Two-dimensional calculation of the heat exchanger taking into account pressure losses and changes in the density of air and gas

Abstract

The article describes an engineering method for calculating an annular cross-flow heat exchanger in a two-dimensional formulation, taking into account the compressibility of the heated air and the cooled gas. The calculation formulas are derived on the basis of the equations of state and continuity in relation to air and gas, the equations of thermal balance, as well as expressions for hydraulic losses. The calculation according to the formulas is carried out in successive iterations, as a result of which the final air and gas temperatures, pressure losses and efficiency of the heat exchanger are found. The rapid convergence of the calculation allows for 2-3 iterations to determine the main – linear – part of the distribution of air and gas parameters in the cross section of the heat exchanger. If necessary, an increase in accuracy is achieved by increasing the number of iterations.