Modified cost analysis integrated with dual parametric sensitivity study for realistic cost assessment of a novel modified geothermal-based multi-generation energy system
Amirhamzeh Farajollahi, Mohsen Rostami, Milad Feili, Hadi Ghaebi, Mohammad Reza Salimi
Abstract
In this investigation, an innovative modification process has been employed to enhance the capability of a novel multi-generation energy system (MGS) utilizing a dual-flash binary geothermal cycle incorporated with two main subsystems. These subsystems include a novel cooling, heat, and power (CCHP) unit by an ejector-based cooling cycle (ERC) joint to an organic Rankine power cycle (ORC) and a hydrogen generation setup via a low-temperature electrolyzer. In addition, a binary mixture consisting of Pentane and R142b has been utilized for the CCHP subsystem as a working fluid. Nonetheless, to assess the actual operating cost of investigated system, the exergetic and energy level-based exergoeconomic (modified exergoeconomic) analysis has been implemented instead of using conventional exergoeconomic analysis; afterward, due to the conflicting trend between design and performance parameters, dual parametric sensitivity study and double-objective optimization using NSGA-II approach have been carried out. According to the outcomes of dual parametric study, the results are further sensitive to the simultaneous variation in second flash tank inlet pressure and vapor generator temperature. Optimization results indicate that the net electricity production has increased from 33.04 kW to 40.59 kW, which improves the exergetic efficiency of the system by 4.39 %. Also, in this case, the total unit product cost has ameliorated by 3.4% and 2.62% in terms of modified and conventional cost approaches. The best representative optimal solution has the optimal energetic efficiency, exergetic efficiency, and unit product cost of 38.35%, 43.50%, and 52.52 $/GJ, respectively.