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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 16, Issue 12 - Dec 2004
Volume 16, Issue 11 - Nov 2004
Volume 16, Issue 10 - Oct 2004
Volume 16, Issue 9 - Sep 2004
Volume 16, Issue 8 - Aug 2004
Volume 16, Issue 7 - Jul 2004
Volume 16, Issue 6 - Jun 2004
Volume 16, Issue 5 - May 2004
Volume 16, Issue 4 - Apr 2004
Volume 16, Issue 3 - Mar 2004
Volume 16, Issue 2 - Feb 2004
Volume 16, Issue 1 - Jan 2004
Selecting the target year
Experimental Study on a Rotary Magnetic Refrigeration Device
Lee Jong Suk ; Hong Jeong Ho ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1101~1106
Magnetic refrigeration is based on the magnetocaloric effect (MCE)-the ability of some materials to heat up when magnetized and cool down when demagnetized. A rotary magnetic refrigeration device using gadolinium (Gd) ribbon and permanent magnets was constructed for experimental study. Gd ribbon attached around a rotating wheel is cyclically magnetized and demagnetized by permanent magnets and exchanges heat with liquid in the surrounding container. Temperature of the liquid in each divided section of the container was measured and the experimental results obtained in this study were discussed.
A Theoretical Analysis on the Factors Affecting the Operation of Loop Heat Pipe
Lee Ki-Woo ; Chun Won-Pyo ; Lee Wook-Hyun ; Park Ki-Ho ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1107~1116
In this paper, the effects of diverse parameters on the operation of loop heat pipe (LHP), such as particle diameter of sintered porous wick, wick porosity, vapor line diameter, thickness of wick and heating capacity were investigated by a theoretical analysis. A LHP has a wick only in its evaporator for the circulation of working fluid, and utilizes a porous wick structure of which pore size is very small to obtain a large capillary force. The working fluid is water and the material of sintered porous wick is copper. For these different parameters, capillary pressure, pressure drop in wick, pressure drops and temperature distribution were analyzed by a theoretical design method of LHP.
Simulation of Compression/Absorption Hybrid Heat Pump System using Industrial Wastewater Heat Source
Baik Young-Jin ; Park Seong-Ryong ; Chang Ki-Chang ; Ra Ho-Sang ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1117~1125
In this study, in order to utilize the waste heat of industrial wastewater in the range of the relatively low temperature of 40～5
as a heat source, a hybrid heat pump system was considered by computer simulation method. In the simulation, an absorber, desorber and solution heat exchanger were modelled by UA values while a compressor and pump performance were specified by an isentropic efficiency. Simulation results show that the performance of hybrid heat pump can be up to 80% higher than that of conventional R134a heat pump when it makes a process hot water of 9
while the wastewater is cooled down to 2
. As the absorber pressure increases, the system performance and deserter pressure increase with a favorable effect of a compressor discharge gas temperature drop.
Measurement of Effective Thermal Conductivity in Silica Gel Packed Bed
Kwon Oh-Kyung ; Yun Jae-Ho ; Kim Joung-Ha ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1126~1133
This paper presents an experimental measurement of effective thermal conductivity in an adsorbent packed bed with silica gel A type. The effective thermal conductivity was measured under different conditions of the adsorbent bed temperature, pressure, particle size and water content by using the transient hot wire method. The measured effective thermal conductivity showed to become bigger with decreasing particle size or increasing water content, but it was a little affected with increasing bed temperature and pressure. The bed temperature was varied in the range of 1
(equation omitted) T (equation omitted) 5
and the pressure in the range of 10 kPa (equation omitted) P (equation omitted) 190 kPa. The results show that 0.10～0.18 W/mㆍK of effective thermal conductivity measured for the zero water content.
Evaporative Heat Transfer Characteristics of Carbon Dioxide in a Horizontal Tube
Son Chang-Hyo ; Lee Dong-Gun ; Kim Young-Lyoul ; Oh Hoo-Kyu ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1134~1139
The evaporative heat transfer coefficient of
(R-744) in a horizontal tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator (test section). The test section consists of a smooth, horizontal stainless steel tube of inner diameter of 7.75 mm. The experiments were conducted at mass flux of 200 to 500 kg/m
s, saturation temperature of -5 to 5
, and heat flux of 10 to 40kW/m
. The test results showed the heat transfer of
has a greater effect on nucleate boiling more than convective boiling. Mass flux of
does not affect nucleate boiling too much, and the effect of mass flux on evaporative heat transfer of
is much smaller than that of refrigerant R-22 and R-134a. In comparison with test results and existing correlations, correlations failed to predict the evaporative heat transfer coefficient of
, therefore, it is necessary to develope reliable and accurate predictions determining the evaporative heat transfer coefficient of
in a horizontal tube.
