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The paper presents relevant information about the working principle of the geothermal heat pumps and a study, based on an original computer simulation, analysing the influences of the working conditions on the heat pump performances. After presenting some basic considerations about the geothermal energy and about the heat pumps working principle, t...
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... The model refers to both the air side and the PCM side and describes both phases of cold accumulation and of cold discharge. This study is continuing previous concerns in the field of energy efficiency at the Technical University of Cluj-Napoca [22][23][24][25][26][27][28][29]. ...
The study presents a numerical analysis of the flow and heat transfer on a latent heat storage device based on a phase change material (PCM) encapsulated in spherical shells. This kind of heat storage system is designed for passive cooling in air conditioning applications by cold accumulation through the solidification of PCM during the night and by cold discharge through the melting of PCM during the day. The numerical analysis is taking into consideration both the PCM solidification and melting processes. The geometry of the analysed system was taken from an experiment available in the literature and the obtained results were compared with those of the experiment. The developed mathematical model proved to be capable to describe the flow and heat transfer in such systems.
... In [2] where determined the average ground temperatures in two locations. In [24] were presented relations between the working conditions and the performances of the heat pump. In [25] where provided preliminary considerations about the ground temperature variation under the influence of a HGC and in [26] were presented general aspects about the parameters of a geothermal heat pump. ...
... °C; -The maximum recorded temperatures in the flow area were higher than the maximum recorded temperatures in the central area at 15 cm with (0-1.7) °C, at 30 cm with (0.6-1.4) °C and at 60 cm with (1.0-1.2) °C; -The maximum recorded temperatures in the return area were higher than the maximum recorded temperatures in the central area at 15 cm with (0.5-0.6) °C, at 30 cm with (0.6-0.7) °C and at 60 cm with (0.5-0.6) °C; -The maximum recorded temperatures in the central area were maintained constant for (29-58) days while the natural temperature variation in the same geographic area does not present any period of constant temperature;-The maximum recorded temperatures in the flow area were maintained constant at 15 cm for(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36) days, at 30 cm for(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) days and at 60 cm for (4-40) days; -The maximum recorded temperatures in the return area were maintained constant at 15 cm for(7)(8)(9)(10)(11)(12)(13) days, at 30 cm for (40-45) days and at 60 cm for (30-48) days;The ground temperature variation around the HGC with both time and position is presented infigure 10.The position axis is associated with the location of the temperature sensors mounted in the ground. The temperature sensor mounted in the central area of the HGC (TC) is located at the position "0". ...
This study presents the results of a 3 year experiment concerning the behavior of a geothermal ground-water heat pump used for heating a small residential house. The study is focused on the one side on the ground temperature variation around the horizontal collector oversized by ≈50%, mounted at 1.7 m depth and on the other side on the working conditions and performances of the heat pump itself. It was highlighted that due to the oversizing of the geothermal collector, the ground temperature did not drop below 2 °C and ground freezing was avoided. The ground temperature recovered each year during the non-heating season. The heat pump coefficient of performance was determined in the range of (3.18–8.59) in different operating periods.
... Heat pump systems are considered as renewable energy technology and they become more and more promising in both residential and commercial applications due to their high utilization efficiency compared to the conventional heating and cooling systems[2]. They are capable to use inexhaustible resources such as air source, geothermal source, waste heat and solar energy, are environmentally-friendly and provide high levels of comfort[2],[3],[4]. The drawback of air source heat pumps is the reduction in efficiency as the outdoor air become colder, resulting in lower heat supply in times when it is most needed. ...
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An air-to water heat pump was implemented in a school placed in rural area near Galati city. This facility was monitored for two years period. The implementation of the heat pump was considered because there is no heating or natural gas network in the village. This study presents an experimental thermo-economic analysis of this type of heat pump, using the results obtained in a cold period of the year. Using the registered values of thermo-electrical parameters by the controller, a medium value of the coefficient of performance of the heat pump was calculated. In the same time, a comparative economic analysis of the heat pump was performed.
Due to the benefits of the recirculating aquaculture system (RAS), many fish farmers are choosing this system. Some farmers chose indoor RAS, where fish tanks are kept inside buildings or greenhouses. Heating the buildings and the makeup water requires a substantial amount of energy since optimum growth temperatures exceed the normal temperature of supply water. In this paper three different heating systems are analyzed: ground source heat pump, natural gas boiler and wood pellet boiler. The annual running cost of the water heating system in both cases (with heat recovery and no heat recovery) is the lowest for the ground source heat pump, followed by the wood pellet boiler and the natural gas boiler.
Based on the technology of heat pumps, a parallel condensing air-source heat pumps water heater systems providing domestic hot water is proposed to improve the energy efficiency of common ASHPWH system. Considering the climate in southern China, two operating modes of system are designed to adapt to the different water temperature conditions. the simulation model was built to analyzed the factors affecting system performance. Taking Changsha, China as an example, the COP and the energy consumption of system in each month are analyzed. We can find that the parallel condensing air-sources heat pumps water heater system can effectively disperse the total heating quantity by steps heating; the average COP in summer mode increases from 5.42 to 6.44, approaching 19.00%; the average COP in winter mode increases from 4.05 to 5.45, approaching 34.68%. The system has excellent energy-saving effect especially in winter.
The manuscript presents results of a 3 years experiment, concerning in the monitoring of working parameters of a ground – water heat pump with horizontal collectors. The measured working parameters of the refrigerant circuit are: evaporating pressure, condensing pressure, superheating temperature, discharge temperature, sub cooling temperature. There were also measured the flow rate and the temperatures on the heating circuit of water and on the horizontal collectors circuit with antifreeze. The methodology of data processing, described in the manuscript, allowed calculation of evaporating temperature and condensing temperature, based on measured corresponding pressures. The main obtained results consist in a complete set of working and performance parameters and their variation in 3 years of operation. Details are presented for operating conditions characteristic for different cases: middle of heating season, end of heating season, middle of non-heating season, beginning of heating season. Some practical conclusions of
the study are also presented in the manuscript. It was indicated how the outside temperature is influencing the values of working and performance parameters, but mainly on the effective number of running periods.
