A performance analysis of vertical steam generator using an entropy generation method

Abstract

In this study, an entropy generation analysis is presented for a shell and tube steam generator. A two-phase model of secondary fluid in the shell side and also a single-phase model of primary fluid in the tube side were derived to calculate thermal hydraulic operational parameters of the system. To reduce the level of entropy generation and consequently to increase the thermal performance of the steam generator system, an entropy generation number was proposed to investigate the irreversibilities occurring due to the heat transfer, pressure drop and mixing effects. The influence of different operational parameters and geometrical constrains such as the inlet temperature and the mass flow rates, the tube diameters ratio, the number of tubes and the length to the diameter ratio on the entropy production were studied. Also, the behavior of heat exchanger design variables such as the effectiveness, versus the mentioned parameters were presented. It was demonstrated that an increase in the magnitude of the tube diameters ratio and the length to the diameter ratio led to a decrease in the entropy generation number. Accordingly, a decrease in the entropy generation number may well result in a higher steam generator performance and thus a higher economical efficiency.