A solid particle central receiver for solar energy

Solar central receiver systems utilize mirrors to reflect and focus the sunlight onto a receiver that resides on top of a centrally located tower. By redirecting the sunlight in this manner, the solar flux at the receiver surface can be equivalent to hundreds of suns. A working fluid in the receiver is heated by absorbing the solar radiation. This fluid can then be used to produce electricity or incorporated into products as process heat. Currently, the working fluids in a solar central receiver are gases or liquids that flow through tubes heated by the solar radiation. An example of such a system is the water/steam central receiver system located near Barstow, California, which produces electrical energy. Other common working fluids include molten salts, molten metals, and air. A novel concept for a central receiver currently being examined employs sand-size refractory particles that freefall in a cavity receiver. A conceptual design of a solid particle receiver is shown. The solid particle central receiver is being evaluated for high-temperature (greater than 550/sup 0/C) applications of solar energy. The advantages of a solid particle receiver over traditional fluid-in-tube receivers are: 1) the particles can directly absorb solar radiation and 2) the particles maintainmore » their integrity at high temperatures. These advantages, coupled with the possibility that the particles can serve as the storage medium, could provide a cost-effective means of high-temperature solar energy utilization. High temperatures are attractive for fuels and chemicals production, industrial process heat applications, or Brayton cycle electricity generation.« less