Parabolic Trough Collectors for District Heating Systems at High Latitudes? - A Case Study

The efficiency of a parabolic trough collector system has been investigated under central European climate conditions. Resulting collector parameters are applied to simulations of the annual energy yield in TRNSYS for the temperature range between 50°C – 200°C. The effect of improvements in the collector technology is computed as well for the TRY Copenhagen. Accordingly parabolic troughs can more efficiently contribute to solar heat production than flat plate collectors above collector temperatures of 60° 75°C. The model parameters are then implemented in a dynamic model of a total district heating system with central solar heating plant. Computations are carried out for three different solar collector types: 1) A plane HT collector by ArCon. 2) The IST parabolic trough collector. 3) An optically improved IST collector. Annual simulation of the performance for a field of the Marstal plant is carried out and results are presented. These indicate, that the trough technology can be more efficient than the plane collector technology, especially at high fluid temperatures. Investment costs of the discussed technologies are comparable for greater installations. Hence, application of trough collectors in largescale solar heating plants should be considered in future designs of such plants.