• Title, Summary, Keyword: Coefficient of performance(COP)

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Performance Characteristics of New LNG Liquefaction Cycles with Temperature Differences in the Heat Exchangers (열교환기 온도차에 따른 새로운 LNG 액화사이클의 성능 특성)

  • Yoon, Jung-In;Son, Chang-Hyo
    • Journal of the Korea Society For Power System Engineering
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    • v.18 no.1
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    • pp.51-56
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    • 2014
  • In this paper, the performance of the $CO_2-C_2H_6-N_2$ cascade liquefaction cycle with respect to temperature differences in the LNG heat exchangers is analyzed theoretically using HYSYS software and then compared the COP(coefficient of performance) of the cascade liquefaction cycles using $C_3H_8-C_2H_4-C_1H_4$ and $CO_2-N_2O-N_2$. In comparison of COP of three cycles, the cascade liquefaction cycles using $C_3H_8-C_2H_4-C_1H_4$ showed the highest COP. And the liquefaction cycle using $CO_2-C_2H_6-N_2$ and $CO_2-N_2O-N_2$ presented the second and third highest COP, respectively. In case of COP, the $C_3H_8-C_2H_4-C_1H_4$ cascade liquefaction cycle yields better COP. But, in terms of the environment and maintain, it is confirmed that the cascade liquefaction cycle using $CO_2-C_2H_6-N_2$ provides favorable characteristics.

Study on Cooling Performance Characteristics of Air Conditioning System Using R744 for a Passenger Vehicle (이산화탄소를 적용한 승용자동차 냉방시스템의 성능특성에 관한 연구)

  • Lee, Ho-Seong;Cho, Chung-Won;Won, Jong-Phil;Lee, Moo-Yeon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.12
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    • pp.5457-5463
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    • 2011
  • The objective of this study is to investigate cooling performance characteristics of mobile air conditioning system using R744 as an alternative of R-134a. In order to analyze the cooling performance characteristics of the air conditioning system using R744 for a passenger vehicle, the developed air conditioning system using R744 was applied in a real passenger vehicle and tested under various operating conditions with the variation of gas-cooler inlet air conditions, evaporator inlet air temperatures and compressor speeds. As a result, cooling capacity and coefficient of performance (COP) of the tested air conditioning system decreased with the rise of the inlet air temperature of the gas cooler but increased with the rise of the inlet air temperature of the evaporator. In addition, cooling capacity and coefficient of performance (COP) increased by 42.2 % with the rise of the compressor speed from 900 rev/min to 1800 rev/min, but it decreased by 55.4%.

Effect on Heat Exchangers Efficiency on Performance of Cryogenic Refrigeration Cycles (열교환기 효율이 초저온 냉동사이클 성능에 미치는 영향)

  • Yoon, Jung-In
    • Journal of the Korea Society For Power System Engineering
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    • v.17 no.4
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    • pp.58-63
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    • 2013
  • This paper presents the new cascade liquefaction cycles using $CO_2-C_2H_6-N_2$ and $CO_2-N_2O-N_2$. The performance of the cascade liquefaction cycles with respect to temperature differences in the LNG heat exchangers is analyzed using HYSYS software and then compared the performance of these cycles with phillips optimized cascade liquefaction cycle. The coefficient of performance of the new liquefaction cycles considered in this study decreases with the temperature differences in the LNG heat exchangers, but the compressor work, expander work and heat capacity in the LNG heat exchanger increases, respectively. From the comparison of performance of three cycles, the cascade liquefaction cycles using $CO_2-C_2H_6-N_2$ showed the highest COP. And the cycles using $CO_2-C_2H_6-N_2$ and $CO_2-N_2O-N_2$ presented the second and third highest COP, respectively. In the view of performance, the optimized cascade liquefaction cycle using $C_3H_8-C_2H_4-C_1H_4$ yields much better COP. But, in the environment view, it is found that the cascade liquefaction cycle using $CO_2-C_2H_6-N_2$ shows favorable characteristics.

Performance Evaluation of Ground Source Heat Pump System Utilizing Energy Pile in Apartment (공동주택에서 에너지 파일을 이용한 지열히트펌프 시스템의 성능 분석)

  • Lee, Jin-Uk;Kim, Taeyeon;Leigh, Seung-Bok
    • KIEAE Journal
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    • v.12 no.4
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    • pp.41-46
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    • 2012
  • In Korea, Apartment houses recently occupy over 80% of all buildings. Ground source system has to be designed to consider feature of apartment house. Most apartment houses use PHC pile to get a bearing power of the soil. Therefore, the purpose of this study is to evaluate performance of ground source heat pump system utilizing energy pile under apartment. Object of experiment is low-energy experiment apartment in Song-do and Energy Pile are applied to 80%, 100% energy reduction model for heat-source. First, performance evaluation of Energy Pile geothermal system was done during summer season. As a result, The COP(coefficient of performance) about geothermal heatpump was approximately 5-6 while cooling. In winter season, Long experiment was performed because it was very important to evaluate ground condition for long time. During heating experiment, Indoor room set temperature was $20^{\circ}C$ and kept constant by heating. Coefficient of performance for heat pump and overall system was calculated. It was 3.5-4.5 for COP and 2.5-3.7 for system COP.

The Performance Investigation of 1/4 Wavelength Thermoacoustic Refrigerator with Helium Refrigerant (헬륨을 냉매로 사용한 1/4파장 열음향 냉동기의 성능 평가)

  • 송규조;박종호;이성노
    • Progress in Superconductivity and Cryogenics
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    • v.4 no.2
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    • pp.52-57
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    • 2002
  • In this study, a thermoacoustic refrigerator, using a resonant standing acoustic wave. has been built. The refrigerant is helium gas. The description of thermoacoustic refrigerator was Presented. The temperature ratio (cold part temperature over hot part temperature) and the COP (Coefficient of Performance) that normalized by carnot's COP are plotted versus the thermal load applied to the cold end, for- various speaker power.

