INNOVATIVE SOLAR THERMAL ENERGY COLLECTORS

The present inventions describes a new concept of a more robust, durable, and cost-effective linear receiver for Concentrated Solar Power (CSP) applications, which is of interest for both, power generation as well as for solar heat for industrial processes. A specific design has been found for a moderate/low temperature range (<300ºC), which takes advantage of an open cavity to reduce convective thermal losses along with an optical system which reinforces stratification and enhances the intercept factor. This design is robust since no critical seals are required, neither high-performance selective coating is essential. An alternative design is proposed for higher temperature ranges (> 300 ºC), as it is the case for solar thermal systems for electricity generation. The existing universal vacuum air collector (UVAC) receivers in current Parabolic Trough Collectors (PTC), are particularly expensive due to the glass-to-metal welding in conjunction with the high performance selective coating needed. The existing vacuum annulus is critical in terms of the thermal efficiency, but after some years after starting operation, it is usual that flaws or leaks in the welding or expansion bellows cause a complete or partial loss of vacuum in the receiver, which in turn drastically reduces its thermal performance. The proposed design lacks of the mentioned weak spots, so thermal performance can be kept across the entire lifespan of the system. In addition, the proposed design can be assembled on-site, which means that in the case that any of its components break, it can be easily replaced without having to discard the entire receiver, leading to a considerable reduction in the operations and management (O&M) costs of these solar plants. The concept of the horseshoe solar receiver proposed in this innovation takes advantage of the upward action of buoyancy forces in natural convection processes. The receiver concept proposes a suitable design for systems with moderate-low operating temperatures thanks to the optical system that fulfills a double function: reducing thermal losses and increasing the concentration factor. It is a simple design, allowing the existence of flexible systems without the need for complex maintenance tasks, and it is of special interest in process heat systems where the operating temperature of the fluid is below 300ºC. This design can be applied to a wide range of industrial systems, from solar heating/cooling, to agri-food processes. The alternative design is thought for higher temperature ranges (> 300 ºC). This new receiver configuration increases its lifespan, since it allows the vacuum inside the glass cavity to be maintained more easily and for much longer periods. This is possible due to the fact that it does not need glass-metal welds. In addition, the area emitting thermal radiation is drastically reduced, not requiring high-efficiency selective coatings. By achieving an increase in the average lifespan of these elements, the amortization period of these plants would be prolonged and their cost of energy production would be reduced. On the other hand, all the pieces that make up the design can be assembled in-situ at the plant, which increases the economy of scale in the manufacture of each of the pieces separately and significantly facilitates maintenance and repair. The proposed designs have been patented. The objective of the institution represented is to license the technology to bring this innovation to the market.