• 대한설비공학회지:설비저널
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• 제11권2호
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• pp.10-15
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• 1982

An experimental study on the storage tank which uses sensible heat of water is done. The influence of inlet flow rate (Re), the difference between initial temperature and inlet water temperature(Gr) and the location of inlet and outlet on the performance of storage tank is studied. Development of stratification is examined by measuring the transient temperatures of 36 points inside the tank. Measured values are transformed to the dimensionless parameters in order to calculate the temperature efficiency of storage tank. In the presence of combined natural and forced convection, the development of stratification becomes clearer and thus the efficiency becomes higher, as $Gr/Re^2$ increases.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.139-145
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• 2001

The purpose of present study is to find design parameters and operating conditions of the HVAC system in a subway platform. The simulation was carried out for the flow, heat and mass transfer for heating, ventilating and air-conditioning(HVAC) environments in the subway platform. The steady-state. incompressible flow assumption and standard $k-{\varepsilon}$ turbulence model are adopted. The location of HVAC air inlet above platform and the volume flow rate of curtain air released from inlet B are chosen as main parameters in this study. The results of present study are following: In the case of existence of train, the heat and contaminant released under the train have no effect on the average temperature and mass fraction of contaminant in the platform, but heat released on the train has influence on the average temperature in the platform. Train acts as an obstacle to exhaust the contaminant in the platform, but has good effect on the average temperature in the platform.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.25-30
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• 2003

Several desiccant cooling systems have been developed in terms of cost and performance. In this study a fin-tube exchanger has been used for liquid desiccant dehumidification system. This dehumidifier has been designed to study the absorption characteristic of the aqueous triethylene glycol(TEG) solution which has the flow range from 20 to 50 LPM. The dehumidifier performance characteristic of working factor variables such as inlet solution flow rate, air flow rate, solution concentration, solution temperature, brine temperature, air temperature and inlet air relative humidity has been analyzed. The result of this experiment can provide useful data for hybrid air conditioning system.

• 한국산학기술학회논문지
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• 제12권12호
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• pp.5457-5463
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• 2011

본 연구의 목적은 이산화탄소를 적용한 자동차용 냉방시스템의 냉방 성능특성을 고찰하는 것이다. 특히 자동차의 실도로 운전 조건을 모사할 수 있도록 실험 조건을 선정하였으며 실제 자동차에 적용된 이산화탄소용 냉방시스템에 대하여 다양한 냉방성능 실험을 진행하였다. 결과적으로, 가스쿨러 입구 공기온도가 증가할수록 냉방용량과 COP는 감소하였고 증발기 입구 공기온도가 증가할수록 냉방용량과 COP는 증가하였다. 또한, 압축기 회전속도가 900 rev/min에서 1800 rev/min으로 증가할수록 냉방용량은 42.2% 증가였으나 냉방 COP는 55.4% 감소하였다.

• 한국산학기술학회논문지
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• 제12권1호
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• pp.26-31
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• 2011

본 논문은 기존의 스파크 점화 방식이 아닌 bulk combustion 방식을 도입하여 별도의 점화장치 없이 상용 단기통 디젤기관에 유입되는 흡입공기를 가열 및 제어하여 흡기관에 분사되는 가솔린연료의 압축착화성을 향상시킴으로서 기관작동을 가능하게 하였다. 제동열효율의 최대값은 공기-연료비가 35부근에서 나타나며, 35이상의 영역에서는 급격히 감소하고 흡입공기 가열온도가 올라갈수록 제동열효율은 증가한다. 따라서 공기-연료비를 감소시키면서 흡입공기의 가열온도를 상승시키는 방식이 열효율 측면에서 효과적이라는 것을 알 수 있다.

• 제어로봇시스템학회논문지
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• 제12권6호
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• pp.539-546
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• 2006

The Air Quality Sensor(AQS), located near the fresh air inlet, serves to reduce the amount of pollution entering the vehicle cabin through the HVAC(heating, ventilating, and air conditioning) system by sending a signal to close the fresh air inlet door/ventilation flap when the vehicle enters a high pollution area. The sensor module which includes two independent sensing elements for responding to diesel and gasoline exhaust gases, and temperature sensor and humidity sensor was designed for intelligent AQS in automobile. With this sensor module, AVR microcontroller was designed with back propagation neural network to a powerful gas/vapor pattern recognition when the motor vehicles pass a pollution area. Momentum back propagation algorithm was used in this study instead of normal backpropagation to reduce the teaming time of neural network. The signal from neural network was modified to control the inlet of automobile and display the result or alarm the situation in this study. One chip microcontroller, ATmega 128L(ATmega Ltd., USA) was used for the control and display. And our developed system can intelligently reduce the malfunction of AQS from the dampness of air or dense fog with the backpropagation neural network and the input sensor module with four sensing elements such as reducing gas sensing element, oxidizing gas sensing element, temperature sensing element and humidity sensing element.

