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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Korean Journal of Air-Conditioning and Refrigeration Engineering
Journal Basic Information
Journal DOI :
The Society of Air-Conditioning and Refrigerating Engineers of Korea
Editor in Chief :
Volume & Issues
Volume 10, Issue 6 - Nov 1998
Volume 10, Issue 5 - Sep 1998
Volume 10, Issue 4 - Jul 1998
Volume 10, Issue 3 - May 1998
Volume 10, Issue 2 - Mar 1998
Volume 10, Issue 1 - Jan 1998
Selecting the target year
Experimental study on the cooling characteristics of thermosyphon for the high power electronic components
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 137~146
The experimental study is concerned with two-phase closed thermosyphons, (i.e., wickless heat pipes) for the cooling of high power electronic components in telecommunication system. The thermosyphon which can deal with a high heat flux of up to
is developed, and the cooling characteristics of thermosyphon is analyzed according to design parameters which are the types of and quantity of working fluid, number of pipes, wire insertion in pipe, inclination angle of thermosyphon, and cooling air velocity. Using water as working fluid is superior cooling performance compared to using acetone, and cooling performance is improved as the number of thermosyphon becomes larger, inserting wires in the pipes, and inclination of
Thermal environment evaluation of KBS open hall with mixing ventilation and downward displacement ventilation systems
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 147~154
This study was carried out for evaluating the interior thermal environment in KBS Open hall with large ceiling height and large space. Ventilation systems of KBS Open hall have combined mixing ventilation and downward displacement ventilation system. Temperature and velocity was measured 130 locations with low level(0.1m), mid level(0.6m) and high level(1.1m). But relative humidity was measured at 15 locations. The subjective thermal sensation was made an inquiry of occupancy at the location measured physical elements.
Exergy analysis of heat pump in consideration of its dynamic response
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 155~164
A multi-type heat pump controls the mass flow rate of the working fluid to cope with variable heat loads when it is under dynamic load condition. This paper describes the exergy analysis associated with the dynamic response of heat pump. First, a basic heat pump cycle is examined at steady state to show the general trends of exergy changes in each process of the cycle. Entropy generation issue in the exchangers is discussed to optimize the heat pump cycle. Second, the performance of the inverter-driven heat pump is compared to that of the conventional one when the heat load is variable. Third, the exergy destruction rate associated with the ON/OFF operations of the heat pump is calculated by simulating the thermodynamic states of the condenser and the evaporator. The inefficiency of the ON/OFF operation during the transient period is quantitatively revealed by the exergy analysis.
Experimental study on heat transfer inside inclined thermosyphon with low integral-fins
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 165~172
An experimental study on the heat transfer of the inclined thermosyphon with low integral-fins in which boiling and condensation occurred is performed to investigate its heat transfer performance. Water and CFC-30 have been used as the working fluids. The operating temperature and the inclination angle of thermosyphon have been used as the experimental parameters. The heat flux input and the inclination angle
towards the vertical position were varied in steps. The heat transfer rate in the thermosyphon was depended upon the inclination angle. In addition, it is to obtain the overall heat transfer coefficients and the characteristics as a operating temperature for the practical applications.
The effect on the seasonal performance of an inverter compressor with higher and lower operating range
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 173~179
An experimental study was conducted on the effect of compressor capacity control range of heat pump on the seasonal energy efficiency ratio with variation of the maximum and minimum compressor input frequencies. To obtain seasonal energy efficiency ratio, steady state test at the maximum, minimum and intermediate compressor speed and cyclic test at the minimum compressor speed should be conducted. Maximum input frequency was varied to 95Hz, 105Hz, and 115Hz, and the minimum input frequency was varied to 35Hz, 45Hz, and 55Hz. The seasonal energy efficiency ratio increased as the input frequency of the compressor decreased. The maximum input frequency had only slight effects on the SEER.
Enthalpy transport in pulse tube refrigerators
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 180~192
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.
