• Title/Summary/Keyword: heat system

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Performance Analysis of R-1270(Propylene) Refrigeration System Using Internal Heat Exchanger (내부 열교환기를 이용한 R-1270용 냉동시스템의 성능 분석)

  • Ku, Hak-Keun
    • Journal of Power System Engineering
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    • v.18 no.4
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    • pp.36-42
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    • 2014
  • This paper considers the influence of internal heat exchangers on the efficiency of a refrigerating system using R-1270. These internal heat exchangers(liquid-gas or suction-line heat exchangers) can, in some cases, yield improved system performance while in other cases they degrade system performance. A steady state mathematical model is used to analysis the performance characteristics of refrigeration system with internal heat exchanger. The influence of operating conditions, such as the mass flowrate of R-1270, inner diameter tube and length of internal heat exchanger, to optimal dimensions of the heat exchanger is also analyzed. The main results were summarized as follows : the mass flowrate of R-1270, inner diameter tube and length of internal heat exchanger, and effectiveness have the influences on the cooling capacity, compressor work and RCI(Relative Capacity Index) of this system. With a thorough grasp of it is possible to design the R-1270 compression refrigeration cycle using internal heat exchanger.

Study on the Optimum Design of a Heat Pump System Using Solar and Ground Heat (태양열 및 지중열원을 이용한 히트펌프 시스템의 최적이용법에 관한 연구)

  • Nam, Yu-Jin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.6
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    • pp.509-514
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    • 2012
  • In this research, a heat pump system with a heat source network is suggested which utilizes solar heat and ground heat as heat source for cooling and heating. This paper describes the summary of the suggested system and the results of the annual energy simulation. The heating and cooling loads, the electric consumption and the COP were calculated by TRNSYS 16 and evaluated in the cases of different local conditions and different system compositions. In the results, the superiority of the suggested system has been quantitatively evaluated comparing with the conventional heat pump system using one heat source. Furthermore, it was more significant in cold climate, in which the heating COP was 146% increased compared the air source heat pump system, than it in subtropical climate, 119% increased.

A Study of Storage Type Cooling and Heating System by Heat Pipe (히트파이프를 이용한 축열식 냉.난방 시스템에 관한 연구)

  • Kim, Seong-Sil;Harm, Seong-Chol;Lee, Yang-Ho;Choi, Byoung-Youn
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.3-8
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    • 2006
  • The heat pump system is attractive alternatives to conventional heating and cooling systems owing to their higher energy utilization efficiency. The thermal loads of commercial and institutional buildings are generally cooling-dominated. In this study have been developed ice storage type heat pump system for cooling and heating by heat pipe. This system was practiced performance test on evaluation criteria for heat storage systems. Accomplished the actual proof examination and looked into the performance of the system. In this study, measurement and analysis of ice storage type heat pump system for cooling and heating by heat pipe. The heat pump unit COP appears 3.05 for cooling and 4.20 for heating. As a result, the method to energy saving and to using a substitute energy actively that is heat pump cooling & heating system is expected by heat pipe. Thermal storage capacity appears $19.5RTH/m^3$ for cooling.

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Design method of heat storage type ground source heat pump system considering energy load pattern of greenhouse (원예시설의 에너지 부하패턴을 고려한 축열식 지열시스템 설계법에 관한 연구)

  • Yu, Min-Gyung;Nam, Yujin;Lee, Kwang Ho
    • KIEAE Journal
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    • v.15 no.3
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    • pp.57-63
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    • 2015
  • Purpose: Ground source heat pump system has been attracted in the horticulture industry for the reduction of energy costs and the increasing of farm income. Even though it has higher initial costs, if it uses in combination with heat storage, it is able to reduce the initial costs and operate efficiently. In order to have significant effect of heat storage type ground source heat pump system, it is required to design the capacity considering various conditions such as energy load pattern and operating schedule. Method: In this study, we have designed heat storage type ground source heat pump system in 5 cases by the operating schedule, and examined the system to find the most economic and having superb performance regarding the system COP(Coefficient of Performance) and energy consumption, using dynamic energy simulation, TRNSYS 17. Result: Conventional ground source heat pump system has lower energy consumption than heat storage type, but following the result of LCC(Life Cycle Cost) analysis, the heat storage type was more economic due to the initial costs. In addition, it has the most efficient performance and energy costs in the case of the smallest heat storage time.

An Experimental Study on Performance of Paper Heat Exchangers for Exhaust Heat Recovery Ventilation System (폐열회수 환기시스템에 사용된 종이 열교환기의 성능에 관한 실험적 연구)

  • Chung, Min-Ho;Oh, Byung-Kil
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.3
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    • pp.240-246
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    • 2012
  • The supply and use of exhaust heat recovery ventilation system as effective energy saving equipment has been increasing steadily. The exhaust heat recovery ventilation system can be installed at ceiling of balcony or emergency space. However, ventilation system can not be installed at emergency space because where have to remain as empty space by law. Therefore, the proper installation space of ventilation system is needed. In this study, to install heat recovery ventilation system in the light weight wall, thickness of heat exchanger was assembled below 140 mm. One or two paper heat exchangers were installed in the ventilation system. The efficiency of heat recovery was analyzed through performance experiment on case of cooling and heating mode.

