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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
Theoretical Performance Analysis of a Modified Rectangular Fin
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 683~690
A modified rectangular fin is analyzed by two-dimensional analytic method and finite difference method. Relative error of heat loss from the modified rectangular fin between analytic method and finite difference method is presented. Comparisons of fin effectiveness and heat loss between a modified rectangular fin and a plane rectangular fin are made as a function of the non-dimensional fin length and wing height for different positions of wings by using analytic method. The ratio of the incremental rate of heat loss to that of the area of a modified rectangular fin is shown as a function of the wing height. One of the results shows that performance of a modified fin is more improved as the wing approaches the fin root.
An Experimental Study on the Thermal Performance of Sinusoidal Axially Grooved Heat Pipe
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 691~697
Experimental study is carried out to investigate the heat transport capability and thermal resistance of sinusoidal axially grooved heat pipe, comparing its performance to trapezoidal axially grooved heat pipe. As a result from this work, the heat transport capability of sinusoidal grooved heat pipe is lower than that of trapezoidal grooved heat pipe for the same size of outer diameter. As the ratio of depth to width of sinusoidal groove heat pipe is higher, the heat transport capability of heat pipe becomes higher. It is found that Aluminum-ammonia heat pipes with sinusoidal and trapezoidal grooves have good thermal resistance, below 0.1
/W at evaporator section and below 0.05
/W at condenser section.
Measurement of Heat Transfer Coefficient in a Flooded Evaporator through Wilson Plot Method
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 698~706
Heat transfer coefficients of enhanced tubes in a flooded evaporator are measured through Wilson Plot method. And the correlations are proposed to design a flooded evaporators. Overall heat transfer coefficients are composed of the heat transfer coefficients both inside and outside tubes. Usually the experiments have been conducted separately. But there have been many difficulties like setting up the equipments and measuring the wall temperature. Wilson Plot method makes it possible to measure the separated transfer coefficients at the same equipment through experimental skills. So the cost and time can be reduced. And the results are reliable enough to use for design. Heat transfer coefficients inside the tube were able to be correlated uniquely in spite of various outside conditions. Boiling heat transfer of R134a is more dependent on the saturation temperature and much higher than that of R123.
A Study on the Flow Characteristics of Piezoelectric Micropumps with Different Numerical Models
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 707~713
A numerical analysis has been conducted for flow characteristics of piezoelectric micropumps. In the present study, FSI (Fluid-Structure Interaction) model and grid deform model have been employed for each of two different geometries of the micropumps with two different frequencies in the piezoelectric diffuser/nozzle based micropumps. The displacement of piezo disk and flow rates have been closely examined at the inlet and outlet. It has been found that the motion of the piezo disk investigated with FSI model is not in accordance with that with grid deform model. The results show that the time averaged flow rate calculated with FSI model is larger than that with grid deform model. This study presents the performance analysis of piezoelectric micropumps with two different numerical models for different types of pumps.
Analysis of Convective Instability Induced by Buoyancy and Heat Transfer Characteristics for Natural Convetion in Nanofluids
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 714~719
The objective of the present study is to investigate the convective instability driven by buoyancy and the heat transfer characteristics of nanofluids. Using the property relations of nanofluid expressed as a function of the volume fraction of nanoparticles, the ratio of nanofluid Rayleigh number to basefluid one, f is newly defined. The results show that the density and the heat capacity of nanoparticles act as a destabilizing factor. With an increase of
which is the ratio of thermal conductivity of nanoparticles to that of basefluid, the thermal instability of nanofluid decreases but the heat transfer rate increases.
Evaluation of Ice Adhesion in an Aqueous Solution with Functional Materials by Stirring Power
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 720~727
In the process of ice-slurry making, the phenomenon of ice adhesion influences extremely to ice making system. In this study, the effect on the ice adhesion by thermal storage material with additives is investigated quantitatively. Various solutions of 300 g in a stainless vessel were frozen under stirring. Through the experiment the ice adhesion between cooling wall and ice-slurry was compared with each other by measuring the stirring power. From the experiment, the stirring power in EG, SCA solution was smaller than those in the solution containing functional materials, such as poly-vinyl-alcohol or kitchen detergent.
