Investigating the Economical Performance of Four Suggested Designs for the Heat Exchangers

Abstract

It is required to investigate the economy of the performance of four suggested heat exchanger designs. The economy criteria are expressed by the ratio of the Nusselt number, Nu, and the pressure loss coefficient, ΔP∗. The four patterns are; rectangular, zigzag, spiral, and narrow-spiral. The air passages of each one of the four types have the same cross-section area and air passage length. Also, the inlet air temperature and flow rate for both; the air and water are the same in the four types. The narrow-spiral pattern has an equal passage thickness for both air and water. Reynolds number, Re, of values; 2535, 7606, 12677, 17748, 20284, 22819, 25355, (based on the hydraulic diameter of the cross-section) are investigated. For validation, the rectangular pattern type was checked experimentally, and the results were close to those of the prediction. For all values of the Reynolds number, the suggested narrow-spiral pattern exhibited the highest values of Nu/ΔP∗. At the Reynolds number of 25355, the ratio, Nu/ΔP∗ could achieve a value of about 15.74 for the narrow-spiral type. For each suggested pattern, (Nu/ΔP∗) and Re are correlated in a suitable formula.