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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 13, Issue 12 - Dec 2001
Volume 13, Issue 11 - Nov 2001
Volume 13, Issue 10 - Oct 2001
Volume 13, Issue 9 - Sep 2001
Volume 13, Issue 8 - Aug 2001
Volume 13, Issue 7 - Jul 2001
Volume 13, Issue 6 - Jun 2001
Volume 13, Issue 5 - May 2001
Volume 13, Issue 4 - Apr 2001
Volume 13, Issue 3 - Mar 2001
Volume 13, Issue 2 - Feb 2001
Volume 13, Issue 1 - Jan 2001
Selecting the target year
Cooling Performance Measurement of a 3 Room Type Inverter Heat Pump System
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 431~439
Recently, multi-room type heat pump system has aroused much attention, because it can achieve much reduction of installation cost and space as well as energy saving in companion with the single room type heat pump system. In the present study, performance characteristics of a 3 room type inverter driven heat pump system, which is widely spread in Japanese market, are measured.. In the single room operation, performances of a heat pump system such s the difference of compressor outlet and inlet pressures and the mass flowrate may increase with the increase of cooling capacity so that COP of the system decrease with the increase of cooling capacity. However, in the 2 room operation, mass flowrate and COP of the total system increase markedly as compared with the single room operation.
A Study on the Boiling Heat Transfer of Heat Surface with Fin Array to R-113
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 440~447
This study investigate experimentally the effect of in height, thickness, and clearance on the boiling heat transfer. The heat surfaces having copper fin array is tested for pool boiling. The gas-liquid exchange interference is investigated based on fin array clearance. These test results can be applied to the design of tube bundle system. The fin height of 2 mm is found to be effective. Effects of heat transfer promotion reaches the highest level when the fin clearance is 0.5mm. Also, heat flux is increased when the fin thickness is smaller. But0.2 mm fin thickness is highly recommended.
Unsteady Numerical Simulation on the Ventilation in a Long Rail Tunnel
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 448~454
In the present study, the transient axi-symmetric numerical simulation of traffic ventilation induced by a train running through a 15.6km-long tunnel is performed by using over 100,000 computational cells. With train running, three cases of ventilation schemes are simulated, which are the case of ventilation fans turned on, the case of no fan but ventilation shafts open, and the case of no fan and no shaft. Results of the ventilation flow rate are pressure transients are compared for the cases considered.
Analysis of Performance and Economical Efficiency through Cycle Simulation for Power Saving BIP(Block Ice Plant)
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 455~461
Domestic ice making companies make effort to obtain products and neglect to introduce low cost product improvements with energy savings. The work presented here is an implementation of ice making method to improve both energy efficiency and productivity. In this present investigation, several ice making cycles are proposed for higher efficiency in the system. COP(Coefficient of Performance), ice making time and electric energy consumption are evaluated and compared with the conventional system. Results shows that COP is improved with more efficient use of time for ice making and electric consumption. Therefore, this can offer an opportunity for more efficient use of energy and higher productivity in ice making.
Effects of Working Fluid Filling Ratio and Heat flux on Correlations of Heat Transfer Coefficient in Loop Thermosyphon
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 462~473
Due to the coupling between momentum and energy transport theoretical analysis of the loop performance is very complicate, therefore it is necessary that these problems be solved by experimental investigation before applying th loop thermosyphon to heat exchanger design. The evaporator and condenser of the loop thermosyphon were made of carbon-steel, and distilled water was used as working fluid in the experiments. From the experimental data correlations of heat transfer coefficient for evaporator and condenser sections were obtained. For heat fluxes in th range of 13~78kW/
, the correlation equations of heat transfer coefficients in evaporator and condenser predict the experimental behavior to within $\p
5% and\;\pm20$% respectively.
Experimental Study on the Performance Improvement of Aluminum Grooved Heat Pipe due to increased number of Grooves
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 474~481
Aluminum/Freon22 grooved hat pipes which have 26 axial grooves in a cross-section were manufactured and tested. The performance test was conducted by varying filling ratio and tilt angle. Operation limit, thermal resistance, overall heat transfer coefficient were investigated. The experimental result was compared with previous study which conducted in the case of a heat pipe with combined wick. The experimental result shows that thermal resistance of this heat pipe is twice smaller than that of the heat pipe with combined wick and operation limit is increased about 75%, comparing with that of heat pipe with combined wick.
The Effect on Fouling Reduction by the Cleaning System in Compressed Type Refrigerator
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 482~489
The present study was conducted to estimate the effect on fouling reduction in tubes of the condenser. It shows in detail how to calculate the fouling factor from the experimental results of refrigeration systems with or without the automatic cleaning system using sponge balls and to predict the variation of the factor with time. It also represents how to calculate the temperature and pressure decrease of the refrigerant vapor in the condenser and the load decrease of the compressor in the refrigeration system by fouling reduction.
