Development of novel hydrogen liquefaction structures based on waste heat recovery in diffusion-absorption refrigeration and power generation units

Abstract

One of the main problems of hydrogen storage by the liquefaction method is the high specific power consumption. Waste heat recovery from different industries can be used to reduce the power consumption of hydrogen liquefaction cycles. In this paper, industrial waste heat is applied for two distinct purposes: to generate refrigeration using the diffusion-absorption refrigeration cycle (the first scenario), and to produce electricity with the support of the organic Rankine cycle (the second scenario). The diffusion-absorption refrigeration integrated structure generates 0.5786 kg/s liquid hydrogen. Two new integrated scenarios have been compared regarding energy, exergy, and economic analyses to use waste heat. The specific power consumption in the first and second scenarios are 4.320 and 4.359 kWh/kgLH2, respectively. The results of the exergy analysis show that the exergy efficiency of the first and second structures are 53.35 and 50.82 %, respectively. Economic analysis of integrated structures developed based on the annualized cost of system method shows that the annualized cost of the product in the first and second systems are calculated at 88.53 MMUS$/year and 82.68 MMUS$/year, respectively. Also, the prime cost of the product in the first and second processes are computed at 4.401 US$/kgLH2 and 4.320 US$/kgLH2, respectively. The findings indicate that utilizing wasted heat for refrigeration production, as opposed to electricity generation in the liquid hydrogen pre-cooling system, is a thermodynamically preferable choice, but it may not be economically viable. The sensitivity analysis of the integrated diffusion-absorption refrigeration structure shows that the payback period and prime cost of liquid hydrogen decrease to 5.041 years and 4.115 US$/kgLH2, respectively when the price of electricity decreases from 0.400 to 0.040 US$/kWh. The payback period and levelized cost of liquid hydrogen decrease to 2.886 years and 4.295 US$/kgLH2, respectively with a reduction in capital cost from 374.4 to 93.60 MMUS$. © 2024 Elsevier Ltd