Entransy dissipation minimization for generalized heat exchange processes

Abstract

This paper investigates the MED (Minimum Entransy Dissipation) optimization of heat transfer processes with the generalized heat transfer law q ∝ (Δ(Tn))m. For the fixed amount of heat transfer, the optimal temperature paths for the MED are obtained. The results show that the strategy of the MED with generalized convective law q ∝ (ΔT)m is that the temperature difference keeps constant, which is in accordance with the famous temperature-difference-field uniformity principle, while the strategy of the MED with linear phenomenological law q ∝ Δ(T−1) is that the temperature ratio keeps constant. For special cases with Dulong-Petit law q ∝ (ΔT)1.25 and an imaginary complex law q ∝ (Δ(T4))1.25, numerical examples are provided and further compared with the strategies of the MEG (Minimum Entropy Generation), CHF (Constant Heat Flux) and CRT (Constant Reservoir Temperature) operations. Besides, influences of the change of the heat transfer amount on the optimization results with various heat resistance models are discussed in detail.