• 설비공학논문집
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• 제18권5호
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• pp.393-401
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• 2006

The regenerative evaporation water cooler is devised and analysed in this study. The regenerative evaporation water cooler is composed of a sensible heat exchanger to cool the incoming air, followed by a latent heat exchanger to cool the water evaporatively with the cooled air flowing out of the sensible heat exchanger. By linearizing psychrometric characteristics, the heat and mass transfer in the regenerative evaporation water cooler is analyzed theoretically. The results show that the water can be cooled down even lower than the wet-bulb temperature of the inlet air. When the inlet air is $32^{\circ}C$ and 20% in relative humidity, and the inlet temperature of the water is $20^{\circ}C$, the regenerative evaporation water cooler provides a larger cooling capacity than the conventional evaporation water cooler if the effectiveness of the latent heat exchanger is higher than 0.6 and that of the sensible heat exchanger is higher than 0.5.

• 한국연소학회지
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• 제20권3호
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• pp.8-12
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• 2015

The CO reduction characteristics of hot air stream diluted with exhaust gas in a perfectly stirred reactor (PSR) were investigated numerically. The dilution ratio ($\Omega$), inlet temperature ($T_{in}$), and residence time ($\tau$) were considered as parameters to investigate the effects of those on the emission indices for CO and $CO_2$ (EICO and $EICO_2$). The roles of dominant reactions and the production rates of major species were analyzed. It was found from the EICO trend that the supplied CO in the air stream was consumed. The EICO increased negatively with $T_{in}$ at fixed $\tau$ regardless of $\Omega$. However, the magnitude of EICO and minimum inlet temperature for CO reduction showed complicated trend according to the variation of $\tau$. It was identified that the OH radical, generated from the reactions, $O_2+H{\leftrightarrow}O+OH$ and $2OH{\leftrightarrow}H+H_2O$, affected the CO reduction by the reaction, $CO+OH{\leftrightarrow}H+CO_2$. However, the CO emission ratio increased at sufficiently high inlet temperature range due to the thermal dissociation of $CO_2$.

• 한국분무공학회지
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• 제26권2호
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• pp.96-103
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• 2021

In order to improve the overall efficiency and meet the emission regulations of boiler systems, the heat exchanging methods between inlet air and exhaust gas have been used in boiler systems, named as the waste-heat-recovery condensing boiler. Recently, to further improve the overall efficiency and to reduce the NOx emission simultaneously, the concept of the water injection into the inlet air is introduced. This study suggests the models for the optimized design parameters of water injection for waste-heat-recovery condensing boilers and performs the analysis regarding the water injection amount and droplet sizes for the optimized water injection. At first, the required amount of the water injection was estimated based on the 1^st law of thermodynamics under the assumption of complete evaporation of the injected water. The result showed that the higher the inlet air and exhaust gas temperature into the heat exchanger, the larger the amount of injected water is needed. Then two droplet evaporation models were proposed to analyze the required droplet size of water injection for full evaporation of injected water: one is the evaporation model of droplet in the inlet air and the other is that on the wall of heat exchanger. Based on the results of two models, the maximum allowable droplet sizes of water injection were estimated in various boiler operating conditions with respect to the residence time of the inlet air in the heat exchanger.

• 설비공학논문집
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• 제16권7호
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• pp.630-638
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• 2004

Liquid desiccant dehumidification systems have the ability to provide efficient humidity and temperature control while saving the electrical energy requirement for air conditioning as compared to a conventional system. The dehumidifier and the regenerator form the heart of this system. The latent part of the cooling load is overcome using liquid desiccant. The model regenerator has been designed to study the absorption characteristic of the aqueous triethylene glycol (TEG) solution which is in the flow range from 20 to 50 LPM. Also, this system designed that was able to change the height of the regenerator and dehumidifier. Because the effect of performance have different result according the height. The effect of performance factors of the regenerator with inlet solution flow rate, air flow rate, solution concentration, solution temperature, brine temperature, air temperature and inlet air relative humidity have been analyzed. Data obtained are useful for design guidance and performance analysis of the hybrid air conditioning system.