Evaluation of the Indoor Thermal Comfort in Consideration of the Solar Radiation
Kim Se-Hyun ; Noh Kwang-Chul ; Oh Myung-Do ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1140~1148
Recently the Predicted Mean Vote (PMV) has been used as an important index to evaluate the degree of the indoor thermal comfort in modern residential buildings. It is known that the PMV is mainly affected by four major factors, which are the air temperature, the air velocity, the humidity and the mean radiant temperature (MRT). Through the numerical calculation of the temperature and the modeling of the mean radiant temperature considering the solar radiation, we proposed the new modeling strategies of the mean radiant temperature and investigated the PMV index and evaluated the MRT. Also, we compared the numerical results with the experimental values. As the results, we found out that the MRT is affected by the wall temperature and the solar radiation. We also knew that the new modeling strategies of the mean radiant temperature is a more correct way of PMV calculation. Especially, the new modeling is necessary for the spaces like an atrium and large rooms with windows mainly influenced by solar radiation.
Heat Transfer in the Vertical Type Fluidized Bed Heat Exchanger with Corrugated Tubes
Ahn Soo Whan ; Bae Sung Taek ; Kim Myung Ho ; Lee Byung-Chang ; Lee Yoon Pyo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1149~1155
An experimental study was performed to investigate the characteristics of heat transfer in a vertical type fluidized bed shell-and-tube type heat exchanger with corrugated tube. Seven different solid particles having the same volume were circulated in the heat of exchanger. The effects of various parameters such as water flow rates, particle geometries, materials, and corrugated tube geometries were investigated. The present work showed that the higher thermal capacities of materials and the geometries closer to the spherical one have higher heat transfer performances. In addition, heat transfer coefficients in the corrugated tubes were a little higher than those in the smooth tubes.
Optimal Design of a Heat Sink using the Sequential Approximate Optimization Algorithm
Park Kyoungwoo ; Choi Dong-Hoon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1156~1166
The shape of plate-fin type heat sink is numerically optimized to acquire the minimum pressure drop under the required temperature rise. In constrained nonlinear optimization problems of thermal/fluid systems, three fundamental difficulties such as high computational cost for function evaluations (i.e., pressure drop and thermal resistance), the absence of design sensitivity information, and the occurrence of numerical noise are commonly confronted. Thus, a sequential approximate optimization (SAO) algorithm has been introduced because it is very hard to obtain the optimal solutions of fluid/thermal systems by means of gradient-based optimization techniques. In this study, the progressive quadratic response surface method (PQRSM) based on the trust region algorithm, which is one of sequential approximate optimization algorithms, is used for optimization and the heat sink is optimized by combining it with the computational fluid dynamics (CFD).
Analysis of the Gravity Effect on the Distribution of Refrigerant Flow in a Multi-circuit Condenser
Lee Jangho ; Kim Moo Hwan ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1167~1174
The method to consider gravity effect on the performance of a condenser is developed, and a simple condenser having 'nU' type two circuits is analyzed. Each circuit has the same length and inlet air-side operational conditions. The only difference between two circuits is the direction of refrigerant flow, which is exactly opposite each other between the upper 'n' type circuit and the lower 'U' type circuit. It is shown that the gravity makes the distribution of refrigerant flow uneven in the two circuits at lower refrigerant flow rates; heat transfer rate also becomes uneven. Moreover, much of the refrigerant exists as liquid state in the circuit having low refrigerant flow rate, which will make the cycle balance unstable in the refrigeration cycle system like a heat pump.
A Study on the Heating Performance of Ground Source Heat Pump System
Woo Joung-Son ; Kim Dae-Ki ; Lee Se-Kyoun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1175~1182
Installations of vertical boreholes for the ground source heat pump system are expensive to install. One way to reduce the initial cost is to increase the specific heat extraction rate of borehole system. However, as the specific heat extraction rate increases the temperature of borehole fluid decreases with the resultant lower Coefficient Of Performance in Heating(COPH) of heat pump system. The purpose of this study is to provide the basic informations about the performance of heat pump system with the specific heat extraction rate and soil thermal properties such as thermal conductivity and temperature. It is shown that the specific heat extraction rate is the most important parameter for the ground source heat pump system. To obtain the reasonable COPH value (COPH > 3) the heat extraction rate should be about 25 W/m or less. Accurate measurements of soil thermal properties are also very important to design the system properly. The effects of borehole thermal resistances are also examined in this study.
