• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.227-232
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• 2008

The present study was investigated the local heat transfer characteristics and temperature distribution on the louver fin by using the expansion model. Heat transfer rate, frost mass and temperature distribution of the louver fin under frosting condition were experimentally investigated. Local heat transfer rate and heat flux on the louver were analyzed by the conduction heat transfer between top and lower part of the louver. The experimental key parameter was brine inlet temperature(-5, -10, $-15^{\circ}C$). The heat transfer performance and frost mass at brine temperature of $-15^{\circ}C$ were increased by maximum 3 time than the brine temperature of $-5^{\circ}C$. At all experimental case, local heat transfer rate and heat flux of the louver were almost symmetry at the louver number of 6. Especially, local heat transfer rate and heat flux were maximum increased on the louver number of 4 and 8.

• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.39-43
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• 2013

The present study has been conducted to investigate the fire combustion properties and fire behavior of an IEEE-383 qualified flame retardant cable. The reference reaction rate and reference temperature which are commonly used in pyrolysis model of fire propagation process was obtained by the thermo-gravimetric analysis of the cable component materials. The mass fraction of FR-PVC sheath abruptly decreased near temperature range of $250{\sim}260^{\circ}C$ and its maximum reaction rate was about $2.58{\times}10^{-3}$[1/s]. For the XLPE insulation of the cable, the temperature causing maximum mass fraction change was ranged about $380{\sim}390^{\circ}C$ and it has reached to the maximum reaction rate of $5.10{\times}10^{-3}$[1/s]. The flame retardant cable was burned by a pilot flame meker buner and the burning behavior of the cable was observed during the fire test. Heat release rate of the flame retardant cable was measured by a laboratory scale oxygen consumption calorimeter and the mass loss rate of the cable was calculated by the measured cable mass during the burning test. The representative value of the effective heat of combustion was evaluated by the total released energy integrated by the measured heat release rate and burned mass. This study can contribute to study the electric cable fire and provide the pyrolysis properties for the computational modeling.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.2
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• pp.182-189
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• 1989

The propose of this study is augmentation of heat transfer without additional external power in 2-dimensional impinging air jet. The passive heat transfer augmentation method tried in this experimental study is placement of rod bundles with the clearance, 2mm, in front of the heat transfer surface. The effects of pitch distance among rods and nozzle-to-target plate distance are investigated. The overall heat transfer rate of flat plate with rods reaches maximum at H/B=10 and P=40mm, and for H/B=2 and P=40mm the augmentation rate of heat transfer becomes maximum to a value which is about 1.57 times that of the flat plate without rods.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1231-1236
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• 2008

The flow and heat transfer performance were measured at high temperatures in CFB heat exchanger with multiple risers and downcomers. The theoretical model for predicting heat exchanger performance was developed in this study. The model predictions were compared with the measured heat transfer rates to show relatively good agreement. The maximum gas cooling rate was $20,300^{\circ}C/sec$, and the dioxin reduction rate was 68%.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.280-285
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• 2001

This paper presents a modelling of thermal discharge performance for a static ice-on-coil ice-storage tank. Through the present study, discharging characteristics were examined with the existing results of theoretical and numerical heat transfer analyses. Also, an experiment was conducted to obtain a real set of discharge performance. The thermal effectiveness, the ratio of the actual heat transfer rate to the maximum possible heat transfer rate, decreased when the stored energy decreased during discharging period. And the effectiveness increased as the coolant flow rate through the storage increased, of which increasing rate decreased abruptly near the maximum and the minimum stored energy. An empirical correlation was obtained from the experimental and the numerical analysis data.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.2
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• pp.155-163
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• 2023

