• Title, Summary, Keyword: Outdoor air cooling

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A Study on Building Energy Saving using Outdoor Air Cooling by Load Prediction (부하예측 외기냉방에 의한 건물에너지 절약에 관한 연구)

  • Kim, Tae-Ho;Yoo, Seong-Yeon;Kim, Myung-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.2
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    • pp.43-50
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    • 2017
  • The purpose of this study is to develop a control algorithm for outdoor air cooling based on the prediction of cooling load, and to evaluate the building energy saving using outdoor air cooling. Outdoor air conditions such as temperature, humidity, and solar insolation are predicted using forecasted information provided by the meteorological agency, and the building cooling load is predicted from the obtained outdoor air conditions and building characteristics. The air flow rate induced by outdoor air is determined by considering the predicted cooling loads. To evaluate the energy saving, the benchmark building is modeled and simulated using the TRNSYS program. Energy saving by outdoor air cooling using load prediction is found to be around 10% of the total cooling coil load in all locations of Korea. As the allowable minimum indoor temperature is decreased, the total energy saving is increased and approaches close to that of the conventional enthalpy control.

Investigation on the Reduction Effect on Cooling Power Consumption and Operating Cost of Mist-spray Outdoor Units in Air Conditioner

  • Lee, Keon-ho;Cho, Dong-woo;Kim, Hyemi;Song, Young-hak
    • Architectural research
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    • v.19 no.4
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    • pp.101-108
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    • 2017
  • The use of the air conditioner is increasing due to the rise of the outdoor temperature during summer, and the problems of the fire and the cooling performance deterioration are caused due to lack of maintenance of the outdoor unit. In particular, overall performance of cooling system and efficiency in outdoor units have been degraded due to an intake of high-temperature outdoor air thereby increasing cooling energy and operating cost. Thus, this study aimed to increase efficiency of outdoor units by evaporating and cooling intake air through mist spray at the intake port surface in the outdoor unit. The measurements results showed that total power consumption of misting outdoor unit compared to that of conventional outdoor units was reduced by 21% approximately, and total power consumption of the entire system including pump was reduced by 16.7%. In addition, the operating cost including water use was reduced by 13.5% approximately. In summary, if a mist-spray nozzle kit is installed in air-cooled outdoor units, the reduction in the usage of cooling energy and operating cost will be achieved without replacement of existing cooling systems or a large scale of repairs.

Reduction of Cooling Load using Outdoor Air Cooling (외기냉방을 이용한 냉방부하 절감 연구)

  • Kim, Min-Yang;Kim, Young-Il;Chung, Kwang-Seop
    • Transactions of the Korea Society of Geothermal Energy Engineers
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    • v.7 no.1
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    • pp.51-58
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    • 2011
  • Due to enhanced sealing and insulation of buildings, extensive use of glasses for building envelopes and increased use of heat generating office equipments, energy consumption of modem buildings for cooling is steadily increasing. With outdoor air cooling(ODAC) system, cooling load can be reduced by exchanging indoor air with the cold outdoor air during spring and fall seasons. If ODAC is operated based only on temperature, total cooling load may virtually increase if the outdoor humidity is high. To overcome this problem, ODAC should be controlled based on enthalpy. In this work energy saving characteristics of enthalpy controlled ODAC is studied using dynamic simulation. The result shows that cooling load can be reduced by 27% by adopting ODAC.

Effects of Control Methods of Outdoor Air Cooling System on Energy Consumption in Building (외기냉방 시스템의 제어방법이 에너지 소비량에 미치는 영향에 관한 연구)

  • Hwang, Jin-Won;Ahn, Byung-Cheon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.6
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    • pp.4253-4259
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    • 2015
  • In this study, the effects of various control methods of outdoor air cooling control system on control characteristics and energy consumption in building are researched by simulation. The system analysis modelling is done by using TRNSYS program package, and the control performances with existing outdoor air cooling methods are compared with the control ones without outdoor air cooling. As a result, appropriate operating temperature conditions of outdoor air cooling system according to outdoor temperature changes are required, and the outdoor air/return air dry bulb temperature comparison control method among the control methods shows best responses in energy savings.

Numerical Analysis on the Performance of a Outdoor Air Cooled Heat exchanger for Cooling Tower (외기이용 하이브리드 냉각탑 성능해석)

  • Kim, Sung-Il;Lee, Wook-Hyun;Lee, Kye-Jung;Chun, Won-Pyo
    • Proceedings of the KSME Conference
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    • pp.2322-2327
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    • 2008
  • This paper is to provide analysis model that can be used to investigate the improvement in energy efficiency for cooling tower by using fresh air. Numerical analysis of Air-cooled heat exchanger for single-phase flow with variations of outdoor air temperature has been performed. A complete set of correlations of the heat transfer in both refrigerant and air sides was employed for predicting the heat transfer rate. The numerical results derived from the correlations were verified with experimental results. The energy consumption for a hybrid cooling tower has been compared for variation of a outdoor air temperature. The results showed that the hybrid cooling tower in low outdoor temperature offers a significant improvement in energy efficiency. The thermal analysis aids significantly in the solution of the design problem of hybrid cooling tower.

