• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.8
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• pp.735-744
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• 2000

In order to define the heat transfer characteristics in a spray column direct contact heat exchanger, the development of a multidimensional numerical model and computational algorithm is essential to analyze the inherent multidimensional characteristics of a direct contact heat exchanger. In the present study, it has been carried out numerical calculations using a two-dimensional model for operation of a direct contact heat exchanger. Such operational and system parameters as the injection velocity, void fraction, aspect ratio and injection temperature of each fluid are examined thoroughly to assess their influence on the performance of a spray column. Analyzed results has shown that our two-dimensional model predicts the heat transfer phenomena well in a spray column.

• Solar Energy
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• v.20 no.3
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• pp.75-84
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• 2000

The purpose of this research is to study on the heat transfer characteristics of separate type heat pipe with a rotor. The heat transfer characteristics of the rotor condenser are various on input heat of evaporator, rotational speeds of rotor, and working fluid amount. The results obtained from the study are as follows. 1. Magnetic fluid using seal of the rotor operated in stability by a variation of temperature and rotation speeds. The configuration of magnetic fluid seal assembly was adequate. 2. Steam ejector is effective in recovering working fluid condensate in the rotor. When steam ejector is operating, the heat flux of working fluid does not change, with the wall temperature in the rotor. 3. The optimum design conditions on working fluid amount and rotational speeds are effective in evaporator volume 50%, rotational speeds 200rpm, 300rpm, and operating temperature $80^{\circ}C$. With working fluid amount increasing, overall heat transfer coefficient decreases linearly.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.515-522
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• 2010

The objective of this study is to investigate the air-side heat transfer characteristics of a spirally-coiled circular fin-tube heat exchanger for various geometric parameters under non-frosting conditions. The heat transfer characteristics of the heat exchanger were analyzed with respect to heat exchanger geometries, and then, the characteristics were compared with those of rectangular-plate fin-tube heat exchangers with discrete fins. The heat transfer coefficient increased with a decrease in the number of tube rows and an increase in the fin pitch. The optimum length of the L-foot was 2.7 mm. In addition, the heat transfer rate increased with a decrease in the tube pitch and the tube thickness. The heat transfer coefficient of the spirally-coiled circular fin-tube heat exchanger was 24.3% higher than that of the rectangular-plate fin-tube heat exchanger.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.1
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• pp.46-55
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• 2004

Thermal characteristics of the various cooling methods in electronic equipment are studied numerically. A common chip cooling system is modeled as a parallel channel with protruding heat sources. A two-dimensional model has been developed for the numerical analysis of compressible. viscous. laminar flow. and conjugate heat transfer between parallel plates with uniform block heat sources. The finite volume method is used to solve this problem. The assembly consists of two channels formed by two covers and one printed circuit board that is assumed to have three uniform heat source blocks. Various cooling methods are considered to find out the efficient cooling method in a given geometry and heat sources. The velocity and the temperature fields. the local temperature distribution along the surface of blocks. and the maximum temperature in each block are obtained. The results are compared to examine the thermal characteristics of the different cooling methods both quantitatively and qualitatively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.4
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• pp.422-429
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• 2000

Plate and shell heat exchanger(P&SHE) is widely applied as evaporators or condensers in the refrigeration and air conditioning systems for their high efficiency and compactness. In order to set up the database for the design of the P&SHE, heat transfer and pressure drop characteristics for single phase flow of water in a plate & shell heat exchanger are experimentally investigated in this study. Single phase heat transfer coefficients were measured for turbulent water flow in a plate and shell heat exchangers by Wilson plot method. The shell side heat transfer resistance was varied and the overall heat transfer coefficients were measured. The single-phase heat transfer coefficients in a plate side were obtained by Wilson plot method. Single-phase heat transfer correlations based on projected heat transfer area and friction factor correlations have been proposed for single phase flow in a plate and shell heat exchanger.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.1
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• pp.92-97
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• 2013

