• 제목/요약/키워드: Refrigeration Cycle

검색결과 445건 처리시간 0.024초

열전달을 고려한 냉동 사이클의 최적 설계조건 (Optimal Design Condition of Refrigeration Cycle with Heat Transfer Processes)

  • 김수연;정평석
    • 대한기계학회논문집
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    • 제14권1호
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    • pp.225-229
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    • 1990
  • 본 연구에서는 외부조건과 입력이 일정하게 주어져 있는 냉동 사이클에 대하 여 열교환기의 용량을 설계변수로 하여 출력과 효율이 최대가 되는 조건, 즉 최적 설 계조건을 살펴 보고자 한다. 아울러 이 조건과 엔트로피 생성 최소조건과의 관계와 비가역 사이클인 경우도 살펴보았다.

Performance Analysis of WHR-ORC Using Hydrocarbon Mixtures for 20kW Gross Power at Low Temperature

  • Kwakye-Boateng, Patricia;Yoon, Jung-In;Son, Chang-Hyo;Hui, Kueh Lee;Kim, Hyeon-Uk
    • 동력기계공학회지
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    • 제18권6호
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    • pp.140-145
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    • 2014
  • Exploitation of renewable energies is on the increase to mitigate the reliance on fossil fuels and other natural gases with rocketing prices currently due to the depletion of their reserves not to mention their diverse consequences on the environment. Divergently, there are lots of industries "throwing" heat at higher temperatures as by products into the environment. This waste heat can be recovered through organic Rankine systems and converted to electrical energy with a waste heat recovery organic Rankine cycle system (WHR-ORC). This study uses the annual average condenser effluent from Namhae power plant as heat source and surface seawater as cooling source to analyze a waste heat recovery organic Rankine cycle using the Aspen HYSYS simulation software package. Hydrocarbon mixtures are employed as working fluid and varied in a ratio of 9:1. Results indicate that Pentane/Isobutane (90/10) mixture is the favorable working fluid for optimizing the waste heat recovery organic Rankine cycle at the set simulation conditions.

축냉시스템을 이용한 냉매과냉각형 냉동시스템의 성능특성에 관한 실험적 연구 (An Experimental Study on the Performance Characteristics of a Refrigerant-Subcooling Refrigeration System with an Ice Storage Tank)

  • 이은지;이동원;김용찬
    • 설비공학논문집
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    • 제22권6호
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    • pp.369-374
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    • 2010
  • A refrigerant-subcooling refrigeration system consisted of a typical single vapor-compression refrigeration cycle, a subcooler, and an ice storage tank. The degree of subcooling at the exit of the condenser can be increased by the heat exchange between the subcooler and the ice storage tank. The cold heat in the ice storage tank was stored by using the refrigeration cycle during night time and then used to absorb the heat from the subcooler during daytime. The performance of the refrigerant-subcooling refrigeration system was measured by varying the degree of subcooling. In addition, the performance characteristics of the present system were compared with those of a conventional refrigeration system. The mass flow rate of the present system was higher than that of the conventional system due to the increase in the degree of subcooling. Generally, the refrigerant-subcooling system showed superior performance to the conventional refrigeration system.

내부 열교환기 부착 R744-R404A용 캐스케이드 냉동시스템의 성능 분석 (Performance analysis of a R744 and R404A cascade refrigeration system with internal heat exchanger)

  • 오후규;손창효
    • 동력기계공학회지
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    • 제16권1호
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    • pp.38-43
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    • 2012
  • This paper describes an analysis on performance of R744-R404A cascade refrigeration system with internal heat exchanger to optimize the design for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree, internal heat exchanger and compression efficiency, evaporating and condensing temperature in the R744 low- and R404A high-temperature cycle and temperature difference of cascade heat exchanger. The main results are summarized as follows : COP of cascade refrigeration system increases with the increasing of compression efficiency, but decreases with the increasing temperature difference of cascade heat exchanger. Also, the COP increases with the increasing of internal heat exchanger efficiency in high-temperature cycle, but decreases with that in low-temperature cycle. Therefore, internal heat exchanger efficiency, compressor efficiency and temperature difference of cascade heat exchanger on R744-R404A cascade refrigeration system have an effect on the COP of this system.

