Abstract
The Department of Energy’s Solar Energy Technologies Office has down selected a particle-based heat transfer and storage medium as the technology most likely to decrease the levelized cost of energy of concentrating solar power to below their 0.05 $/kWh target by 2030. A particularly challenging component within a particle-based system is the particle to supercritical CO2 heat exchanger due to the relatively low thermal conductivity and poor heat transfer characteristics of the particle media. Fluidized bed heat exchangers have widely been used in industry for alternative applications and feature high particle side heat transfer coefficients that can help reduce the cost of the heat exchanger. This increase in heat transfer coefficient is achieved by bubbling air through the particles which increases their movement relative to the tube bundle heat transfer surface. The parasitic power associated with the delivery of air into the heat exchanger introduces a concern that the levelized cost of energy would be negatively impacted when compared to the state of the art parallel plate heat exchanger which relies on gravity for particle flow. The presented study reveals that the levelized cost of electricity of the fluidized bed heat exchanger design was up to 0.007 $/kWh lower than the state of the art parallel plate heat exchanger despite the increased parasitic power consumption. It is also presented that the increase in heat transfer coefficient, and thus decreased heat exchanger material, gained from increased airflow in the bed does not result in lower levelized cost of energy. The minimum air flow required for fluidization provides in the lowest levelized cost of energy due to the minimal parasitic power consumption.
