Long term measured and simulated performance of a combined solar district heating plant with flat plate collectors and parabolic trough collectors in series
Abstract
Large scale solar heating plants develop fast in Europe, especially in Denmark. Most solar collectors used in previous solar heating plants are flat plate collectors. Flat plate collectors have relatively low efficiency at high temperature levels, such as 70 - 95 ℃, which is the supply temperature of district heating networks. Parabolic trough collectors keep a high efficiency at the high temperature level. To maximize the advantages of flat plate collectors and parabolic trough collectors, a novel combined solar heating plant with flat plate collectors and parabolic trough collectors in series has been constructed in Taars, Denmark. The flat plate collectors preheat the return water from the district heating networks to about 75℃, then the parabolic trough collectors heat the preheated water from the flat plate collector field to the required supply temperature of the district heating network. The thermal performance of the combined plant was measured from September, 2015. More than 2 years` thermal performance will be presented in this paper.