Abstract: Based on the second law of thermodynamics and pinch theory, a new parameter named effective heat transfer factor (EHTF) is introduced to evaluate the performance of heat transfer processes. By using such a parameter for process optimization of a heat storage system, it is found that the EHTF is a much better indicator for heat transfer assessment as it considers not only state parameters but also processes.

Key words: pinch point theory, heat exchange network, systematic optimization