The Effects of an Additive on the Thermal Properties of a Clathrate Compound (III) - The Case of TMA Clathrate Compound with Acetone -
Kim Jin Heung ; Chung Nak Kyu ; Kim Suk Hyun ; Kim Chang Oh ; Kang Seung Hyeon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1183~1189
An experimental investigation is conducted to measure phase change temperature and supercooling when acetone is added to TMA 30 wt% clathrate during cooling process in heat source. Also rate of volume change is investigated when acetone is added to TMA 30 wt% clathrate during the cooling process in heat source -8
. The results show that phase change temperature is about 4.5～5.5
when acetone is added to TMA 30 wt% clathrate during the cooling process for heat sink temperature of -6, -7
. Supercooling is repressed about 2～1
when 0.08 wt% acetone is added to it and rate of volume change is decreased about 2.9% when 0.1 wt% acetone is added for the heat sink temperature of -8
Study on Thermal Property in Urban Area - Quantitative Estimation of Heat Island in Urban area using the Simple Urban Canopy Model -
Son Won-Tug ; Lee Sung ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1190~1196
Significant air temperature increases in urban areas are known as the heat island phenomenon in a global scale. Therefore, we propose numerical model in order to analyze quantitative effects of building environmental factors on the heat island phenomenon in urban area. In this paper, we propose a predicting model to analyze the heat island phenomenon quantitatively. Using this model, numerical simulation is performed in order to analyze quantitative effects of many factor on the heat island phenomenon.
An Experimental Study on Air Leakage and Heat Transfer Characteristics of a Rotary-type Heat Recovery Ventilator
Han Hwataik ; Kim Min-Kyu ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1197~1203
This study investigates the air leakage and heat transfer characteristics of a rotary-type air-to-air heat exchanger with a fiber polyester matrix. The leakage airflow rate is measured using a tracer gas method for various ventilation rates and rotational speeds of the matrix wheel. A correlation equation for air leakage is obtained by combining the pressure leakage and the carryover leakage. The pressure leakage is observed to be a function of ventilation airflow rate only, and the carryover leakage is found to be a linear function of rotational speed. The real efficiency of the heat exchanger can be obtained from its apparent efficiencies by taking into account the air leakage ratio. As the ventilation rate increases, the heat recovery efficiency decreases. As the rotational speed of the matrix increases, the efficiency increases initially but reaches a constant value for the rotational speeds over 10 rpm.
ADPI Characteristics of Line Diffuser in a Room with Perimetric Heating Load
Cho Young-Jin ; Kang Seok-Youn ; Moon Jong -Sun ; Lee Jae-Heon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1204~1211
It is difficult to apply a conventional selection guide for diffusers when the diffuser is installed in a perimeter zone, because the air diffusion performance index (ADPI) vs. throw/length (T/L) ratio curve listed in conventional guide does not consider the perimetric heating load through the walls. The objective of this study is to evaluate the effect of the perimetric heating load on the ADPI and propose a selection guide for a proper line diffuser when perimetric heating load exists. The velocity and temperature distributions and the ADPI values are obtained numerically with various heat load ratios and air flow rates. The velocity and temperature distributions and the ADPI values are analyzed by CFD in case of various heat load ratios and air flow rates. Also, ADPI was calculated by those results. The ADPI values by numerical results are compared with an existing experimental data to verify the method for the evaluation of ADPI proposed in a present study. In case of a line diffuser installed at the high side wall, the ADPI decreases according to the increases of the flow rate on every heat load ratio of the present study except 0.75. The ADPI vs. T/L ratio curves have been proposed for the heat load ratios of 0.25, 0.5, 0.75 to guarantee the comport thermal environment when diffusers are installed in perimeter zone.
