• 제목/요약/키워드: Refrigerant heating

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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.

태양열 이용 비프레온계 $CF_3CH_2F$(R-134a)적용 열펌프시스템에 의한 학교교실 난방에 관한 연구(II) (The performance of solar heat pump with non-freon refrigerant $CF_3CH_2F$(R-134a) for school classroom heating[II])

  • 선경호;정현채;김기선
    • 태양에너지
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    • 제17권1호
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    • pp.3-15
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    • 1997
  • 본 연구는 R-12($CF_2Cl_2F$) 대체냉매인 R-134a($CF_3CH_2F$) 적용 태양열 열펌프시스템에 의하여 학교교실($20{\sim}25$평형)이나 학교 화장실($13{\sim}17$평형)의 난방에 관한 것으로서 대체냉매 적용할 때 시스템의 안정성과 성능에 관해 실험되어졌다. 학교교실 난방을 위한 방법 중에서 온풍난방을 택하여 실험하였는데 대체냉매 적용 실제와 모형시스템의 난방성능을 비교 해석하였다. 이 결과를 근거로 R-22($CHClF_2$)와 그 대체냉매들에 대한 성능을 예측하였다. 서울지방 봄 가을철, 겨울철의 외기 온도에서 실내온도가 $18{\sim}20^{\circ}C,\;23{\sim}25^{\circ}C$로 유지할 수 있도록 설계 제작되었다.

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국부적인 발열부분을 가진 표면에서의 잠김 비등열전달 -전자부품 액침 냉각에서의 응용- (Boiling Heat Transfer from a locally Heated Surface -A Simulated Electronic Device under Liquid Immersion Cooling-)

  • 하광순;최상민
    • 대한기계학회논문집
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    • 제15권2호
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    • pp.685-692
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    • 1991
  • The pool boiling behavior of a heated surface has been investigated experimentally, focusing on the cases when only a part of the contact surface is heated. Characteristic boiling curves are obtained with circular metal surface test pieces heated below while immersed in Refrigerant-113. Locally heated test pieces are fabricated by inserting a heating block at the center inside a larger conducting block. Overall heat transfer rates are measured while the experimental conditions are systematically varied. The local temperature profiles along the radius are measured for conducting blocks. It is found that the conjugated boiling condition exists and the total heat fluxes should be correlated to a suitably defined temperature difference.

전자 소자를 이용한 연소열 측정 (Measurement of Calorific Value Using Flame Calorimeter)

  • 임기원;전진용;이병준
    • 한국연소학회지
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    • 제15권3호
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    • pp.40-47
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    • 2010
  • Calorific value of mixed gas, like liquefied natural gas (LNG), is strongly depends on its compositions which are affected by the mining place and producing time. The variation in calorific value have an direct influence on the combustion characteristics and performances of boiler, burner, vehicle, power plants etc. Thus, developing experimental method to measure exact calorific value is becoming an issue in the related industrial fields. Flame calorimeter is developed to get calorific value at the dynamic equilibrium state using electric substitution method. Refrigerant-11 carries heat from combustor and/or heater to the Peltier elements which pumped it out to the cooling water. It is found out that error in the measured calorific value of methane is 2.86% compared with the theoretical one. Developed design technique and the experimental data will be applied to design the national standard gas calorific value measuring apparatus.

가변속 스크롤 압축기의 운전조건의 변화에 따른 성능 해석 (Performance Analysis on the Variable Speed Scroll Compressor with Operating Conditions)

  • 박홍희;박윤철;김용찬
    • 설비공학논문집
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    • 제12권7호
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    • pp.649-658
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    • 2000
  • Thermodynamic modeling of low-pressure scroll compressor was developed by combining continuity and energy conservation equation. Suction gas heating was considered using energy balance inside the low pressure shell. Pressure, temperature and mass of refrigerant-22 as a function of orbiting angle were calculated by solving the governing equations using fourth order Rung-Kutta scheme. Motor efficiency was taken by experiments with a variation of frequency. The developed model was applied to the analysis of an inverter driven scroll compressor with a variation of frequency, pressure ratio and operating conditions. The model was verified with the experimental results at the same operating conditions. The developed model was adequate to predict performance of the inverter driven scroll compressor as a function of operating conditions. Calculated parameters from the model were discharge temperature, mass flow rate, power input, COP, and thermodynamic properties with respect to orbiting angle. To enhance the performance of a scroll compressor, it is essential to diminish leakage at low frequency level and improve the mechanical efficiency at high frequency level.

