Investigation of heat transfer in rectangular microchannels

Abstract

An experimental investigation was conducted to explore the validity of classical correlations based on conventional-sized channels for predicting the thermal behavior in single-phase flow through rectangular microchannels. The microchannels considered ranged in width from 194 m to 534 m, with the channel depth being nominally five times the width in each case. Each test piece was made of copper and contained ten microchannels in parallel. The experiments were conducted with deionized water, with the Reynolds number ranging from approximately 300 to 3500. Numerical predictions obtained based on a classical, continuum approach were found to be in good agreement with the experimental data (showing an average deviation of 5 percent), suggesting that a conventional analysis approach can be employed in predicting heat transfer behavior in microchannels of the dimensions considered in this study. However, the entrance and boundary conditions imposed in the experiment need to be carefully matched in the predictive approaches.

Theoretical and Experimental Investigation of Heat Transfer Characteristics through a Rectangular Microchannel Heat Sink

“…From graph 5.1, it is observed that for higher flow rates experimental value is closer to the theoretical results and compared with the graph of P. S. Lee et al [5] which is draw by using correlation given in journal paper. The heat transfer losses to the surrounding atmosphere due to radiation and conduction losses through acrylic are not taken into account for calculation of the theoretical heat transfer coefficient.…”

“…Hence, there is deviation observed between theoretical and experimental value. From graph 5.3, it is observed that thermal resistance deceased with the increase in Reynolds number for experimental, theoretical and P. S. Lee et al [5] graph which is drawn by correlation given in journal paper, also experimental value is more than that of theoretical. This is happen due to heat supplied to the microchannel increases and temperature difference of water between inlet and outlet of microchannel is decreased, hence according to Fourier law of conduction and Newton's law of cooling the thermal resistance is decreased as Reynolds number increases.…”

“…This is happen due to heat supplied to the microchannel increases and temperature difference of water between inlet and outlet of microchannel is decreased, hence according to Fourier law of conduction and Newton's law of cooling the thermal resistance is decreased as Reynolds number increases. From graph 5.4, it is observed that friction factor deceased with the increase in Reynolds number, this was compared with a P. S. Lee et al [5] journal, It's happened because of thin boundary layer developed at microchannel surface is increases and also time spend by water in microchannel is decreases as Reynolds number increases. Due to layer of water, the friction which is occurred at low Reynolds number is high as compared with high Reynolds number.…”

“…Flow boiling is superior to single-phase liquid cooling from two main considerations-namely a high heat-transfer coefficient during flow boiling and higher heat removal capability for a given mass-flow rate of the coolant. Poh-Seng Lee et al [5] discuss experimental results of rectangular microchannel, consider a microchannels width from 194 µm to 534 µm, with the channel depth being nominally five times the width in each case. Each test piece was made of copper and contained ten microchannels in parallel.…”

“…Therefore, heat sinks with larger extended surfaces, highly conductive materials and more coolant flow are key parameters to reduce the base temperature [4]. For intermediate heat fluxes, single-phase cooling offers an alternative that is simpler to implement and thus preferable [5].…”