Exergy Transfer Criteria on Enhanced Heat Transfer Performance Evaluation

Abstract

Based on the exergy transfer performance analysis of forced convective heat transfer through a tube with constant heat flux/ constant wall temperature for thermally and hydrodynamic fully developed turbulent flow, extended performance evaluation criteria for enhanced heat transfer surfaces based on the exergy transfer theorem have been developed. An exergy transfer performance evaluation criterion ΔNue or ΔE, which is defined as the difference of exergy-transfer Nusselt number or exergy transfer rate before and after enhanced heat transfer, is put forward. By reference to spirally grooved tube, the effect of Reynolds number, structure parameters of tube, dimensionless wall temperature difference and heat flux on the exergy transfer process is discussed. The results show that the exergy transfer performance of enhanced heat transfer with constant wall temperature is quite different from that with constant wall heat flux. An effective approach for exergy transfer performance evaluation and the optimal process parameters and configuration choice of enhanced heat transfer tube are provided.