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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 15, Issue 12 - Dec 2003
Volume 15, Issue 11 - Nov 2003
Volume 15, Issue 10 - Oct 2003
Volume 15, Issue 9 - Sep 2003
Volume 15, Issue 8 - Aug 2003
Volume 15, Issue 7 - Jul 2003
Volume 15, Issue 6 - Jun 2003
Volume 15, Issue 5 - May 2003
Volume 15, Issue 4 - Apr 2003
Volume 15, Issue 3 - Mar 2003
Volume 15, Issue 2 - Feb 2003
Volume 15, Issue 1 - Jan 2003
Selecting the target year
The Partial Fault Detection of an hir-Conditioning System by the Neural Network Algorithm using Normalized Input Data
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 15, issue 3, 2003, Pages 159~165
The fault detection and diagnosis technology may be applied in order to decrease the energy consumption and the maintenance cost of the air-conditioning system. To detect partial faults of the air-conditioning system, a neural network algorithm may be used. In this study, the neural network algorithm using normalized input data by the standard deviation was applied. And the [7
1] neural network structure was selected. Test results showed that the neural network algorithm using normalized input data was very effective to detect the condenser fouling and the evaporator fan fault of an air-conditioning system.
Comparison of Performance Variation between R-22 and R-410A Refrigeration Systems
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 15, issue 3, 2003, Pages 166~176
Experiments have been conducted in order to make comparisons of a alternative refrigerant (R-410A) cycle characteristic with an existing refrigerant (R-22) cycle characteristic in terms of cooling capacity and coefficient of performance (COP). The parameters examined in the present work include air flow rate, indoor/outdoor air temperatures, and indoor relative humidity. These two refrigeration cycles share all components except compressor, accumulator, oil separator, and piping connecting them. The measurements were made using an air-enthalpy calorimeter. The experimental results show that the R-410A cycle has many advantages over indoor conditions while the R-22 cycle has better performance over outdoor conditions.
Flow Characteristics of a Turbulent Pulsating Flow in a Straight Duct Connected to a Curved Duct by using an LDV
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 15, issue 3, 2003, Pages 177~186
In the present study, the flow characteristics of developing turbulent flows are investigated at the exit region of a square cross-sectional 180" curved duct with dimensions of 40mm
length). Smoke particles produced from mosquito coils were used as seed particles for the LDV measurement. Experiments were carried out to measure axial velocity profiles, shear stress distributions and entrance lengths by using an LDV system and Rotating Machinery Resolver RMR with PHASE software. Experimental results clearly show that the time-averaged Reynolds number does not affect oscillatory flow characteristics because the turbulent components tend to balance the oscillatory components in the fully developed flow region. Also, the velocity profiles are in good agreement with 1/7power law such as the results of steady turbulent flows. The turbulent intensity linearly increases along the walls and is slightly higher, especially in the period of deceleration. On the other hand, the LDV measurements show that shear stress values in slightly higher in the period of deceleration due to the flow characteristics in the exit region. The entrance length where flows become stable appears at the point that is 40 times the length of hydraulic diameter.eter.
Performance Characteristics with Capacities of Heat Exchangers of a Refrigeration System
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 15, issue 3, 2003, Pages 187~195
The geometric size and the refrigeration capacity of a refrigeration system are strongly dependent on the capacity of heat exchanger, which is one of the key design parameters. In this paper, the effect of the capacities of heat exchangers on the performance of a real refrigeration system operated in a vapor compression cycle was analyzed by the numerical simulation. From the results, the conditions that gave the maximum values of the refrigeration capacity or COP were respectively determined as a function of the capacities of condenser and evaporator under the given ambient and operating condition.
Modeling of the Safety Distance between Defrost Heater and Plastic Inner Wall of Refrigerator
;;Alexei V. Tikhonov;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 15, issue 3, 2003, Pages 196~202
Two dimensional modeling was carried out to find the safety distance between the defrost heater and the plastic inner wall of domestic refrigerator Estimation was processed for the three cases; the estimation of plastic wall temperature (1) without any protection, (2) with an aluminum foil attached on a wall, and (3) with an aluminum shield installed between heater and wall. The former two cases are found to be dangerous during defrosting process, because the temperatures of inner wall reach above 80'C , which is the upper temperature limit of the wall material. The case with an aluminum shield is considered to be safe by maintaining the temperature of the wall in the range of 6
during defrosting process.