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자동차용 평행류 응축기의 열성능 모델링 (Thermodynamic Modeling of Parallel Flow Condenser for Automotive Air Conditioning System)

  • 김일겸;고재윤;박상록;임장순
    • 설비공학논문집
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    • 제13권8호
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    • pp.771-779
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    • 2001
  • In this study, a simulation program has been developed to predict the performance of a parallel flow condenser of an air conditioning system for an automobile. The well-known correlations for he heat transfer rates and the pressure drops are included in this model. It is fond that the numerical model can predict the heat transfer rate and the pressure drop accurately. As the condensing pressure increases of fixed air inlet temperature, the heat transfer rate increases and the pressure drop decreases. The effect of he degree of subcooling on the performance of the condenser is greater than that of the degree of super-heating because the ratio of the area occupied by he tow-phase refrigerant the total area is significantly affected by he degree of subcooling rather than the degree of superheating.

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실내온도조절을 위한 인버터 열펌프의 주파수 제어에 관한 연구 (A study of frequency control of an inverter heat pump for indoor air temperature adjustment)

  • 박윤철;민만기
    • 대한기계학회논문집B
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    • 제21권10호
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    • pp.1262-1272
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    • 1997
  • An experimental study on the frequency control of an inverter heat pump to get the desired indoor room temperature has been conducted for the performance characteristics during the steady, 4, 8, and 16 step frequency operations. The heat pump model used in this study was operated to meet the experimental conditions of ASHRAE standard. The performance of the system was tested by measuring the temperature and pressure of the refrigerant, and cooling capacity, power consumption, etc. of the system. As the controlling frequency steps increased, the running time of the compressor increased as well as the electric consumption of the system and the cooling energy due to the wall heating load. However, the average cooling COP was improved.

액분사 사이클을 이용한 공기 열원 열펌프의 사이클 시뮬레이션 (Cycle Simulation of an Air Source Heat Pump Using Liquid Injection)

  • 김욱중;홍용주;남임우;강원일;공용상
    • 설비공학논문집
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    • 제12권3호
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    • pp.244-250
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    • 2000
  • An air source heat pump using liquid injection technique, which can be applied for very low temperature climate, has been simulated to examine the design options. Comparison between the simulation and experiment has been carried out to validate the simulation method. Effects of various design parameters such as liquid injection rate and injection pressure are Investigated to optimize the performance of the heat pump. Finally, optimal liquid infection rate and injection pressure to maintain sufficient heating capacity and moderate discharge refrigerant temperature are suggested when the heat pump was operated at very low outdoor temperature.

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Toward residential building energy conservation through the Trombe wall and ammonia ground source heat pump retrofit options, applying eQuest model

  • Ataei, Abtin;Dehghani, Mohammad Javad
    • Advances in Energy Research
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    • 제4권2호
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    • pp.107-120
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    • 2016
  • The aim of this research is to apply the eQuest model to investigate the energy conservation in a multifamily building located in Dayton, Ohio by using a Trombe wall and an ammonia ground source heat pump (R-717 GSHP). Integration of the Trombe wall into the building is the first retrofitting measure in this study. Trombe wall as a passive solar system, has a simple structure which may reduce the heating demand of buildings significantly. Utilization of ground source heat pump is an effective approach where conventional air source heat pump doesn't have an efficient performance, especially in cold climates. Furthermore, the type of refrigerant in the heat pumps has a substantial effect on energy efficiency. Natural refrigerant, ammonia (R-717), which has a high performance and no negative impacts on the environment, could be the best choice for using in heat pumps. After implementing the eQUEST model in the said multifamily building, the total annual energy consumption with a conventional R-717 air-source-heat-pump (ASHP) system was estimated as the baseline model. The baseline model results were compared to those of the following scenarios: using R-717 GSHP, R410a GSHP and integration of the Trombe wall into the building. The Results specified that, compared to the baseline model, applying the R-717 GSHP and Trombe wall, led to 20% and 9% of energy conservation in the building, respectively. In addition, it was noticed that by using R-410a instead of R-717 in the GSHP, the energy demand increased by 14%.

온수제조용 CO2 히트펌프의 가스쿨러 열전달 성능 해석 (Analysis of Heat Transfer Performance of a Gas Cooler of CO2 Heat Pump for Water Heating)

  • 권정태;이창경;백동석;권영철
    • 한국산학기술학회논문지
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    • 제14권11호
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    • pp.5317-5322
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    • 2013
  • 본 연구에서는 ${\epsilon}$-NTU 방법을 사용하여 $CO_2$ 히트펌프 가스쿨러의 열전달 성능을 해석하였고, 공개된 실험결과와 비교하였다. $CO_2$ 히트펌프 가스쿨러의 열전달률, 냉매측/순환수측 출구온도를 EES로 계산하였다. 해석은 시험부를 하나의 구간으로 설정하여 냉매와 순환수측 입출구의 평균온도를 물성치로 적용한 평균해석과 시험부를 50구간으로 나누어 각 구간에서의 출구온도를 다음 구간의 입구온도로 사용한 국소해석으로 진행되었다. 실험결과로부터 평균해석보다는 국소해석의 결과가 실험값을 더 만족하였으며, 열전달률은 0.3~1.1%, 순환수측 출구온도는 1.31~1.88%, 냉매측 출구온도는 3.12~5.18% 정도의 오차를 보였다.