Heat Transfer Enhancement in Pool Boiling of Distilled Water Using Gridded Metal Surface With Protrusions Over Microporous-Coated Surface

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Vidushi Chauhan ◽  
Manoj Kumar ◽  
Anil Kumar Patil
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Metal Surface ◽  
Boiling Heat Transfer ◽  
Particle Diameter ◽  
Saturation Temperature ◽  
Grid Size ◽  
Boiling Heat Transfer Coefficient ◽  
Coated Surface

Abstract The nucleate pool is a useful technique of heat dissipation in a variety of thermal applications. This study investigates the effect of the gridded metal surface (GMS) with and without protrusions on the heat transfer from a surface maintained at a temperature above the saturation temperature of water. The experimental data have been collected pertaining to boiling heat transfer at atmospheric pressure by varying the grid size of gridded metal surface with protrusions from 6 mm to 22.5 mm placed over a boiling surface having microporous coating. The mean particle diameter of coating is varied as 11, 24, and 66 μm during the experimentation. It is observed that the increase in the boiling heat transfer coefficient of the aluminum disk with GMS with protrusions of grid size 11.5 mm compared to that of the smooth boiling surface is found to be 10.7%. Furthermore, the effect of GMS having protrusions with coated surface on the heat transfer is studied. The results showed that by using GMS having protrusions and with coated surface, the heat transfer is further enhanced. The boiling heat transfer coefficient obtained in case of GMS with protrusions (grid size = 11.5 mm) and microporous-coated surface (dm = 66 μm) shows the maximum enhancement of 39.93% in comparison to the smooth surface.

Heat Transfer Characteristics for a Single Fin in a Boiling Liquid

2000 ◽  
Author(s):  
Yingzong Bu ◽  
Allan D. Kraus ◽  
Benjamin T. F. Chung
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Saturation Temperature ◽  
Base Temperature ◽  
Heat Transfer Characteristics ◽  
Boiling Liquid ◽  
Transfer Characteristics ◽  
Boiling Heat Transfer Coefficient

Abstract This work utilizes the cascade algorithm to predict the heat transfer characteristics of a one-dimensional longitudinal fin of rectangular profile in a boiling liquid. In this analysis, the geometric parameters of the fin, the temperature at the fin base and the saturation temperature of the boiling liquid are assumed. With the utilization of experimental boiling heat transfer coefficient curves, the heat flux, temperature profile, and boiling heat transfer coefficient of each point on the fin are obtained. The effectiveness of the fin in a boiling liquid is plotted for different fin thicknesses. It is found that the fin conductivity, boiling liquid, fin geometry and fin base temperature all affect the effectiveness of the fin in boiling. The effectiveness curves clearly indicate whether a fin should be used or when it is advantageous to use a fin in boiling liquid.

Experiment and CFD Simulation of Boiling Heat Transfer Coefficient of R410A in Minichannels

2015 ◽  
Vol 23 (04) ◽  
pp. 1550032 ◽  
Author(s):  
Nguyen Ba Chien ◽  
Kwang-Il Choi ◽  
Jong-Taek Oh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Saturation Temperature ◽  
Boiling Heat Transfer Coefficient

This study performed a comparison between experimental and computational fluid dynamic (CFD) simulation results of boiling heat transfer coefficient of R410A in a small tube. The experimental data were obtained in the horizontal circular tubes of 3.0[Formula: see text]mm inner diameter, the length of 3000[Formula: see text]mm including: mass flux and heat flux in a range from 300[Formula: see text]kg/m2s to 600[Formula: see text]kg/m2s and from 5[Formula: see text]kW/m2 to 10[Formula: see text]kW/m2, respectively, and the saturation temperature constantly kept at 20[Formula: see text]C. In the simulation procedure, the Eulerian multiphase with wall boiling were obtained. The effects of mass flux and heat flux on the heat transfer coefficient of R410A were analyzed. The comparative data between CFD and experiment was also illustrated.

Enhanced Heat Transfer for Boiling of a Refrigerant on a Micro-Structured Cylindrical Surface and Effect of Saturation Temperature

2010 ◽  
Author(s):  
Tailian Chen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Smooth Surface ◽  
Saturation Temperature ◽  
Structured Surface ◽  
Cylindrical Tubes ◽  
Boiling Heat Transfer Coefficient ◽  
Micro Structures

