• Title/Summary/Keyword: Outdoor Heat Exchanger

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Characteristic of Cabin Temperature According to Thermal Load Condition of Heat Pump for Electric Vehicle (전기자동차용 히트펌프의 열 부하 조건에 따른 캐빈온도 특성)

  • Park, Ji Soo;Han, Jae Young;Kim, Sung-Soo;Yu, Sang Seok
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.2
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    • pp.85-91
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    • 2016
  • The Positive Temperature Coefficient (PTC) is used for cabin air heating of a battery electric vehicle, which is different from conventional vehicles. Since the PTC heater consumes a large quantity of power in a parasitic manner, many valuable studies have been reported in the field of alternative heat pumps. In this study, a model for an R134a heat pump taking into account the thermal environment of the cabin was developed for a MATLAB/SIMULINK(R) platform. Component and cabin models are validated with reference values. Results show that the heat pump is more competitive for parasitic power consumption over all ambient temperature conditions. Additionally, the method of waste heat recovery to overcome disadvantages when temperatures are below zero is applied to efficiently operate the heat pump.

Prediction of Characteristics for the Air-side Particulate Fouling in Finned-Tube Heat Exchangers of Air Conditioners used in the Field (실공간 사용 공기조화기용 열교환기의 공기측 파울링 특성 예측)

  • Ahn, Young-Chull;Jung, Sung-Hak;Hwang, Yu-Jin;Lee, Chang-Gun;Kim, Doo-Hyun;Jung, Seong-Ir;Lee, Jae-Keun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.8
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    • pp.563-568
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    • 2007
  • The air-side particulate fouling in the heat exchangers of HVAC applications degrades the performances of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. An empirical modeling equation has been derived from the experimental results using accelerated tests and it showed good predictions of the fouling characteristics of the slitted finned tube heat exchangers. However the modeling equation predicts only the fouling characteristics of new heat exchangers and it can not predicts fouling characteristics obtained from actual field data which contains the effect of hydrophilicity deterioration. Therefore an modified modeling equation is proposed and it shows good predictions of the actual fouling characteristics of finned-tube heat exchangers.

Flow Noise in the Outdoor Unit of an Air-conditioner (에어컨 실외기에서의 유동소음)

  • 이승배;이재환;김휘중;최진규;진성훈;박윤서
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.04a
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    • pp.594-601
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    • 1997
  • Propeller fans are commonly equipped in outdoor units of air-conditioners to provide effective cooling in a dried heat exchanger. A new design technique was developed to satisfy requirements of aerodynamic and aeroacoustic performance, which employs the intersection method of two cylinders for mean camber line. Three proto-types of propeller fan including Palm-Shaped, Highly-Swept(PSHS) fan (proto 3)were not only to provide low lift forces for dipole sound, but also to reduce the organized tip vortices interacting with the fan guide causing narrow-banded rotating instabilities. Cross-correlation technique was applied to study flow noise source characteristics for three proto-type fans designed. The cross-correlations between a microphone at far field and a hot-wire sensor at near field show that flows near hub region of proto 3 fan are less organized and the flow structures especially at high flow rate coefficients for proto 3 fan are less correlated with noise generated than other proto-types fans.

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An Experiment on Performance Evaluation of a Vapor Condensation Type Air Washer System for Semiconductor Clean Rooms (반도체 클린룸용 수증기 응축식 에어와셔 시스템의 성능평가)

  • Yeo, Kuk-Hyun;Park, Sang-Tae;Yoo, Kyung-Hoon;Son, Seung-Woo
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.442-447
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    • 2006
  • In semiconductor manufacturing clean rooms, it becomes important to remove airborne molecular contaminants as well as particulate contaminant in outdoor air introduced into clean rooms. One suitable control technique for these chemical contaminants is air washing by water in an outdoor air handling unit. In order to enhance the removal efficiency of chemical contaminants the effect of adding a heating and humidifying process before an air washer was examined.

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Heating Performance of a Ground Source Heat Pump System through Actual Operation (지열원 히트펌프시스템의 실사용을 통한 난방성능연구)

  • Koo, Kyoung-Min;Jeong, Young-Man;Hwang, Yu-Jin;Lee, Jae-Keun;Jang, Se-Yong;Kim, In-Kyu;Jin, Sim-Won;Lee, Dong-Hyuk
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.1341-1346
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    • 2008
  • This paper presents the heating performance of a water-to-refrigerant type ground source heat pump system (GSHP) installed in a school building. The evaluation of the heating performance has been conducted under the actual operating conditions of GSHP system in the winter. Ten units with the capacity of 10 HP each were installed in the building. Also, a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth was constructed for the GSHP system. For analyzing the heating performance of the GSHP system, we monitored various operating conditions, including the outdoor temperature, the ground temperature, and the water temperature of inlet and outlet of the ground heat exchanger. Simultaneously, the heating capacity and the input power were evaluated for determining the heating performance of the GSHP system. The average heating coefficient of performance (COP) of the heat pump was found to be 5.1 at partial load of 46.9%, while the overall system COP was found to be 4.2.