$H_{2}O/LiBr+HO{(CH_{2})}_{3}OH$를 이용한 2중 효용 흡수식 냉동기 특성해석 (Characteristic Analysis of Double Effect Absorption Refrigeration Machine using $H_{2}O/LiBr+HO{(CH_{2})}_{3}OH$)

  • 문춘근
    • Journal of Advanced Marine Engineering and Technology
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    • 제22권6호
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    • pp.792-799
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    • 1998
  • Further improvement of existing $H_{2}O/LiBr$ absorption refrigeration machine is absolutely neces-sary to promote the utilization of gas-cooling system Among various methods to improve the per-formance of the absorption refrigeration machine this research has focused on the use of a new working fluid that has better properties than the existing $H_{2}O/LiBr$ working fluid. In the series of the research, $H_{2}O/LiBr+HO{(CH_{2})}_{3}OH$ system was selected as the most promisable candidate. The absorption refrigeration machine is water-cooled double-effect, $H_{2}O/LiBr+HO{(CH_{2})}_{3}OH$ sys-tem with series flow type. In this study we found out the characteristic of new working solution through the cycle simulation and compared the result with that of LiBr solution to evaluate. Theoptimum designs and operating conditions were determined based on the operating constraints and the coefficient of performance. Results demonstrate that new working fluid subsrantially increases COP by as much as 10% and has a wider working range with 8% higher crystallization limits compared to the conventional $H_{2}O/LiBr$.

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비단열 모세관 접합방법이 증기압축식 냉동사이클 성능에 미치는 영향 해석 (Analysis of Vapor Compression Refrigeration Cycle Performance Depending on Different Joining Method of Non-adiabatic Capillary Tube)

  • 이대용;박상구;김현정;정지환
    • Journal of Advanced Marine Engineering and Technology
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    • 제33권8호
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    • pp.1144-1151
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    • 2009
  • 냉동기는 비단열모세관을 채택하여 사용함으로써 사이클의 효율을 향상시킬 수 있다. 비단열모세관은 모세관과 흡입관을 접합함으로써 둘 사이에 열전달이 일어날 수 있도록 한 장치로서 SLHX 라고 부른다. 두 관을 접합하는 방법은 다양하며 이는 사이클의 성능에 영향을 미칠 수 있다. 본 연구에서는 가장 널리 사용되는 두 가지 접합방법이 냉동사이클에 미치는 영향을 해석하였다. 실험결과 용접형 SLHX의 열저항이 테이프형 SLHX의 열저항 보다 크게 작은 것으로 나타났다. 이를 이용한 사이클해석 결과 용접형 SLHX는 COP 와 냉동능력을 5.09%와 14.77% 향상시키고 테이프형 SLHX는 각각 5.05%와 14.75% 향상시켜 둘 사이의 차이는 매우 작은 것으로 나타났다.

축열조를 이용한 냉매과냉각 시스템의 전력수요관리 효과에 대한 연구 (A Study on the DSM Effect of a Refrigerant-Subcooling Refrigeration System with an Ice Storage Tank)

  • 김정배;이은지;이동원
    • 설비공학논문집
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    • 제22권12호
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    • pp.845-851
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    • 2010
  • This study was experimentally performed to find the effects of refrigerant subcooling in the refrigeration system and to propose how to get the efficient use of energy. A refrigerant-subcooling refrigeration system consisted of a typical single vapor-compression refrigeration cycle, a subcooler, and an ice storage tank. The degree of subcooling at the exit of the condenser can be increased by the heat transfer between the subcooler and the ice storage tank. The cold heat in the ice storage tank was stored by using the refrigeration cycle during night time and then used to absorb the heat from the subcooler during daytime. The cooling capacity and COP of this system were higher than those of the conventional system due to the increase in the degree of subcooling. Typically, the refrigerant-subcooling system showed superior performance to the conventional refrigeration system and would also contribute to load leveling.

