A 3E evaluation on the interaction between environmental impacts and costs in a hydrogen liquefier combined with absorption refrigeration systems

Abstract

3E)exergy/exergoeconomic/exergoenvironmental) analysis is considered to evaluate a novel hydrogen liquefaction process. The proposed process is a simple Claude cycle combined with two absorption refrigeration systems (ARSs). The mass flow rate of the liquid hydrogen LH2 production is about 260 tones per day and the specific energy consumption (SEC) and the exergy efficiency of the system are12.7kWh/kgLH2 and 31.6% respectively. The results show that the HX-201 and HX-203 heat exchangers have the highest total environmental impact and total exergy cost. Therefore, they are in the priority of improving to achieve better performance for overall the process. In addition, the P-101 pump has the highest exergoeconomic and exergoenvairomental coefficient. Therefore, its capital investment cost and its environmental impact should be reduced to decrease the cost and environmental impact of the whole system. Furthermore, the HX-201 heat exchanger has the lowest exergoeconomic and exergoenvairomental coefficient. Therefore, the technical performance of this device should be improved to reduce the cost and environmental impact of the whole system. In addition, a 3D sensitivity analysis is investigated to consider simultaneously the interaction between technical, economic, and environmental aspects of the system. Accordingly, there is an optimum value for the isentropic efficiency of the C-1 compressor that should be examined, and the more/fewer is its pressure ratio, the more/fewer are its exergy costs and/or environmental impacts. Moreover, whilst an optimum pressure ratio should be found out for EXP-2 expander, a higher isentropic efficiency definitely decreases its exergy cost and environmental impact. In addition, the less/more is the temperature approach ΔTmin of HX-1 heat exchanger, the less/more are its exergy costs and/or its environmental impacts. As well as, its input pressure should be maximized to achieve minimum exergy costs and environmental impacts of the component. Finally, tower pressure should be raised as much as possible to achieve the least exergy costs and environmental impacts of the T-101 generator. However, its inlet temperature has an optimum value that should be found out.