• Title/Summary/Keyword: Hybrid heat exchanger

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Simulation of Compression/Absorption Hybrid Heat Pump System using Industrial Wastewater Heat Source (산업폐수열원 이용 증기압축식/흡수식 하이브리드 히트펌프 시스템의 시뮬레이션)

  • Baik Young-Jin;Park Seong-Ryong;Chang Ki-Chang;Ra Ho-Sang
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.12
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    • pp.1117-1125
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    • 2004
  • In this study, in order to utilize the waste heat of industrial wastewater in the range of the relatively low temperature of 40~5$0^{\circ}C$ as a heat source, a hybrid heat pump system was considered by computer simulation method. In the simulation, an absorber, desorber and solution heat exchanger were modelled by UA values while a compressor and pump performance were specified by an isentropic efficiency. Simulation results show that the performance of hybrid heat pump can be up to 80% higher than that of conventional R134a heat pump when it makes a process hot water of 9$0^{\circ}C$ while the wastewater is cooled down to 2$0^{\circ}C$. As the absorber pressure increases, the system performance and deserter pressure increase with a favorable effect of a compressor discharge gas temperature drop.

Study on Heating Performance of Hybrid Heat Pump System Using Geothermal Source and Solar Heat for Protected Horticulture (시설원예용 지열 및 태양열 이용 하이브리드 히트펌프 시스템의 난방성능에 관한 연구)

  • Jeon, Jong Gil;Lee, Dong Geon;Paek, Yee;Kim, Hyung Gweon
    • Journal of the Korean Solar Energy Society
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    • v.35 no.5
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    • pp.49-56
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    • 2015
  • In this study a hybrid heating system based on geothermal source and solar heat was developed in order to save energy for greenhouse heating and its field performance was evaluated. Developed system are composed of following parts: water tank, heat exchanger, heat pump, fan coil unit and heat storage unit. The working performance test was carried out in a greenhouse cultivating oriental orchids being managed by $23^{\circ}C$. Field performance test results showed that average heating coefficient of performance ($COP_h$) was 3.4 for the period from mid-January to mid-March 2013. Heating coefficient of performance ($COP_h$) of developed hybrid heat pump system was more sensitive to water tank temperature than outside air temperature. This study showed that developed hybrid heat pump system has a potential to save the heating costs up to 91% compared to conventional agricultural oil heaters.

A Study on the Performance Evaluation of Hybrid Energy System with Geothermal and Solar Heat Sources (지열-태양열원 복합시스템의 성능평가에 관한 연구)

  • Hwang In-Ju;Woo Nam-Sub;Lee Hong-Chul
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.3
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    • pp.279-286
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    • 2006
  • The present study concerns the annual performance evaluation of a hybrid-renewable energy system with geothermal and solar heat sources for hot water, heating and cooling of the residential buildings. The hybrid energy system consists of ground source heat pump of 2 RT for cooling, solar collectors of $4.8m^2$, storage tank of 250 liters and gas fired backup boiler of 11.6 kW. The averaged coefficients of performance of geothermal heat pump system during cooling and heating seasons are measured as 4.1 and 3.5, respectively. Also solar fraction for hot water is measured as 35 percent. Overall, the results shows that the hybrid-renewable energy system satisfactorily operated under all climatic conditions.

Evaluation on in-situ Heat Exchange Efficiency of Energy Slab According to Pipe Materials and Configurations (파이프 재질 및 형태에 따른 에너지 슬래브의 현장 열교환 성능 평가)

  • Lee, Seokjae;Oh, Kwanggeun;Han, Shin-in;Park, Sangwoo;Choi, Hangseok
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.13 no.4
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    • pp.1-7
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    • 2017
  • The energy slab is a ground coupled heat exchanger equipped in building slab structures, which represents a layout similar to the horizontal ground heat exchanger (GHEX). The energy slab is installed as one component of the floor slab layers in order to utilize the underground structure as a hybrid energy structure. However, as the energy slab is horizontally arranged, its thermal performance is inevitably less than the conventional vertical GHEXs. Therefore, stainless steel (STS) pipes are alternatively considered as a heat exchanger instead of high density polyethylene (HDPE) pipes in order to enhance thermal performance of GHEXs. Moreover, not only a floor slab but also a wall slab can be utilized as a heat-exchangeable energy slab in order to maximize the use of underground space effectively. In this paper, four field-scale energy slabs were constructed in a test bed, which consist of the STS and HDPE pipe, and a series of thermal response tests (TRTs) was conducted to evaluate relative heat exchange efficiency per unit pipe length according to the pipe material and the configuration of energy slabs. The energy slab equipped with the STS pipe shows higher thermal performance than the energy slab with the HDPE pipe. In addition, thermal performance of the wall-type energy slab is almost equivalent to the floor-type energy slab.

