Experimental testing of the heat exchanger with star-shaped fins

Increase of the heat flow rate by applying finned surfaces is common in gas-liquid heat exchangers. Thereby, devices with annular fins are frequently used. Demands for higher capacity lead to size and mass increase of heat exchangers which over time becomes a significant problem, especially if the application of stainless steel is required. The solution to this problem is in a more efficient heat exchange on the gas side. This paper analyses the application of stainless steel star-shaped fins which increase the turbulence of fluid flow with their shape and in that way the heat exchange. For this purpose, two heat exchangers of identical size were made: one with annular fins and one with star-shaped fins. Both heat exchangers were experimentally tested with the same equipment and under identical conditions in the Reynolds number range from 2000 to 13,000. The test results indicate an increase in the heat flux by 39.3% when applying the star-shaped fins relative to annular fins, with the reduction of the heat exchanger mass by 23.8%. (C) 2019 Elsevier Ltd. All rights reserved.