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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 14, Issue 12 - Dec 2002
Volume 14, Issue 11 - Nov 2002
Volume 14, Issue 10 - Oct 2002
Volume 14, Issue 9 - Sep 2002
Volume 14, Issue 8 - Aug 2002
Volume 14, Issue 7 - Jul 2002
Volume 14, Issue 6 - Jun 2002
Volume 14, Issue 5 - May 2002
Volume 14, Issue 4 - Apr 2002
Volume 14, Issue 3 - Mar 2002
Volume 14, Issue 2 - Feb 2002
Volume 14, Issue 1 - Jan 2002
Selecting the target year
Sensitivity Analysis on the Thermal Response of Electronic Components during Infrared Reflow Soldering
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 1, 2002, Pages 1~9
The thermal response of electronic components during infrared reflow soldering is studied by a two-dimensional numerical model. The convective, radiative and conduction heat transfer within the reflow oven as well as within the card assembly are simulated. Parametric study is also performed to determine the thermal response of electronic components to various conditions such as conveyor velocities, exhaust velocities and emissivities. The results of this study can be used in selecting the oven operating conditions to ensure proper solder melting and minimization of thermally induced card assembly stresses.
Numerical Simulation on Dynamic Characteristics of a Water Heater System Driven by a Heat Pump
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 1, 2002, Pages 10~20
A dynamic model of a water heater system heated by a heat pump was developed. The water heater system was composed of heat pump and hot water reservoirs. Finite volume method (FVM) was applied to describe the heat exchangers. A new constraint on electronic expansion valve (EEV) or thermostatic expansion valve (TXV) that can control superheat after the evaporator was developed. Dynamic performances were evaluated for various sizes of the reservoir. In order to compare those performances, time scale was normalized by time constant representing the characteristics of reservoir size. Time constant was determined from quasi steady-state simulation of the system. From the simulation, the size of the water heater reservoir was found to have a large influence on the transient performance of the sys- tem. Therefore, the optimization of the reservoir size is needed in a design process.
Condensation Heat Transfer on the Horizontal Tubles of a Modular Shell and Tube-Bundle Heat Exchanger
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 1, 2002, Pages 21~30
The thermal performance of a modular shell and tube-bundle heat exchanger has been analyzed using section-by-section method. Investigated are the effects of air and water inlet conditions on condensation heat transfer of horizontal tubes. It is found that they are significant for the heat transfer of the modular shell and tube-bundle heat exchanger It is shown that the predictions and experimental results are in good agreements.
Experiment of Characteristic on the Charge and Discharge of Cold in Ice Storage System Applied Ice Making Method In-Water
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 1, 2002, Pages 31~37
This paper is concerned with the development of a new method for making and separating ice and saving floated ice by installing an evaporation plate at in-water within a storage tank. In a conventional harvest-type ice storage system, a tank saves ice by separating a formed ice from an installed evaporation plate, which is located above an ice storage tank as an ice storage system. A new harvest-type method shows very good heat transfer efficiency than a convectional method. It is because the evaporation panel is directly contacted with water in a storage tank. Also, at a conventional system a circulating pump, a circulating water distributor and a piping are installed, but these components are not necessary in a new method. In this study two kinds of ice storage systems are experimentally investigated to study the thermal characteristics of ice storage tanks. The results showed discharge of cold capacity of new type indicated the high values about 30~40% based on five time of drive, the temperature difference of inlet/outlet occurred the big range about
. So, the new type which makes ice in water showed superiorly.
An Experimental Study on the Characteristics of Evaporative Heat Transfer of Carbon Dioxide
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 1, 2002, Pages 38~45
Evaporative heat transfer characteristics of carbon dioxide have been investi- gated by experiment. The experiments have been carried out for a seamless stainless steel tube of the outer diameter of 9.55 mm, the inner diameter of 7.75 mm and the length of 5.0 m. Direct heating method was used for supplying heat to the refrigerant where the test tube was uniformly heated by electric current which was applied to the tube wall. Experiments were conducted with
of purity 99.99% at saturation temperatures of 0.0 to 10.5
, heat fluxes of 12 to 27kW/
s and mass fluxes of 212 to 530 kg/
s. The heat transfer coefficients of
are decreased as the vapor quality increases and these phenomena are explained by dimensionless Weber and Bond numbers. The heat transfer coefficients of
increase when the heat and mass fluxes increase, and the saturation temperature effects are minor in the test range of this study. The present experimental data are compared with six renowned correlations with root-mean-squared deviations ranging from 23.0 to 94.9% respectively.