Performance Evaluation of Air Source Multi Heat Pump Floor Heating System in Apartment (공동주택 공기열 멀티 히트펌프의 바닥난방 성능 평가)

  • LEE, C.H.;Nah, H.S.;JUNG, H.;Kim, K.S.
    • Journal of the Korean Society of Mechanical Technology
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    • v.13 no.3
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    • pp.93-98
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    • 2011
  • To analyze and evaluate the performance of developing air to water multi heat pump, the heat pump was installed and tested at low energy house in Daejeon, korea. Heating capacity of heat pump is 16.5KW and cooling capacity is 14.0KW. Space heating/cooling, floor heating and hot water is available. The results performance evaluation of heat pump in lab test showed that the coefficient of performance (cop) was 3.75, and heating capacity was 16.0KW in ambient temperature $7^{\circ}C$. Also at ambient temperature $-15^{\circ}C$, the COP was 1.69. At a low energy house, floor heating is controled by a floor heating water temperature and a room temperature. The COP of heat pump is decreased with frequent on/off operation for controlling of floor heating water temperature.

A Numerical Simulation of Air-Cooled Ammonia/Water GAX Absorption Cooling Cycle (공냉형 암모니아/물 GAX 흡수식 냉동 사이클의 수치 해석)

  • Jeong, S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.7 no.3
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    • pp.488-500
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    • 1995
  • An air-cooled ammonia/water GAX(Generator-Absorber heat eXchange) absorption cooling cycle is proposed and its performance is numerically evaluated. It is shown that the performance of the system is greatly dependent on the quality of the refrigerant leaving the evaporator. For any refrigerant concentration in the investigated range(99.1~99.9% ammonia), the cycle COP(coefficient of performance) reaches the highest value, when some amount(about 7%) of refrigerant evaporates in the refrigerant heat exchanger. Among temperature differences in various heat exchangers, the temperature difference between GAX-absorber and the GAX-generator shows the greatest effect on the system performance, whereas pressure losses cause no significant decrease in COP. The system COP increases almost linearly with increasing evaporator temperature, decreasing absorber temperature or decreasing condenser temperature. If both absorber and condenser temperature increase simultaneously, the decrease in the COP becomes larger.

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Experimental Study of Standalone Cooling and Heating System using Thermoelectric Element for Vehicles (열전소자를 이용한 차량용 독립 냉난방시스템에 대한 실험적 연구)

  • Lee, Dae-Woong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.8
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    • pp.375-380
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    • 2014
  • The purpose of this paper is to investigate the cooling and heating performance of a standalone-type thermoelectric system equipped with a thermoelectric module. The system consists of a blower and two thermoelectric modules with a fin, which is soldered onto both sides of the thermoelectric module and a courtesy light. The thermoelectric system experiment is conducted with the intake voltage to find the optimum cooling and heating performance of each. The results showed that the cooling capacity and coefficient of performance (COP) were 22 W and 0.31, and the heating capacity and COP were 147 W and 1.1, respectively. In the vehicle cooling and heating performance test in a climate wind tunnel, the results showed that the standalone thermoelectric system's cooling performance was slightly better than the base system; and the heating performance of the standalone thermoelectric system was $54.1^{\circ}C$ and the COP was 1.3, compared to the base system.

Performance of A Three-Stage Condensation Heat Pump

  • Lee, Yoon-Hak;Jung, Dong-Soo;Kim, Chong-Bo
    • International Journal of Air-Conditioning and Refrigeration
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    • v.7
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    • pp.55-68
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    • 1999
  • In this study, computer simulation programs were developed for single-stage, two-stage, and three-stage condensation heat pumps and their performance with CFC11, HCFC123, HCFC141b was examined under the same external conditions. The results showed that the coefficient of performance(COP) of an optimized 'non-split type' three-stage condensation heat pump is 25-42% higher than that of a conventional single-stage heat pump. The increase in COP, however, differed among the fluids tested. The improvement in COP is largely due to the decrease in average LMTDs in condensers, which results in the decrease in thermodynamic irreversibility in heat exchange process. For the three-stage heat pump, the highest COP is achieved when the total condenser area is evenly distributed among the three condensers. For the two-stage heat pump, however, the optimum distribution of the total condenser area varies with an individual working fluid. For the three-stage system, 'splitting the condenser cooling water'for the use of intermediate and high pressure subcoolers helps increase the COP further. When the individual cooling water entering the intermediate and high pressure subcoolers is roughly 10% of the total condenser cooling water, the maximum COP is achieved showing roughly an 11% increase in COP as compared to that of the 'non-split type' heat pump.

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The Performance Analysis and On-site Performance Test of a Dedicated Outdoor Air System (외기 전용 공조기의 성능 분석 및 현장 성능시험)

  • Kim, Young-Il;Kim, Jung-Min;Chung, Kwang-Seop;Park, Seung-Tae
    • Proceedings of the SAREK Conference
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    • pp.346-351
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    • 2007
  • Dedicated outdoor air(DOA) system which conditions the outdoor air separately is superior to conventional cooling+reheating system with respect to energy consumption and indoor comfort. Since the sensible and latent load characteristics of indoor and outdoor are different, it is more efficient to treat them separately. In this study, cycle analysis and on-site performance test of DOA system have been conducted. The study shows that DOA requires 48.8% less equivalent energy that conventional system. The on-site performance test of the prototype shows that the coefficient of performance(COP) of the DOA system is 37.4% higher than the conventional system.

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