Experimental Investigation on the Effect of Dimple-Protrusion Surfaces in a Counter Flow Heat Exchanger

APEX Group is proud to congratulate Sakina Tinwala for her successful graduation 'honored with cum laude' at the Technical University of Delft. Sakina has written her master thesis in collaboration with our R&D Engineers and also while doing the experiments in APEX Group’s Laboratory. After graduation, we welcomed her to be part of our permanent R&D Department.

Flat plate heat exchangers are widely used in industrial and domestic applications. Industrial plate type heat exchangers generally operate in the turbulent flow regime. Although, increase in flow speeds leads to higher transport of heat, it also causes a rise in the pressure loss which is undesirable. Therefore, to combat the problem of high pressure drop, this thesis explores the use of a passive enhancement technique to improve heat transfer. The aim of this thesis is to experimentally investigate the effect of dimple-protrusion surfaces in a counter flow type heat exchanger. The flow behaviour is studied using Laser Doppler Anemometry and the local heat transfer characteristics are investigated with the help of Infrared thermography. The average Nusselt number and friction factor data is compared with those of a flat plate and it is found that the use of dimple-protrusion surfaces provide maximum improvement in the performance of the heat exchanger by 21% in the laminar-to-turbulent transition regime, at Reynolds number ≈ 2900.