변형 Roebuck 압축기를 이용한 J-T 네온 냉각시스템의 열역학적 설계 (Thermodynamic Design of J-T Neon Refrigeration System Utilizing Modified Roebuck Compression Device)

  • 정제헌;정상권
    • 설비공학논문집
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    • 제15권5호
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    • pp.432-438
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    • 2003
  • This paper describes a modified Roebuck compression device as a potential compression device of a rotating cryogenic refrigeration system in superconducting machine such as generator or motor. The conventional cryogen transfer method from stationary refrigeration system to rotating system can be eliminated by an on-board cryogenic refrigeration system that utilizes well-designed multi-stage modified Roebuck compression device. This paper shows basic thermodynamic analysis of modified Roebuck compression device and its application for compressing neon at 77 K with substantial pressure ratio when the rotor diameter is 0.8 m with rotating speed of 3600 rpm. The device does not require any moving part in rotating frame, but two separate thermal reservoirs to convert thermal energy into mechanical compression work. The high temperature thermal reservoir is atmospheric environment at 300 K and the low temperature thermal reservoir is assumed as a liquid nitrogen bath at 77 K. The concept of the compression device in this paper demonstrates its usefulness of generating high-pressure neon at 77 K for rotating J-T neon refrigeration cycle of superconducting rotor.

$NH_3-CO_2$를 사용하는 이원 냉동 시스템의 성능 분석 (Performance Analysis of an Ammonia(R717) and Carbon Dioxide(R744) Two-Stage Cascade Refrigeration System)

  • 손창효
    • 한국가스학회지
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    • 제14권1호
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    • pp.1-7
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    • 2010
  • 본 논문은 암모니아-이산화탄소용 이원 냉동시스템의 작동변수에 대한 최적의 설계자료를 제공하고자 이원 냉동시스템의 사이클 성능을 분석하였다. 작동변수로는 암모니아용 고온사이클과 이산화탄소용 저온사이클내의 과냉각도와 과열도, 압축기효율, 응축과 증발온도이다. 이에 대한 주요결과를 요약하면 다음과 같다. 이원 냉동사이클의 과냉도가 증가할수록 COP는 증가하는 반면 과열도가 증가할수록 COP는 감소하는 것을 알 수 있다. 이원 냉동사이클의 응축온도가 증가할수록 이원 냉동사이클의 COP는 증가하는 반면 증발온도가 증가할수록 COP가 감소함을 알 수 있다. 또한, 이원 냉동사이클의 압축효율이 증가할수록 COP가 증가한다. 따라서, 과열도, 과냉각도, 압축효율, 증발온도, 응축온도 등의 인자들이 R717과 R744용 이원 냉동사이클의 COP에 영향을 미친다.

R718-R744용 캐스케이드 냉동시스템의 최대 성능 예측 (Prediction on Maximum Performance of Cascade Refrigeration System Using R717 and R744)

  • 노건상;손창효
    • 한국산학기술학회논문지
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    • 제10권10호
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    • pp.2565-2571
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    • 2009
  • 본 논문은 시스템의 운전조건하에서 R717-R747용 이원냉동 사이클의 성능 분석에 대한 기초 설계자료를 제공하는 것이다. 본 논문에서 고려한 운전변수는 암모니아 고온사이클과 이산화탄소 저온사이클의 과냉각도, 과열도, 응축과 증발온도이다. 이원 냉동사이클의 성적계수는 과열도가 증가할수록 증가하는 반면, 과냉각도가 증가할수록 감소한다. 그리고, 이원 냉동사이클의 성적계수는 응축온도와 함께 증가하지만, 증발온도와는 반대로 감소한다. 따라서, 과열도, 과냉도, 응축과 증발온도는 본 시스템의 성적계수에 영향을 미치는 것을 알 수 있었고, 최대 성능계수와 최적의 증발온도에 대한 수학 방정식을 개발하기 위해 이러한 변수들을 포함시켜 다중 회귀분석을 통해 제안하였다.