Experimental Investigation on Forced Convection Heat Transfer Augmentation Using Annular Blockages

Abstract

Abstract— Heat exchangers have several industrial and engineering applications. The design procedure of heat exchangers is quite

complicated, as it needs exact analysis of heat transfer rate and pressure drop estimations apart from issues such as long-term

performance and the economic aspect of the equipment. Whenever inserts are used for the heat transfer enhancement, along with the

increase in the heat transfer rate, the pressure drop also increases. This increase in pressure drop increases the pumping cost. Therefore

any augmentation device should optimize between the benefits due to the increased heat transfer coefficient and the higher cost

involved because of the increased frictional losses.

Experimental work on heat transfer augmentation using annular blockages. Inserts when placed in the path of the flow of the

fluid, create a high degree of turbulence resulting in an increase in the heat transfer rate and the pressure drop. The work includes the

determination of friction factor and heat transfer coefficient for various annular blockages and annular blockages having different

diameter. The results of annular blockages having different diameter have been compared with the values for the plain tube. Four

annular blockages (di=20%, 30%, 40% & 50% reduction in outer diameter) are used in the study.