Control Methods of the VAV Air Handling Unit for the Required Outdoor Air Demand
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 15, issue 3, 2003, Pages 203~209
Control algorithms of an air handling unit by using the mixing box plenum pressures were developed and verified by experiments. Control algorithms developed for this study were the setpoint algorithms for the outdoor damper position, the outdoor/fixed plenum pressure, and the return/exhaust plenum pressure. The outdoor/fixed plenum pressure setpoint was used to control the bypass damper position, and the return/exhaust plenum pressure setpoint was used to control the return fan speed. Experimental results showed the good control of the required outdoor air demand. Therefore, setpoint algorithms developed for this study may effectively be applied for the control of the VAV air handling unit.
A Study of Laminated Evaporator Performance Characteristics through Numerical Analysis
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 15, issue 3, 2003, Pages 210~219
A laminated evaporator performance simulation software has been developed and the performance characteristics have been examined with variation of important design parameters, number of plate (
), plate inner height (
), Plate thickness (
) and plate wetted Perimeter (
). To confirm the program, performance experiment was carried out for two different evaporators. The simulation results matched with experiments within
10%. Through the parametric studies,
was shown to be most influential. The
had a maximum cooling capacity point in the calculation range. In case of
, the smaller was the better.ter.etter.ter.
Evaluation of Air-side Heat Transfer and Friction Characteristics on Design Conditions of Condenser
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 15, issue 3, 2003, Pages 220~229
An experimental study on the air-side pressure drop and heat transfer coefficient of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side heat transfer coefficients in the literature is not based on a consistent approach. This paper focuses on new method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry surface heat transfer estimation in fin-tube heat exchanger having refrigerant on the tube-side. Results are presented as plots of friction f-factor and Colburn j -factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of 150~250 kg/
s with air flows at velocity ranges from 0.6 m/s to 1.6 m/s.
An Experimental Study on Condensation Characteristics at Various Condensation Pressure of R407C
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 15, issue 3, 2003, Pages 230~238
R407C is considered as alternative refrigerant of R22 for air conditioners. Experimental investigation is made to study the condensation heat transfer characteristics of slit fin-tube heat exchanger using alternative refrigerant, R407C. Experiments are carried out at condensation pressure of 2110 kPa and 1943 kPa with the degree of superheat of 1
and mass flux varying from 150 to 250 kg/
s for refrigerant side. The inlet air condition is dry bulb temperature of 35
, relative humidity of 50% and air velocity varying from 0.8 to 1.6 m/s. Experiments show that pressure drop gets smaller at a higher condensation pressure especially when condensation pressure is raised from 1943 to 2110 kPa. Heat transfer rate gets smaller at a lower condensation pressure in the range of experimental condition.
The Effect of Turbulence Penetration on the Thermal Stratification Phenomenon Caused by Leaking Flow in a T-Branch of Square Cross-Section
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 15, issue 3, 2003, Pages 239~245
In the nuclear power plant, emergency core coolant system (ECCS) is furnished at reactor coolant system (RCS) in order to cool down high temperature water in case of emergency. However, in this coolant system, thermal stratification phenomenon can occur due to coolant leaking in the check valve. The thermal stratification produces excessive thermal stresses at the pipe wall so as to yield thermal fatigue crack (TFC) accident. In the present study, effects of turbulence penetration on the thermal stratification into T-branches with square cross-section in the modeled ECCS are analysed numerically.
model is employed to calculate the Reynolds stresses in momentum equations. Results show that the length and strength of thermal stratification are primarily affected by the leak flow rate of coolant and the Reynolds number of the main flow in the duct. Turbulence penetration into the T-branch of ECCS shows two counteracting effects on the thermal stratification. Heat transport by turbulence penetration from the main duct to leaking flow region may enhance thermal stratification while the turbulent diffusion may weaken it.