Design, installation and evaluation of a solar thermal system with evacuated tube collectors for water at 90 °C

Solar energy could be harnessed in several ways. One of the most promising energy forms are solar collectors with thermal conversion, which can be used to heat water or air. There are two common types of stationary collectors used in solar water heating systems, flat plate collectors (FPCs) and most modern evacuated tube collectors (ETCs). Use of solar collectors in agricultural production has increased over the last decades; FPCs are used in most cases. Their benefits however are greatly reduced when conditions become unfavorable during cold, cloudy and windy days. In addition, FPCs are not suitable for applications at the temperature of above 80 degrees C. The vacuum envelope of ETCs reduces convection and conduction losses. ETCs can perform even in cold weather when FPCs perform poorly due to heat loss. In addition. ETCs are suitable for applications at the temperature of above 80 degrees C This study analyzes the use of solar thermal energy systems with evacuated collectors for obtaining water above 90 degrees C. For that purpose, we have carried out the design, installation and evaluatio of a solar thermal system for water supply at 90 degrees C. Under defined test conditions in Madrid, it was found that the average performance in the collector can reach 60%. falling to 50% in the interaccumulator. The results could be useful for agro-industrial applications as drying snuff, cleaning equipment in livestock buildings, wood drying, etc.