Entropy generation analysis in an evaporative air-cooled heat exchanger

Abstract

In the present study, air-side entropy generation rate for an evaporative air-cooled heat exchanger has been investigated using thermodynamic second-law analysis. For this purpose, entropy generations due to heat transfer, friction loss and evaporation were taken into consideration. From the results of this study, it was observed that the total air-side entropy generation was increased by increasing the air-side Reynolds number. Actually, increasing of air mass flow rate, increases irreversibilities due to both evaporation and friction. Stepping up of ambient temperature leads to increasing of irreversibility due to water evaporation. The results showed when the ambient temperature approaches to inlet process fluid temperature, the contribution of the entropy generation rate due to water evaporation becomes the dominant term in the total entropy generation rate. Moreover, it was seen that the effect of deluge water mass flow rate changes on entropy generation rate is slight.

Keywords

• thermodynamic analysis
• entropy generation
• second law
• evaporative
• air cooled heat exchanger
• deluge water