• Title/Summary/Keyword: Comfort air-conditioning

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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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A Study on the Indoor Environment Condition in Green Building Certification Criteria (학교시설 친환경인증 사례를 통한 실내 환경 평가항목 분석)

  • Shin, Yoo-Jin;Kwag, Moon-Geun;Choi, Chang-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.9
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    • pp.579-588
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    • 2010
  • According to the increasing concern about health and environment, students need to study in comfort and clean environment facilities. We did field survey on 40 primary schools to analyze the present condition of design and construction for the part of indoor environmental performance in the certificated green school building. We hope that this paper will offer the important data about the indoor environment standards and performances in primary school facilities.

The Performance of a Heat Pump with a Variation of Expansion Valve at Various Charging Conditions (냉매 충전량과 팽창장치 변화에 따른 열펌프 시스템의 성능특성에 관한 연구)

  • 최종민;김용찬
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.8
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    • pp.661-666
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    • 2003
  • Constant area expansion devices such as capillary tubes, short tube orifices are being gradually replaced with electronic expansion valves (EEVs) because of increasing focus on comfort and energy conservation. In this study, the performance of a water-to-water heat pump as a function of refrigerant charge is investigated in steady state, cooling mode operation with expansion devices of a capillary tube and an EEV. The performance of the capillary tube system varies drastically according to the change of refrigerant charge amount and inlet temperature of the secondary fluid in the condenser. Cooling capacity and COP of the EEV system show little dependence on the refrigerant charge, while those are strongly dependent on the secondary fluid temperature at the condenser inlet. In general, for a wide range of operating conditions the EEV system shows much higher performance as compared with the capillary tube system. The performance of the EEV system can be optimized by adjusting EEV opening to maintain a constant superheat at all test conditions.

Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 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.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. 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 heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were 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 thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen 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, and renewable energies, piping in the buildings. Proposed designs, performance 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 was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

A Field Measurement Study on Heat Storage/Emission Characteristics of Tower Type Apartment Structures in Winter Season (겨울철 난방시 탑상형 아파트 구조체의 축·방열 특성에 대한 현장측정 연구)

  • Chang, Hyun-Jae;Cho, Keun-Je
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.2
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    • pp.190-195
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    • 2012
  • In this study, as a complementary study of the former study on indoor thermal environment in a tower type apartment house at tropical nights, a field measurement was conducted in winter season. Mainly, characteristics of heat storage and heat emission in apartment structures, in this study, were investigated. As results, indoor air temperature was changed in the range of $22.5^{\circ}C{\pm}1.0^{\circ}C$, and followed not the change of outdoor air temperature but the changed pattern of floor surface temperature. Wall surface temperature was unresponsive to the change of floor surface temperature compared with the change of indoor air temperature because wall structure was composed of concrete which has large heat capacity, and was changed in the range of $22.3^{\circ}C{\pm}0.6^{\circ}C$. Heat was stored continuously into the structures of wall and ceiling through the measurement term. and this means that a large heat capacity of the apartment structure acts as a disadvantage in winter season, too. As a total review of the study with the former study, a large heat capacity of the apartment structure acts against indoor thermal comfort in winter season as well as in summer season.

Evaluation of Apartment Cooling System by Multi-Criteria Decision Making Analysis (다기준 의사결정 분석에 의한 공동주택의 냉방시스템 평가)

  • Kang, Byoung-Min;Cho, Jin-Hwan;Kim, Young-Il;Chung, Kwang-Seop
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.8
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    • pp.580-586
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    • 2011
  • In this study, 3 cooling systems of apartment which are air-cooled air conditioner with indoor unit, water-cooled air conditioner with indoor unit and small capacity absorption chiller-heater with FCU have been evaluated by Multi-Criteria Decision Making Analysis. Weights of 7 selected factors which are economics, space, billing, constructability, human comfort, visibility and reliability are determined by expert group of 30 system designers and 30 construction engineers. Final weights were derived for 101 and 166 $m^2$ apartments. Analysis shows that small capacity absorption chiller-heater with FCU is the most favorable system for apartment cooling system.

