Solar Upgrading of Methanol: Driven Combined Cycle Using Middle Temperature Solar Collectors

Abstract

In this paper, we have proposed a novel solar–driven combined cycle with solar upgrading of methanol in middle temperature solar collectors, and investigated the effects of integration of solar thermal energy and methanol decomposition on the performance of the proposed cycle. The process of solar upgrading methanol is a catalytically endothermic decomposition reaction and proceeds in a range of 130–250° C. As a result, the proposed cycle has a breakthrough performance, with net solar–to–electric efficiency of 32.93% at the collector temperature of 220° C, and the turbine inlet temperature of 1062° C, superior to that of the present advanced cycle (REFOS of 20%). The exergy loss in indirect combustion of methanol proposed here is 7.5 percent points lower than that of the direct combustion. The optimum pressure ratio for thermal efficiency is approximately equal to 14. A key point emphasized here is that the proposed new cycle can utilize middle–temperature solar collector with lower cost. The promising results obtained here indicated that this novel solar–driven combined cycle could make a breakthrough in field of solar thermal power generation through integration of solar thermal energy and effective use of synthetic clean fuel.