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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 17, Issue 12 - Dec 2005
Volume 17, Issue 11 - Nov 2005
Volume 17, Issue 10 - Oct 2005
Volume 17, Issue 9 - Sep 2005
Volume 17, Issue 8 - Aug 2005
Volume 17, Issue 7 - Jul 2005
Volume 17, Issue 6 - Jun 2005
Volume 17, Issue 5 - May 2005
Volume 17, Issue 4 - Apr 2005
Volume 17, Issue 3 - Mar 2005
Volume 17, Issue 2 - Feb 2005
Volume 17, Issue 1 - Jan 2005
Selecting the target year
Analysis of Heat Transfer Characteristics of Internal Heat Exchanger for
Refrigerator using the Hardy-Cross Method
Kang Hee-Dong ; Kim Ook Joong ; Seo Tae-Beom ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 1~7
The heat transfer characteristics of an internal heat exchanger for
refrigeration cycle are numerically investigated. The numerical model is verified using the published experimental results for the concentric tube type internal heat exchanger. The Hardy-Cross Method gives very good agreement between the calculation and experimental results on the heat transfer rates and exit temperatures. Also, appropriate combination of heat transfer correlations is found. The operating parameters of the heat exchanger are calculated at transcritical region of
The heat transfer rate of the counter flow type heat exchanger shows the
greater than that of the parallel flow type heat exchanger. The increase of heat exchanger length enhances the heat transfer rate. The thermodynamic characteristics and heat transfer coefficient of
in the internal heat exchanger are estimated.
A Study on the Helical Flow of Newtonian and non-Newtonian fluid
Kim Young-Ju ; Kim Chul-Soo ; Hwang Young-Kyu ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 8~15
This study concerns the characteristics of helical flow in a concentric and eccentric annulus with a diameter ratio of 0.52 and 0.9, whose outer cylinders are stationary and inner ones are rotating. Pressure losses and skin friction coefficients have been measured for fully developed flows of water and
aqueous of sodium carboxymethyl cellulose(CMC), respectively, when the inner cylinder rotates at the speed of
rpm. The effect of rotation on the skin friction coefficient is significantly dependent on the flow regime. In all flow regimes, the skin friction coefficient is increased by the inner cylinder rotation. This study shows the change of skin friction coefficient and wall shear stress corresponding to the variation of rotating speed of the inner cylinder, radius ratio, eccentricity, and working fluids.
Verification Experiment and Analysis for 6kW Solar Water Heating System(Part 3 : Optimum Design and Economic Evaluation)
Choi Bong Su ; Lee Bong Jin ; Kang Chaedong ; Hong Hiki ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 16~24
The goal of the present paper is to show the optimum design and operation conditions on 6 kW solar water heating system by using computer simulation with verified modelling. As the object functions, we took not only the amount of acquired and auxiliary heat but LCC, which has a relative importance and decisive role in economy. As expected, the maximum heat is acquired at the slope of collector with the equal degree to the latitude, facing the south. The capacity increase of the circulation pump and the storage tank lead to the increase of acquired heat and the decrease of auxiliary heat, but do not necessarily give economical advantages owing to additional electrical power consumption. In the present system, the minimum LCC can be obtained at the storage tank volume of 450 L and the mass flow rate of 0.344 kg/s.
An Experimental Study on the Effects of Porous Layer Treatment on Evaporative Cooling of an Inclined Surface
Lee Dae Young ; Lee Jae Wan ; Kang Byung Ha ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 25~32
Falling film heat transfer has been widely used in many applications in which heat and mass transfer occur simultaneously, such as evaporative coolers, cooling towers, absorption chillers, etc. In such cases, it is desirable that the falling film spreads widely on the surface forming thin liquid film to enlarge contact surface and to reduce the thermal resistance across the film and/or the flow resistance to the vapor stream over the film. In this work, the surface is treated to have thin porous layer on the surface. With this treatment, the liquid can be spread widely on the surface by the capillary force resulting from the porous structure. In addition to this, the liquid can be held within the porous structure to improve surface wettedness regardless of the surface inclination. The experiment on the evaporative cooling of an inclined surface has been conducted to verify the effectiveness of the surface treatment. It is measured that the evaporative heat transfer increases about
by the porous layer treatment as compared with that from orignal bare surfaces.
A Numerical Study on the Performance Characteristics of a Piezoelectric Micropump for Different Inlet and Outlet Positions
Kim Dong Hee ; Jeong Jin ; Kim Chang Nyung ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 33~38
This study has been conducted to investigate flow characteristics of a micropump with piezoelectric materials. In this study, the change of flow rates has been investigated for different positions of the inlet and outlet and for different distances between them. The FSI(Fluid Structure Interaction) method has been employed for numerical analysis of the piezoelectric diffuser/nozzle based micropump. It has been found that time averaged flow rate is greater in the case that distance between the inlet and outlet is longer. For the cases where the positions of the inlet are different with the position of the fixed outlet at the center, the flow rate is increased as the inlet is located farther from the center. This study may supply fundamental understandings for the design and analysis of the prototypes of piezoelectric micropumps.
