Comparative exergy, multi-objective optimization, and extended environmental assessment of geothermal combined power and refrigeration systems
Abstract
In the present work a comparative exergy analysis, multi-objective optimization, as well as extended environmental analysis of a geothermal-based power and refrigeration system, is carried out. Different arrangements with the ammonia-water refrigeration cycle, organic Rankine cycle (ORC), and thermoelectric
generator (TEG) are investigated. The current work novelties are the presentation of a novel power-refrigeration system driven by a geothermal source and the employment of TEG units to recover geothermal
energy, besides extended environmental assessment. The results of sensitivity analysis indicate that the
highest net output work capacity is for the suggested system (configuration 3). Exergy analysis exhibits that
in all cases, the absorber has the highest exergy destruction rate and one of the lowest exergy efficiency
because it is the first component, which gains the heat from the geothermal source. The suggested system
produces 495.2 kW net output power and the highest energy efficiency of 19.42%, which are 131.7 kW, and
3.84% higher than configuration 1(base system). Optimization results represent that in the optimum point,
Wnet shows about 33.3% improvement compared with the un-optimized condition. It is found that configuration 3 which consists of cogeneration with two loops of ammonia-water power cycle with refrigeration system along with an additional thermoelectric generator for enhanced waste heat recovery has
the highest environmental footprints because of multiple components installed that would occupy more
space, electricity, materials, and other resources for its construction, operation, maintenance, and end-of life.
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