Performance evaluation of a solar based Brayton cycle integrated vapor compression-absorption trigeneration system for power, heating and low temperature cooling

Abstract

Among the various solar technologies, solar power tower (SPT) technology is being widely used for large-scale energy generation. Therefore, this work developed a trigeneration system for SPT plant that produces power, heating and cooling at low temperature efficiently from a high temperature SPT heat source. In order to create heating and low temperature (at −20°C) cooling benefits for food preservation, this trigeneration unit integrates a cascaded vapor compression-absorption refrigeration system combined with a helium Brayton cycle for power generation. The exergy-energy analysis was performed by the numerical technique using engineering equation solver software to evaluate the performance of the proposed SPT plant. The power output, exergy and energy efficiency of the SPT plant were found as 14,865 kW, 39.53% and 28.82%, respectively. The coefficient of performances values for cooling and heating were observed as 0.5391 and 1.539, respectively. Exergy evaluation revealed that approximately 78.18% of the total energy destruction of the entire plant is attributed to the solar subsystem only. Furthermore, a parametric investigation shows that the temperature of the evaporator, generator and helium turbine inlet, and the efficiency of the heliostat and receiver all have a significant impact on the plant performance. Furthermore, a comparative analysis with relevant previous studies has shown that the proposed system outperforms systems based on supercritical CO2 cycles and the Rankine cycles.