Fabrication and testing of CONTISOL: A new receiver-reactor for day and night solar thermochemistry

The CONTISOL concept is a new vision of an integrated solar receiver/reactor for a variety of thermochemical processes. The concept includes a single monolithic solar absorber with two inter-mixed, but non-intersecting sets of gas channels. One set of channels is always used for a chemical process. During daytime operation, the other set of channels is used to heat air which is sent to thermal storage. During nighttime operation, the air flow is reversed, transferring heat from thermal storage to the monolith through the same set of channels, thus providing energy to continue chemical processing continuously through day and night. In this paper we introduce the general operation of the system and discuss its benefits applied to solar methane reforming as an example process. Past solar reactors which influenced the development of CONTISOL are discussed. A 5 kW scale demonstration prototype has been constructed at DLR and thermal experiments have been conducted using the DLR high flux solar simulator. A statistical design-of-experiments procedure has been applied to evaluate the influence of absorber temperature, gas flow rates, and gas inlet temperatures on heat transfer rates to gas streams, and to construct a thermal performance map of the device. The target gas outlet temperatures of over 850 °C were reached during these tests. Limitations on the initial design of the monolith are discussed including recommendations for future improvements.