Techno-economic analysis of a concentrating solar collector with built-in shell and tube latent heat thermal energy storage

Abstract

In this paper, the feasibility of a medium temperature, low profile concentrated solar thermal collector integrated with latent heat thermal energy storage (LHTES) is investigated. The proposed modular integrated collector storage (ICS) system consists of six solar receiver units and seven cylindrical shell and tube LHTES tanks. By implementing an innovative optical concentration assembly and an internal linear tracking mechanism, the collector can concentrate beam radiation to the tube receivers during the highest flux hours of a day without any external or rotational motion. The collector's efficiency correlations were obtained experimentally and its integrated performance – with the LHTES units – was evaluated numerically.To demonstrate the potential of this proposed ICS system, an annual analysis was carried out for a characteristic industrial application – a dairy dehydration process that requires a constant 50 kWth of heat in the 120–150 °C temperature range. It was found that adding the storage units will increase the capital costs by ∼10%, but it can increase the annual thermal output of the system by up to ∼20%. A solar fraction of 65% was achievable with some design alternatives, but the optimum techno-economic design had a solar fraction of ∼35% and an annual charging efficiency of nearly 100%. It was also found that if the capital cost of the ICS (collector and LHTES tank) system could be reduced by 50% from an estimated ∼1000 US$/m2 to ∼500 US$/m2 through mass production and/or further design optimizations, this system could provide industrial process heat with a levelized cost of heating (LCOH) of ∼0.065 US$/kWhth.