Advanced Microchannel Radial Receivers for the Economic Feasibility of Solar Thermal Power Plants

Abstract

A key aspect for the development of solar thermal technology is to improve cost-competitiveness without compromising efficiency. One of the more expensive items in a solar thermal power plant is the heliostat field, which accounts for 40-50% of the total plant investment. One way to decrease this cost is to reduce the size of the field by improving the efficiency in the thermal exploitation of this concentrated solar radiation.

This work presents a novel radial solar receiver design based on compact structures, which allows solar radiation to be absorbed more efficiently by reducing the absorber area and shaping a macroscopic sun trap geometry to reduce heat losses. These compact structures are specially designed to work with pressurised gases, so their coupling to supercritical CO₂ power cycles is straightforward. Specifically, the direct coupling to a novel sCO₂ cycle is considered, where the heat is supplied in the low-pressure line of the cycle and the CO₂ is compressed at low temperature, which reduces the auxiliary consumption, increasing the net efficiency.

The advantages of the microchannel radial receiver have been highlighted by a thermo-economic comparison between this receiver and a conventional external receiver, resulting in a significantly lower total plant investment (171 Mio.$ vs. 195 Mio.$). This difference is due to the smaller heliostat field required, due to the improved thermal performance of the novel receiver design compared to the more conventional one.