The Effect of Water Contact Angles of the Fin Surfaces of the Fin-and-Tube Heat Exchangers on the Water Hold-up
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 490~496
An experimental study on the behavior of the water hold-up by condensation of a fin-and-tube heat exchanger with regard to the surface characteristics, i.e., contact angle, was conducted. The static and dynamic contact angles were measured, and condensation experiments were conducted. Flow patterns on the fins with different surface characteristics were visualized. Results showed that the static contact angle is proportional to the dynamic contact angle within the range of this study. The water hold-up of the heat exchanger increases as the static or dynamic contact angle of its surfaces increases. Existence of transition of flow patterns was found as the static or dynamic angle increase. Due to the transition in the flow patterns, changes in the gradient of the water hold-up is occurred around the static angle of 8
An Analytic and Experimental Study on the Performance Characteristic of the Rotary Compressor
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 497~504
A study to improve the accuracy of a map-based compressor model with experiment was performed. Corrections on the effects of suction gas superheat and heat leakage from a compressor shell are required to apply the compressor amp model based on the empirical performance data(map) of compressor manufacturers to the actual system. So experiments to assess the effects of superheat and hat leakage were performed and the corrected equations were made. Compressors and refrigerant used in the experiment were the high pressure type rotary compressor and R-22, experiments were performed by compressor calorimeter. From the experiment, a volumetric efficiency correction factor
showed the value of 0.77, slightly higher than 0.75 proposed by Dabiri and Rice for low pressure type reciprocating compressor, and the heat leakage from the compressor shell turned out to be a factor that influenced the discharged mass flow rate. The relation between heat leakage of compressor shell and the variation of discharged mass flow rate from compressor was considered in compressor map modeling as an empirical function. With this function, the prediction accuracy of compressor model in system conditions was improved.
A Numerical Analysis of a Revised VX Absorption Cooling Cycle
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 505~513
A revised VX cycle using ammonia/water as the working fluid is a cycle which is suitable to produce cooling utilizing low temperature hat sources. The cycle was analyzed numerically to investigate the effects of the design and operating conditions on the performance. It was shown that both COP and cooling capacity were significantly influenced by the performance of he rectifier. Insufficient UA of the rectifier reduced both ammonia mass fraction and mass flow rate of the vapor entering the condenser, which produced cooling effect in the evaporator. As the temperature and the mass flow rate of the heat source increased, both COP and exergetic efficiency decreased due to the irreversibilities produced in heat exchangers, but cooling capacity did not vary much. Cooling capacity increased significantly as the coolant temperature decreased, although COP and exergetic efficiency remained nearly constant.
Analysis of Transient Thermal Characteristics in a Gas-Loaded Heat Pipe
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 514~523
The thermal performance characteristics of gas-loaded heat pipe(GLHP) were investigated by using transient diffuse-front model. Numerical evaluation of the GLHP is made with water as a working fluid and Nitrogen as control gas in the stainless steel tube. The transient vapor temperature and wall temperature were obtained. It is found that the temperature profiles and gas mole fraction distribution have been mainly influence by the diffusion between working fluid and noncondensable control gas in the condenser of GLHP. It is also found that he large power input make the diffusion region smaller.
Analysis of Temperature and Humidity Distribution in a Dry Room
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 524~531
The temperature and humidity distribution in a dry room are studied numerically by using standard
turbulence model. In order to evaluate effective heat and moisture ventilation characteristics inside the room, the heat removal capacity and moisture exhaust efficiency are introduced. An effective ventilation control is analyzed by evaluating quantitatively temperature and humidity distributions. It was found that the mean absolute humidity inside the room was almost constant with approximately 0.1905g/kg air regardless of the models and the heat generation rates. This was believed that the moisture generation by workers was relatively small. 40% improvement of the critical decay time was achieved, through the modifications of design variables.
A Study on the Control of Water Flow and Water Temperature in the Radiant Cooling System through Simulations
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 532~540
The objectives of this study are to analyze the control variables according to condensation occurrence, to find the range in floor surface temperature and frequency of condensation, and to evaluate the control methods through simulations when the radiant heating system is used for cooling. Through the simulation analysis the control methods such as on/off control, variable flow control and outdoor reset with indoor temperature feedback control are evaluated and compared. The results show that the lowest floor surface temperature is around
, the surface condensation can be prevented by controlling indoor humidity within 20g/kg(DA0, and that outdoor reset with indoor temperature feedback control is more appropriate than on/off control and variable flow control with regard to prevention of the condensation and thermal comfort.
A Study on the Thermal Environmental Analysis and the Application of Radiant Floor Cooling in Apartment Building
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 13, issue 6, 2001, Pages 541~548
The objective of this study is to analyze the possibilities and considerations for the application of the radiant floor cooling system by analyzing the problems of a conventional cooling system through field tests and thermal performance simulations of the radiant floor cooling in an apartment building. The results are as follows. (1) Problems of he conventional cooling system with PAC()packaged air conditioner)'s include draft, local discomfort, and excessive electrical peak demand. (2) According to the measurement during the cooling and intermediate seasons, the floor surface temperatures which are experienced at the time of cooling with PAC\`s and during intermediate season are similar to the temperatures for radiant floor cooling. (3) The radiant floor cooling system is applicable to apartment buildings during the cooling season, especially on hot and clear days.