• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.6
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• pp.73-77
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• 2019

In this paper, the heat pump system was designed using heat absorption of the refrigerant or condensation heat. The cooperation system has been developed to pass a heat source of low temperature to a high temperature or to pass the heat source of high temperature to a low temperature. Heat pump for using the valve as a function of switching a condenser and an evaporator in a refrigerating cycle. As a result, heat pump system was developed by air source method. Therefore cooperating system for energy saving to solve at the same time as the cooling and heating by system of one was equipped.

• Solar Energy
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• v.17 no.3
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• pp.43-49
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• 1997

Cycle simulaton of the double effect parallel flow model is applied to a Lithium-Bromide/water system, with the objective of evaluation the possibilities of effectively utilizing waste-heat as a secondary heat source for the low-temperature generator. In this study, cycle simulation has been carried out to clarify the effect heat exchange in order to predict the performance of absorption refrigeration cycles using waste heat.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.12
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• pp.793-799
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• 2016

In a hybrid fuel cell system, low-temperature reforming technology, which uses waste heat as a heat source, is applied to improve system efficiency. A low temperature reformer is required to optimize geometry in low thermal conditions so that the reformer can achieve the proper methane conversion rate. This study analyzed internal temperature distributions and the reaction patterns of a reformer by considering the change of the shape factor on the limited heat supply condition. Unlike the case of a high temperature reformer, analysis showed that the reaction of a low temperature reformer takes place primarily in the high temperature region of the reactor exit. In addition, it was confirmed that the efficiency can be improved by reducing the GHSV (gas hourly space velocity) or increasing the heat transfer area in the radial direction. Through reacting characteristic analysis, according to change of the aspect ratio, it was confirmed that a low temperature reformer can improve the efficiency by increasing the heat transfer in the radial direction, rather than in the longitudinal direction.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.4
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• pp.907-911
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• 1990

본 연구에서는 비열이 일정하고 초기온도가 주어진 열원으로부터, 일정한 열 전달 용량의 열교환기를 사용하여 최대의 에너지를 전달시키기 위한 조건을 구해 보기 로 한다. 즉, 저온유동은 고온의 열원유동과 대항류로서 열교환하며 위치에 따라 저 온유체의 온도가 가역 단열압축 또는 팽창에 의하여 임의로 조절될 수 있는 일반적인 경우에 대하여, 저온유체가 최대의 가용 에너지를 흡수하기 위한 온도분포를 변분법 문제로서 해석하고 그에 다른 부수조건들을 검토하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.483-491
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• 2014

In this study, a thermodynamic analysis was carried out for a combined power generation system using a low-temperature heat source in the form of sensitive energy and liquefied natural gas cold energy. An ammonia-water mixture, which is a zeotropic mixture, was used as the working fluid, and systems with and without a regenerator were comparatively analyzed. The effects of the mass fraction of ammonia and the condensation temperature of the working fluid on the system variables, including the net work production, exergy destruction, and thermal and exergy efficiencies, are analyzed and discussed. The results show that the performance characteristics of the system varied sensitively with the ammonia concentration or condensation temperature of the working fluid. The system without regeneration was found to be better in relation to the net work per unit mass of the source fluid, whereas the system with regeneration was better in relation to the thermal or exergy efficiency.

• 월간 기계설비
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• s.46
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• pp.65-73
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• 1994

도시생활폐수에 포함되어 배출되는 폐열을 열펌프의 열원으로 하는 폐수열원 열펌프 시스템에 대한 관심이 오래전부터 집중되어 있었지만 폐수 열교환기 전열면의 오염문제 때문에 실용화에 커다란 진전을 보지 못하고 있다. 한편, 생활페수는 비교적 저온이기 때문에 열펌프시스템의 설계에 특별한 주의를 기울여야 한다. 즉, 이러한 폐열을 회수하여 유효에너지 자원화 하기 위한 신기술이 이루어 져야한다. 본 연구에서는 이러한 점을 감안하여 도시생활 폐수열의 이용가능성을 검토하고 이를 열원으로 하는 열펌프의 개발을 위한 폐수 열교환기의 모델을 개발하였다.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.191-194
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• 2011

Low-grade waste heat has generally been discarded in industry due to lack of efficient recovery methods. In recent years, organic Rankine cycle(ORC) has become a field of intense research and appears as a promising technology for conversion of heat into useful work of electricity. In this work thermodynamic performance of ORC with superheating of vapor is comparatively assessed for various working fluids. Special attention is paid to the effects of system parameters such as the evaporating temperature on the characteristics of the system such as maximum possible work extraction from the given source, volumetric flow rate per 1 kW of net work and quality of the working fluid at turbine exit as well as thermal efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.10
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• pp.919-926
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• 2013

Experiments were conducted to determine the operating characteristics of a small-scale ORC (organic Rankine cycle) system for various low-temperature heat sources. A small-scale ORC power generation system adopting R-245fa as a working fluid was designed and manufactured. Hot water was used as the heat source, and the temperature was controlled using 110-kW electric resistance heaters that provided temperatures of up to $150^{\circ}C$. An open-drive oil-free scroll expander directly connected to a synchronous generator was installed in the ORC unit. Experiments were conducted by varying the rotational speed of the expander under the same heat source temperature conditions. The factors that influence the performance of the small-scale ORC system were analyzed and discussed.

• Korea Journal of Geothermal Energy
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• v.7 no.4
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• pp.56-63
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• 2011

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.9
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• pp.589-596
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• 2016

Recently organic flash cycle (OFC) has been proposed which is a vapor power cycle where heat addition occurs with the working fluid remaining in the liquid state. This study proposes a modified OFC with regeneration and carries out thermodynamic performance analysis of the system utilizing low-temperature heat source in the form of sensible energy. Effects of working fluid and flash temperature are systemically investigated on the system performance such as net power production and thermal efficiency. Results show that the net power production has a peak value with respect to the flash temperature but the thermal efficiency increases with the flash temperature. The regenerative system shows higher thermal efficiency compared to the original OFC and improved potential for recovery of low-temperature heat sources.