Go to the main menu
Skip to content
Go to bottom
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 23, Issue 12 - Dec 2011
Volume 23, Issue 11 - Nov 2011
Volume 23, Issue 10 - Oct 2011
Volume 23, Issue 9 - Sep 2011
Volume 23, Issue 8 - Aug 2011
Volume 23, Issue 7 - Jul 2011
Volume 23, Issue 6 - Jun 2011
Volume 23, Issue 5 - May 2011
Volume 23, Issue 4 - Apr 2011
Volume 23, Issue 3 - Mar 2011
Volume 23, Issue 2 - Feb 2011
Volume 23, Issue 1 - Jan 2011
Selecting the target year
Development of Performance Analysis Program and the Study of Substitution Refrigerant R1234yf for Vehicle Refrigerant Compressor
Lee, Tae-Jin ; Kim, Ki-Beom ; Lee, Seung-Won ; Lee, Geon-Ho ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 11, 2011, Pages 699~704
DOI : 10.6110/KJACR.2011.23.11.699
The compressor's efficiency affects on the fuel consumption of the vehicle because the compressors for car air-conditioning system are operated by engine-driven. Especially, the refrigerant is being changed recently from R134a to substitution refrigerant to protect environment pollution that people concerned about. However, that leads to lower efficiency of the car airconditioning system and worse fuel consumption of the vehicle. Thus, this paper is focused on the methods for improvement of the compressor's efficiency that affects on the fuel consumption of the vehicle by numerical analysis for compressor's performance and the measurement of cylinder volume and pressure when the compressor is being operated.
A Study on Steady-State Criterion based on COV and a Fault Detection Method during GHP Operation
Shin, Young-Gy ; Oh, Se-Jae ; Jeong, Jin-Hee ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 11, 2011, Pages 705~710
DOI : 10.6110/KJACR.2011.23.11.705
Fault detection has to be proceeded by steady state filtering to get rid of transient effect associated with thermal capacity. Coefficient of variance (COV), ratio of standard deviation devided by moving average, was employed as steady-state filter. Engine speed and refrigerant pressures were selected as parameters representing system dynamics. The filtered values were registered as members of steady-state DB. They were found to show good functional relationship with ambient temperature. The relationship was fitted with a second order polynomial and the distribution bounds of the data around the fitted curve were expressed by visual inspection because of varying average and random data interval. Fault data were compared with the steady-state data obtained during normal operation. The fault data were easily isolated from the fault-free one. To make such isolation reliable, tests to construct good DB should be designed in a systematic way.
An Experimental Study on Ventilation and Thermal Performance of Passive Ventilation Building Envelopes
Yoon, Seong-Hwan ; Lee, Tae-Cheol ; Kang, Jung-Sik ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 11, 2011, Pages 711~717
DOI : 10.6110/KJACR.2011.23.11.711
In this study, 5 types of PVS(Passive ventilation system) units are made and experimented its ventilation performance, thermal performance according to open rate and hole diameter of perforated aluminum plane. Results are as follows. 1) The ventilation performance increases approximately 50~70% according by the open rate of PVS increasing. Also, the ventilation performance increases about 2%~12% according by the hole diameter of PVS increasing. 2) In winter temperature/pressure condition(in :
, out :
: 0.2~5.0Pa) the temperature of inflow air decreases according by the open rate of PVS increasing. Heat gain performance decreases 10.1%, 25.6% when open rate increases 3) In the same condition, Heat gain performance decreases 18.3%, 18.8% according by the hole diameter of PVS increasing.
Convective Boiling Two-phase Flow in Trapezoidal Microchannels : Part 2-Heat Transfer Characteristics
Kim, Byong-Joo ; Kim, Geon-Il ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 11, 2011, Pages 718~725
DOI : 10.6110/KJACR.2011.23.11.718
Characteristics of flow boiling heat transfer in microchannels were investigated experimentally. The microchannels consisted of 9 parallel trapezoidal channels with each channel having 205
of bottom width, 800
of sidewall angle, and 7 cm of length. Tests were performed with R113 over a mass velocity range of 150~920
, heat flux of 10~100
and inlet pressures of 105~195 kPa. Flow boiling heat transfer coefficient in microchannels was found to be dominated by heat-flux. However the effect of mass velocity was not significant. Contrary to macrochannel trends, the heat transfer coefficient was shown to decrease with increasing thermodynamic equilibrium quality. A new correlation suitable for predicting flow boiling heat transfer coefficient was developed based on the laminar single-phase heat transfer coefficient and the nucleate boiling dominant equation. Comparison with the experimental data showed good agreement.
A Study on the Optimization of Discharge Grille of Outdoor Unit of Air Conditioner
Choi, Seok-Ho ; Oh, Sai-Kee ; Kim, Hyun-Jong ; Jin, Geun-Ho ; Oh, Si-Young ; Kim, Byung-Soon ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 11, 2011, Pages 726~732
DOI : 10.6110/KJACR.2011.23.11.726
The aerodynamic and aeroacoustic performance of discharge grille of outdoor unit of air-conditioner was investigated in this study. Discharge grille is one of outdoor unit's important parts to affect the flow rate and Overall Sound Pressure Level(OSPL). New type of discharge grille was suggested based on the results of numerical simulation. To simulate the flow pattern near the propeller fan, commercial flow solver FLUENT was used. Sliding mesh method was used for rotating propeller fan and initial condition for unsteady model was calculated by Multiple Reference Frame(MRF) method. To minimize the interaction noise between fan blade wake and discharge grille, new discharge grille has radial rib which is aligned with trailing edge of fan blade. And inclined radial rib was adopted for reducing flow rate drop in discharge grille. The optimization of inclined angle of radial grille was performed experimentally.