Cooling Characteristics of Wing Fin Heat Sink
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 728~740
Heat sink has extended surface area for enhanced heat transfer. The enhanced convection heat transfer has been used widely, such as cooling electronic chips in the electronics industry. Heat sink usually requires an increase in the heat transfer and a decrease in the pressure drop, and must improve the performance in the flow field of industrial plants. In this study, wing fin heat sink was studied and tests were conducted in a rectangular cross sectional channel with wing fin heat sinks. The leading and trailing ends of a wing fin have a sharp edge, simulating the airfoil feature. Empirical correlations have been developed for wing fin heat sink types. And wing fin heat sinks have better cooling performance than elliptic fin and square fin types.
The Experimental Study on Cooling-Heating System Using Thermoelectric Module and Parallel Flow Type Oscillating Heat Pipe
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 741~747
The purpose of this study was to develop a cooler/heater using a thermoelectric module combined with a parallel flow type oscillating heat pipe with R-142b as a work ing fluid. The experiment was performed for 16 thermoelectric modules (6 A/15 V, size: 40
4 mm), varying design parameters of the heat pipe (inclination angle, working fluid charging ratio, etc) . Experimental results indicate that the optimum charging ratio and the inclination angle of the parallel flow type oscillating heat pipe were 30% by volume and 30%, respectively. The maximum cooler/heater capacity were 479W (COP : 0.47) and 630W (COP : 0.9), respectively.
An Experimental Study of Flow Boiling Heat Transfer inside Small-Diameter Round Tubes
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 748~755
Flow boiling heat transfer in small-diameter round tubes has been experimentally studied. The experimental apparatus consisted mainly of refrigerant pump, condenser, receiver, test section of a 1.67 mm inner-diameter round tube and pre-heater for control of refrigerant quality at the inlet of test section. To investigate the effect of bubble nucleation site characteristics of different tube materials, three different tubes of copper, aluminum and brass were used. The ranges of the major experimental parameters were 5∼30 ㎾/
of the wall heat flux, 0.0∼0.9 of the inlet vapor quality and the refrigerant mass flux was fixed at 600 kg/
s. The experimental results showed that the flow boiling heat transfer coefficients in small tubes were affected only by heat flux, but independent of mass flux and vapor quality. The effect of tube material on flow boiling heat transfer was observed small.
The Study on Performance Characteristics of Superheating the Suction Vapor in
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 756~761
Since the use of CFC and HCFC refrigerants are to be restricted due to the depletion of ozone layer, this experiment applies the NH
gas to study the performance characteristics from the superheat control for improving the energy efficiency. The experiments are carried out for the condensing pressure of refrigeration system from 14.5 bar to 16.0 bar by 0.5 bar and for superheat temperature from
at each condensing pressure. As a result of experiment, when the superheat temperature is 1
at each condensing pressure, the refrigeration system has the highest performance.
A Study on Design Decision of Qualitative Design Factors in Selecting of HVAC Type for Building
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 762~769
Not only in building design but also in HVAC system design, it is important to ensure an objectivity in schematic design. In the study, the author suggested a method to make a logical decision for quality design factors a(footing the selection of HVAC type in initial design process, and to provide objective design values. Fuzzy theory, one of the theories describing in quantitative way the ambiguous-natured linguistic values, was used to determine the qualitative design factors of linguistic parameter nature. It was found that it has a potential as a method to determine a HVAC type satisfying the required values of qualitative design factors involved in selection of the system type. But this needs further studies to be settled in the selecting of HVAC type.
Fouling Reduction Characteristics of a Fluidized Bed Heat Exchanger for Flue Gas Heat Recovery
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 16, issue 8, 2004, Pages 770~777
Fouling and cleaning tests are performed for a uniquely designed 7,000 ㎉/hr fluidized bed heat exchanger for exhaust gas heat recovery. Fuel rich condition is maintained in the combustor for a limited time period to generate soot that is to be deposited on the heat transfer surfaces (fouling) and 600 Um glass beads are circulated inside the heat exchanger system for cleaning and enhancing the heat transfer performance. According to the present experimental study, performance degradation mode could be monitored and the effect of particle circulation on the heat transfer improvement could be identified. Through the present study, it is demonstrated that circulating particles contribute not only to the fouling reduction in gas side, but also to the heat transfer enhancement of the unit, while other possible aging factors including water side corrosion seemed to contribute to the accumulated performance deterioration.