Enhanced of fluids mixing and heat transfer in a novel SSK static mixer Organic Rankine Cycle direct contact heat exchanger

Abstract

In this study, new gas-liquid-liquid three phase direct contact heat exchangers based on SSK mixing elements and annular ribs are proposed to improve the thermal efficiency of the Organic Rankine Cycle. Three types of heat exchangers, including hollow tube heat exchanger, SSK heat exchanger and SSK annular rib combined heat exchanger, are established to compare their heat transfer performance. The heat transfer performance, turbulence intensity, turbulence kinetic energy and pressure drop of three heat exchangers are numerically investigated. The results show that the volumetric heat transfer coefficient, outlet temperature of gaseous working medium, turbulence intensity and turbulent kinetic energy of the combined heat exchanger are significantly higher than those of the SSK heat exchanger and the hollow tube heat exchanger. In addition, the pressure drops of the SSK heat exchanger and the combined heat exchanger are basically the same, which are slightly larger than the pressure drop of the empty tube heat exchanger. In summary, the combined heat exchanger has improved heat transfer performance without causing excessive pressure drop.