Using organic fluids in natural circulation loop systems for absorbing of heat from low temperature renewable energy sources

Abstract

The main objective of this paper is to investigate the usage of organic fluids as the working fluid in the two-phase natural circulation system. Also, this paper discusses the effects of fluid material properties on the performance of the system. For this purpose, five working fluids are selected, include water, R113, R11, Cyclohexane, and R245fa. The mathematical simulation of the system is done by applying a two-phase flow model. The mass flow rate of the two-phase natural circulation for five working fluids are shown in different heating power and sub-cooling conditions. To analyze the transient state behavior of the two-phase natural circulation loop, the stability maps of the system for five working fluids are sketched. According to obtained results, using organic fluids instead of ordinary water can increase both the stability and capability of removal heat. Furthermore, the second law of thermodynamic is applied to calculate the amount of entropy generation, and consequently to study the thermal-hydraulic performance of the different working fluid used in the loop.