Sodium heat pipe use in solar Stirling power conversion systems

Sodium heat pipes were selected for use as a thermal transport method in a focus-mounted, distributed concentrator solar Stirling power conversion system intended to produce 15-20 kWe per unit. Heat pipes were used both to receive thermal power in the solar receiver and to transmit it to a secondary heat pipe containing both latent heat salt (for up to 1.25 hours of thermal storage) and the heat exchanger of the Stirling engine. Experimental tests were performed on five solar receiver heat pipes with various internal wicking configurations. The performance of the heat pipes at various power levels and operating attitudes was investigated at temperatures near 1550 F; the unidirectional heat transfer in these heat pipes was demonstrated in normal operating attitudes and particularly in the inverted position required during overnight stowage of the concentrator.