• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.2
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• pp.180-192
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• 1998

Enthalpy transport in a pulse tube was investigated by two-dimensional analysis of mass, momentum and energy equations assuming that the axial temperature gradient in the pulse tube is constant. Time-averaged second-order conservation equations of mass, momentum and energy were used to show the existence of steady mass streaming and enthalpy streaming. Effects of axial temperature gradient, velocity amplitude ratio and heat transfer between the gas and the wall on the steady mass streaming and enthalpy streaming were shown. Enthalpy loss due to the steady mass streaming is zero for basic and orifice pulse tube refrigerators, but it is proportional to the axial temperature gradient and steady mass flow rate through a pulse tube for double inlet pulse tube refrigerators.

• International Journal of Air-Conditioning and Refrigeration
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• v.7
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• pp.33-44
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• 1999

Enthalpy transport in a pulse tube was investigated by two-dimensional analysis of mass, momentum and energy equations assuming that the axial temperature gradient in the pulse tube was constant. The time-averaged second-order conservation equations of mass, momentum and energy were used to show the existence of steady mass and enthalpy streaming. Effects of the axial temperature gradient, velocity amplitude ratio, and heat transfer between the gas and the tube wall On the steady mass and enthalpy streaming were shown. Enthalpy loss due to the steady mass streaming is zero for basic and orifice pulse tube refrigerators, but it is proportional to the axial temperature gradient and steady mass flow rate through a pulse tube for double inlet pulse tube refrigerators.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.113-119
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• 1999

In this study, the incineration of MEK and toluene was studied on a Pt supported alumina catalyst at temperature range from 200 to $350^{\circ}C$. An approach based on the Mars-van Krevelen rate model was used to explain the results. The object of this study was to study the kinetic behavior of the platinum catalyst for deep oxidation. The conversions of MEK and toluene were increased as the inlet concentration was decreased and the reaction temperature was increased. The maximum deep conversion of MEK and toluene were 91.81% and 55.69% at $350^{\circ}C$, respectively. The ${\kappa}_3$ constant increases with temperature faster than the ${\kappa}_1$ constant, that is, the surface concentration of ($VOCs{\cdots}O$) is higher than that of (O) at higher temperature according to the Mars-van Krevelen mechanism. Also the activation energy of toluene was larger than MEK for toluene is aromatic compound which have stronger bonding energy.Therefore, the catalytic incineration kinetics of MEK and toluene with Mars-van Krevelen mechanism could be used as the basic data for industrial processes.

• Solar Energy
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• v.10 no.1
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• pp.38-46
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• 1990

For the optimal design and the efficient operation of the double pipe type latent heat storage equipment, the effect of the parameters of the system were analysed. The statistical analysis showed that the theoretical and the experimental results of the volume change rate and the temperature variations were well agreed. Therefore, this theoretical model is reasonable to analyze two dimensional moving boundary problems. In the analysis of the effects of the parameters, the heat extraction fraction and the water outlet temperature of the system as function of the time were analysed depending on the initial temperature of PCM, water inlet temperature, water mass flow rate and the dimension of the inner tube.

• Tribology and Lubricants
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• v.3 no.2
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• pp.68-71
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• 1987

This paper deals with some thermal Characteristics of journal bearing such as the behaviour of the maximum bearing temperature, the lubricant's carry-over in the inlet region and so on. Temperatures of the bearing and the lubricants being supplied and discharged were measured along with shaft speed and bearing load. The results showed that with the increase of the Shaft speed, the maximum temperature rose at any shaft speed at a defferent rate of change defending on the flow regime of the lubricant film. And the lower eccentricity ratio is the more lubricant's carry-over occur. Additionally it was partially proved that the oil discharge temperature and the maximum temperature changed in quite different each other.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1518-1523
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• 2003

The objective of the present work is to investigate an effect on the solution crystallization temperature difference and the cooling capacity of the absorption chiller by a solution cooler in the absorber. The cooling capacity of the absorption chiller can be higher, with the enhanced performance of the solution heat exchangers. But, because the solution crystallization temperature difference becomes smaller at the absorber inlet, the heat capacity of the solution heat exchangers might be limited by the danger of crystallization, which can cause the serious damages. In this paper, the heat capacity ratio of the solution cooler is defined as the ratio of the heat capacity of the solution cooler to that of the absorber. If it becomes larger in the additional type solution cooler, the solution crystallization temperature difference is augmented and the cooling capacity is also increased.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.50-55
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• 1986

Characteristics of the flow and heat transfer in a channel of 37 rods are investigated numerically. The flow is taken to be a fully developed incompressible laminar flow and it has an uniform temperature profile at the inlet and flows down through the channel of constant wall temperature. A boundary-fitted coordinate system is used for the complex geometry. Calculation is initiated by calculating the developed flow profile and then proceeds to temperature development. Through the calculation the details of the flow and temperature distribution characteristics are found, and discussion is made on the mechanism of the transport phenomena in the complex geometry in terms of wall shear stress distribution, non-dimensionalized velocity, friction factor, Nusselt number distribution, Reynolds number, and porosity. Also the effects of the eccentricity in rod configuration are analyzed and its importance is emphasized.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.4
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• pp.453-462
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• 1994

An unsteady quasi one-dimensional model of momentum, heat and mass transfer in a falling film of a vertical plate absorber which is cooled by air was developed using the integral method. Energy conservation of the absorber wall is considered in the model. The model can predict absorption rate, film thickness and mean velocity as well as concentration and temperature profiles. Predictions of steady state temperature and concentration profiles for LiBr/water system for constant wall temperature condition are in good agreement with the two-dimensional finite difference method solutions. Effects of operating conditions, such as convective heat transfer coefficient between the cooling air and the absorber wall, cooling air temperature and film thickness at inlet, on absorption rate of water vapor into LiBr/water solution were shown.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.90-99
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• 2002

The main purpose of this study lies on the development of micro dilution tunnel based on the Sierra Dilution chamber model. As a primary examination, characteristics of flow and temperature distributions during the steady dilution process in dilution chamber are observed with numerical analysis. The penetration of dilution air through porous tube as well as wall temperature and temperature gradient inside porous tube are examined. The thermophoretic velocity in terms of temperature behavior inside porous tube are defined and examined. Based on the ratio of penetration and thermophoretic velocities, all part of porous tube are shown to be safe from the particulate depositions. However, The inlet portion of porous tube in addition to the portion of impinging of dilution air are marginally safe from the particulate depositions. Generally the safer design against particulate deposition is required in provision f3r steady dilution process and for transient process as well.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.10
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• pp.844-853
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• 2002

A dynamic model which simulates the coupled heat and mass transfer within a vertical tube absorber was developed. The liquid film is a binary mixture of two components, and both of these components are present in the vapor phase. The pressure, concentration, temperature and mass flow rate of the vapor are obtained by assuming that the pressure is uniform within an absorber. The model was applied to an absorber for an ammonia/water absorption refrigerator. The transient behaviors of the pressure, the outlet temperature and the concentration of the solution and the cooling water outlet temperature on a step change at the absorber inlet of the cooling water temperature, the vapor mass flow rate and the concentration of the solution were shown.