• Title, Summary, Keyword: Outdoor air cooling

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An Experimental Study on Four-season Dedicated Outdoor Air Handling Unit (사계절 외기 전용 공조기에 대한 실험적 연구)

  • Park, Seung-Tae;Kim, Jong-Cheon;Hong, Young-Ju;Kim, Youn-Gil
    • Proceedings of the SAREK Conference
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    • pp.577-582
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    • 2008
  • The present study has been conducted to study the performance of Dedicated outdoor air handling unit. Dedicated outdoor air handling unit consists of pre-cooler, dehumidification and after cooler. By combining dedicated outdoor air-conditioning and heat pump, a new four-season dedicated outdoor air handling unit has been developed. Amount of energy saved and condition when this new system is superior to conventional vapor-compression cooling system has been presented.

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Optimization of flow performance by designing orifice shape of outdoor unit of air-conditioner (에어컨 실외기 냉각팬 시스템의 오리피스 형상 설계를 통한 유량 성능 최적화)

  • Ryu, Seo-Yoon;Kim, Sanghyeon;Cheong, Cheolung;Kim, Jong-Uk;Park, Byeong Il;Park, Se Min
    • The Journal of the Acoustical Society of Korea
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    • v.36 no.6
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    • pp.371-377
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    • 2017
  • The performance of an air conditioner is closely related to the cooling performance of a split-type outdoor unit so that, in most of the relevant preceding studies, the independent performance of an axial fan in an outdoor unit has been studied. However, there is a lack of research on the effects of other components in an outdoor units was rarely investigated. Therefore, in this paper, the effects of the fan orifice among other parts on the flow performance of the outdoor unit was numerically investigated. A virtual fan tester consisting of 18 million grids was developed for highly resolved flow simulation. The unsteady RANS (Reynolds-averaged Navier-Stokes) equations are numerically solved by using finite-volume CFD (Computational Fluid Dynamics) techniques. In order to verify the validity of the numerical methods, the predicted P-Q curve of the cooling fan in a full outdoor unit is compared with the measured one. Optimization of orifice shape was carried out for maximum flow performance of the outdoor unit using the validated numerical method.

Temperature characteristics of condenser and evaporator of Air-conditioner applying variable capacity compressor under cooling condition (가변용량 압축기를 적용한 에어컨의 냉방운전 시 응축 및 증발온도 특성)

  • Kwon, Young-Chul;Chun, Chong-Keun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.8 no.6
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    • pp.1325-1331
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    • 2007
  • In order to investigate the cooling capacity of an air-conditioner applying a variable capacity compressor and the temperature characteristics on a condenser and an evaporator, the experiment on the operation characteristics of the air-conditioner was performed along a compressor operation ratio and an indoor/outdoor temperatures, under a cooling operation mode. The system characteristics were measured by the psychrometric calorimeter. The cooling capacity increased with decreasing the outdoor temperature and increasing the indoor temperature. Also, it increased with increasing the compressor operation ratio. The temperature of the condenser was more sensitive for the variation of the outdoor temperature and the temperature of the evaporator was more sensitive for the variation of the indoor temperature. The operation characteristics of the cycle used in this present were also analyzed by a pressure-enthalpy chart.

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Cooling Enhancement Potential of an Air-Cooled Condenser by Evaporative Cooling (증발냉각에 의한 공랭 응축기의 성능향상 가능성에 관한 연구)

  • 이대영;백영진;김영일
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.3
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    • pp.203-210
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    • 2004
  • This paper describes the potential advantages in applying evaporative cooling to air-cooled condensers. The cooling characteristics of an air-cooled condenser with its surface fully covered with thin water film are investigated and compared with that of an air-cooled condenser with usual dry surface. By applying the evaporative cooling, the cooling performance of the condenser is shown to improve enormously. When the outdoor air is 35$^{\circ}C$ and 40% in relative humidity, the condensing temperature of the refrigerant is decreased by 2$0^{\circ}C$. Even when the incoming air is fully saturated with water vapor, the evaporation from the wet surface occurs to cause a decrease in the condensing temperature by 1$0^{\circ}C$. The main reason for this improvement is assessed as the addition of an efficient cooling mechanism which is the water evaporation resulting in latent heat absorption.

Experimental Study on the Performance of a Simultaneous Heating and Cooling Heat Pump in the Heat Recovery Mode (동시냉난방 열펌프의 전열회수 성능 특성에 관한 연구)

  • Choi, Jong-Min;Chung, Hyun-Joon;Joo, Young-Ju;Kang, Hoon;Kim, Yong-Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.11
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    • pp.718-726
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    • 2008
  • The cooling load in winter is significant in buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. Hence, the development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the performance of a simultaneous heating and cooling heat pump was investigated in the heat recovery mode (HR mode). The system adopted a variable speed compressor using R410A with four indoor units and one outdoor unit. In the HR mode, the capacity and COP were improved as compared with those in the cooling or heating mode because the waste heat in the outdoor unit was utilized as useful heat in the indoor units. However, energy imbalance between heating and cooling capacity of each indoor unit was observed in the 2H-1C HR mode. Therefore, the performance of the system in the 2H-1C HR mode was enhanced by controlling refrigerant flow rate through the outdoor unit.

