A study on the performance characteristics of a testing facility for a water-to-water heat pump

Amoabeng, Kofi Owura,Lee, Kwang Ho,Choi, Jong Min Elsevier 2018 International Journal of Refrigeration Vol.86 No.-

<P><B>Abstract</B></P> <P>Heat pump testing facility is used to investigate the performance and reliability of a heat pump unit. During the testing period, energy is utilized by the facility mainly through cooling with a refrigeration unit and heating with an electric heater to control and maintain the test conditions of the heat pump unit. However, research study on the energy consumption analysis of the heat pump test facility is rarely found in literature. In this study, the performance characteristics of the testing facility for a water-to-water heat pump are investigated according to the variation of heat pump capacity and COP in both cooling and heating operating modes. The objective is to analyze the energy consumption of the test facility used to investigate the performance of a water-to-water heat pump unit. The analysis of experimental test results showed that the total energy consumption rate of the heat pump test facility increased as capacity and COP of heat pump increased in both cooling and heating modes. However, the increment according to COP variation was smaller than capacity variation. Also, the total energy consumption rate of the testing facility was about ten times more than the energy consumption rate of the heat pump unit.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The performance characteristics of a water-to-water heat pump test facility were investigated. </LI> <LI> Experiments were performed with the variation in capacity and COP of heat pump. </LI> <LI> The study was conducted in both heating and cooling operating modes of heat pump unit. </LI> <LI> The energy consumption of the water-to-water heat pump test facility was analyzed. </LI> </UL> </P>

Energy saving potentials from the application of heat pipes on geothermal heat pump system

Lim, Hyunjeong,Kim, Chanjoong,Cho, Yeonjoo,Kim, Minsung Elsevier 2017 Applied thermal engineering Vol.126 No.-

<P><B>Abstract</B></P> <P>A ground-loop heat exchanger is one of the key components to collect low grade ground heat for a ground source heat pump system. A typical ground source heat pump consists of a refrigerant loop operated by a compressor and a geothermal brine loop operated by a circulation pump. Although ground source heat pumps are known as one of the most efficient HVAC devices, their performance still need to be improved since the energy consumption by the peripherals like the circulation pump are considerable and estimated more than 10% of the total electricity input. In order to reduce the ground circulation energy, a variety of researches such as direct expansion geothermal heat pumps are studied, but no apparent performance improvement was found due to other negative effects like the increase of pressure drop in the ground loop. Geothermal heat pipe can be a good alternative to replace ground-loop heat exchanger for heating purpose. The energy saving potential using heat pipe as ground heat exchanger was investigated by comparing the energy consumption and COP of three types ground source heat pump. As a result, energy consumption for heating in Seoul by 10.3% than direct expansion ground source heat pump and 21.1% than secondary loop ground source heat pump. Therefore, ground source heat pump with geothermal heat pipe can be a suitable choice to save energy in a cold region.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The characteristics of vertical closed-loop ground source heat pumps were compared in a typical type, direct expansion type, and heat pipe type, respectively. </LI> <LI> The model to estimate ground temperature along the depth was improved reflecting the influence of local and seasonal climate. </LI> <LI> Annual performances of the three different types of ground source heat pumps were evaluated for Anchorage, Ottawa and Seoul. </LI> <LI> Circulation pumps for ground-loop heat exchanger are a main reason for poor performance at part-load operation. </LI> </UL> </P>

