• Proceedings of the KSME Conference
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• 2001.06d
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• pp.624-629
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• 2001

An experimental study was performed to investigate adiabatic wall temperature and heat transfer coefficient around on a module with longitudinal fin heat sink cooled by forced air flow. In the first method, inlet air flow(1-7m/s) and input power(3-5W) was varied after a heated module were placed on an adiabatic floor($320{\times}550{\times}1mm^{3}$). An adiabatic wall temperature was determinated to use liquid crystal film(LCF). In the second method to determinate heat transfer coefficient, inlet air flow(1-7m/s) and the heat flux of rubber heater($0.031-0.062\;W/cm^{2}$) was varied after an adiabatic module was placed on rubber heater covering up an adiabatic floor. In addition, surface oil-film visualization were performed to characterize the macroscopic flow-field around a module.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.4
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• pp.351-357
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• 2012

To reduce the summertime cooling load of a plant factory, a concept design was performed for the double skin window which utilizes the low temperature air from a ground coupled heat exchanger. The design parameters were selected as the number of cavity air inlet, the cavity thickness, the location of cavity air inlet, and the configuration of cavity air outlet. A parametric study was conducted in a systematic way to evaluate the heat transfer characteristics of the double skin window. As the number of cavity air inlet and the cavity thickness increase, the heat flux from outside air to indoor air was decreased. The effect of the location of cavity air inlet was not significant and the larger cavity air outlet area gave us relatively better heat blocking performance from outside hot air. This study demonstrated that it is possible to develop an improved double skin window by utilizing a ground coupled heat exchanger.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.3
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• pp.267-273
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• 2013

In order to provide effective operating conditions for the fan in a wet cooling tower with film fill, a new program to search for the minimum fan power was developed using a model of the optimal total annual cost of the tower based on Merkel's model. In addition, a type of design map for a cooling tower was also developed. The inlet water temperature and heat load were considered as key parameters. The present program was first validated using several typical examples. The results showed that for a given heat load, a three-dimensional graph of the fan power (z-axis), mass flux of air (x-axis, minimum fan power), and inlet water temperature (y-axis, maximum of minimum fan power) showed a saddle configuration. The minimum fan power increased as the heat load increased. The conventionally known fact that the most effective cooling tower operation coincides with a high inlet water temperature and low air flow rate can be replaced by the statement that there exists an optimum mass flux of air corresponding to a minimum fan power for a given inlet water temperature, regardless of the heat load.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.11
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• pp.873-879
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• 2014

In the present study, water vapor is injected at various positions in a Clean Dry Air (CDA) system such as a system inlet duct, compressor inlet, and compressor outlet by humidified air turbines. The application of evaporative cooling reduces the compression work and enhances the Energy Consumption Index (ECI) per unit volume. The main purpose of this study is to investigate the compressor power performance with different inlet air temperatures and humidity conditions. It is found that the actual power consumption and discharge flow are significantly influenced by the inlet air temperature as well as relative humidity. The results obtained during this study are compared both numerically and experimentally and are found to be in very good agreement.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1834-1839
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• 2003

Temperature and velocity distributions of hot air flows in rotational molding machines with two different shapes and structures of oven and inlet were investigated by using FLUENT, a commercial computational fluid dynamics code. The shape and structure of oven and inlet in current rotational molding machine were improved. Two different sizes of mold inside each oven were considered in the analysis. Temperature and velocity distributions of hot air flows in two different rotational molding machines were compared to each other. In order to reduce cycle time and improve product quality in current rotational molding machine, the improved shape and structure of oven and inlet were proposed.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.4 no.2
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• pp.119-128
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• 1975

Natural draft and flow which low temperature moist gas produces in the chimney of an Ondol heating system were numerically analysed. Among several factors involved inlet gas temperature has the strongest influence on the chimney performance and then next specific humidity of the gas. Thermal conductivity of the chimney wall, however, has little influence on the performance of such a low temperature chimney. Under given flow conditions there exists an optimum chimney height which gives a maximum flow rate for a given chimney diameter. This optimum value of chimney height inereases with increase in chimney diameter, inlet gas temperature and specific humidity.

• Journal of the Korean Society of Combustion
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• v.8 no.2
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• pp.7-16
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• 2003

The transfer of air pollutants between passenger room and service room in train are investigated by the computational analysis. The effects of service room temperature, inlet velocity, initial concentration and heating are studied. The flow induced by the difference of density between two rooms is found to take the major role in transfer of polluted air. Low temperature of service room enhances the polluted air flow into passenger room along the floor. Exhaust fan above the door between two rooms is not effective for this case. Strong inlet flow is found to suppress polluted air flow from service room. The heating of passenger room can promote air pollution.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.18-24
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• 2015

An experimental investigation was conducted to figure out the effects of the inlet air temperature on the combustion efficiency using the fuel grains which were highly loaded with boron carbide. The results showed that the normalized combustion efficiency increased with the inlet air temperature, apparently the result of enhanced combustion of the boron particles. Even though the combustion efficiency is increased, the overall efficiency through the semi-empirical method, is decreased with the increasing inlet air temperature. Brayton cycle analysis has been performed using the heat input parameter and combustor Mach number, those two parameters are important role for the performance and similar trends are shown at the experimental results.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1664-1669
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• 2004

Design analysis of the solid oxide fuel cell and gas turbine combined power system is performed considering different methods for preheating cell inlet air. The purpose of air preheating is to keep the temperature difference between cell inlet and outlet within a practical design range. Three different methods are considered such as a burner in front of the cell, a preheater in front of the cell and recirculation of the cathode exit gas. Analyses are carried out for two maximum cell temperature differences. The greater temperature difference ensures higher efficiency. The cathode exit gas recirculation exhibits better performance than other methods.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.7
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• pp.549-556
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• 2001

Heat flow characteristics during hot water extraction process was studied experimentally. Data were taken at various outlet port type for the fixed inlet port type, inlet-outlet temperature differences and mass flow rates. In this study, the temperature distribution in a storage tank and an outlet temperature were measured to predict a flow pattern in the storage tank, and a hot water extraction efficiency was analysed with respect to the variables dominating a extraction process. Experimental results show that the extraction efficiency is high in a low flow rate in case of using modified distributor I(MDI) as a outlet port type.