Experimental investigation on effect of random packing with uniform sized spheres inside concentric tube heat exchangers on heat transfer coefficient and using water as working medium

Concentric tube heat exchangers are used extensively by the energy industry. In the present study, the behavior of overall heat transfer coefficient with randomized packing of uniformly sized spheres inside the concentric tube heat exchangers is investigated at the laboratory scale. In this work, the heat transfer coefficient on the tube side is calculated using the experimental measured hot and cold fluid temperature differences, mass flow rates of hot and cold fluid. The correlations of are used to calculate the convective heat transfer coefficient (ho) on the annular side and tube side of the concentric tubes packed with uniform sized spheres. However, the logarithmic mean temperature difference is the assumption made for the temperature difference across the packed bed. The calculated overall heat transfer coefficient using correlation and experimental measured one are in very good agreement for a given heat load. The reduction in length in comparison to heat exchangers without packing is found to be ∼95%. A packed bed heat exchanger design methodology is presented.