New non-iterative method for computation of tubular cross-flow heat exchangers

Abstract

A novel semi-analytical method was proposed for the performance and design computation of the tubular heat exchangers with cross and mixed flows of fluids. The heat exchanger is segmented into small elements (finite volumes). Closed analytical relationships express the fluid temperatures at the outlets of the finite volumes. Calculations of two heat exchangers, a steam superheater and a car cooler, are presented to illustrate the effectiveness of the developed method. Exact formulas for calculating the temperature of steam and flue gas in the superheater and of water and air in the automotive radiator are derived to evaluate the accuracy of the proposed method. The results obtained by the proposed method were found to be in perfect agreement with the results obtained by exact formulas and experimental results. Temperature-dependent physical properties of fluids can also be easily considered. The method presented in this paper is also competitive in terms of computation time due to the elimination of iterations when determining the fluid temperatures. When the one-pass of the superheater under analysis is divided into 20 control volumes, the computing time on a personal computer for temperature-dependent heat capacities of the steam and flue gas is less than 0.5 s.