• Title, Summary, Keyword: Outdoor air cooling

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Evaluation of energy efficiency ratio in the mixed air conditioner system (혼합 공조 시스템의 EER(A) 평가)

  • 김병순;이승홍
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.4
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    • pp.542-548
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    • 1999
  • Instead of testing split air conditioners, an empirically based calculation procedure may be used to estimate the Energy Efficiency Ratio at ARI A test conditions. Typically, the system involving the indoor unit well sold and the given outdoor unit is called the matched system. All other systems involving a given outdoor unit and other indoor units are called the mixed systems. To estimate the EER(A) for the mixed systems, EER(A) for the matched system must be known, Generally, the EER(A) for the matched system is known. This procedure relies on independent measurements and calculations made on an outdoor unit in conjunction with a matched indoor and a mixed indoor coil. A heat pump simulation model was used to quantify the effects of individual system components on the system performance. The procedure is applicable to all air-conditioning units having rated cooling capacities less than 19,000W and charged with refrigerant 22.

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Evaluation on the Indoor Thermal Environment and Cooling Operation Characteristics of Thermally Activated Building System integrated with Dedicated Outdoor Air System during Cooling Operation in Hot and Humid Climate of Seoul (국내 여름철 기후조건에서 DOAS와 TABS 통합시스템 냉방운전시 실내온열환경 및 운전특성 평가)

  • Lee, YoonSun;Lee, Keo-Re;Chung, Woong June;Lim, Jae-Han
    • Journal of the Architectural Institute of Korea Planning & Design
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    • v.34 no.11
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    • pp.45-55
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    • 2018
  • To reduce the energy consumption of HVAC system in buildings, thermally activated building system(TABS) has been applied to low energy building because of energy efficient performance and reduction of peak load. DOAS coupled with a parallel sensible cooling could be promising because TABS handles sensible heat load only. The purpose of this study was to evaluate the indoor thermal environment and cooling operation characteristic of TABS with dedicated outdoor air system(DOAS) in Korea climate. Indoor thermal environment and operation characteristic of TABS integrated with DOAS are investigated at different TABS operation schedules and climate conditions by simulation tests. The result shows that the DOAS is more suitable for hot and humid climates. And also it show that the potential of intermittent operation of TABS.

An Experimental Study on the Performance of Outdoor Heat Exchanger for Heat Pump Using $CO_{2}$ ($CO_{2}$이용 열펌프의 실외열교환기 성능에 관한 실험적 연구)

  • Chang Young Soo;Lee Min Kyu;Ahn Young San;Kim Young Il
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.2
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    • pp.101-109
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    • 2005
  • The purpose of this study is to investigate the performance of outdoor heat exchanger for heat pump using carbon dioxide. Two types of fin and tube heat exchangers (2 rows for type A and 3 rows for B) are tested. Both heat exchangers have counter-cross flow and 1-circuit arrangement. Test results such as heat transfer rate, pressure drop characteristics and temperature distribution in the heat exchanger are shown with respect to mass flow rate of refrigerant and frontal air velocity For cooling mode, the minimum temperature difference between air and refrigerant of type B is smaller than that of type A by $1^{circ}C$, but the pressure loss of air side is much higher for type B by $29\%$. It is found that a large temperature gradient of carbon dioxide during gas cooling Process Promotes thermal conduction through tube wall and fins which results in degradation of heat transfer performance. For heating mode operation, type B heat exchanger shows higher heat transfer performance compared to type A. However, because pressure loss of refrigerant side of type B is much greater than that of type A, the refrigerant outlet pressure of type B becomes lower than that of type A.

Comparison of Cooling-Energy Performance Depending on the Economizer-Control Methods in an Office Building (이코노마이저 제어 방법에 따른 사무소 건물의 냉방 에너지 성능 비교)

  • Son, Jeong-Eun;Hyun, In-Tak;Lee, Jea-Ho;Lee, Kwang Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.8
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    • pp.432-439
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    • 2015
  • Current building procedures seek to minimize external air supplies to reduce the energy consumption of air conditioning, resulting in a high dependency on mechanical ventilation. We therefore studied an economizer-cycle system, whereby the introduction of external air saves energy. We analyzed different economizer-control methods, addressing mixed-air temperatures and outdoor-air fractions according to outdoor-air temperatures; also, we analyzed the energy consumption of the three economizer-cycle control types using detailed EnergyPlus simulation modeling. A differential enthalpy control method showed a lower energy consumption range from 5.8% to 6.2% than that of other methods during the simulated period. A differential dry-bulb control method showed a 12.7% lower energy consumption than the no-economizer method in the intermediate period, but also showed 7.1% more energy consumption during the summer period. When latent heat was not removed due to high summer humidity, we found a significant level of resultant energy consumption.

