A doctoral thesis at the College of Engineering at the University of Basrah discussing (studying the performance of cooling systems with microwave channels using channels of variable cross-section and different arrangements of channels and the direction of fluid flow)

The thesis presented by the student Sahib Shehab Ahmed. The heat sink of radial micro-channels was studied numerically. A number of factors were investigated. These factors represent the criteria that deal with the most suitable configuration and design. These factors are velocity, heat sink surface temperature, fluid temperature, thermal resistance, pressure drop, Nusselt number, performance index distributions, and heat transfer optimization performance. Two flow arrangements, outflow and inward flow direction. The effect of changing the wall thickness between the channels and the wall thickness between the layers on the thermal performance was studied. Four materials - copper, aluminum, iron and silicon were studied. 

This thesis aims to study the performance of refrigeration systems with micro-channels when using channels of variable cross-section

The thesis concluded the implementation of a comparison between radial and micro-channel heat sinks in the current thesis to show the most useful heat sink by using channels of similar size. This indicates an excellent agreement with these studies