Dynamic simulation of a solar ejector-based trigeneration system using TRNSYS-EES co-simulator

In this paper, a new configuration of a solar combined cooling, heating, and power (CCHP) system is proposed to recover the waste thermal energy of a steam power plant, which provides the cooling and heating needs of an apartment complex located in Tehran. The required energy of the system is supplied by the parabolic trough solar collectors (PTCs) and, if necessary, an auxiliary heater is also used. An ejector refrigeration cycle (ERC) and a steam Rankine cycle are used for cooling and power generation, respectively. The cycle is dynamically modeled over a year using a TRNSYS-EES co-simulator. It is found that the highest Rankine cycle efficiency is obtained in the cold months (January) because of the decrease of turbine backpressure. With increasing the turbine inlet temperature from 190 to 210 degrees C, the Rankine cycle and the overall cycle efficiencies increased about 1% and 2%, respectively. The maximum cooling, heating, and power generation, as well as the maximum solar fraction, are obtained at the turbine inlet temperatures of 210 degrees C, which are 185.46, 598.65, 680.49 kW, and 70%, respectively. The annual overall performance and the solar fraction of the proposed CCHP system are 32.5% and 9.5%, respectively, based on 3000 m(2) collector aperture area. The exergy analysis indicated that the maximum annual exergy destruction is related to the solar collectors, which have comprised 27% of the total exergy destruction. In addition, the yearly exergy efficiency of the proposed system is 39.9%.

Automated summary

This paper proposed a new configuration of a solar combined cooling, heating, and power (CCHP) system to recover waste thermal energy, with the highest efficiency found in cold months and performance improvements with increased turbine inlet temperature. Exergy analysis showed that solar collectors accounted for the highest annual exergy destruction, while the overall system's exergy efficiency was 39.9%.