A Cost Analysis of the Heat Recovery Ventilator under Various Condition (열회수형 환기장치의 운전조건에 따른 경제성 평가에 관한 연구)

  • Kang, Tae-Wook;Koh, Jae-Yoon
    • Journal of the Korean Solar Energy Society
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    • v.26 no.1
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    • pp.21-28
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    • 2006
  • Changes in building construction methods and repairing of older buildings have reduced infiltration rate. Synthetic materials, release airborne particles and uneven healthy odor are increased. For preventing pollutants introduce fresh outdoor air into the building, simply letting fresh outdoor air into building, however, Is not a cost-effective way to ventilation. When additional ventilation is added to an existing HVAC system, the heating and cooling equipment, often cannot handle the increased load. A HRV provides a way to minimize in energy costs while introducing fresh air to a building. In this study, the economical research of HRV, made of three types of materials, are conducted. Heat recovering characteristics are studied at seasonal outdoor air conditions based on the outdoor air property condition at, Seoul in 2002. As a results, the average sensible effectiveness is 0.75 in the sensible heat exchanger and average total effectiveness is 0.65 in the total heat exchanger. The pay back period of the sensible heat exchangers are $3.2{\sim}3.5$ year and it of total heat exchanger is 2.2 years.

Optimal Control Algorithms for the Full Storage Ice Cooling System (전축열방식 빙축열 시스템의 최적제어 알고리즘)

  • 한도영;이준호
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.4
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    • pp.350-357
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    • 2002
  • Optimal control algorithms for the full storage ice cooling system were developed by using a dynamic simulation program. Control algorithms for the storage charging mode were developed for the chiller outlet temperature setpoint control and the chiller capacity control. Control algorithms for the storage discharging mode were developed for the proper mode selection, the storage-only mode control, and the storage-priority chiller-shared mode control. Two different cases of the expected outdoor air temperature profile and the expected cooling load profile were used to analyze the effectiveness of these algorithms. Simulation results show the energy savings and the satisfactory controls of the ice storage system. Therefore, control algorithms developed for this study may effectively be used for the improved control of the ice storage cooling system.

The Characteristics of a Bypass Air Conditioning System for Load Variation (부하변동에 대한 바이패스 공조시스템의 특성)

  • 김보철;신현준;김정엽
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.3
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    • pp.240-246
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    • 2002
  • Bypass air conditioning systems are divided into three types; an outdoor air bypass, a mixed air bypass and a return air bypass system. What makes the return air by pass system more effective is that it directs all of moist outdoor air through the cooling coil. The bypass air conditioning system can maintain indoor R.H (Relative Humidity) less than a conventional CAV (Constant Air Volume) air conditioning system by adjusting face and bypass dampers at part load. When a design sensible load (the ratio of sensible load to total sensible load) is 70 percent (at this time, RSHF (Room Sensible Heat Factor) . 0.7), indoor R.H was maintained 59 percent by the return air bypass system, but 65 percent by the conventional CAV air conditioning system (valve control system). The bypass air conditioning system can also improve IAQ (Indoor Air Quality) in many buildings where the number of air change is high.

Evaluation of the operating reliability on the concurrent heating-cooling system air conditioner for different refrigerant flow rates with high-head and long-line conditions (동시냉난방 시스템 에어컨의 냉매량 변화에 따른 고낙차 장배관 운전 신뢰성 평가)

  • Lee, Seung-Chan;Kim, Tae-An;Tae, Sang-Jin;Jung, Gyoo-Ha;Moon, Je-Myung;Kim, Youn-Jea
    • Proceedings of the SAREK Conference
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    • pp.304-309
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    • 2008
  • The heating and cooling performances of system multi-air conditioner for various refrigerant flow rates with high-head and long-line conditions are experimentally investigated. The maximum head and tube length were 110 m and 1000 m, and the two different adjustments of refrigerant flow rates were +20 % and -20 %, respectively. The experimental system was composed of 4 outdoor units with module systems, and 13 indoor units which were joined with the mode change unit by single-tube circuit. Field tests without indoor and outdoor temperature control were performed in a general office building with two different refrigerant flow rates. Especially, the oil level in the compressor was normally maintained at the safety zone. Experimental results were prepared on the p-h diagram.

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Characteristic Analysis of Hybrid Desiccant Cooling System for District Heating in Residential Environment (지역난방에 연계된 하이브리드 제습냉방시스템의 주거환경에서의 성능 분석)

  • Ahn, Joon;Kim, Jaeyool;Kang, Byung Ha
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.7
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    • pp.571-579
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    • 2014
  • A series of field tests on hybrid desiccant cooling systems were conducted in July-August, 2013. The temperature and humidity of the supply and return air, power, and heat consumption were monitored and transferred in real time through the Internet. The performance parameters of the cooling system, namely, cooling capacity and COP (coefficient of performance), were evaluated from the measured data and their variations under outdoor conditions was analyzed. It was found that with increase in the outdoor temperature, the total energy decreases and cooling capacity increases whereas the latter decreases with increase in the outdoor humidity. The COP was also found to increase with the increase in outdoor temperature.

A Study on the Evaluation of Air Change Efficiency of Multi-Air-Conditioner Coupled with Ventilation System

  • Kwon, Yong-Il;Han, Hwa-Taik
    • International Journal of Air-Conditioning and Refrigeration
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    • v.15 no.3
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    • pp.101-107
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    • 2007
  • Indoor air quality becomes of a concern recently in view of human health. This study investigates the air diffusion performance and the air change efficiency of a classroom, when outdoor air is introduced in two different ways in addition to the heating/cooling operation of a ceiling-mounted heat pump. A CFD analysis has been performed to investigate the effect of the discharge angle of the air jets from the heat pump for both parallel and series types of outdoor air system. It is observed that the series type creates more uniform indoor environment compared to the parallel type in general. It can be concluded the discharge angle should not be larger than 40o for the parallel type, in order not to generate thermal stratification in the room.