A simplified LMTD approach to assess the effectiveness of a chevron-type plate heat exchanger

Abstract

Designing heat exchangers (HEXs) for a wide range of applications, involves a complex interplay of factors like cost, maintenance, material selection, pressure drop, fluid flow configuration, and heat transfer. Due to this complexity, empirical relationships are used performance evaluation, focusing on heat transfer rate (q), overall heat transfer coefficient \(\left( U \right)\), and effectiveness \(\left( \varepsilon \right)\). Testing is crucial to measure the outlet temperatures for specific inlet conditions and fluid flow characteristics. This paper introduces a simple and reliable iterative procedure for estimating cold (\(T_{\text{co}}\)) and hot (\(T_{\text{ho}}\)) fluid outlet temperatures in a Chevron plate heat exchanger (CPHE). This procedure relies on two basic equations of heat transfer rate (q), and logarithmic mean temperature difference (LMTD),\(\Delta T_{\text{lm}}\), incorporating specified inlet parameters. The proposed approach was validated by comparing its predictions to measured data. The method is general and adaptable to other HEX types. by properly defining the temperature differences in the LMTD and evaluating the HEX performance using relevant empirical relationships for the output responses with estimates of \(T_{\text{co}}\) and \(T_{\text{ho}}\) to the inlet parameters. The estimated and measured cold fluid outlet temperature (\(T_{\text{co}}\)) exhibited a relative error of 1.8 to 2.6%. Similarly, the hot fluid outlet temperature (\(T_{\text{ho}}\)) showed a relative error of 2.4 to 3.5%. This work provides valuable insights for designers, enabling them to assess HEX performance before conducting costly and time-consuming testing.