An experimental study on performance evaluation for development of compact steam unit applied with hybrid plate heat exchanger (하이브리드 판형 열교환기 적용 컴팩트 스팀 유닛 개발을 위한 성능 평가에 관한 실험적 연구)

  • Park, Jae-Hong;Cho, Sung-Youl;Lee, Jun-Seok;Lee, Sang-Rae;Kim, Seung-Hyun;Lim, Gye-Hun;Seo, Jung-Wan;Kim, Jeung-Hoon
    • Journal of Advanced Marine Engineering and Technology
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    • v.41 no.4
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    • pp.296-301
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    • 2017
  • In various industrial places such as power generation plants, petrochemical and unit factories, the demands of systems that produce hot water by utilizing wasted or surplus steam have been increased. Compact steam unit(CSU) is a system that can meet these demands and produce hot water by using surplus or wasted steam, and it is also one of the good solutions in view of energy reuse. The new CSU with a capacity of 1,600 kW was developed with a hybrid plate heat exchanger of which thermal performances are better than a conventional plate heat exchanger, an improved temperature control valve, a user-friendly control system, and other components in this study. The purpose of this study was to obtain performance data of the new CSU through various experiments and utilize them for the CSU commercialization. The experimental results show that heat balances between the hot side(steam) and the cold side(cold water) were within ${\pm}0.77%$, and the fluctuations of outlet temperature of the secondary side which are one of the most important evaluation factors in the CSU were $(0{\sim}0.3)^{\circ}C$.

Numerical Analysis on Heat Gain of Liquid from Ambient Air with Various Fin Heights and Pitches of Fin-and-Tube Heat Exchanger in Hybrid Solar Collector (핀-튜브 열교환 구조를 갖는 복합집열기에서 핀 높이 및 간격에 따른 공기열 이용 액체 가열 성능에 관한 수치해석 연구)

  • Choi, Hwi-Ung;Fatkhur, Rokhman;Lyu, Nam-Jin;Yoon, Jung-In;Son, Chang-Hyo;Choi, Kwang-Hwan
    • Journal of the Korean Solar Energy Society
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    • v.36 no.3
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    • pp.53-61
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    • 2016
  • Solar assisted heat pump system uses solar thermal energy as a heat source of evaporator of heat pump. So, COP can be enhanced as well as collector efficiency. For improving performance of this system, some research about hybrid solar collector that has fin-and-tube heat exchanger has been conducted. This collector can get a thermal energy from ambient air for liquid heating, so heated liquid can be used as a heat source of evaporator in heat pump even the solar radiation is not enough. In this study, numerical analysis was conducted for confirming heat gain of liquid according to fin height and pitch of fin-and-tube heat exchanger in collector. As a result, higher heat gain was obtained on lower fin height and narrow fin pitch, but the pressure drop also increased with increment of heat gain. Thus the JF factor considering both heat transfer enhancement and pressure drop was investigated and the maximum value was shown when the fin height and pitch were 40mm and 45mm. So it is considered that this installation condition has a highest heat transfer improvement when comparing with pressure drop. However heat gain of liquid at this condition was less than the other installation conditions of fin pitch on same height. Then, after establishing a proper minimum heat gain of liquid, actual production and experiment of collector will be conducted with fin height and pitch showing maximum JF factor and satisfying selected minimum heat gain of liquid on the basis of results of this study.

Comparative Evaluation of the Cooling and Heating Performance of a $CO_2$ Heat Pump System for Vehicles (차량용 이산화탄소 열펌프 시스템의 냉난방 성능 비교평가)

  • Kim, Sung-Chul;Kim, Min-Soo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.2
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    • pp.126-131
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    • 2009
  • A $CO_2$ heat pump system was designed for both cooling and heating in the cabin of electric vehicles, hybrid vehicles or fuel cell vehicles, In this study, the performance characteristics of the heat pump system without any supplementary heating device were analyzed and the heating performance was compared with the cooling performance for various operating conditions. Experiments were carried out by changing the speed of electric drive compressor, the air flow rate of interior heat exchanger and the air inlet temperature and speed of exterior heat exchanger. Therefore, the cooling/heating capacities and the corresponding COPs are quantified. Also, the heat pump system showed an improved performance for the cooling operation and the heating operation. In this study, the experimental results can be used to evaluate the effect of system design changes on system performance as well as the development of a highly efficient heat pump system.

