Receiver

Introduction

ALE is aware of the important drawback caused by the quantity of cooling water required by traditional technology needs. As the steam generated by current receivers is at just 380°C wet cooling for the turbine condenser is required, therefore generating a huge amount of water consumption (~700’000 m3 per year). Moreover, the heat fluid currently being used is thermal oil, which is expensive, degradable, toxic and typically requires 1’000’000 l for a 50 MW plant.

Current developments go towards direct steam generation, which helps provide a solution to the problem of water consumption but does not provide a simple and efficient storage system; efforts are also moving towards molten salt technology which allows heat storage but are technically very difficult and in some sort also dangerous in case of leakages. Furthermore, it must not be forgotten that at a temperature of about 230°C salt becomes solid.

Air as Thermal Fluid

ALE has approached the problem in a different way. Our innovative receiver design uses Air as thermal fluid, enabling the operation at higher temperatures reaching up to 600°C without facing particular technical problems such as phase change or oxidation requiring special materials.

The main difficulty with using air as thermal fluid is its intrinsic lower heat transport capacity compared to steam or oil. Moreover, thermal convection/conduction is lower so a large heat exchange surface is required.

ALE‘s innovative concept uses the well known cavity principle whereas the entrance is small but the internal surface is extensive. For this reason, the air flows around the cavity where the surface is large enough to exchange all of the incoming energy.

Energy losses caused by back radiation are low.

Using fins or other system to increase the above mentioned exchange, the surface will drammatically increase pressure drop in the receiver causing an enormous waste of energy in the blowers just allowing the air to circulate in the pipes of the solar fields.