The study of entropy generation during flow boiling in a micro-fin tube

• The variation of geometrical parameters of micro-fin tube on entropy generation is discussed.
• The effect of variation in flow conditions on entropy generation is studied.
• We study the effect of geometrical parameters and flow conditions on IDR and Bejan number.
• The comparison between entropy generation for the micro-fin tube and the smooth straight one is investigated.
• The study on entropy generation number for micro-fin tube and helically coiled one is presented.

Increasing in the heat transfer rate in flow boiling is a common and key issue for engineers. Generally, the heat transfer coefficient augmentation methods are divided into two main categories (active and passive methods). In passive methods the increase in heat transfer rate causes the increase in pressure drop. In order to evaluate the contribution of heat transfer and pressure drop mechanisms, the entropy generation analysis is used. In this paper, the entropy generation in micro-fin tube is investigated under flow boiling condition. The effect of different geometrical parameters and flow conditions is discussed on pressure drop contribution and heat transfer one in entropy generation, irreversibility distribution ratio (IDR) and Bejan number (Be). The frictional pressure drop and heat transfer coefficient in the micro-fin tube and the helically coiled one are compared as two enhancements passive heat transfer methods with the smooth straight tube in the literatures. Therefore, by introducing entropy generation number (Ns), the favorable geometry between the micro-fin tube and the helically coiled one with respect to the smooth straight tube is recognizable at equivalent boundary conditions.