Surface Tension Effects on Convective Boiling Heat Transfer in Compact Heat Exchangers With Offset Strip Fins

1985 ◽  
Vol 107 (4) ◽  
pp. 970-974 ◽  
Author(s):  
V. P. Carey
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Heat Exchangers ◽  
Boiling Heat Transfer ◽  
Convective Boiling ◽  
Compact Heat Exchangers

EHD Enhanced Convective Boiling of R-134a in Grooved Channels—Application to Subcompact Heat Exchangers

1997 ◽  
Vol 119 (4) ◽  
pp. 805-809 ◽  
Author(s):  
M. Salehi ◽  
M. M. Ohadi ◽  
S. Dessiatoun
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Flow Boiling ◽  
Flow Direction ◽  
Reynolds Numbers ◽  
Convective Boiling ◽  
Field Polarity ◽  
Electrical Field Strength ◽  
Compact Heat Exchangers ◽  
R 134A

Electrohydrodynamically (EHD) enhanced flow boiling of refrigerant R-134a inside grooved channels of approximately 1-mm hydraulic diameter was investigated with the objective of addressing the applicability of the EHD technique in highly compact heat exchangers. Two sets of experiments were performed. The first set included experiments in a channel with a smooth heat transfer wall, whereas in the second set a corrugated (enhanced) surface was used. In each case experiments were conducted as a function of the applied electrical field strength, electric field polarity, flow Reynolds number, inlet test section vapor quality, and flow direction (upward, downward, or horizontal). It is demonstrated that in all cases the EHD effect can substantially increase the heat transfer coefficient particularly at low Reynolds numbers and when applied over the enhanced heat transfer wall.

Two Phase Boiling Heat Transfer of Water in Minichannel

2017 ◽  
Author(s):  
Ye Tian ◽  
Wei Huang ◽  
Pengfei Li ◽  
Simin Cao ◽  
Yan Sun
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Absolute Error ◽  
Nuclear Industry ◽  
Working Fluid ◽  
Two Phase ◽  
Compact Heat Exchangers ◽  
Compact Size

Printed Circuit Heat Exchangers (PCHE) is a new type of compact heat exchangers, it will be widely used for nuclear industry due to its higher heat transfer area density, compact size, and design flexibility. The hydraulic diameter of PCHE tubes ranges from 1mm to 2mm which belongs to mini-channel according to Kandlikar and Grande (2003)’s study.[1] In this paper, two-phase flow boiling heat transfer of water in mini-channel is discussed. The most of previous literatures in this field mainly focused on flow boiling of refrigerants, but the main working fluid in PCHE tubes is water. A composite correlation of flow boiling of water through mini-channel has been developed on basis of a database of water in this paper. Mean absolute error (MAE) method is used to evaluate relative error. Comparing with the experimental data, the MAE of the new correlation is 23.4%.

Visualization of Boiling Heat Transfer on Micro Porous Coated Surface in Confined Space

2013 ◽  
Author(s):  
Chien-Yuh Yang ◽  
Chien-Fu Liu
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Boiling Heat Transfer ◽  
Heat Transfer Performance ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
Confined Space ◽  
Two Phase ◽  
Nucleate Boiling Heat Transfer ◽  
Coated Surface

Numerous researches have been developed for pool boiling on microporous coated surface in the past decade. The nucleate boiling heat transfer was found to be increased by up to 4.5 times than that on uncoated surface. Recently, the two-phase micro heat exchangers have been considered for high flux electronic devices cooling. The enhancement techniques for improving the nucleate boiling heat transfer performance in the micro heat exchangers have gotten more importance. Previous studies of microporous coatings, however, have been restricted to boiling in unconfined space. No studies have been made on the feasibility of using microporous coatings for enhancing boiling in confined spaces. This study provides an experimental observation of the vapor generation and leaving processes on microporous coatings surface in a 1-mm confined space. It would be helpful for understanding the mechanism of boiling heat transfer and improving the design of two-phase micro heat exchangers. Aluminum particles of average diameter 20 μm were mixed with a binder and a carrier to develop a 150 μm thickness boiling enhancement paint on a 3.0 cm by 3.0 cm copper heating surface. The heating surface was covered by a thin glass plate with a 1 mm spacer to form a 1 mm vertical narrow space for the test section. The boiling phenomenon was recorded by a high speed camera. In addition to the three boiling regimes observed by Bonjour and Lallemand [1], i.e., isolated deformed bubbles, coalesced bubbles and partial dryout at low, moderate and high heat fluxes respectively in unconfined space, a suction and blowing process was observed at the highest heat flux condition. Owing to the space confinement, liquid was sucked and vapor was expelled periodically during the bubble generation process. This mechanism significantly enhanced the boiling heat transfer performance in confined space.

Computational Insights Into Air-Side Flow and Heat Transfer in Compact Heat Exchangers

2005 ◽  
Author(s):  
D. K. Tafti
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Heat Exchangers ◽  
Three Dimensional ◽  
Computer Experiments ◽  
Transfer Coefficients ◽  
Substantial Impact ◽  
Compact Heat Exchangers ◽  
Thermal Phenomena ◽  
Side Flow

The paper describes two- and three-dimensional computer simulations which are used to study fundamental flow and thermal phenomena in multilouvered fins used for air-side heat transfer enhancement in compact heat exchangers. Results pertaining to flow transition, thermal wake interference, and fintube junction effects are presented. It is shown that a Reynolds number based on flow path rather than louver pitch is more appropriate in defining the onset of transition, and characteristic frequencies in the louver bank scale better with a global length scale such as fin pitch than with louver pitch or thickness. With the aid of computer experiments, the effect of thermal wakes is quantified on the heat capacity of the fin as well as the heat transfer coefficient, and it is established that experiments which neglect accounting for thermal wakes can introduce large errors in the measurement of heat transfer coefficients. Further, it is shown that the geometry of the louver in the vicinity of the tube surface has a large effect on tube heat transfer and can have a substantial impact on the overall heat capacity.

scholarly journals Study on Forced-Convective Boiling Heat Transfer of Seawater with Sea Salt Deposition

2017 ◽  
Vol 31 (2) ◽  
pp. 162-170
Author(s):  
Shinichiro UESAWA ◽  
Yasuo KOIZUMI ◽  
Mitsuhiko SHIBATA ◽  
Taku NAGATAKE ◽  
Hiroyuki YOSHIDA
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Sea Salt ◽  
Convective Boiling ◽  
Salt Deposition ◽  
Sea Salt Deposition
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