Heat transfer - A review of 2001 literature

The advent of high-power electronic system components and slim margin errors require the proper understanding of particle deposition characteristics and its effects on the thermal performance of electronic heat sinks of electronic devices. In this work, we investigate the effects of particle deposition on the thermal performance of convective-radiative porous fin heat sink of an electronic component using Chebyshev spectral collocation method. The numerical solutions from the developed thermal models are also used to study the influence of thermal conductivity, porosity, convection, and radiation parameter on the temperature distribution and overall fin efficiency. The analysis establishes that presence of particles or thermal fouling on the surface of the fin increases the temperature distribution and temperature uniformity of the fin whilst decreasing the heat transfer rate from the fin. The study also establishes that decrease in heat transfer rate from the fin is due to the particle deposition on the fin, which depends on the particle size, particle density and cooling air flow rate. Moreover, the fin efficiency decreases with an increasing value of the fouled Biot, Darcy and radiation numbers, and thermo-geometric parameter. The study further shows that the efficiency of the fouled porous fin is always greater than the efficiency of the clean porous fin. The analysis established that the result of Chebyshev spectral collocation method is in good agreement with that of the convectional numerical method using Runge-Kutta coupled with shooting method.

Effects of particles deposition on thermal performance of a convective-radiative heat sink porous fin of an electronic component

This work presents an investigation on the effect of particle deposition and adhesion on the thermal behaviour of convective-radiative porous fin heat sink using Differential Transform method (DTM). The numerical solutions of the developed thermal models are also used to study the influence of thermal conductivity, porosity, convection and radiation factors on the thermal distribution and efficiency of the fin. The analysis reveals the impact of particles or thermal fouling on the surface of the fin, which causes a rise in the temperature uniformity and distribution in the fin while reducing the rate of heat transfer from the fin. Moreover, the study also establishes that the heat transfer rate decreases due to particle deposition on the fin which depends on the particle size, particle density and cooling air flow rate. The fin efficiency decreases with increasing value of the fouled Biot, Darcy and radiation numbers, and thermo-geometric parameter. Furthermore, the analysis shows that the efficiency of the fouled porous fin is always greater than the efficiency of the clean porous fin. The result of this study shows an excellent agreement with the established results of Runge-Kutta with shooting method.

Performance of convective-radiative porous fin heat sink under the influence of particle deposition and adhesion for thermal enhancement of electronic components

Fouling from cooling tower water is a serious problem in both power and refrigeration industries. The effect of fouling on enhanced tubes could be worse than that on smooth tubes because fouling may degrade the superior heat transfer performance by filling the gaps between the roughness elements with foulant. Condensers that use cooling tower water usually experience four different fouling mechanisms: corrosion, scaling, particulate, and biological fouling. Corrosion is prevented with chemical inhibitors, which pacify the piping and protect the metal surfaces. Cooling tower water can also be treated with biocide to prevent biological fouling. Therefore, the current paper addresses scaling and particulate fouling. The paper also establishes a database of water quality based on chemical analysis of samples collected from cooling towers across the country. The objective of the database is to determine water qualities that are typical of those found in actual cooling towers. From chemical analysis, th...

A survey of cooling tower water quality for condenser tube fouling potential

Effects of particle fouling and magnetic field on porous fin for improved cooling of consumer electronics

The time dependent performance of extended surfaces subjected to fouling is addressed in this work. Where fins are used for augmenting boiling heat transfer, the interaction of local values of temperature excess, fouling resistance and surface characteristics of the deposit can be quite complex. Taking typical asymptotic fouling growth parameters from literature for reverse solubility salts, three kinds of fin geometry are analysed – rectangular, triangular and annular. For various values of the fin parameter mL, the temperature distribution and variation of fouling resistance are obtained as a function of time. To interpret the performance of a fouled fin, a new term `cleanliness efficiency' is introduced. The necessity of choosing an optimal value of mL for the fin is also highlighted here. It is shown that for all three fin configurations, cleanliness efficiency differs little, thus simplifying the geometry dependence. The approach set out in this work will help in the design of finned heat exchangers subjected to fouling and thereby minimise their overdesign.

H. S. Aparajith

Papers

Performance analysis of extended surfaces subjected to fouling