Thermal process simulation and multi-variable study/optimization of a novel geothermal-driven multi-generation process using bi-evaporator with zeotropic mixture

Bi-evaporator technology is a robust tool, operating in two levels of coolant production for normal cooling and freezing purposes. The current study is motivated to assess the feasibility of integrating a bi-evaporator technology and a single-flash geothermal power plant. The main novelty of this paper is to design a novel combined cooling and power (CCP) production cycle relying on an organic Rankin cycle and a modified bi-evaporator refrigeration cycle. In addition, the use of a zeotropic mixture (Pentane/Isobutane) fed to the CCP is another difference between the current research and the available literature review. In addition to the power and cooling, the entire system is boosted by the use of a multi-generation process, producing heating via a heating production unit and hydrogen (H2) via a low-temperature electrolyzer. The proposed system was analyzed from the energy, exergy, specific exergy costing, and net present value points of view. Therefore, a coherent single- and dual-sensitivity study is done, and the variability of the main performance metrics is viewed against the decision parameters. In addition, owing to the incompatible trend of the newly devised plant's chief performance metrics, an advanced tripleobjective optimization through a NSGA-II method is regraded from the standpoints of thermodynamics and economics. The objective functions include the coefficient of performance, exergy efficiency, and sum unit cost of products, and the optimum solution reveals their values of 33.56%, 63.2%, and 6.0 $/GJ, respectively.

Automated summary

The feasibility of integrating bi-evaporator technology and a single-flash geothermal power plant is assessed in this study. A novel combined cooling and power (CCP) production cycle is designed using organic Rankin cycle and modified bi-evaporator refrigeration cycle. The use of a zeotropic mixture (Pentane/Isobutane) in the CCP is another difference from previous research. The proposed system is analyzed from energy, exergy, specific exergy costing, and net present value perspectives, and an advanced triple-objective optimization is conducted.