• 제목/요약/키워드: Cooling Temperature

검색결과 4,671건 처리시간 0.029초

모세구동 소형 냉각시스템의 실험적 연구 (An Experimental Study on Small Capillary Pumped Cooling System)

  • 양재경;이규정;이정현
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 춘계학술대회논문집B
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    • pp.234-239
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    • 2000
  • The capillary pumped cooling system (CPCS) is a cooling system which controls temperature of the small electronic devices, such as IC device systems, notebook computers, etc. An important feature of CPCS is that a working fluid circulates in a system by capillary force in tubes instead of mechanical input power. The cooling effect of CPCS is investigated with respect to heat flux, condensation temperature under different working fluids (water, ethanol, methanol). Capillary pumped flows are visualized under various conditions and mass flow rate and temperature are experimentally measured. It is shown that the increasing tendency of mass flux for each working fluid is observed as the temperature of evaporator increases, and that the cooling possibility of CPCS depends on the performance of evaparator and condenser which sustains the steady state temperature continuously.

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냉각수 보급이 가정용 흡수식 냉난방기의 성능에 미치는 영향 (Effect on Household Absorption Chiller by the Supply of the Cooling Water)

  • 이호생;김동휘;최병권;김재돌;윤정인
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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    • pp.267-272
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    • 2002
  • The electric heat pump requiring HCFCs as a refrigerant has been for most residential air-conditioners in Korea. They cause a surge up electric power demand during summer. Moreover, the use of HCFCs and HFCs causes a serious problem to the global environment such as global warming and ozone layer destruction. An absorption chiller and heater could solve such problems. It was built and tested for analyzing the performance of the absorption chiller/heater. Experiment was done with a 1.5RT household absorption chiller and heater. It was experimented that the cooling capacity, gas capacity, COP were researched by the temperature of cooling water. The change of the cooling water temperature have effect the temperature(or pressure) of the parts on absorption chiller The result of the change of the cooling water temperature have the effects of the absorption chillers. This data will help to operate the household absorption chiller and heater.

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A Numerical Study on Cavitation Suppression Using Local Cooling

  • Zhang, Yuan-Yuan;Sun, Xiao-Jing;Huang, Dian-Gui
    • International Journal of Fluid Machinery and Systems
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    • 제3권4호
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    • pp.292-300
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    • 2010
  • This study strives to develop an effective strategy to inhibit cavitation inception on hydrofoils by using local cooling technique. By setting up a temperature boundary condition and cooling a small area on the upper surface of a hydrofoil, the fluid temperature around the cooling surface will be decreased and thereby the corresponding liquid saturation pressure will drop below the lowest absolute pressure within the flow field. Hence, cavitation can never occur. In this paper, a NACA0015 hydrofoil at $4^{\circ}$ angle of attack was numerically investigated to verify the effectiveness of the proposed technique. The CFD results indicate that the cooling temperature and the cooling surface roughness are the critical factors affecting the success of such technique used for cavitation suppression.

고온환경 하에서 착용하는 인체냉각 보조도구로서의 Cooling Vest 연구(1) -Local Cooling에 따른 인체의 온열생리학적 특성- (Efficacy of Cooling Vest for Auxiliary Body Cooling in Hot Environments (1) -Thermophysiological Response of Human Body in Local Cooling-)

