• Solar Energy
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• v.17 no.4
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• pp.45-56
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• 1997

The purpose of this research was to study the characteristics of heat transfer of snow removing facilities using heat pipe by experimental method. Heat pipes was constructed a flexible tube connected between evaporator and condenser ends for altitude adjustment of evaporator and it was constituted an internal diameter of 25.4mm, a length of 950mm for heating section and a length of 6000mm for condenser section with copper material for closed system. The results showed that the effect of heat transfer was increased when inclination angle and inlet temperature of heating water increased. Wall temperature response by inclined angle $4.5^{\circ}c-9^{\circ}c$ and working fluid amount 0.96 from to 1.3 times of evaporator volume were better than those of other working fluid and angle.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.12
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• pp.1139-1144
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• 2005

This study has been performed to investigate the thermal performance of variable conductance heat pipe (VCHP) with meshed wick. The length of condenser portion in a VCHP is varied by the expansion of inert gas with the operation temperature, and the heat transport capacity is thus varied with the operating temperature. In this study, numerical evaluation of the VCHP is made for the thermal performance of VCHP, based on the diffusion model of inert gas. Water is used as a working fluid and nitrogen as a control inert gas in the copper tube. As a result, the thermal performance of VCHP has been compared with that of constant conductance heat pipe (CCHP) according to the variation of operation temperature. Maximum heat transport capacity of VCHP is mainly presented for operation temperature and the variation of operation temperature is also presented for heat transfer rate of VCHP.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.4
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• pp.297-303
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• 2006

Friction and heat transfer coefficients were measured inside the corrugated tube using water as the working fluid. The test is performed for 16 tubes which outer diameter of tubes are 12.7 mm. These specifications are 4 indentation depths and 4 indentation pitches, respectively. The range of the water velocity inside the tube is from 0.5 to 3.0 m/s (8,500

• Journal of the Society of Disaster Information
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• v.15 no.3
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• pp.380-390
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• 2019

Purpose: Recently, in addition to increase in the use of electric ranges, fires have also been increasing. Method: To find out the fire risk of induction and highlights range, looked at the structure and operation methods. Combustion tests, heat transfer tests, and ignition tests were performed on both types. Results: The highlight electric range burned the towel two minutes later, takes about 25 minutes for the residual heat to cool down after cooking, and the energy of the red color disappeared in three to four minutes and no sparks were seen. Conclusion: Experiments have shown that burn and fire hazards exist, especially if there is cracks in the top, there is a risk of fire and explosion.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.3
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• pp.113-121
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• 2021

In this study, the thermal characteristics of cold and hot water mattress units equipped with thermoelectric modules were investigated via numerical analyses. Cold and hot water mattress products that are currently in existence use manual methods requiring refrigerants to be added to the hot water boiler. However, the cold and hot water mattress units using thermoelectric modules can provide improved efficiency via energy savings and actively resolving environmental pollution problems. To determine the efficiency of the thermoelectric module, the mattress was modeled and its efficiency was analyzed for the cooling and heating processes using two 100-W-class and one 200-W-class thermoelectric modules, respectively. From the results of this study, it was confirmed that when two 100-W-class modules were used, the application area was larger than when a single 200-W-class module was used, with uniform temperature distribution and improved performance compared to existing products in terms of electrical energy.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.6 no.1
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• pp.1-8
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• 1977

This paper describes an experimental investigation which has been carried out with distilled water with the range of heat flux and pressure covering 7,400-28,000kcal/$m^2/h$ and 0.42-1.0332kg/$cm^{2}abs$, respectively. In this experiment, Nickel coated mirror surface heater of 5 cm O.D. was used as a heating source. The conclusions summerized as follows;1. The useful correlation of the test data for the heat transfer coefficient is presented as a function of the pressure. $$a/a_{s}=c{\times}p\;0.18$$ where a is the heat transfer coefficient and $a_s$ is the heat transfer coefficient at atmospheric pressure and p is the pressure, C is constant. 2. The bubble diameter near the heating surface and rising velocity increased with the heat flux. 3. A decrease in pressure results in the decrease of the number of nucleation sites and the increase of the bubble volume. 4. Bubble rising velocity differences are incrased maximumly up to $200\%$ of that at atmopheric pressure.

