Integrated heat pump options for heat upgrading in Cu-Cl cycle for hydrogen production

Abstract

The Copper Chlorine (Cu-Cl) hydrogen production cycle is a promising green method to meet the future demand for hydrogen. The Cu-Cl cycle has a number of endothermic reactions that take place at high temperature level. One of the highest temperature demanding components in the Cu-Cl cycle is the copper oxychloride decomposition reactor. This thesis proposes two potential methods to address this demand by using a cuprous chloride (CuCl) vapor compression heat pump cascaded with a mercury heat pump as a first option, and cascaded with a biphenyl heat pump as a second option. These cascaded heat pumps are meant to upgrade heat from nuclear power plants with a heat input of approximately 300⁰C or industrial waste heat to meet the copper oxychloride decomposition reactor demand. A comprehensive energetic, exergetic, and exergoeconomic assessment is made to understand the heat pump performance and costs. The CuCl-mercury heat pump had an overall energetic coefficient of performance of 1.93 and an exergetic performance of 1.25. Its total estimated cost is US$1,446,554 which is 62% higher than that estimated for its CuCl-biphenyl counterpart. Nevertheless, the CuCl-mercury heat pump has the lowest exergy destruction cost flow rate of 2,045 $/hour. The CuCl-biphenyl heat pump, on the other hand, also shows high coefficient of performance for certain operating conditions of compressors isentropic efficiencies, and excess CuCl feed temperature. Its base energetic and exergetic coefficient of performances are 1.76 and 1.15, respectively. Its estimated cost of $892,440 is lower than its CuCl-mercury counterpart. However, its overall exergy destruction cost flow rate was two times higher, 4,903 $/hour.