  • 권오경;김진아;김태규
    • 한국의류산업학회지
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    • 제2권3호
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    • pp.265-271
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    • 2000
  • Heat stress results in fatigue, a decline in strength, alertness., and mental capacity. The problem is compounded when high humidity exists. To help relieve worker heat stress, many types of cooling units are marketed. While workers may experience some cooling, critical body core temperatures often continue to elevate. This study was designed to find the effects of three kinds of cooling vest with portable frozen gel strips on thermophysiological parameters and on temperature and humidity within clothing. The heart rate, rectal, and skin temperature as well as sweat rate and clothing microclimate were measured during 80 min in 5 healthy males. Inquiries were also made into the subjective rating thermal, humidity comfort, and fatigue sensations. The main findings in our experiments are as follows: (a) Physiological parameters such as rectal temperature was the lowest in garb A1, intermediate in garb A, and the highest in garb A2 throughout the experiment. And mean skin temperature was the lowest in garb A, intermediate in garb A1, and the highest in garb A2; (b) Temperature and humidity within clothing (back) were garb in Al, intermediate in garb A, and the highest in garb A2. But the temperature and humidity within clothing (chest) were garb in A, intermediate in garb A1, and the highest in garb A2; (c) Most participants (4 out of 5 persons) answered that they felt more comfortable and fatigueless in garb A1 than in garb A and A2. It is concluded that local cooling in garb A1 of the upper torso could physiological reduce the thermal strain in participants wearing cooling vest.

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에탄올에 의한 TMA-포접화합물의 냉각특성 개선에 대한 연구 (A Study on the Cooling Characteristics Improvement of TMA-Water Clathrate Compound by Ethanol)

  • 이종인;김창오
    • 한국자동차공학회논문집
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    • 제15권1호
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    • pp.23-28
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    • 2007
  • This study aims to find out cooling characteristics of TMA(Tri-Methyl-Amine, $(CH_3)_3N$) 25wt%-water clathrate compound with ethanol($CH_3CH_2OH$) such as supercooling, phase change temperature and specific heat. For this purpose, ethanol is added as per weight concentration and cooling experiment is performed at $-6{\sim}-8^{\circ}C$, cooling heat source temperature, and it leads the following result. (1) Phase change temperature is decreased due to freezing point depression phenomenon. Especially, it is minimized as $3.8^{\circ}C$ according to cooling source temperature in case that 0.5wt% of ethanol is added. (2) If 0.5wt% of ethanol is added, average supercooling degree is $0.9^{\circ}C$ and minimum supercooling is 0.8, $0.7^{\circ}C$ according to cooling heat source temperature. The restraint effect of supercooling is shown. (3) Specific heat shows tendency to decrease if ethanol is added. It is $3.013{\sim}3.048\;kcal/kg^{\circ}C$ according to cooling heat source temperature if 0.5wt% of ethanol is added. Phase change temperature higher than that of water and inhibitory effect against supercooling can be confirmed through experimental study on cooling characteristics of TMA 25wt%-water clathrate compound by adding additive, ethanol. This can lead to shorten refrigerator operation time of low temperature latent heat storage system and improve COP of refrigerator and efficiency of overall system. Therefore energy can be saved and efficiency can be improved much more.

탄소강 담금질시의 상변태열과 이를 포함한 냉각곡선의 계산 (The Latent Heat of Phase Transformation of the Carbon Steel and the Calculation of Cooling Curves Including the Latent Heat in Quenching)

  • 윤석훈;김경근
    • Journal of Advanced Marine Engineering and Technology
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    • 제18권3호
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    • pp.10-16
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    • 1994
  • This study aimed at measuring the latent heat of phase transformation of S45C carbon steel in quenching and at conducting the analytical researches into the calculation of cooling curves including the latent heat. The temperature of phase transformation of steel and its latent heat are dependant upon the cooling rates at the temperature of A1 phase transformation point. The effect of the latent heat of phase transformation is especially manifest at the cooling curve of center of specimens. The higher the cooling rates became, the lower fell the temperature region of phase transformation. In the figures of cooling rates, the phenomena of cooling rate dropping into zero was caused by the latent heat of phase transformation.