Performance Characteristics of the Desiccant Cooling System in Various Outdoor and Load Conditions (외기조건에 따른 제습냉방시스템의 성능 특성)

  • Lee, Dae-Young;Chang, Young-Soo
    • Proceedings of the SAREK Conference
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    • pp.623-628
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    • 2009
  • Desiccant based air conditioning system offers a promising alternative to conventional one using vapour compression refrigeration for energy saving and greenhouse gas reduction. It is a heat driven cycle which has high potential for the use of low grade heat source such as the waste heat from the cogeneration plant or the solar thermal energy. In this study, the cooling performance of a desiccant cooling system incorporating a regenerative evaporative cooler was characterized in various operation conditions through numerical simulation. The cooling capacity and COP were evaluated at various outdoor conditions, regeneration temperatures, and supply flow rates. Based on the performance characteristics, the optimal control scheme was discussed to minimize the cooling cost at part load condition.

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The Study of Thyristor Valve Water Cooling Control Systems (대전력 반도체 정류기 수냉식 냉각 설비 냉매 온도 제어시스템에 관한 연구)

  • 임익헌;류호선
    • Proceedings of the KIPE Conference
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    • pp.230-233
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    • 1999
  • The design and implementation of thyristor water cooling control systems in considered in this pape Coolant water is pumped through the thyristor heat sinks where heat is transferred from the thyristo to the water. This water is then pumped through outdoor air-to-water heat exchangers where heat I transferred to the outside air. Since the water must be pure, it is filtered and de-ionized. Also the water temperature must be below dew-point temperature. Redundant pumps, outdoor heat exchangers, power supply system, controller monitoring system are provided for system reliability and availability.

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A Study on the Control of Water Flow and Water Temperature in the Radiant Cooling System through Simulations (시뮬레이션을 통한 바닥복사냉방 시스템의 공급유량 및 냉수온도 제어에 관한 연구)

  • 김용이;윤혜림;여명석
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.6
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    • pp.532-540
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    • 2001
  • The objectives of this study are to analyze the control variables according to condensation occurrence, to find the range in floor surface temperature and frequency of condensation, and to evaluate the control methods through simulations when the radiant heating system is used for cooling. Through the simulation analysis the control methods such as on/off control, variable flow control and outdoor reset with indoor temperature feedback control are evaluated and compared. The results show that the lowest floor surface temperature is around $23^{\circ}C$, the surface condensation can be prevented by controlling indoor humidity within 20g/kg(DA0, and that outdoor reset with indoor temperature feedback control is more appropriate than on/off control and variable flow control with regard to prevention of the condensation and thermal comfort.

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System Performance with Variation of Outdoor Unit Layouts at Building Re-entrants

  • Koh, Jae-Yoon;Lee, Hyun-Gu;Zhai, John
    • International Journal of Air-Conditioning and Refrigeration
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    • v.16 no.1
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    • pp.15-21
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    • 2008
  • Air-cooled split-type air conditioners (AC) are very popular in high-rise residential and commercial buildings in Korea. The performance of such AC systems varies significantly with system characteristics and environmental conditions. Particularly, the outdoor condensing unit of the system, if poorly cooled due to high density of AC distribution and restricted outdoor space, will result in large decrease of cooling efficiency and increase of electrical energy consumption and may further jeopardize the system reliability. This paper presents a numerical analysis on the thermal and energy performance of a group of air-cooled air conditioners installed at a courtyard of a high-rise building. The study introduces a series of new energy performance indices to assess the group performance of the AC condensers with different outdoor unit layouts. The results not only indicate the COP of the systems, but also quantify the system capacity and energy consumption. The evaluation method and indices developed are useful for guiding the design of the distribution plan of the AC units at building re-entrants.

A Study on Prediction of Temperature and Humidity for Estimation of Cooling Load (냉방부하 추정을 위한 온도와 습도 예측에 관한 연구)

  • Yoo, Seong-Yeon;Lee, Je-Myo;Han, Kyou-Hyun;Han, Seung-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.5
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    • pp.394-402
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    • 2007
  • To estimate the cooling load for the following day, outdoor temperature and humidity are needed in hourly base. But the meteorological administration forecasts only maximum and minimum temperature. New methodology is proposed for predicting hourly outdoor temperature and humidity by using the forecasted maximum and minimum temperature. The correlations for normalized outdoor temperature and specific humidity has been derived from the weather data for five years from 2001 to 2005 at Seoul, Daejeon and Pusan. The correlations for normalized temperature are independent of date, while the correlations for specific humidity are linearly dependent on date. The predicted results show fairly good agreement with the measured data. The prediction program is also developed for hourly outdoor dry bulb temperature, specific humidity, dew point, relative humidity, enthalpy and specific volume.