• Journal of Bio-Environment Control
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• v.22 no.3
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• pp.270-278
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• 2013

The objective of the present study is to provide data needed to decide covering method to be able to increase the thermal insulation and light transmittance efficiency of commercial greenhouse. The thermal insulation effect, PPF transmittance and quantity of condensation water were estimated in experimental tomato greenhouses covered with three types of coverings of single layer, air inflated and conventional double layers covering. The overall heat flow of air inflated double layers greenhouse was similar to that of conventional double layers greenhouse, but the temperature between covering material and thermal screen in air inflated double layers greenhouse was lower than that in conventional double layers greenhouse at the same outside temperature condition due to air leakage through the gap of roof vent. The overall heat transfer coefficients acquired by experiment that was performed in single layer and conventional double layers greenhouses were close to those obtained from model experiment. Even though the PPF transmittance of air inflated double layers greenhouse was lower than that of single layer greenhouse, which was greater than that of conventional double layers greenhouse. The quantity of condensation water on covering surface of single layer greenhouse was greater than that of air inflated double layers greenhouse due to lower covering surface temperature.

• Korean Journal of Food Science and Technology
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• v.15 no.4
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• pp.414-420
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• 1983

Heating characteristics for retort pouches of Kimchi heated in hot water were determined as a function of various parameters for processing. Processing conditions in laboratory and commercial retort were also evaluated on the basis of storage test. D values for Lactobacillus plantarum isolated from test sample ranged from $D^{1.08}\;to\;D^{0.18}$ and z value was $10.5^{\circ}C$. Thermal diffusivity of Kimchi increased from 1.15 to $1.44{\times}10^{-3}cm/s$ by blanching for 15 min at $80^{\circ}C$. The rate of heat penetration was significantly decreased with increasing the thickness of the pouch although the decreases was less significant below 1.0cm thickness. Increasing in the ratio of solid to syrup up to 90:10 proportionately decreased $f_h$ value, but above the ratio $f_h$ values were nearly constant.

• Solar Energy
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• v.16 no.2
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• pp.113-122
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• 1996

This study presents experimental results of heat transfer characteristics of P.C.M. during outward melting process in a vertical cylinder. The experiment was carried out in six conditions, i. e., three different inlet temperature($7^{\circ}C,\;4^{\circ}C\;and\;1^{\circ}C$) and two directions of working fluid(upward and downward). Melting P.C.M. produced a bell-shaped phase change interface. When the inlet temperature was $7^{\circ}C$, the lower region remained at $4^{\circ}C$ until the temperature of upper region reached $4^{\circ}C$. This was due to the state of maximum density of the lower region. When the direction of the working fluid in the case of $7^{\circ}C$, inlet temperature, was upward, the rate of melting and the total melting energy were higher than when it's direction was downward. But the rate of melting and the total melting energy appeared higher value as it's direction was downward when the inlet temperature is $4^{\circ}C$ and $1^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.21-26
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• 2017

In this study, performance tests were conducted to investigate the applicability of a double-tube heat recovery ventilation system. Paper, aluminum, polymer, were investigated as materials for the inner tube using the same exhaust-air volume. In all cases, the temperature exchange efficiency of the aluminum tube was the highest, while the paper tube showed similar results to those of the polymer tube. This probably resulted from the differences in thermal conductivity and thicknesses of the materials. The humidity exchange efficiency was the highest for the paper tubes in all cases, while the aluminum tubes and polymer tubes showed similar results. The total heat exchange efficiency, which includes the values of humidity exchange and temperature exchange, was highest in the case of the paper tube, and the aluminum tube and the polymer tube showed similar results. In the case of the paper tube, sensible heat and latent heat exchange occur at the same time, and the coefficient of energy of the aluminum tube and polymer tube are large values, when to be compared with only applicably sensible heat exchange coefficient of the aluminum tube and the polymer tube of total heat exchange efficiency value. The results of this study could be applied to the design of a ventilation system.