This study deals with the maximum thermal load analysis and optimal capacity determination method of tank culture system for applying seawater source heat pump to save energy and realize zero energy. The location of the fish farm was divided into four sea areas, and the heat load in summer and winter was analyzed, respectively. In addition, two representative methods, the flow-through aquaculture system and the recirculation aquaculture system were reviewed as water treatment methods for fish farms. In addition, the concept of the exchange rate was introduced to obtain the maximum heat load of the fish farms. Finally, power consumption for heat pumps was analyzed in the view point of sea areas, tank capacity, and exchange rate based on the calculated maximum thermal load.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.10
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• pp.2607-2616
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• 1995

The influences of number of spark plug on ignitability, combustion characteristics and combustion promotion effect were examined to establish the design conception of spark ignition system for lean burn. Ignitability was increased remarkably by increasing of number of spark plug at combustion wall. Combustion duration was shortened and maximum combustion pressure was increased in accordance with increasing of spark plug number. Rate of overall combustion promotion considered of combustion duration and combustion pressure was 28% in two point ignition and 40% in four point ignition. It was verified that heat release, heat loss and combustion duration were affected by flame area, heat transfer area and maximum flame travel distance respectively.

• Solar Energy
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• v.19 no.2
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• pp.37-44
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• 1999

Experimental investigation has been carried out to determine drag reducing effects of polymer additives for a plate type heat exchanger(evaporator or condenser) in OTEC power plant applications, where the pressure drop in the heat exchangers takes up $70{\sim}80%$ of the total pumping power in the existing system. The rate of drag reduction was investigated with various polymer concentrations and mass flow rates. Experiments were undertaken for a test section in Alfa-Laval plate heat exchanger utilizing Poly Ethylene Oxide(Mw $5{\times}10^6$) as polymer additives. Concentrations of polymer additives were 5, 10, 20, 30, 40, 50, 100, 200, 400 wppm at $25^{\circ}C$ and mass flow rates were 0.6kg/s, 0.7kg/s, 0.8kg/s and 0.9kg/s in normal operating ranges for a 15kW Alfa-Laval plate heat exchanger. The maximum effects of drag reductions were found at approximately 0.7kg/s of mass flow rate. The results show that there exists the optimum mass flow rate for the plate heat exchanger to obtain maximum drag reductions. Drag reduction of 20% means considerable savings in pumping power for a large size of OTEC plant.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.855-860
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• 1999

An experimental study of jet impingement on the surface with linear temperature gradient is conducted with the presentation of the turbulent characteristics and the heat transfer rates measured when this jet impinges normally to a flat plate. The jet Reynolds number ranges from 30,000 to 90,000, the temperature gradient of the plate is 2~$4.2^{\circ}C$/cm and the dimensionless nozzle to plate distance(H/D) is from 6 to 10. The results show that the peak of heat transfer rate occurs at the stagnation point, and the heat transfer rate decreases as the radial distance from the stagnation point increases. A remarkable feature of the heat transfer rate is the existence of the second peak. This is due to the turbulent development of the wall jet. Maximum heat transfer rate occurs when the axial distance from the nozzle to nozzle diameter(H/D) is 8. The heat transfer rate can be correlated as a power function of Prandtl number, Reynolds number and the dimensionless nozzle to plate distance(H/D). It has been found that the heat transfer rate increases with increasing turbulent intensity.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.11-17
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• 2005

This paper reports an experimental study on the performance evaluation of air-to-air heat exchanger with rotary type newly developed in this study. Air flow rate is varied from 10 to 120 m3/h. The range of RPM of the porous rotating discs mounted inside the heat exchanger unit is 0 to 50. The temperature of the return air side is set by adjusting heat supply at heater. The material of the porous rotating discs is cooper and its thickness is 1.0 mm. The heat transfer rate increased with the increase in air flow rate. It was found that the heat transfer rate, as the temperature of the return air side was increased, was improved due to higher temperature difference. The heat exchange performance increased with the increase in the temperature of the return air side at the conditions of the same RPM. The sensible heat exchange efficiency was maximum 68 to 76 percent, and enthalpy exchange efficiency 64 to 74 percent.