This study was conducted to understand the quality characteristics of salt fermented anchovies with heat treatment by measuring their chemical compositions. The heat-treated and non-heat treated salt fermented anchovies contained, respectively, 63.21 and 66.51% of moisture, 2.24 and 2.12% of total nitrogen (TN), and 1,537 and 1,520 mg/100 g of amino nitrogen (AN). In addition, heat-treated and non-heat-treated salt fermented anchovies contained 127 and 134 mg/100 g of volatile basic nitrogen (VBN), respectively. Moreover, measured the microbial level of heat-treated and non-heat-treated salt fermented anchovies was $2.58{\times}10^4$ and $3.61{\times}10^2$ CFU/mL, respectively. Also, the heat-treated and non-heat-treated salt fermented anchovies 3.65 and 0.30 units of protease activities, respectively. The total free amino acid contents in heat-treated and non-heat-treated salt fermented anchovies was 4,964 and 6,638 mg/100 g, respectively. The major free amino acid were glutamic acid, leucine, lysine, alanine, valine, isoleucine. Our results provide the characteristics of salt fermented anchovies and encourage their application for the food industry and cooking.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1154-1161
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• 2016

The heat transfer characteristics between liquid lead bismuth eutectic (LBE) and helium are of great significance for the two-loop cooling system based on an accelerator-driven system (ADS). This paper presents an experimental study on the resistance characteristics and heat transfer performance in a LBE-helium experimental loop of ADS. Pressure drops in the LBE loop, the main heat transfer, and the coupled heat transfer characteristics between LBE and helium are investigated experimentally. The temperature of LBE has a significant effect on the LBE thermo-physical properties, and is therefore considered in the prediction of pressure drops. The results show that the overall heat transfer coefficient increases with the increasing helium flow rate and the decreasing inlet temperature of helium. Increasing the LBE Reynolds number and LBE inlet temperature promotes the heat transfer performance of main heat transfer and thus the overall heat transfer coefficient. The experimental results give an insight into the flow and heat transfer properties in a LBE-helium heat exchanger and are helpful for the optimization of an ADS system design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.9
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• pp.373-380
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• 2016

Spray cooling is a technology of increasing interest for electronic cooling and other high heat flux applications. In this study, heat transfer coefficients (HTCs) and critical heat fluxes (CHFs) are measured on a smooth square flat copper heater of $9.53{\times}9.53mm$ at $36^{\circ}C$ in a pool, a smooth flat surface and Thermoexcel-E surfaces are used to see the change in HTCs and CHFs according to the surface characteristics and FC-72 is used as the working fluid. FC-72 fluid has a significant influence on heat transfer characteristics of the spray over the cooling surface. HTCs are taken from $10kW/m^2$ to critical heat flux for all surfaces. Test results with Thermoexcel-E showed that CHFs of all enhanced surface is greatly improved. It can be said that surface form affects heat transfer coefficient and critical heat flux.

• Horticultural Science & Technology
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• v.34 no.1
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• pp.1-14
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• 2016

Heat stress is an agricultural problem for Gerbera jamesonii, and it often causes poor seedling growth, reduced flower yield and undesirable ornamental characteristics of flowers. However, little is known about the effect of heat stress on the morphological, physiological and biochemical characteristics of gerbera plants. Here, the responses of six cultivars of Gerbera jamesonii to heat stress were investigated. Under a 1-d heat treatment at $45^{\circ}C$, the leaves of gerbera cultivars showed yellowing, wilting, drying and death to varying degrees. The heat treatment also resulted in increased electrical conductivity, decreased soluble protein and chlorophyll contents, and the accumulation of malondialdehyde (MDA) and proline in leaves. Moreover, heat tolerance differed among the six tested gerbera cultivars. Our results demonstrated that among the six gerbera cultivars, 'Meihongheixin' is a heat-resistant cultivar, whereas 'Beijixing' is a heat-sensitive one. 'Shijihong' and 'Linglong' are relatively heat-resistant cultivars, and 'Dadifen' and 'Taiyangfengbao' are relatively heat sensitive.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.9
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• pp.522-528
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• 2013

Spray cooling is a technology of increasing interest for electronic cooling and other high heat flux applications. In this study, heat transfer coefficients (HTCs) and critical heat fluxes (CHFs) were measured on a smooth square flat copper heater of $9.53{\times}9.53$ mm at $36^{\circ}C$ in a pool, with a smooth flat surface, and 26 fpi. Low-fin surfaces were used to see the change in HTCs and CHFs according to the surface characteristics, and FC-72 was used as the working fluid. FC-72 fluid had a significant influence on the heat transfer characteristics of the spray over the cooling surface. HTCs were taken from 10 $kW/m^2$ to critical heat flux, for all surfaces. Test results with Low-fin showed that the CHFs of all the enhanced surface were greatly improved. It can be said that the surface form affects the heat transfer coefficient and critical heat flux.