• 제목/요약/키워드: Water-to-refrigerant

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설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제26권12호
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

LiBr작동유체 중에서 가스흡수식 냉온수기의 국부부식 특성에 관한 연구 (A Study on the Characteristics of Local Corrosion for Gas Absorption Refrigeration and Hot Water Systems in LiBr-$H_2O$ Working Fluids)

  • Uh- Joh Lim;Ki-Cheol Jeong;Byoung-Du Yun
    • Journal of Advanced Marine Engineering and Technology
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    • 제27권6호
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    • pp.714-720
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    • 2003
  • Due to the electric power shortage in summer season and regulation of freon refrigerant, the application of gas absorption refrigeration and hot water systems are considerably increasing trend. But, this system consists of condenser, heat exchanger, supply pipe and radiator etc. which are easily corroded by acidity and dissolved oxygen and gases. In result, this system occurs scale attachment and corrosion damage like pitting and crevice corrosion. In this study, electrochemical polarization test of heat exchanger tubing material (copper, aluminium brass, 30% cupronickel(30% Cu-Ni)) was carried out in 60% lithium bromide solution at $95^{\circ}C$. As a result of polarization test, corrosion behavior by impressed potential and local corrosion. such as galvanic corrosion, pitting corrosion behavior, of tubing materials was investigated. The main results obtained are as follows: (1) The effect of pitting and crevice corrosion control of 30% cupronickel in 60% LiBr solution at $95^{\circ}C$ is very excellent. (2) Dissimilar metal corrosion of 30% cupronickel coupling to aluminium bronze is the most sensitive. (3) Current density behavior of tube materials by impressed potential is high in order of copper > aluminium brass > 30% cupronickel.

유하액막식 암모니아 흡수기에서 증기 유동방향에 따른 열 및 물질전달 특성 (Heat and Mass Transfer Characteristics of a Falling Film Ammonia Absorber with Respect to the Vapor Flow Direction)

  • 권경민;정시영;김병주;정은수
    • 설비공학논문집
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    • 제16권1호
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    • pp.16-25
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    • 2004
  • The flow and heat/mass transfer in the falling-film of a heat exchanger can be influenced by the motion of the surrounding refrigerant vapor. In this study, the effect of the vapor flow direction on the absorption heat transfer has been investigated for a falling-film helical coil which is frequently used as the absorber of ammonia/water absorption refrigerators. The experiments were carried out for different solution concentration. The heat and mass transfer performance was measured for both parallel and counter-current flow. The effect of vapor flow on the heat and mass transfer is found to be increased with decreasing solution concentration. In the experiments with low solution concentration, whose vapor specific volume is great, the counter-current flow of vapor resulted in uneven distribution of falling-film and reduced the heat transfer performance of the absorber. The direction of the vapor flow hardly affected the thermal performance as the solution concentration became stronger since the specific volume of the ammonia/water vapor was much smaller than that of the water vapor.

함정용 패키지 에어콘 응축기 핀튜브(Cu-Ni 70/30) 누설파괴 원인 분석 (Failure Analysis of Condenser Fin Tubes of Package Type Air Conditioner for Navy Vessel)

  • 박형훈;황양진;이규환
    • 한국표면공학회지
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    • 제49권5호
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    • pp.439-446
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    • 2016
  • In 2015, a fin tube (Cu-Ni 70/30 alloy) of package type heat exchanger for navy vessel was perforated through the wall which led to refrigerant leakage. This failure occurred after only one year since its installation. In this study, cause of the failure was determined based on available documents, metallographic studies and computational fluid dynamics simulation conducted on this fin tube. The results showed that dimensional gap between inserted plastic tube and inside wall of fin tube is the cause of the swirling turbulent stream of sea water. As a result of combination of swirling turbulence and continuing collision of hard solid particles in sea water, erosion corrosion has begun at the end of inserted plastic tube area. Crevice corrosion followed later in the crevice between the outer wall of plastic tube and inner wall of fin tube. It was found that other remaining tubes also showed the same corrosion phenomena. Thorough inspection and prompt replacement will have to be accomplished for the fin tubes of the same model heat exchanger.

250kW급 폐열회수 시스템 공정설계에 관한 연구 (A Study on the Engineering Design for 250kW-Grade Waste Gas Heat Recovery)

  • 김경수;방세경;서인호;이상윤;정은익;이중섭
    • 한국기계가공학회지
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    • 제18권5호
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    • pp.90-95
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    • 2019
  • This study aims to gain the design data through the process design of the organic Rankine cycle, which can produce 250kW of electric power through waste heat recovery. In this study, a simulation was conducted using APSEN HYSYS to make the model for the process design of the 250kW-class waste heat recovery system. For the thermodynamic model, the test was conducted with hot water as the heat source, the water steam as the cooling water for the cooler, and the refrigerant R245FA in the cycle. In the final design, it was expected and found from the simulation that the cycle efficiency was 12.62% and that 250kW of power was produced considering the margin of 80%.