Study on the flow characteristics and heat transfer enhancement on flat plate in potential core region of 2-dimensional air jet
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 193~201
A heat exchanging system employing the impinging air jet is still widely used In the various fields due to its inherent merits that include the easiness in engineering applications and the high heat and/or mass transfer characteristics. The purpose of this study is to investigate the enhancement of heat transfer and flow characteristics by placing a turbulence promoters in front of heat exchanging surface. In this study, a series of circular rods are placed at the upstream of a flat plate heat exchanger that is located at potential core region(H/W=2) of a two-dimensional impinging air jet. Heat transfer enhancement is achieved by inserting turbulence promoter that results in the flow acceleration and disturbance of boundary layer. The average Nusselt number of the flat plate with the turbulence promoters is found to be around 1.42 times higher than that of the flat plate without the turbulence promoters. Based on the results of flow visualization with a smoke wire, it is confirmed that the heat transfer enhancement is caused by the flow separation and disturbance of boundary layer by inserting the turbulence promoter.
Computer simulation for the performance analysis of automobile air conditioning system
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 202~216
A computer simulation for the performance analysis of automobile air conditioning components is carried out for the various operating conditions. The automobile air conditioning system consists of laminated type evaporator, swash plate type compressor, parallel flow type condenser, externally equalized thermostatic expansion valve and receiver drier. The overall heat transfer coefficient and the pressure drop in laminated type evaporator were obtained through experiments. In parallel flow type condenser, the performance analysis computer program using the empirical equation for heat transfer coefficient has been developed and the results are compared with experimental results. A model for matching the performance analysis programs of respective components .of automobile air conditioning system is introduced. Further, the effects of varying condenser size and refrigerant charge on the performance of automobile air conditioning system are discussed clearly.
Simulation of buoyant turbulent flow in a stairwell
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 217~226
A numerical study has been carried out for two- and three-dimensional buoyant turbulent flow in a stairwell model. The Reynolds-averaged Navier-Stokes and energy equations are solved with the authors'own computer program. Two models by the Boussinesq approximation and the density-gradient form are used for buoyancy terms in the governing equations. Two- and three-dimensional predictions of the velocity and temperature fields are presented and the results are compared with experimental data. Comparisons have also been made in detail with two-dimensional predictions. Two-dimensional and three-dimensional simulations have predicted the overall features of the flow satisfactorily. A better agreement with experiment is achieved with three-dimensional simulations.
Development of program for the automotive air conditioning system analysis
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 227~237
A numerical simulation has been carried out for the automotive air conditioning system. The purpose of this simulation is to present the methods for simulating car air conditioning components, systems and cool-down performance by computerized mathematical model and to analyze the performance of A/C system. In analyzing the heat exchanger(evaporator and condenser), the finite volume model which has a merit in predicting the temperature field in detail because it can consider partial variation of thermal property and heat transfer coefficient is used. In analyzing the compressor, the polytropic approach which regards the actual compression process as a reversible polytropic process is employed. In analyzing vehicle passenger compartment, the thermal network is employed to simulate the car cool down process. This A/C system program can be used for analyzing a component performance when a component is alternated or designed and for analyzing the engine cooling system when A/C system is operated.
Investigation of vapor-liquid equilibrium of HFC125/134a system
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 10, issue 2, 1998, Pages 238~250
Vapor-liquid equilibrium apparatus is designed and set up. The vapor-liquid equilibrium data of the binary system HFC125/134a are measured in the range between 268.15 and 283.15K at five compositions. Twenty-five equilibrium data are obtained. To verify consistency of these data, they are tested for thermodynamic consistency. Based upon the present data, the binary interaction parameter for CSD and RKS equation of state is calculated at five isotherms and comparison with the data in the open literatures is made. Results of Nagel and Bier are in very good agreements with those from this study within 0.32∼1.11% for bubble point pressure and －0.66∼0.18% for vapor mole fraction.