The Development of an sCO2 Test Facility for Particle-to-sCO2 Heat Exchanger Performance Evaluation

This paper describes the development of a supercritical carbon dioxide test facility to mimic the primary heat exchanger inlet operation conditions of a recompression sCO2 Brayton cycle. The experimental facility is used to test and evaluate the heat transfer performance of a particle-to-sCO2 heat exchanger for concentrated solar power applications. The sCO2 flow loop is comprised of five main components: a positive displacement gear pump, piston accumulator, sCO2 preheater, experimental test section, and sCO2 post cooler. The test facility is instrumented with measurement devices to quantify the heat and mass flows within the system. The loop operates at isobaric conditions up to 20 MPa and is split into a hot and cold side. On the cold side, the sCO2 is cooled below room temperature by the post cooler, increasing the density of the sCO2 high enough such that it can be circulated using the gear pump. The 10.8 kW preheater delivers sCO2 to the test section at temperatures up to 600°C at flow rates up to 0.013 kg s-1. Within the test section the sCO2 is further heated by inert CARBO HSP 40/70 particles. The development of the novel particle-to-sCO2 heat exchanger is also reported in this work. The heat exchanger was tested at dilute and dense flow conditions in the particle domain. The heat transfer performance and particle-to-sCO2 recovery effectiveness are characterized and compared to model predictions. By validating the model with the collected experimental data, it can be used to guide the design of future larger scale particle-to-sCO2 heat exchangers.