해저터널을 위한 동결공법 냉매로서의 액화공기 적용성에 대한 실험적 연구 (Experimental study on the applicability of liquid air as the refrigerant in artificial ground freezing for subsea tunnels)

  • 손영진;최형철;문흥만;최항석;고태영
    • 한국터널지하공간학회 논문집
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    • 제18권2호
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    • pp.175-181
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    • 2016
  • 본 연구는 액체질소와 같이 급속 동결이 가능하면서 질식의 위험을 배제할 수 있는 냉매로서 액화공기를 선정하였고 이의 적용성을 평가하였다. 액화공기의 안정성을 평가하기 위해 액체질소와 액체산소가 혼합된 액화공기의 산소 농도가 산업안전보건법에 제시된 산소 농도 기준에 부합되는지를 실험적으로 검증하였으며, 액체질소 및 액체산소의 혼합 비율, 액화공기 저장용기의 압력변화 및 유량변화에 따른 액화공기 산소 농도변화를 살펴보았다. 그 결과, 액체질소 및 액체산소를 8:2로 혼합하였을 경우 산업안전보건법에 제시된 산소 농도 기준에 부합되는 것을 확인하였다. 액화공기 저장용기의 압력변화 및 유량변화는 액화공기의 산소 농도에 큰 영향을 미치지 않는 것으로 나타났다.

이산화탄소 급탕 열펌프의 난방 성능에 관한 실험적 연구 (Experimental Study on the Heating Performance of a $CO_2$ Heat Pump Water Heater)

  • 백창현;이응찬;강훈;김용찬;조홍현;조성욱
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2008년도 동계학술발표대회 논문집
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    • pp.310-315
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    • 2008
  • In this study, experimental study on the heating performance of a $CO_2$ heat pump water heater with a variation of operating conditions such as refrigerant charge amount, outdoor temperature, compressor frequency, EEV opening and water mass flow rate. Based on the test results, the optimum charge amount was 1800 g. At the water mass flow rates of 75, 85, 95 kg/hr, the water heating temperature was 62, 67, $74^{\circ}C$ and COP was 2.6, 2.8, 3.0, respectively. Besides, the water mass flow rate and compressor frequency were varied to maintain above the water heating temperature of $60^{\circ}C$ with the decrease of outdoor temperature. So, The compressor frequency increased beyond 65 Hz and the water mass flow rate was 45 kg/hr at the outdoor temperature of $-13^{\circ}C$, 65 kg/hr at $-8^{\circ}C$, 75 kg/hr at $-3^{\circ}C$ and 85 kg/hr at 2, $7^{\circ}C$. As the outdoor temperature decreased, the heating COP decreased by 2.5-39.8%.

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절삭유 냉각용 낮은 핀관의 응축 및 비등 열전달 성능에 관한 연구 (A Study on the Performance of the Condensation and the Boiling Heat Transfer of Low Fin Tubes Used in Cooling of the Cutting Oil)

  • 이종선
    • 한국생산제조학회지
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    • 제8권4호
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    • pp.68-78
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    • 1999
  • Heat transfer performance is studied for boiling and condensation of R-11 on integral-fin tubes. Nine tubes with trapezoidal integral-fins having fin densities from 748 to 1654fpm and 10,30 grooves and finned tubes with caves of 0.55 and 0.64 mm height respectively are tested. in case of condensation CFC-11 condensates at saturation stat of 32$^{\circ}C$ on the outside surface cooled by inside cooling water flows. And in case of boiling the refrigerant evaporates at a saturation state of 1 bar on the outside tube surface and heat is supplied by hot water which circulates inside of the tube,. The tube having fin transfer coefficient concerns fin tubes with caves show higher valve than low fin tube having find density of 1299fpm and 30grooves. The overall heat transfer coefficient of fin tube with caves is about 5155 W/mK at 2.8m/s of water velocity, The value is abuot 2.7 times higher than plain tube and 1.3 times higher than low fin tube having fin density of 1299fpm and 30 grooves.

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절삭유 냉각용 낮은 핀관의 응축 및 비등 열전달 성능에 관한 연구 (A Study on the Performance of the Condensation and the Boiling Heat Transfer of Low Fin Tubes Used in Cooling of the Cutting Oil)

  • 조동현;이종선
    • 한국생산제조학회지
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    • 제8권4호
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    • pp.65-65
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    • 1999
  • Heat transfer performance is studied for boiling and condensation of R-11 on integral-fin tubes. Nine tubes with trapezoidal integral-fins having fin densities from 748 to 1654fpm and 10,30 grooves and finned tubes with caves of 0.55 and 0.64 mm height respectively are tested. in case of condensation CFC-11 condensates at saturation stat of 32℃ on the outside surface cooled by inside cooling water flows. And in case of boiling the refrigerant evaporates at a saturation state of 1 bar on the outside tube surface and heat is supplied by hot water which circulates inside of the tube,. The tube having fin transfer coefficient concerns fin tubes with caves show higher valve than low fin tube having find density of 1299fpm and 30grooves. The overall heat transfer coefficient of fin tube with caves is about 5155 W/mK at 2.8m/s of water velocity, The value is abuot 2.7 times higher than plain tube and 1.3 times higher than low fin tube having fin density of 1299fpm and 30 grooves.

20kW급 폐열회수 시스템 공정 설계에 관한 연구 (A Study on the Engineering Design for 20kW-Grade Waste Gas Heat Recovery)

  • 김경수;방세경;정은익;이중섭
    • 한국기계가공학회지
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    • 제17권4호
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    • pp.91-96
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    • 2018
  • This study is collects design data through the process design of the organic Rankine cycle, which can produce 20kW of electric power through the recovery of waste heat. In this study, the simulation was conducted by using APSEN HYSYS in order to make the model for the process design of the 20kW class waste heat recovery system. For the thermodynamic model, the test was conducted with hot water as the heat source, with the water steam used as the cooling water for the cooler and the refrigerant R245fa in the cycle. In Case 1 and Case 2, it was expected and found that the cycle efficiency was 10.6% and that 36.86kw was produced, considering the margin of 84% of 20kW. In Case 3 and Case 4, it was expected and found from the simulation that the cycle efficiency was 12% and that 30.0kw was produced, considering the margin of 84% of 20kW.