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균일 냉각을 고려한 Thick-Wall 형상의 플라스틱 렌즈 쾌속 금형 제작 (Manufacturing of Rapid Tooling for Thick-Wall Plastic Lens Mold with Conformal Cooling Channel)

  • 박형필;차백순;이상용;최재혁;이병옥
    • Design & Manufacturing
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    • 제1권1호
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    • pp.27-32
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    • 2007
  • In the optical application demand for high quality lens is increasing. Plastics lenses are demanded more than glass lenses for large size lenses as well as micro-size lenses. It is difficult to apply typical straight cooling channels of injection mold to lens molding due to its non-uniform temperature distribution. In this study, we manufactured molds for plastic lenses with the conventional cooling channels and conformal cooling channels produced by the DMLS process. We evaluated cooling performance for the 2 molds by injection molding experiment. Also, uniformity of the temperature distribution was tested by infrared camera and temperature monitoring. We confirmed that the cooling performance and temperature uniformity with the conformal cooling channels is much improved from the ones with the conventional. The cooling time with the conformal cooling channels was reduced 30% compared with the conventional cooling channels.

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건물예냉과 실내온도의 선형상승에 의한 피크냉방수요 저감 (Reducing Peak Cooling Demand Using Building Precooling and Modified Linear Rise of Indoor Space Temperature)

  • 이경호;양승권;한승호
    • 설비공학논문집
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    • 제22권2호
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    • pp.86-96
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    • 2010
  • The paper describes development and evaluation of a simple method for determining gradient of modified linear setpoint variation to reduce peak electrical cooling demand in buildings using building precooling and setpoint adjustment. The method is an approximated approach for minimizing electrical cooling demand during occupied period in buildings and involves modified linear adjustment of cooling setpoint temperature between $26^{\circ}C$ and $28^{\circ}C$. The gradient of linear variation or final time of linear increase is determined based on the cooling load shape in conventional cooling control having a constant setpoint temperature. The potential to reduce peak cooling demand using the simple method was evaluated through building simulation for a calibrated office building model considering four different weather conditions. The simple method showed about 30% and 20% in terms of reducing peak cooling demand and chiller power consumption, respectively, compared to the conventional control.

온도, 습도 및 냉방부하 예측에 관한 연구 (A Study on the Estimation of Temperature, Humidity and Cooling Load)

  • 유성연;한승호;이제묘;한규현;노관종
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2006년도 하계학술발표대회 논문집
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    • pp.80-85
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    • 2006
  • The peak demand of electricity in summer season mainly comes from the day time cooling loads. Ice thermal Storage System (ITSS) uses off-peak electricity at night time to make ice for the day time cooling. In order to maximize the use of cold storage in ITSS, the estimation of day time cooling load for the building is necessary. In this study, we present a method of cooling load estimation using 5 years of normalized outdoor temperature, relative humidity, and the building construction data. We applied the hourly-based estimation to a general hospital building with relatively less sudden heat exchange and the results are compared with the measured cooling load of the building. The results show that the cooling loads estimation depends on the indoor cooling design temperature of the building.

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동시냉난방 열펌프 시스템의 냉방전용 및 냉방주체 운전모드에서의 실내기온 변화에 따른 성능특성에 관한 실험적 연구 (An Experimental Study on the Performance of a Simultaneous Heating and Cooling Heat Pump in the Cooling-only and Cooling-main Operation Mode with the Variation of the Indoor Air Temperature)

  • 안재환;주영주;강훈;정현준;김용찬;최종민
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회B
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    • pp.2165-2170
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    • 2008
  • The cooling load in winter season is significant in many commercial buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. Therefore, the development of a multi-heat pump which can cover heating and cooling simultaneously for each indoor unit is required. In this study, the characteristics and performance of a simultaneous heating and cooling heat pump in the cooling-only and cooling-main operating mode was investigated experimentally with a variation of indoor air dry bulb temperature which is from $21^{\circ}C$ to $35^{\circ}C$. EEV opening was adjusted from 20% to 24% during the tests. When the indoor air temperature varied, the performance in the cooling-only mode was more sensitive to the temperature than in the cooling-main mode. The total capacity and COP were increased by 53.8% and 48.1%, respectively, in the cooling-main, while those were increased by 19.6% and 19.3% in the cooling-only mode. The performance differences between the two operating modes became larger at lower temperatures, especially for the COP.

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