Based on the experience gained with Loop Heat Pipes (LHP) for space, the objective is to adapt and extend the design (different working fluids, different container materials, etc.) of such devices for integration/application/use in solar-dynamic energy conversion processes for terrestrial energy conversion. The know-how and experience in high-temperature two-phase technology (LHP) gained from this proposed actvity for a terrestrial application, could be of interest in the space domain for e.g. leading edge cooling of entry/re-entry vehicles or for future deep-space missions where electrical energy will be generated via a thermodynamic process using a nuclear energy source.

The use of Solar energy applying conversion processes based on higher temperatures (use of solar concentrators) and thermodynamic cycles (e.g. Stirling cycle) can provide high conversion efficiencies. For such process high temperature loop heat pipes (LHP) can provide efficient means to transport the heat from the solar concentrator to the thermodynamic cycle (e.g. Stirling engine). Unlike currently used heat pipes, LHPs exhibit much less ground operation constraints and hence the use of such high temperature LHPs could also provide advantages for the integration and operation of such systems: (1) the Stirling engine can be placed on the ground next to the solar receiver (and does not have to be part of the dish design);(2) in addition, it will be possible to integrate a thermal storage system, which could allow a 24 operation, increasing the overall efficiency and at the same time avoiding a daily start-up and shut-down of the overall system. Such high temperature LHP - using high temperature working fluids (possibly liquid metals) - will need to be developed, manufactured and extensively tested. Major challenges are material compatibility, handling of high temperature working fluids, LHP start-up, etc.Based on the experience with LHP's for space applications (at lower temperatures) combined with existing knowledge on high temperature heat pipes (used in the past for terrestrial applications), the proposed activity shall start with a critical review and completion of the requirements, followed by an extensive trade-off (covering different concepts and aspects like materials, working fluids, long-term behaviour, etc.). A breadboard shall then be designed and manufactured and submitted to a complete test programme.