Hybrid thermal seasonal storage and solar assisted geothermal heat pump systems for greenhouses

  • Ataei, Abtin;Hemmatabady, Hoofar;Nobakht, Seyed Yahya
    • Advances in Energy Research
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    • v.4 no.1
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    • pp.87-106
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    • 2016
  • In this research, optimum design of the combined solar collector, geothermal heat pump and thermal seasonal storage system for heating and cooling a sample greenhouse is studied. In order to optimize the system from technical point of view some new control strategies and functions resulting from important TRNSYS output diagrams are presented. Temperatures of ground, rock bed storage, outlet ground heat exchanger fluid and entering fluid to the evaporator specify our strategies. Optimal heat storage is done with maximum efficiency and minimum loss. Mean seasonal heating and cooling COPs of 4.92 and 7.14 are achieved in series mode as there is no need to start the heat pump sometimes. Furthermore, optimal parallel operation of the storage and the heat pump is studied by applying the same control strategies. Although the aforementioned system has higher mean seasonal heating and cooling COPs (4.96 and 7.18 respectively) and lower initial cost, it requires higher amounts of auxiliary energy either. Soil temperature around ground heat exchanger will also increase up to $1.5^{\circ}C$ after 2 years of operation as a result of seasonal storage. At the end, the optimum combined system is chosen by trade-off between technical and economic issues.

Cooling Performance of Cooling Tower-Assisted Ground-Coupled Heat Pump (GCHP) System Applied in Hospital Building (병원 건물에 설치된 냉각탑 병용 지열 히트펌프 시스템의 냉방 성능)

  • Sohn, Byonghu;Lee, Doo-Young;Min, Kyung-Chon
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.12 no.1
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    • pp.7-16
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    • 2016
  • This paper presents the measurement and analysis results for the cooling performance of ground-coupled heat pump (GCHP) system using a cooling tower as a supplemental heat rejector. In order to demonstrate the performance of the hybrid approach, we installed the monitoring equipments including sensors for measuring temperature and power consumption, and measured operation parameters from May 1 to October 30, 2014. The results showed that the entering source temperature of brine returning from the ground heat exchanger was in a range of design target temperature. Leaving load temperatures to building showed an average value of $11.4^{\circ}C$ for cooling season. From the analysis, the daily performance factor (PF) of geothermal heat pumps ranged from 4.4 to 5.2, while the daily PF of hybrid GCHP system varied from 3.0 to 4.0 over the entire cooling season.

Performance Analysis of Hybrid Heat Pump System of the Air-to-Air/Air-to-Water with the Ambient Temperature (외기온 변화에 따른 공기-공기/공기-물 형태로 된 복합형 열펌프 시스템의 성능 특성 분석)

  • 송현갑
    • Journal of Biosystems Engineering
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    • v.25 no.4
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    • pp.273-278
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    • 2000
  • The hybrid heat pump system of the air to air and / or air to water was composed and its COP was analyzed with the ambient temperature on the opened and closed loop system respectively. The results be indicated by the equation(7) that the COP(Coefficient of Performance) of air-source(air to air and / or air-water) heat pump is effected with the ambient air temperature and AVACTHE.(Automatic Variable Area Capillary Type Heat Exchanger) 2. The COP of air-to-water heat pump without AVACTHE decreased in accordance with the ambient temperature decrease, however in case of the heat pump with AVACTHE the COP was maintained at 2.8∼3.0 level when the ambient temperature decrease from -$5^{\circ}C$ to $-11^{\circ}C$. 3. The COP of the air-to-water heat pump operated on the open loop was higher 40∼58% than that of the heat pump operated on the close loop. 4. The lower ambient temperature air effect on the COP of the air-to-air heat pump operated on the semi closed loop could be controlled using the AVACTHE, and at the high ambient air temperature the COP increased using the Bypass circuit.

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