The Effects of an Additive on the Thermal Properties of a Clathrate Compound (IV) - The Case of TMA Clathrate Compound with Surfactant -
Chung Nak Kyu ; Kim Jin Heung ; Kim Chang Oh ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1212~1217
This study investigated the improvement effect of a small portion of surfactant on the supercooling and the phase change temperature of TMA 30 wt% clathrate compound when surfactant is added to the clathrate compound. The experiments are carried out under various conditions; the concentration of additive ranges between 0.08～0.12 wt% and the temperature of heat source ranges between -8 and -6
. The experimental results show that the phase change temperature with the surfactant of 0.1 wt% is lower by 1
than TMA 30 wt% and the supercooling is reduced by 1
Study on Fresh Air Load Reduction System by Using Geothermal Energy - Reducing Effect of a Fresh Air Load by Combining with Air-heated Solar Collector -
Son Won-Tug ; Lee Sung ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1218~1226
This paper presents thermal behaviors and performances of a fresh air load reduction system by using earth tube system combined with air-heated solar collector. The earth tube system reduces a fresh air load by heat exchange with soil throughout the year. In the previous experimental research, it was clarified that the earth tube system was very useful as a fresh air load reduction system. However, since outlet temperature of the fresh air which was heated by earth tube system was below 15
in winter, it is not suitable to introduce the fresh air into the place of residence directly. Therefore, a simulation model using the simple heat diffusion equation was used to examine a rising effect of outlet air temperature in winter by combining with air-heated solar collector. An improvement of annual performance by control of operation is also quantitatively examined. In conclusion, it is confirmed that its performance is improved by control of operation throughout the year and outlet air temperature rose by combining with air-heated solar collector.
Evaluation of Energy Consumption of HVAC System for Air Filter Pressure Difference Change in Commercial Buildings
Won Keun-Ho ; Kwak Ro-Yeul ; Huh Jung-ho ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1227~1233
Air handling unit (AHU)'s air filter pressure difference is important for energy consumption and indoor air quality. Both energy Performance data and air filter differential pressure of AHU in real office buildings were monitored and analyzed to investigate quantitatively energy impact as dust buildup level on air filter grows. We also modeled and simulated CAV system using HVACSIM＋ program to examine the energy effect of dust buildup on filters. Through analysis of time series pressure drop data, the filter pressure difference rate has been increased due to cumulative supply air flow rate increase. As filter pressure drop increased to 1 inch water column, it is found that the supply air flow rate was decreased by 10%, the chilled water flow rate was increased by 5.9% and the pump energy consumption was increased to 5.9%.
Recent Progress in Air Conditioning and Refrigeration Research - A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2002 and 2003 -
Chung Kwang-Seop ; Kim Min Soo ; Kim Yongchan ; Park Kyoung Kuhn ; Park Byung-Yoon ; Cho Keumnam ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 12, 2004, Pages 1234~1268
A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2002 and 2003 has been carried out. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment/design. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation in diverse facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat transfer, humidity was also interesting to promote comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing research topics. Well developed CFD technologies were widely applied for analysis and design of various facilities and their systems. (2) Heat transfer characteristics of enhanced finned tube heat exchangers and heat sinks were extensively investigated. Experimental studies on the boiling heat transfer, vortex generators, fluidized bed heat exchangers, and frosting and defrosting characteristics were also conducted. In addition, the numerical simulations on various heat exchangers were performed and reported to show heat transfer characteristics and performance of the heat exchanger. (3) A review of the recent studies shows that the performance analysis of heat pump have been made by various simulations and experiments. Progresses have been made specifically on the multi-type heat pump systems and other heat pump systems in which exhaust energy is utilized. The performance characteristics of heat pipe have been studied numerically and experimentally, which proves the validity of the developed simulation programs. The effect of various factors on the heat pipe performance has also been examined. Studies of the ice storage system have been focused on the operational characteristics of the system and on the basics of thermal storage materials. Researches into the phase change have been carried out steadily. Several papers deal with the cycle analysis of a few thermodynamic systems which are very useful in the field of air-conditioning and refrigeration. (4) Recent studies on refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement when new alternative refrigerants are applied. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and new alternative refrigerants including natural refrigerants. Efficiency of various compressors and performance of new expansion devices are also dealt with for better design of refrigeration/air conditioning system. In addition to the studies related with thermophysical properties of refrigerant mixtures, studies on new refrigerants are also carried out. It should be noted that the researches on two-phase flow are constantly carried out. (5) A review of the recent studies on absorption refrigeration system indicates that heat and mass transfer enhancement is the key factor in improving the system performance. Various experiments have been carried out and diverse simulation models have been presented. Study on the small scale absorption refrigeration system draws a new attention. Cooling tower was also the research object in the respect of enhancement its efficiency, and performance analysis and optimization was carried out. (6) Based on a review of recent studies on indoor thermal environment and building service systems, it is noticed that research issues have mainly focused on several innovative systems such as personal environmental modules, air-barrier type perimeterless system with UFAC, radiant floor cooling system, etc. New approaches are highlighted for improving indoor environmental conditions and minimizing energy consumption, various activities of building energy management and cost-benefit analysis for economic evaluation.