Numerical Study of Performance Variation Under Frost and Non-frost Condition of Refrigerating System in the Refrigerator Truck
Kim, Sang-Hun ; Myung, Chi-Wook ; Cho, Hong-Hyun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 11, 2011, Pages 733~740
DOI : 10.6110/KJACR.2011.23.11.733
To analyze the cooling performance in the refrigerator truck according to frost growth, the analytical model of refrigeration system was developed under frost and non-frost condition using EES. The system performance was analyzed with outdoor temperature, storage temperature, outdoor front air velocity and compressor speed in order to investigate the system performance characteristics with operating conditions. Besides, the system performance under frost condition was compared with that under non-frost condition. As a result, the frost thickness was 0.9 mm when the refrigerating capacity of frost condition was decreased by 30%. The maximum of the system COP was shown at compressor speed of 1500 rpm for non-frost and frost condition, simultaneously. The performance under frost condition was more sensitive to the operating condition compared to that under non-frost condition.
Improvement of University Education to Supply Technical Manpower for Plant Engineering Industry in Mechanical Engineering Field
Shim, Hyun-Sun ; Kim, Young-Il ; Chung, Kwang-Seop ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 11, 2011, Pages 741~746
DOI : 10.6110/KJACR.2011.23.11.741
In this study, improvements of university education are suggested so that university graduates can work in plant engineering industry without major retraining which is required in plant engineering companies. Before disposition of manpower to the plant engineering site, new recruits are retrained by the company for about 2~3 years, since university education is not sufficient and appropriate to handle plant engineering tasks. It is urgent to integrate into university education practical plant engineering that can be used effectively after graduation. In case of S2 University located in Seoul, it is enough to supplement interdisciplinary program to plant engineering subjects if proper texts are developed. To replace plant engineering education offered by the company with the university education, following measures should be taken. First, basic plant engineering should be taught for 15 hours. Second, education on design and drawings should be reinforced.
Ventilation Rate Impact on Heating and Cooling Energy Consumption in Residential Buildings : Concentrated on a Detached House in Cold and Hot/Humid Climatic Zones of USA
Moon, Jin-Woo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 11, 2011, Pages 747~753
DOI : 10.6110/KJACR.2011.23.11.747
The purpose of this study was to quantify the impact of the ventilation rate on heating and cooling energy consumption in a detached house. For it, a series of simulations for the application of the diverse ventilation rate (ACH) were computationally conducted for a prototypical detached residential building in the cold climate (Detroit, Michigan) and hot/humid climate (Miami, Florida) of USA. Analysis revealed that ventilation is a significant heat losing source in the cold climate; thus, the higher ventilation rate significantly increases the heating energy consumption and energy cost in the cold climate; while the impact on energy increase for heating and cooling energy consumption is similar in hot/humid climate with less significancy compared to cold climate. The research outcome of this study could be a fundamental data for determining the optimal ventilation rate in terms of indoor air quality, but also building energy performance well.
A Numerical Study on the Heat Transfer Characteristics of the Multiple Slot Impinging Jet
Kim, Sang-Keun ; Ha, Man-Yeong ; Son, Chang-Min ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 11, 2011, Pages 754~761
DOI : 10.6110/KJACR.2011.23.11.754
The present study numerically investigates two-dimensional flow and heat transfer in the multiple confined impinging slot jet. Numerical simulations are performed for the different Reynolds numbers(Re=100 and 200) in the range of nozzles from 1 to 9 and height ratios(H/D) from 2 to 5, where H/D is the ratio of the channel height to the slot width. The vector plots of velocity profile, stagnation and averaged Nusselt number distributions are presented in this paper. The dependency of thermal fields on the Reynolds number, nozzle number and height ratio can be clarified by observing the Nusselt number as heat transfer characteristic at the stagnation point and impingement surface. The Nusselt number at the stagnation point of the central slot shows unsteadiness at H/D=3 and Re=200. The value of Nusselt number at the stagnation point of the central slot decreases with higher Reynolds number and number of nozzle although overall area averaged Nusselt number increases. Hence careful selection of geometrical parameters and number of nozzle are necessary for optimization of the heat transfer performance of multiple slot impinging jet.
A Study of Flow Characteristics through the Speed Control and Flow Resistance
Oh, Byung-Kil ; Kim, Hway-Suh ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 11, 2011, Pages 762~768
DOI : 10.6110/KJACR.2011.23.11.762
We use floor radiant heating system in the house of commons in winter Floor radiant heating system, which transfer heat by radiation, is one of the energy efficient and comfortable systems that. Floor radiant heating system is configured to be controlled by the room for energy-saving. Proper flow rate to a comfortable heating in the room is important. However, Using a constant speed circulation pump in separate rooms, heating system may cause an imbalance because of the difference of length of coil when operating in the rooms. In this study, our Research team examined heating imbalance due to the variation length through the coil length changes and flow control of the circulation pump.