공기열원 히트펌프 융복합시스템의 최적제어를 위한 해석적 연구: 부하율 및 펌프유량에 따른 시스템 성능검토

채수원,배상무,남유진 대한설비공학회 2022 설비공학 논문집 Vol.34 No.11

융복합시스템은 구성요소가 다양하여 건물의 냉난방 부하를 정확하게 예측하고 효율적인 운전수법을 마련하는 것이 필요하다. 본 연구에서는 축열-히트펌프 시스템의 기간 및 온도에 따른 운전계획을 수립하고 정유량 시스템의 성능을 평가 후 공통 주요 변수인 실내외 열교환기의 순환수 유량 변화에 따른 성능 분석을 수행하여 다음의 결론을 얻었다. (1) 정유량 융복합시스템에서, 히트펌프를 직접 이용한 난방운전의 히트펌프 COP는 외기온도보다 난방부하에 의존하였으나 냉방운전의 경우 냉방부하가 증가함에도 불구하고 외기온도가 높아짐에 따라 히트펌프 COP가 감소하는 것을 확인할 수 있었다. 한편, 축열조를 이용한 냉난방 운전의 경우 히트펌프 COP는 외기온도보다 축열부하에 의존하였다. 축열조를 이용한 난방운전은 외기온도가 높아짐에도 축열부하가 감소할 경우 히트펌프 COP가 감소하였으며 냉방운전의 경우 외기온도가 낮아짐에도 축열부하가 감소하여 히트펌프 COP가 크게 감소함을 확인하였다. 냉난방 및 축열 부하감소로 인해 히트펌프 COP가 감소할 경우, 순환수 유량을 낮춘다면 히트펌프의 입출수 차온을 증가시켜 히트펌프 COP를 개선할 수 있을 것으로 사료된다. (2) 정유량 융복합시스템의 성능해석 결과, 열교환에 불리한 조건의 기후일수록 축열조를 이용한 냉난방 시스템은 히트펌프를 직접 이용한 냉난방 운전과 비교하여 히트펌프 성능 면에서 상대적 우위를 가질 수 있었다. 하지만 냉난방 부하가 크게 요구되지 않는 환경에서는 히트펌프를 직접 이용한 냉난방 성능이 상대적 우위에 있음을 확인하였다. 이것은 건물의 용도 및 에너지 사용량, 공기열원의 상태에 따라 효율적인 운전수법을 마련한다면 융복합시스템의 용량 최적화 구현이 가능하다는 것을 시사한다. (3) 실내외 열교환기의 순환수 유량을 히트펌프 정격유량 이상으로 증가시킬 경우 히트펌프 유닛의 채열량이 감소하고 압축기의 소비동력이 증가하여 히트펌프 COP가 미소하게 감소함을 확인하였다. 순환수 유량을 FRR 1.00에서 FRR 0.65로 감소시킬 경우 축열조 이용 난방운전의 시스템 COP는 3%, 냉방운전의 경우 4% 증가하였다. 또한 히트펌프를 직접 이용한 난방운전의 시스템 COP는 5%, 냉방운전의 경우 7% 증가하였다. 그러나 순환수 유량 감소로 인해 히트펌프 입출수 차온이 지나치게 증가할 경우 압축기 입출구의 압력이 증가하여 히트펌프 성능이 일시적으로 저하됨을 확인하였다. 본 연구에서는 태양광열, 공기열원 히트펌프 융복합시스템의 운전수법과 순환수 유량별 성능해석을 실시하였다. 결론적으로 실내외 열교환기의 입출수 차온과 공기열원의 상태에 따른 시스템 성능을 고려하여 축열조 이용률을 결정한다면 압축기의 소비동력을 감소시킴과 동시에 쾌적한 실내 열환경을 제공할 수 있을 것이다. 또한, 다양한 조건에서의 축열조 부하와 실내 부하의 변동에 따른 시스템 COP 값을 학습데이터로 마련한 후 인공신경망 모델을 통해 높은 시스템 COP에 대응하는 순환수의 유량을 예측하여 융복합시스템의 순환수 유량을 제어한다면 추가적인 에너지절감의 가능성을 높일 수 있을 것으로 기대된다. Since an integrated system has various components, it is difficult to accurately predict heating and cooling loads of a building and apply an efficient operation method. In this paper, the operation method of a constant flow rate system for efficient system operation of an integrated system based on photovoltaic-thermal and air source heat pump was established and system performance according to flow rate was evaluated. In the case of heating and cooling operation using a heat storage tank in an integrated system, the heat pump COP depended on heat storage load rather than outside temperature. The heat pump COP of the heating operation using a heat pump was dependent on the heating load rather than the outside temperature. In the case of a cooling operation using a heat pump, the heat pump COP decreased as the outside temperature increased despite an increased cooling load. If the pump's flow rate is increased to more than the rated flow rate of the heat pump, the heat exchange rate of the heat pump decreases while the power consumption of the compressor increases, thereby slightly reducing the COP of the heat pump. As a result of performance analysis according to operation method and pump’s flow rate, it is possible to reduce power consumption of a heat pump and provide a comfortable indoor environment.

