Does heat pumps perform energy efficiently as we expected: Field tests and evaluations on various kinds of heat pump systems for space heating

Deng, Jiewen; Wei, Qingpeng; Liang, Muxuan; He, Suqin; Zhang, Hui

doi:10.1016/j.enbuild.2018.10.014

Cited by 70 publications

(17 citation statements)

References 21 publications

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“…where T e and T c are evaporating and condensing temperature in K. Due to the difficulty in monitoring the T e and T c , the values could be reckoned with Equations (7) and 8,…”

Section: Analysis Methodologymentioning

confidence: 99%

What Is the Main Difference between Medium-Depth Geothermal Heat Pump Systems and Conventional Shallow-Depth Geothermal Heat Pump Systems? Field Tests and Comparative Study

Deng

Wei

et al. 2019

Applied Sciences

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Recently, the medium-depth geothermal heat pump systems (MD-GHPs) have been applied for space heating in China. Theoretically, the MD-GHPs use deep borehole heat exchangers (DBHEs) to extract heat from the medium-depth geothermal energy with the depth of 2~3 km, thus, improving the energy performance of whole systems obviously. This paper conducts field tests of nine conventional shallow-depth geothermal heat pump systems (SD-GHPs) and eight MD-GHPs to analyze the energy performance of heat pump systems, as well as heat transfer performance of ground heat exchangers. Then the comparative studies are carried out to analyze the difference between these two ground coupled heat pump systems. Field test results show that the outlet water temperature of DBHEs in MD-GHP can reach more than 30 °C with heat extraction of 195.2 kW~302.8 kW per DBHE with a depth of 2500 m, which are much higher than that of SD-GHPs. However, the heat pumps and water pumps in the ground side should be specially designed to fit the high-temperature heat source instead of following operation mode of SD-GHPs. Then with variable speed compressor which has high energy efficiency under a wide range of load rate and compressor ratio, and with the ground-side water pumps which efficiently operate under high water resistance and low flow rate, the COP of heat pumps and COPs of whole systems could reach 7.80 and 6.46 separately. Thus, the advantage of high-temperature heat source could be fully utilized to achieve great energy-saving effects.

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“…where T e and T c are evaporating and condensing temperature in K. Due to the difficulty in monitoring the T e and T c , the values could be reckoned with Equations (7) and 8,…”

Section: Analysis Methodologymentioning

confidence: 99%

What Is the Main Difference between Medium-Depth Geothermal Heat Pump Systems and Conventional Shallow-Depth Geothermal Heat Pump Systems? Field Tests and Comparative Study

Deng

Wei

et al. 2019

Applied Sciences

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“…A research study by Deng et al [14] have carried out field tests and evaluation on 32 heat pump systems used for space heating. The results from this study are interesting as some suggestions made are advantageous to the performance of the heat pump systems.…”

Section: Typical Capital Cost (£)mentioning

confidence: 99%

Air-to-air heat pump: review of recent advances and future potential

2019

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As the demand for energy is increasing and due to more focus on the utilization of low impact energy heat sources, heat pumps are a renewable energy technology that transfers thermal energy from one place to another. Heat pumps are used in various applications such as space heating, space cooling, heating water and many others. Heat pumps have many configurations but in essence they compose of components which are found in all units. The framework for 2030 climate and energy policy has decided that greenhouse emissions must be reduced by 40%. This has therefore, increased the need to utilize low grade energy. Heat pumps have the capability to utilize the upgrade of low grade energy and reuse it within any domestic and industrial application. This paper will explain the working principle of an air-to-air heat pump, describing the different configurations, and evaluate the performance of such systems.

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“…Последовательная и каскадная схемы включения ТНУ на озонобезопасных хладагентах рассмотрены в [11,12]. В [9,13] отмечена перспективность создания теплонасосных установок с двухступенчатым сжатием. В связи с этим авторы настоящей статьи расширили область разработок по исследованию эффективности циклов парокомпрессионных тепловых насосов (ПКТН) со ступенчатым сжатием на определенных рабочих хладагентах.…”

Section: Introductionunclassified

Evaluation of the Energy Efficiency of the Stage Compression Heat Pump Cycle

et al. 2019

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The increase in production and modernization of existing heat pumps are global trends in the development and implementation of heat pump technology. Application of refrigerant with zero potential ozone depletion relative to fluorinetrichloromethane and minimum values of global warming potentials relative to carbon dioxide is environmentally justified in pumps. Prospective are stage compression heat pump units and, also, consecutive and cascade schemes of inclusion which provide higher temperature of the heat carrier in the system of heat supply. Improving the efficiency of the heat pump depends on the perfection of the thermodynamic cycle, on the choice of the working agent and on the quality of the operation of the unit in off-design conditions of a temperature mode. The article presents the results of a study of the performance of stage compression heat pump. The concepts of application of the heat pump of two-stage compression of the working agent are formulated. Experimental researches has been fulfilled with the use of Altal GWHP26Н heat pump of 24.2 kW capacity operating on an eco-friendly refrigerants of R134a and R600а. The results of comparative calculation of performance indicators of one- and two-stage heat pumps are presented. Various schemes of realization of a thermodynamic cycle for one- and two-stage heat pumps are considered. The efficiency of two-stage heat pumps that implement thermodynamic cycle with supercooling of condensate and regeneration of steam heat of the working agent has been proved. The two-stage thermodynamic cycle of the heat pump is accompanied by minimal losses during the throttling of the liquid refrigerant, and it solves the problem of useful heat use to increase the temperature of the heated coolant for heating and hot water supply systems. Steam regeneration of the working agent at the outlet from the evaporator through the use of regenerative heat exchanger also provides the additional effect of minimization of thermodynamic losses and improving efficiency of cycles with vapor compression heat pumps in the conditions of large temperature differences in the evaporator and the condenser.

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Does heat pumps perform energy efficiently as we expected: Field tests and evaluations on various kinds of heat pump systems for space heating

Cited by 70 publications

References 21 publications

What Is the Main Difference between Medium-Depth Geothermal Heat Pump Systems and Conventional Shallow-Depth Geothermal Heat Pump Systems? Field Tests and Comparative Study

What Is the Main Difference between Medium-Depth Geothermal Heat Pump Systems and Conventional Shallow-Depth Geothermal Heat Pump Systems? Field Tests and Comparative Study

Air-to-air heat pump: review of recent advances and future potential

Evaluation of the Energy Efficiency of the Stage Compression Heat Pump Cycle

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