Explicit Calculation Method for Heat Exchanger Considering Variable Physical Property Treatment

This work presents a heat exchanger calculation method characterized by the explicit temperature solution (ETS) for the working medium. This method is derived for both parallel-flow and counter-flow patterns based on the traditional LMTD method. As the temperature distribution is given in an explicit form related to the mixing temperature, the heat transfer performance of heat exchangers can be solved without iterations, improving the efficiency of heat exchanger design. Considering the practical engineering application, the influence of variable physical property is discussed. The temperature distributions of the reference temperature method and the integral method (whole length) are compared with the accurate distribution of the adaptive-grid method (segmented). Results indicate that the temperature distribution obtained by the integral method highly coincides with the accurate one, showing a relative error of only 0.36 %. The proposed ETS method with integral physical property treatment is an efficient and accurate way for heat exchanger design.