Boiling on the outside surface of cylindrical tubes is an important heat transfer process widely used in industry applications. It is known that boiling heat transfer coefficient increases with increasing saturation temperature. However, a quantitative measure of saturation temperature effect on boiling heat transfer is not readily available, especially for boiling on surfaces of microstructures. This work was motivated by the need to predict evaporator performance in a chiller while taking into account the effect of saturation temperature on boiling heat transfer coefficient. Experiments of boiling of refrigerant R123 on the micro-structured outside surface of an evaporator tube have been performed at three saturation temperatures in the range of 4.4 to 17.8°C. Water flows inside the test tubes and provides heat to the refrigerant for boiling. In addition, experiments of R123 boiling on smooth cylindrical tubes have been performed at the saturation temperature 4.4°C to provide a baseline to quantify the enhancement in boiling heat transfer due to microstructures on the test tubes. For boiling on the micro-structured surface, the boiling heat transfer coefficient increases by nearly 15% for the temperature range considered in this work. Measurements also showed that heat transfer coefficient for boiling on the test tubes of micro-structures is 12.3 times higher than boiling on the smooth surface. The Cooper correlation over-predicted by 40% the boiling heat transfer coefficient on the smooth cylindrical surface, but significantly under-predicted the performance for boiling on the tubes of micro-structures. It is found that the prediction of Cooper correlation multiplied by an enhancement factor 7.9 has a good agreement with measured heat transfer coefficient for boiling on the tubes of micro-structures at all the three saturation temperatures. Visual observations indicated that bubble departure characteristics on the micro-structured surface are different from those on the smooth surface. In addition to promoted bubble nucleation by re-entrant cavities on the micro-structured surface, the different bubble departure characteristics also contribute to the enhancement of boiling performance.

Surface wettability effect of plain and plasma-sprayed copper-coated surfaces on CHF enhancement during saturated pool boiling of FC-72

2021 ◽  
pp. 095440622110574
Author(s):  
Rajiva Lochan Mohanty ◽  
Subhakanta Moharana ◽  
Mihir Kumar Das
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Coating Thickness ◽  
Boiling Heat Transfer ◽  
Boiling Heat Transfer Coefficient ◽  
Coated Surface ◽  
Plain Surface ◽  
Coated Surfaces ◽  
Plasma Sprayed

In the current scenario, CHF study is essential for the safe operation of electronics equipment comprising a two-phase heat transfer process. Therefore, the present experimental investigation involves saturated pool boiling and CHF study of FC 72 over a plain stainless steel surface (SS) and microporous copper-coated SS surfaces under atmospheric conditions. Accordingly, three different plasma-sprayed copper-coated surfaces with coating thicknesses of 65 μm, 105 μm, and 145 μm prepared using micro copper particles of size 25–45 μm. The analysis of the results shows that with an increase in heat flux values, the boiling heat transfer coefficient increases over plain as well as coated surfaces. The plasma-spayed copper-coated surfaces with a coating thickness of 65 μm and 105 μm exhibit a higher boiling heat transfer coefficient as than the plain surface. On the other hand, a 145 μm thick coated surface resulted in a comparable boiling heat transfer coefficient with the plain SS surface. Among the three porous-coated surfaces, the boiling heat transfer coefficient decreases continuously from 65 μm to 145 μm of the coated surface. On the contrary, to the observed nucleate boiling behavior, all the porous-coated surfaces show a higher value of CHF than the plain surface, and the CHF value is found to increase continuously from 65 μm to 145 μm of the coated surfaces. The enhancement of CHF values was found to be 66.29%, 69.17%, and 77.75% for a coating thickness of 65 μm, 105 μm, and 145 μm, respectively, compared with the plain surface. The porous coating thickness of 65 μm shows a greater value of heat transfer coefficient than 105 μm and 145 μm whereas 145 μm exhibits a higher value of CHF as than 65 μm and 105 μm.

Characteristics of Two-Phase Flow Boiling Heat Transfer and Pressure Drop of NH3, C3H8 and CO2 in Horizontal Circular Small Tubes

2010 ◽  
Author(s):  
Kwang-Il Choi ◽  
Maulana Rifaldi ◽  
Agus S. Pamitran ◽  
Jong-Taek Oh
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Saturation Temperature ◽  
Nucleate Boiling ◽  
Two Phase ◽  
Nucleate Boiling Heat Transfer ◽  
Boiling Heat Transfer Coefficient

An experimental investigation on the characteristics of two-phase boiling heat transfer of NH3, C3H8 and CO2 in horizontal small stainless steel tubes of 1.5 and 3.0 mm inner diameters are presented in this paper. Experimental data were obtained over a heat flux range of 5 to 70 kW/m2, mass flux range of 50 to 600 kg/m2s, saturation temperature range of 0 to 12°C, and quality up to 1.0. The test section was heated uniformly by applying an electric current to the tubes directly. Nucleate boiling heat transfer was the main contribution, particularly at the low quality region. Laminar flow was observed in the small tubes. The heat transfer coefficient of the present working refrigerants was compared with other correlations. A new boiling heat transfer coefficient correlation based on the superposition model for refrigerants in small tubes was developed.

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