냉동/냉장/냉난방 일원화 고효율 히트펌프 시스템 개발

정현준(Hyun Joon Chung),김용찬(Yongchan Kim) 대한설비공학회 2018 대한설비공학회 학술발표대회논문집 Vol.2018 No.6

Freezing, refrigerating, cooling and heating loads occurs at the same time in the supermarket, convenient store, etc. An all-in-one heat pump were proposed to handle these loads efficiently. The performance characteristics of the all-in-one heat pump were numerically investigated and compared with those of the multi heat pump and dual heat pump. The cooling mode COP of the all-in-one heat pump using R404c was 133.6% and 33.4% higher than those of the multi and dual heat pump, respectively. The cooling mode COP of the all-in-one heat pump using R410a was 146.0% and 40.5% higher than those of the multi and dual heat pump, respectively. The heating mode COP of the all-in-one heat pump using R404c was 63.7% and 6.5% higher than those of the multi and dual heat pump, respectively. The heating mode COP of the all-in-one heat pump using R410a was 67.9% and 9.2% higher than those of the multi and dual heat pump, respectively.

Applicability of thermoelectric heat pump in a dedicated outdoor air system

Cheon, Seong-Yong,Lim, Hansol,Jeong, Jae-Weon Elsevier 2019 ENERGY Vol.173 No.-

<P><B>Abstract</B></P> <P>The main objective of this research is to propose a dedicated outdoor air system assisted by a thermoelectric heat pump, and to evaluate the operating energy performance of the proposed system compared with a reference system. The proposed dedicated outdoor air system consists of an enthalpy wheel, a desiccant wheel, and the thermoelectric heat pump to condition the introduced outdoor air to provide required ventilation air to the conditioned zone at neutral temperature, while the reference system consists of a desiccant wheel, a sensible heat exchanger, a cooling coil, and a regeneration air heater. To develop an empirical model for the thermoelectric heat pump applicable to the energy simulation of the proposed system, a thermoelectric heat pump prototype was built, and its operating data were collected in a fully controlled laboratory environment. By integrating the existing models of each system component used in both dedicated outdoor air systems, detailed energy simulations were performed to compare the energy performance of the proposed dedicated outdoor air system with the reference system. The results showed that the proposed system assisted by the thermoelectric heat pump consumed 23% more operating energy than the reference system because of the lower coefficient of performance of the thermoelectric heat pump compared with the conventional vapor compression system. For comparable energy performance, the proposed dedicated outdoor air system should have heat exchange effectiveness values greater than 49% at least at both the process and secondary air channels of the thermoelectric heat pump, and the figure of merit of the thermoelectric modules used in the thermoelectric heat pump should be over 1.35.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A dedicated outdoor air system integrated with a thermoelectric heat pump was proposed. </LI> <LI> A prototype of the thermoelectric heat pump was built to analyze its characteristics. </LI> <LI> The proposed system was analyzed via energy simulation with an empirical model of the thermoelectric heat pump. </LI> <LI> Desirable heat exchange effectiveness and figure of merit of thermoelectric heat pump for energy savings were determined. </LI> </UL> </P>

다중열원 히트펌프 난방 성능에 관한 실험적 연구

김진영(Jinyoung Kim),이민우(Minwoo Lee),김용찬(Yongchan Kim) 대한설비공학회 2019 대한설비공학회 학술발표대회논문집 Vol.2019 No.11

Ground-source heat pumps, also called geothermal heat pumps, show better performance in heating mode than air-source heat pumps owing to higher temperature of the ground heat source. However, the ground temperature decreases progressively in an area where heat extrusion from the ground is much larger than injection into the ground. To prevent this problem, another heat source is necessarily involved in the system. In this study, dual source heat pump which uses secondary heat source as well as ground heat source is presented. To analyze the performance of the dual source heat pump, experiments are conducted and the performance is compared with that of the conventional ground-source heat pump. As a result, the dual source heat pump achieves higher heating capacity in the condenser by 13 to 25 %, and lower ground heat usage in the ‘Evaporator I’ by 43 to 83 % than the ground-source heat pump system. In addition, the dual source heat pump achieves 1 to 7 % higher COP than the ground-source heat pump system.

Heat Pump에 Vapor Injection 적용 시 기대되는 성능향상 Potential 연구

김모세(Mo Se Kim),김민수(Min Soo Kim) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.6

Improving the efficiency of the heating equipment of an electric vehicle is one of the most important problems for supplying the electric vehicles to the public. An electric vehicle generally shows short driving distance compared to gasoline vehicles and this problem becomes more severe when heating is required. In this reason, saving electric consumption for heating equipment is very important and heat pump is one of the good candidates as an efficient heating solution. However, heat pump generally has insufficient heat capacity in very cold outdoor conditions and the heat capacity of the heat pump should be increased for practical use. Vapor injection is generally used for large capacity heat pump to increase the heat capacity in cold weather conditions. The types of vapor injection technology generally can be divided in two categories; phase separator type and internal heat exchanger type. In this study, the theoretical performance improvement is calculated for the conventional heat pump, internal heat exchanger type vapor injection heat pump and phase separator type vapor injection heat pump.

