Preliminary Design of Heat-Extraction System for the ANL (Argonne National Laboratory) Research Salt Gradient Solar Pond

摘要

Two methods of heat extraction are compared. For both methods the heat exchangers are sized for 30 kW, with a peak load capability of 60 kW. In the first method, fresh water is circulated through a plastic heat exchanger submerged in the pond to a liquid-to-air fin-tube heat exchanger external to the pond. In the second method, hot brine is withdrawn from the bottom of the pond, circulated through a brine-to-air heat exchanger, and the cooled brine is returned to the bottom of the pond. The brine-to-air heat exchanger will be constructed from copper-nickel to minimize corrosion. The effects of both heat extraction methods on the stability of the salt gradient are investigated. It is expected that the submerged heat exchanger will have minimal effect on the gradient because the disturbances associated with the natural convection caused by the heat extraction will remain in the heat storage zone and not reach the gradient zone boundary. The disturbances associated with brine withdrawal are expected to have a larger impact. The effect of these disturbances on the gradient are characterized according to flow velocity, diffuser size, etc.