Transport efficiency of thermal energy - A new performance evaluation criteria of heat transfer enhancement

Based on the unavailable heat consumed in heat transfer process, a new physical quantity defined as transport efficiency of thermal energy was presented. Then, the approach of minimum heat consumption was applied to optimize the laminar and turbulent convective heat transfer of air in the circular tube. Furthermore, the transport efficiency was calculated and compared in these cases. It can be found that the transport efficiencies of optimized circular tubes are much higher than the pure tubes for the convective heat transfer in the tube, so is the Nu number. Therefore, the transport efficiency of thermal energy is a good criteria to evaluate the heat transfer enhancement in the tube.