The Measurement of the Indoor Air Quality in Subway (전동차의 실내 공기청정도 측정 평가)

  • So, Jin-Sub;Yoo, Seong-Yeon;Yun, Cha-Jung;Kim, Wan-Jong;Kang, Sung-Hae;Park, Duk-Sin;Cho, Young-Min;Kwon, Soon-Bark;Park, Eun-Young
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.1325-1329
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    • 2007
  • Indoor air quality is an important determinant of human health and comfort. However, the complexity of pollution sources and the multitude of parties responsible for creating indoor exposures makes the improvement of air quality difficult. The HVAC(Heating, Ventilating and Air-Conditioning) system is important facility to provide comfortable environment passenger service. The Ministry of Environment is established "Indoor Air Quality Management guidelines in Public Facilities"in December 2006. Hereupon, the train and the subway are included. In this research air quality in the Subway compartment has been measured. As a result, the concentrations of PM10 and $CO_2$ were reached to 93% and 61% of the regulation values, respectively. Thus, the indoor air qualities of subway have been proved that they satisfy the recommended guidelines by the Ministry of Environment.

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The Measurement of the Indoor Air Quality in KTX Train (KTX 객실내 공기청정도 측정)

  • So, Jin-Sub;Lee, Sung-Uk;Park, Duck-Shin;Yoo, Seong-Yeon
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.1210-1213
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    • 2006
  • Indoor air quality is an important determinant of human health and comfort. However, the complexity of pollution sources and the multitude of parties responsible for creating indoor exposures makes the improvement of air quality difficult. The KTX HVAC(Heating, Ventilating and Air-Conditioning) system is important facility to provide comfortable environment passenger service. The Ministry of Environment is planning to enforce$\square\square$Indoor Air Quality Management law in Public Facilities$\square\square$in year 2008. Hereupon, the train and the subway are included. In this research air quality in the KTX Train compartment has measured. As a result, The average amounts of PM10(particulate matters), $CO_2$(carbon dioxide)measured $20{\mu}g/m^3$, 1,097ppm in KTX respectively. There are compare to regulation the value is 10% for PM10 and 43% for $CO_2$. Thus, the indoor air quality of KTX train have been proved satisfy the recommendation the Ministry of Environment guidelines.

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A Study on the Operation Strategy of Radiant Floor Cooling in Apartment Buildings (공동주택에서 바닥복사냉방의 적정 운영방안에 관한 연구)

  • 조영흠;석호태;여명석;김광우
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.6
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    • pp.574-583
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    • 2004
  • In this study, the operation strategy of the radiant floor cooling is evaluated in terms of indoor environmental conditions and energy consumption through simulations using the TRNSYS comparing the existing cooling operation. The operation strategy during continuously operated for cooling is proposed that a representative room had additional equipments and other rooms were operated with only a radiant floor cooling system and that system and control method for cooling are varied with period while intermittently operated for cooling. Specifically, when there are no people in the room, rooms were operated by only radiant floor cooling system using cooling storage and when people are occupied, rooms were operated by dehumidification and supplementary cooling device with radiant floor cooling system. The results of this study show that proposed operation strategy can stably maintain the set room air temperature and can reduce the energy consumption compared to the existing cooling method during continuously operated for cooling. While intermittently operated for cooling, the difference of set room air temperature by proposed operation strategy does not happen, satisfying comfort standards and the radiant floor cooling can expect to supply stable electric power because of decreasing demand for peak electric power of energy consumption.

An Energy Performance Evaluation of UFAD System under the Various Conditions of Thermal Load (실내 부하조건에 따른 바닥공조 시스템의 에너지 성능 평가)

  • Yoon, Seong-Hoon;Jang, Hyang-In;Kim, Kyung-Ah;Yu, Ki-Hyung;Suh, Seung-Jik
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.1
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    • pp.14-19
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    • 2013
  • The present study has been conducted for evaluating and comparing the performance of the underfloor air distribution system(UFAD) and the ceiling based air distribution system(CBAD) under cooling condition. Simulations and experiments were carried out for verifying the model by TRNSYS program about UFAD and CBAD. The results of simulation for various conditions of thermal load are summarized as followings. UFAD had an advantage for making thermal comfort because of lower temperature of the floor surface. Moreover, UFAD showed lower fan power about 30~50% than CBAD under the same conditions of thermal load. The energy saving rates of UFAD were increased to 17.7% in proportion to the thermal load on unoccupied zone(lighting). Ultimately, additional investigations should be done for analyzing optimized operating conditions of UFAD with considering the thermal performance of building envelop and the thermal load.