible operation cycles of AD system have been described. A thermodynamic model has been developed in order to study the operational parameters that influence the fresh water production rate (FWPR) and energy consumption of silica gel based AD system. Water adsorption on the silica gel is modelled using a Langmuir isotherm and the factors studied are the heating and cooling water temperatures, which supply and remove heat from the silica gel respectively, and the set temperature of the evaporator. The result shows that the cooling water temperature has far more significant impact on the both water productivity and energy consumption compared to the heating water temperature. The paper also discusses in detail the impact of evaporator temperature on the thermodynamic cycle when the system is operated in desalination mode only.