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Heating Performance of a Ground Source Heat Pump System through Actual Operation (지열원 히트펌프시스템의 실사용을 통한 난방성능연구)

  • Koo, Kyoung-Min;Jeong, Young-Man;Hwang, Yu-Jin;Lee, Jae-Keun;Jang, Se-Yong;Kim, In-Kyu;Jin, Sim-Won;Lee, Dong-Hyuk
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.788-793
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    • 2008
  • This paper presents the heating performance of a water-to-refrigerant type ground source heat pump system (GSHP) installed in a school building. The evaluation of the heating performance has been conducted under the actual operating conditions of GSHP system in the winter. Ten units with the capacity of 10 HP each were installed in the building. Also, a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth was constructed for the GSHP system. For analyzing the heating performance of the GSHP system, we monitored various operating conditions, including the outdoor temperature, the ground temperature, and the water temperature of inlet and outlet of the ground heat exchanger. Simultaneously, the heating capacity and the input power were evaluated for determining the heating performance of the GSHP system. The average heating coefficient of performance (COP) of the heat pump was found to be 5.1 at partial load of 46.9%, while the overall system COP was found to be 4.2.

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An Experimental Study on Oil Effect of CO2 in Heat Pump Outdoor Heat Exchanger (CO2용 실외열교환기의 오일 영향에 따른 성능변화에 대한 실험적 연구)

  • Lee, Jin-Gwan;Chang, Young-Soo;Kim, Seo-Young;Kim, Yong-Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.4
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    • pp.243-250
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    • 2011
  • In order to investigate the effects of PAG oil concentration on heat transfer performance and pressure drop during gas cooling process of $CO_2$, the experiments on fin-tube heat exchanger of $CO_2$ heat pump were performed. The experimental apparatus consists of a gas cooler, a heater, a chiller, a mass flow meter, a pump and measurement system. Experiments were conducted in various experimental conditions, which were inlet temperature($110^{\circ}C$), mass flow rates (50, 55, 60, 65, 70 g/s) and PAG oil concentration(0 to 2.6 wt%). Heat transfer rate decreased with the increase of the oil concentration and the decrease of inlet pressure. And pressure drop increased with the increase of the oil concentration and mass flow rate of refrigerant. The COP reduction by deterioration of gas cooler performance with oil concentration was analyzed. When inlet pressure of gas cooler is 100 bar, the COP reduction was estimated by 6% under 1 wt% of oil concentration.

Performance Characteristics on Environment Change of A/C applied Fin-tube and PF Heat Exchangers (환경변화에 따른 핀-관, PF 열교환기 적용 공조기 성능 특성 실험 연구)

  • Park, K.M.;Um, U.S.;Kwon, Y.C.;Lee, S.J.
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.1267-1271
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    • 2009
  • In the present study, performance characteristics on environment change of A/C applied fin-tube and PF heat exchangers were experimentally investigated. Capacity and COP changing an outlet air velocity, an indoor/outdoor temperature and a relative humidity were obtained. Air-enthalpy calorimeter was used. As the air velocity, indoor temperature and relative humidity increase, capacity and COP increase. PF A/C has smaller refrigerant weight than the fin-tube A/C. The performance of PF-2 A/C with the squarer fin was more excellent than that of PF-1 A/C with the triangler fin.

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The Effect of Load Variation on the Performance of an Injection Heat Pump with an Economizer (이코너마이저 적용 열펌프 시스템의 부하변화에 따른 성능 특성 연구)

  • Choi, Jong Min;Park, Yong-Jung;Kang, Shin-Hyung
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.10 no.3
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    • pp.1-7
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    • 2014
  • Heat pumps have received a fair amount of attention all over the world for their high efficiency and low environmental impact. Employing heat pumps for residential heating and cooling produces only about 2038 kg-$CO_2$/year, an amount which is less than half that of conventional boiler systems. However, the use of single-stage heat pumps becomes uneconomical when they are operated at very low evaporating temperature or high condensing temperature. Two-stage heat pumps systems can be used successfully for low or high temperature applications. In this paper, the experimental study on the performance of two-stage heat pump with an economizer was executed in heating mode. When the secondary fluid inlet temperature to the indoor heat exchanger increased, the COP enhancement rate of two-stage heat pump with an economizer was increased. For all outdoor inlet temperature conditions, the performance of the heat pump with an economizer was higher than it without an economizer.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. 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 flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (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 of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.