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Solar/Thermal energy
Solar/Thermal energy


A Spanish university has developed and patented two inventions that propose a new concept of more robust, durable, and cost-effective linear receivers for Concentrated Solar Power (CSP) applications. Both designs present great advantages compared to those that currently exist and can be applicable both for power generation as well as for solar heat for industrial processes. License or alternatively technical cooperation agreement is sought.



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.

Advantages & innovations

Cooperation plus value: 
Current parabolic trough collector plants use vacuum receivers (UVAC) based on concentric cylinders. These items are very expensive and have limited durability. This implies the reduction of their optical and thermal performance over the course of a few years of operation, which has direct effects on the energy production of the plants and on their maintenance costs. This invention proposes a new approach that manages to eliminate the most vulnerable elements of the receiver (glass-metal welding as well as expansion bellows) from a new innovative design that offers new alternatives to reduce the levelized cost of energy (LCOE) of PTC 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 present invention provides multiple benefits compared to conventional system: • It is a more robust design, since it can maintain adequate vacuum levels for longer periods than current receivers. • The application of a high-efficiency selective coating on the interior surface of the receiver can be avoided since the glass is practically opaque to thermal radiation and its thermal conductivity is low. Furthermore, the radiation emitting surface (lower aperture width) is reduced relative to the perimeter of a conventional absorber tube. • In the event of breakage in any of the receiver elements, it is not necessary to replace the entire receiver, but only the affected element. • The thermal insulation material (eg rock wool) ensures that there is no heat flow along the upper boundary of the absorber, and therefore contributes to reduce thermal gradients, which avoids the risk of severe thermal bending. • No bellows would be needed, since the elements are embedded, which allows sliding between the upperface of the glass piece and the rest of the elements to compensate for the different coefficients of expansion.

Stage of development

Cooperation stage dev stage: 
Under development/lab tested

Partner sought

Cooperation area: 
Companies that want to enter into a licensing agreement or alternatively technical agreement in order to explore the new possibility in the solar thermal industry. The open receiver is applicable to generate heat in any production process that requires heat above 80 degrees. It can also be applied for solar cooling (absorption systems). The case of the closed receiver would be for electricity production plants using parabolic trough collectors.

Type and size

Cooperation task: 
SME 11-50,SME <10,>500 MNE,251-500,SME 51-250