Performance of Air Source Heat Pump with a Fiber Belt Heat Regeneration System (섬유벨트 열재생 시스템을 부착한 공기 열원 열펌프의 난방 성능 특성)

  • 유영선;장진택;김영중;강금춘;윤진하;이건중
    • Journal of Biosystems Engineering
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    • v.25 no.5
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    • pp.385-390
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    • 2000
  • The heat pump is one of heating and cooling systems driven by electricity using natural energy as a heat source. The heat pump system was mainly adopted to a cooling system or a refrigeration system. In regions with a large amount of electricity, it is used as a heating system or a heating and cooling system of houses, buildings and agricultural facilities. During cold weather, air source heat pumps do not work well because of some technical problems, such as frosting on evaporator coil when outside air temperature is below -5$^{\circ}C$. In this research, the heat regenerative technology was employed to eliminate the frosting on evaporator coil and improve the COP of the heat pump system. This fiber belt heat regeneration system(FBHRS) has very simple structure consisting of a geared motor and a porous fiber belt passing through alternatively between cold and warm air duct. The laboratory test showed that the heat pump system with a FBHRS yielded an impressive COP higher than 3.5 at the outside air temperature of -7$^{\circ}C$ in heating mode.

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Temperature monitoring and seasonal borehole heat exchange rate characteristics of a geothermal heat pump system (지열 히트펌프 시스템의 계절별 지중 열교환 특성 및 지반내 온도 변화)

  • Shim, Byoung-Ohan
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.06a
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    • pp.452-455
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    • 2007
  • The geothermal heat pump system is designed for cooling and heating for three stories building (2,435 $m^2$) includes total 79 heat pumps. Therefore, the monitoring system is installed for each floor and the data is automatically transmitted to the monitoring system. Heat exchange rate and temperature of a geothermal heat pump system have been monitored for a long period. The seasonal operation of geothermal heat pump shows the different shape of heat exchange rate for cooling and heating. Ground water flow can influence on heat exchange rate and thermal storage of the system. In order to define the hydraulic characteristics and groundwater temperature variation, the relationships among air temperatures, groundwater temperatures, water table, and precipitation are analysed.

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VALIDATION OF A DESIGN CODE FOR SODIUM-TO-SODIUM HEAT EXCHANGERS BY UTILIZING COMPUTATIONAL FLUID DYNAMICS (전산유체역학을 이용한 소듐-소듐 열교환기 설계코드의 검증)

  • Kim, D.;Eoh, J.H.;Lee, T.H.
    • Journal of computational fluids engineering
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    • v.21 no.1
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    • pp.19-29
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    • 2016
  • A Prototype Gen-IV Sodium-cooled Fast Reactor which is one of the $4^{th}$ generation nuclear reactors is in development by Korea Atomic Energy Research Institute. The reactor is composed of four main fluid systems which are categorized by its functions, i.e., Primary Heat Transport System, Intermediate Heat Transport System, Decay Heat Removal System and Sodium-Water Reaction Pressure Relief System. The coolant of the reactor is liquid sodium and sodium-to-sodium heat exchangers are installed at the interfaces between two fluid systems, Intermediate Heat Exchangers between the Primary Heat Transport System and the Intermediate Heat Transport System and Decay Heat Exchangers between the Primary Heat Transport System and the Decay Heat Removal System. For the design and performance analysis of the Intermediate Heat Exchanger and the Decay Heat Exchanger, a computer code was written during previous step of research. In this work, the computer code named "SHXSA" has been validated preliminarily by computational fluid dynamics simulations.

Performance analysis of dual source heat pump system with single unit dual source evaporator (SUDS증발기를 사용한 2중열원 열펌프의 성능해석)

  • 우정선;이세균;이재효;박효순
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.3
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    • pp.391-400
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    • 1999
  • The efficiency and capacity of an air source heat pump system decrease as the ambient temperature drops. One strategy of avoiding the decrease of the efficiency and capacity in air source heat pump system is to switch to another thermal energy source. Water can be a good candidate for the heat source. This paper presents the results of the performance analysis of heat pump system with a single unit dual source(SUDS) evaporator The heat exchanger combines two separated evaporators into a single evaporator and the object of the SUDS evaporator is to recover energy from dual heat sources, i.e. air and water. Simulation program is developed for the dual source heat pump system with a SUDS evaporator and experimental data are obtained and compared with the simulation results. Differences in heating capacity and COP are 7% and 8% respectively. Simulation results are in good agreement with the test results. Therefore, the developed program is effectively used for the design and performance prediction of the dual source heat pump system with a SUDS evaporator.

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A Study on The Characteristics of Heat Pump Heating System Utilizing Heat Storage Tank (축열수조를 이용하는 열펌프식 난방의 특성에 관한 연구)

  • Kim H.K.;Lee G.Y.;Park M.S.;Hwang I.S.
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.16 no.4
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    • pp.392-405
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    • 1987
  • A study of appling solar assisted heat pump heating system to Korean climatic charac-teritics has been undertaken through computer simulation using TRNSYS (A Transient System Simulation Program). It is insufficient for heating system composed of each of solar and heat pump system to supply heat met with heating load. So SAHP (Solar Assisted Heat Pump) heating systems which combined solar system with heat pump system are analized using the standard weather data of Korea. And SAHP heating systems are categorized into the series system in which the solar storage is used as the source for the heat pump, the parallel system in which ambient air is used as the source for the heat pump, and the dual source system in which the storage or ambient is used as the source depending on which source yields the lowest work input. These combined system are better than each of solar and heat pump heating system in view of thermal performance, and parallel system is most effective among these combined systems.

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