Process Heat Collectors State of the Art within Task 33/IV (Weiss/Rommel 2008)

The use of solar energy in commercial and industrial companies is currently insignificant compared to those mentioned above. Solar applications in industrial processes have only occurred on a relatively small scale and been mostly experimental in nature.

However, if one compares the energy consumption of the industrial, transportation, household and service sectors then one can see that the industrial sector has the highest energy consumption in OECD countries at approximately 30%. Just one third of this energy demand is related to electricity, but two thirds are related to heat. The major share of the heat, which is needed in commercial and industrial companies for production, processes and heating production halls, is below 250°C. The low temperature level (< 80°C) is consistent with the temperature level, that can easily be reached with solar thermal collectors already on the market.

Process Heat Collector Developments For applications requiring temperatures up to 250°C there is limited experience and suitable collectors are still needed. Therefore, for these applications the development of high performance solar collectors and system components is necessary. One of the objectives of Task 33/IV was to develop, improve and optimise solar thermal collectors for the temperature level from 80°C to 250°C. The collectors investigated, in co-operation with industry, were double glazed flat plate collectors with anti-reflection coated glazing, stationary CPC collectors, evacuated tube collectors, small parabolic trough collectors, linear concentrating Fresnel collectors, and a concentrating collector with a stationary reflector.

In these activities, the investigation of materials suitable for medium temperature collectors was important, and so appropriate durability tests were applied to specific materials and components to allow the prediction of service lifetime and to generate proposals for international standards. This report gives an overview and some background information on the present state of process heat collector development carried out in the framework of the IEA SHC Task 33/SolarPACES IV on Solar Heat for Industrial Processes.