Heat Transfer Characteristics on Design Conditions of Finned-Tube Evaporators
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 1, 2002, Pages 46~54
To investigate the design effects of a heat exchanger on a tube type, a tube circuit and a fin pitch, an experimental study on the heat transfer characteristics of finned- tube evaporators was performed. The refrigerant was R-22. A refrigerant loop was established to measure the heat transfer rate, the air heat transfer coefficient. The experimental results showed that the heat transfer characteristics of the evaporators were affected by the design parameters. And the heat transfer rate of the slit fin was better about 25%, compared to those of the louver fin. In the present experimental range, the heat transfer performance with the straight tube circuit was more remarkable than that of the zigzag tube circuit, as seen from temperature variations of the evaporator exit.
-factor on the tube type, the tube circuit and the fin pinch decreased, as increasing Reynolds number.
A Study on the Performance Evaluation of Infiltration Prevent Devices in refrigerated Warehouse
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 1, 2002, Pages 55~62
In this paper, several types of infiltration prevention devices that are currently in use have been studied through experimental investigation. Firstly, the types of infiltration prevention devices were defined through investigating actual conditions of refrigerated warehouse in operates. Based on this investigation results, measured change of temperature and figured out air change rates of the type of infiltration prevention devices by using scale down model. After that, found the amount of air change rate in order to estimate the load of air change easily in facility plan.
Sound Transmission Loss Measurement for Sound Isolation Sheets by Two-Microphone Impedance Tube Method
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 1, 2002, Pages 63~72
The main objective of this study is to propose a practical two-microphone impedance tube method to measure the sound transmission loss for flexible sound isolation sheets without the use of the time-consuming and expensive reverberation room. This method was based on the sound decomposition theory developed by Seybert using the spectral density functions of the incident and reflected sound waves. In order to verify the validity of the experimental results, the measured sound transmission losses from the proposed method were compared with the measured data from the reverberation room method and the calculated data from the theory satisfying the mass law of sound isolation material. The resulted trends of the sound transmission losses versus frequencies for several different sound isolation sheets were almost same for each other and agreed quite well in both methods except at some low frequency region. From the experimental results, it was found that the accuracy of sound isolation capability obtained by two-microphone impedance tube method depends upon the microphone spacing, the distance from the first microphone to the test sample surface and the test sample location.
Performance Characteristics of Propane/isobutane Mixtures in a Small Refrigeration System
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 1, 2002, Pages 73~82
A small refrigeration system used in a water purifier was tested by employing propane/isobutane (R-290/R-6OOa) mixtures as an alternative refrigerant of R-12. The drop-in tests were performed by varying mass fraction of propane at 0.25, 0.5 and 0.75 with a change of both refrigerant charge amount and capillary tube length in order to find an optimum composition in aspect of performance and reliability of the system. As a result, the mixture of 50% propane-50% isobutane showed the best performance and reliability among them in a small refrigeration system. During steady state operations, both the COP and refrigeration capacity increased by 4% and 9%, respectively, as compared to the baseline R-12 system. In addition, the propane/isobutane (50/50) mixture system yielded advantages in the minimization of modification and redesigning of system components due to very similar saturation tempera- ture and pressure characteristics with R-12.
An Experimental Study on the Performance of a Brazed Plate Heat Exchanger
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 14, issue 1, 2002, Pages 83~90
An experimental study on the performance evaluation of a brazed plate heat exchanger with 10USRT of normal cooling capacity has been carried out. In the present study, a brazed plate heat exchanger was tested at a chevron angle
with refrigerant R-22. Refrigerant mass flux was ranged from 23 to 58 kg/
s in condensation, and from 22 to 53 kg/
s in evaporation. The heat transfer coefficients and pressure drops are increased as the mass flux increases. The water side pressure drop is increased as the cooling water flow rate and chilled water flow rate increase, while mass flux has little effect. It is also shown that the system performance can be improved by enlarging condensation heat transfer area.