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Calculation of Outdoor Air Fraction through Economizer Control Types during Intermediate Season

  • Hong, Goopyo;Hong, Jun;Kim, Byungseon Sean
    • KIEAE Journal
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    • v.16 no.6
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    • pp.13-19
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    • 2016
  • Purpose: In this study, we examined outdoor air fraction using historical data of actual Air Handling Unit (AHU) in the existing building during intermediate season and analyzed optimal outdoor air fraction by control types for economizer. Method: Control types for economizer which was used in analysis are No Economizer(NE), Differential Dry-bulb Temperature(DT), Diffrential Enthalpy(DE), Differential Dry-bulb Temperature+Differential Enthalpy(DTDE), and Differential Enthalpy+Differential Dry-bulb Temperature (DEDT). In addition, the system heating and cooling load were analyzed by calculating the outdoor air fraction through existing AHU operating method and control types for economizer. Result: Optimized outdoor air fraction through control types was the lowest in March and distribution over 50% was shown in May. In case of DE control type, outdoor air fraction was the highest of other control types and the value was average 63% in May. System heating load was shown the lowest value in NE, however, system cooling load was shown 1.7 times higher than DT control type and 5 times higher than DE control type. For system heating load, DT and DTDE is similar during intermediate season. However, system cooling load was shown 3 times higher than DE and DEDT. Accordingly, it was found as the method to save cooling energy most efficiently with DE control considering enthalpy of outdoor air and return air in intermediate season.

Experimental Study on Energy Saving Performance of Outdoor Temperature Reset Control Strategy for Central Cooling System (중앙 냉방시스템에 대한 외기보상제어의 절약 성능에 관한 실험적 연구)

  • Kim, Dong-Cheol;Song, Jae-Yeob;Ahn, Byung-Cheon
    • Transactions of the Korea Society of Geothermal Energy Engineers
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    • v.7 no.2
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    • pp.30-36
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    • 2011
  • In this study, energy saving performance of outdoor temperature reset control strategy for central cooling system is researched by experiments. Outdoor temperature reset control is the control method to change indoor air set temperature according to outdoor air temperature change. The range of indoor air set temperature is represented by the comfort temperature range of indoor air temperature offered from ASHRAE and indoor air set temperature is programmed between $22^{\circ}C$ and $27^{\circ}C$ by outdoor air temperature $20^{\circ}C{\sim}32^{\circ}C$ in summer. As a result of applying outdoor temperature reset control to central cooling system, the suggested control method shows better performances of energy savings than the conventional method which indoor temperature maintains constantly.

Application of Four-season Dedicated Outdoor Air Handling Unit in Central and Personal Air-conditioning (중앙공조 및 개별공조에서의 외조기 적용)

  • Park, Seung-Tae;Kim, Young-Il;Lee, Tae-Ho;Choi, Se-Young
    • Proceedings of the SAREK Conference
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    • pp.591-596
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    • 2008
  • The present study has been conducted to study the performance of dedicated outdoor air handling unit in central and personal air-conditioning. With conventional central and personal air-conditioning systems which are designed according to the maximum load, humidity increase above comfort level can not be avoided as the cooling load decreases. The adoption of dedicated outdoor air handling unit, however, can solve this problem. Moreover, the dedicated outdoor air handling unit has the characteristics of anti-bacteria due to dry coil, energy saving and good indoor air quality. During cooling seasons, dedicated outdoor air handling unit can save energy up to 30% than the conventional cooling+reheating system for controlling both temperature and humidity.

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Analysis of the Energy Consumption in Underfloor Air Distribution System depending on Outdoor Air Intake Rates (외기 도입에 따른 바닥급기 시스템의 에너지 사용량 분석)

  • Kim, Dong-Hee;Huh, Jung-Ho;Cho, Dong-Woo;Yu, Ki-Hyung;Yu, Ji-Yong
    • Proceedings of the SAREK Conference
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    • pp.826-831
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    • 2006
  • In this paper, we discussed the energy performance of underfloor air distribution(UFAD) and overhead air distribution system according to outdoor air intake rates in a office building. For this, the laboratory(S lab.) is selected for measuring the thermal environments of UFAD system and overhead system. Based on the measured data, the TRNSYS simulation is used to evaluate the energy performance of UFAD system and the overhead system according to outdoor air intake rates. By increasing outdoor air intake rates from required outdoor air intake rates(100CMH) to maximum air intake rates, the energy savings of UFAD system comparing with overhead system are varied $15%{\sim}25.6%$ in summer, $12.8%{\sim}19%$ in fall/spring and not varied in winter(8%). As results of simulations on stratification height and cooling set temperature, the lower the stratification height and the higher cooling set temperature, the larger cooling energy savings of UFAD comparing with overhead system according to outdoor air intake rates.

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Dynamic Simulation of a Dedicated Outdoor Air-conditioning System (외기 전용 공조기의 동특성 시뮬레이션)

  • Kim, Jung-Min;Kim, Young-Il;Chung, Kwang-Seop;Park, Seung-Tae
    • Proceedings of the SAREK Conference
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    • pp.322-327
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    • 2007
  • Dedicated outdoor air-conditioning(DOA) system that utilizes pre-cooling and desiccant dehumidification can be superior to conventional cooling and reheating system with respect to energy consumption and indoor thermal comfort. In this work, simulation has been conducted to study various factors that affect the performance of DOA. Dynamic simulation shows the transient variation of temperature and humidity as the on/off control logic is imposed. Exit humidity of process air and flow rate are varied to study the effect on exit temperature of process air, dehumidification quantity, required regeneration temperature and exit humidity of regeneration air. For an outdoor air condition of $28.5^{\circ}C$ temperature, 16 g/kg humidity ratio and 2000 cmh flow rate, the dehumidification efficiency is increased by 4.6% as the flow rate is doubled.

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