Simulation on the Performance of Carbon Dioxide and Hydrocarbon Heat Pumps for Moderate to High Temperature Heating

백영진,김민성,나호상 대한설비공학회 2014 International Journal Of Air-Conditioning and Refr Vol.22 No.1

In order to compare the performance of the carbon dioxide, propane and isobutane heat pumps formoderate to high temperature heating, the three heat pump cycles were optimized using a simulationmethod. To fairly compare the performance of the cycles by using different working fluids,each cycle was optimized from the viewpoint of heating COP by two design parameters. The first is the gas cooler (or condenser) exit temperature and the other is the ratio of the overall heatconductance of the gas cooler to the combined overall heat conductance of the gas cooler and theevaporator. The inlet and outlet temperatures of secondary fluid of the gas cooler (or condenser)were fixed at 40/90°C and 40/150°C. The heat source inlet temperature was fixed at 10°C. The°ow rates of both the heat source and the heat sink were also fixed. The results shows that thehydrocarbon heat pumps have 11–17% higher heating COP than carbon dioxide heat pump underthe simulation conditions considered in the present study. However, for a high temperatureheating, even though the isobutane heat pump shows the best performance, the carbon dioxideheat pump looks promising due to hydrocarbon heat pumps' high compression ratio.

난방 및 급탕 겸용 히트펌프의 바닥 난방 및 공기 난방 방식에 따른 에너지 성능 비교

조수영(Su-Young Jo),김범준(Beom-Jun Kim),동혜원(Hye-Won Dong),정재원(Jae-Weon Jeong) 대한설비공학회 2021 대한설비공학회 학술발표대회논문집 Vol.2021 No.6

Recently, in order to reduce the energy used in buildings, not only energy regulations for new buildings but also energy performance improvement policies for existing buildings are being promoted. Among energy performance improvement technologies, the heat pump, which is a major technology, is suitable for use as an integrated system because it is capable of cooling, heating, and hot water supply with a single device. Therefore, in this study, energy consumption for air heating and floor heating was compared because the capacity of the heat pump varies depending on the heating method. At this time, the case of using a single heat pump and a case of using a binary heat pump were analyzed. . In this study, a simulation was performed on the case of supplying winter heating and hot water to the integrated system, and the cases presented for comparative analysis were classified into a total of 4 cases according to the heating method and the type of heat pump. As a result of the simulation, it was found that energy savings of 8.15% were high in the case of air heating by using a single heat pump and by using a binary heat pump in the case of floor heating by 4.14% according to the heating method.

Performance investigation of a novel calorimeter for a heat pump system according to flow loops

Kofi Owura Amoabeng,이광호,JONGMIN CHOI 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.4

Heat pumps cover a wide range of heating and cooling applications owing to their means of drawing out heat from ground, air and water at low temperature. In order to acquire performance data for heat pump certification and rating, the calorimeter is used in measuring the heat pump. In conventional approach of measuring the heat pump with standard test conditions, a great amount of energy is used in the calorimeter for cooling and heating. Using innovative ways to enhance the calorimeter performance is significant for energy and cost savings. Therefore, a novel calorimeter was developed for heat pump measurement. Two different flow loop configurations, specified as cases (1) and (2) were adopted. In the case (1), secondary fluid flow through the heat recovery unit was directly from heat pump test unit heat exchanger while in case (2), secondary fluid flow through heat recovery unit was from constant temperature water bath directly. The energy usage of the novel calorimeter based on the impact of each configuration was analyzed. Experiments were conducted using a water-to-water heat pump unit in heating and cooling approach with variation in operating conditions. Energy analyses based on test data indicated that energy reduction of the novel calorimeter was at least 72 % for heating and 69 % for cooling in relation to energy used in conventional calorimeter. Moreover, for novel calorimeter, case (1) resulted in energy savings of at least 9.1 % for cooling and 13 % for heating in relation to case (2). However, for heat pump units with very low capacities, tests measurements were executed using case (2) configuration because the tests in case (1) resulted in large thermal fluctuations such that the steady operating conditions of the water setpoint temperatures at inlet to the indoor and outdoor heat exchangers of the test unit were unattainable.