Strategic integration of single flash geothermal steam cycle (SFGSC) and ejector assisted dual-evaporator organic flash refrigeration cycle (EADEOFRC) for power and multi-temperature cooling: 2nd law performance study

In the present study, an ejector-assisted dual-evaporator organic flash refrigeration cycle (EADEOFRC) is integrated with a single flash geothermal steam cycle (SFGSC). The EADEOFRC also consists of a two-phase expander extracting power from the high pressure fluid before the flashing. Isopentane and n-pentane are used as the working fluid of the EADEOFRC. It is observed that EADEOFRC can be operated at an organic fluid flash pressure corresponding to which refrigeration effects of both evaporators are equal. Corresponding to this operating condition of EADEOFRC, the integrated cycle yields higher second law efficiency compared to that of the SFSC. However, this yielded second law efficiency is lower than that of the dual flash steam cycle (DFSC). In the absence of the flash chamber, the ejectors and the evaporators, the EADEOFRC becomes merely a trilateral cycle (TLC), yielding only power output. Integration of SFSC and TLC yield substantially higher second law efficiency compared to that of the DFSC. Performance of the combined cycle slightly improves if n-pentane is used as the working fluid instead of isopentane.

Automated summary

In this study, an ejector-assisted dual-evaporator organic flash refrigeration cycle is integrated with a single flash geothermal steam cycle. The integrated cycle shows higher second law efficiency compared to the single flash geothermal steam cycle, but lower than a dual flash steam cycle. When components are removed, the organic flash refrigeration cycle only produces power output, while the integrated single flash geothermal steam cycle and organic flash refrigeration cycle yield higher efficiency than the dual flash steam cycle. Using n-pentane as the working fluid instead of isopentane slightly improves the performance of the combined cycle.