On-sun experiments on a particle heating receiver with red sand as the working medium

Particle heating receivers are a promising technology that can allow operation of CSP systems at temperatures higher than what today’s commercial molten salt systems can achieve, making them suitable for use in a variety of applications, including supercritical CO2 cycles, air Brayton cycles, and high-temperature process heat. One of the ways to improve costcompetitiveness of particle heating receivers is to use low-cost particulate materials, such as sand, as the working medium. Red sand is particularly attractive due to its abundance and acceptable absorptance. This paper presents the results of on-sun testing of a particle heating receiver that uses red sand as the working medium. Tests were conducted at the experimental central receiver facility at King Saud University in Riyadh, Saudi Arabia. Performance of the receiver was assessed in two ways. First, the rate of thermal energy absorption was calculated using the measured temperature rise across the receiver, particle flow rate, and red sand’s specific heat. Second, receiver efficiency was calculated using the rate of thermal energy absorption and the thermal power incident on the receiver, which was estimated using a raytracing software. Results show that a temperature rise of 130°C was achieved with an incident heat flux of 230-280 kW/m. Receiver efficiency was found to range from 60% to 70%. These results are encouraging and show that red sand is a promising particulate material, especially when it is used with a proper cavity receiver design where the effect of absorptance of the particulate material becomes less significant.