An Experimental Study on the Performance of a Heat Pump for the Cold Climate
Ju Jeong-Dong ; Bae Kyung-Su ; Hwang Young-Kyu ; Lee Yun-Yong ; Jeong Gyoo-Ha ; Oh Sang-Kyong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 39~46
The present study concerns an experimental study of a R-22 heat pump system consisted of liquid and liquid heat exchangers. The test was performed for various systems of a single-, tandem-, and two stage-cycle at the same environmental conditions of temperature. Various experiments of the heat pump system were peformed to compare the heating capacity and COP, when the outdoor temperature is near
and the indoor temperature is
As the results of the present study, the system of Tandem(parallel) cycle showed the best heating performance, while the discharge temperature of refrigerant was too high. In case of the system of two stage cycle, the performance characteristics were significantly improved by employing the inter cooler.
Studies on the Performance Variation of a Variable Speed Vapor Compression System under Fault and Its Detection and Diagnosis
Kim Minsung ; Kim Min Soo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 47~55
An experimental study has been peformed to develop a scheme for fault detection and diagnosis(FDD) in a vapor compression refrigeration system. This study is to analyze fault effect on the system performance and to find efficient diagnosis rules for easy determination of abnormal system operation. The refrigeration system was operated with a variable speed compressor to modulate cooling capacity. The FDD system was designed to consider transient load conditions. Four major faults were considered, and each fault was detected over wide operating load range by separating the system response to the load change. Rule-based method was used to diagnose and classify the system faults. From the experimental results, COP degradation due to the faults in a variable speed system is severer than that in a constant speed system. The method developed in this study can be used in the fault detection of refrigeration systems with a variable speed compressor.
A Study on the Evaluation of Air Change Efficiency of Multi-Air-Conditioner with Ventilation System for Heating Season
Kwon Yong-Il ; Han Hwataik ; Kim Kyung-Hwan ; Chung Baik-Young ; Lee Gam-Gue ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 56~61
Indoor air quality becomes of a concern recently in view of human health. This study investigates the air diffusion performance and the air change efficiency of a classroom, when outdoor air is introduced in addition to the heating/cooling operation of a ceiling-mounted heat pump. A CFD analysis has been performed to investigate the effect of the discharge angle of the air jets from the heat pump for both parallel and series types of outdoor air system. It is observed that the series type creates more uniform indoor environment compared to the parallel type in general. It can be concluded the discharge angle should not be larger than 40o for the parallel type, in order not to generate thermal stratification in the room.
Heat Transfer Performance of Evaporator Used in a Domestic Refrigerator/Freezer Under Frosting Condition
Lee Jang-Seok ; Lee Kwan-Soo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 62~70
In this study, the air-side heat transfer coefficients of several types of evaporators in the household freezer/refrigerators are investigated. The types considered in this work are: discrete flat plate fin-and-tube type(in-lined tube array), continuous flat plate fin-and-tube type(staggered tube array), and spine fin-and-tube type(in-lined tube array). The heat transfer correlations obtained from this study for each heat exchangers could expect heat transfer coefficients less than
of errors. The result indicates that the air-side heat transfer performance of spine fin-and-tube type evaporator shows the highest value under dry conditions, but discrete flat plate fin-and-tube type evaporator shows the highest value among these three evaporators under frosting conditions.
Cooling and Heating Performance Evaluation of a GSHP System
Sohn Byong Hu ; Cho Chung-Sik ; Shin Hyun-Jun ; An Hyung-Jun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 71~81
The main objective of the present study is to investigate the performance characteristics of a ground-source heat pump(GSHP) system with a 130 m vertical and 62 mm nominal diameter U-tube ground heat exchanger. In order to evaluate the performance analysis, the ground-source heat pump connected to a test room with
floor area in the Korea Institute of Construction
was designed and constructed. This ground-source heat pump system mainly consisted of ground heat exchanger, indoor heat pumps and measuring devices. The cooling and heating loads of the test room were 5.5 and 7.2 kW at design conditions, respectively. The experimental results were obtained from July 2, 2003 to July 1, 2004. The cooling and heating performance coefficients of the system were determined from the measured data. The average cooling and heating COPs for the system were obtained to be 4.90 and 3.96, respectively. The temperature variations in ground and the ground heat exchanger pipe surface at different depths were also measured.
Characteristics of Energy Consumption in an Office Building located in Seoul
Park Byung-Yoon ; Chung Kwang-Seop ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 82~87
The purpose of this study is to suggest the characteristics and actual state of energy consumption by the analysis of energy consumption data in an office building. This study examines and analyzes daily and monthly energy consumption of an office building located in Seoul, Korea regarding type of load and business classification within a building. The results are as follows. 1) Energy consumption of office building for each type of load show similar consumption patterns, regardless of seasons such as cooling period and heating period. 2) Out of all annual energy consumption, consumption for lighting took about
general electric Power about
and cooling power
showing that the consumption for lighting was highest, and the percentage of energy consumption for cooling power for operation of cooling facilities took the lowest percentage. 3) Annual gas consumption used for heating and hot water supply were
for officetel and office respectively, and
for arcade. 4) Electricity consumptions used for cooling power for each use of building, office and officetel recorded in July and August of cooling seasons. Even though it shows different patterns for each month, energy consumption showed unique pattern throughout the cooling seasons.
Strategy of Energy Saving and Thermal Environment Improvement for Intermittent Heating System in Apartment Buildings
Ahn Byung-Cheon ; Lee Tae-Won ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 17, issue 1, 2005, Pages 88~93
In this study, the operational characteristics on heating performance and energy consumption for intermittent hot water heating system in apartment buildings were research by simulation. The effects of apartment inlet hot water temperature and operation time per day on energy consumption and indoor thermal environment are investigated. The strategy of energy saving and thermal environment improvement is suggested in comparison with the existing ones.