Field study of a direct absorption solar collector with eco-friendly nanofluid

Abstract

The concept of direct absorption solar collector (DASC) was introduced in the 1970s. Multiple laboratory studies proved that nanofluid-based DASCs presented a fruitful alternative to conventional solar collectors. However, due to environmental and cost limitations of nanofluids, there are few records of real-size DASCs operating in field conditions. Filling the gap, we report a 5-month seasonal field study for a full-scale DASC with an eco-friendly and low-cost nanofluid. Throughout the experiments, the DASC competed with a commercial flat-plate solar collector mounted in the exact location. The results showed that the commercial collector had an average daily efficiency of about 65.9%, while the direct absorption collector had a daily efficiency of 57.7% to 86.1%. The most important parameters influencing the efficiency of the DASC are the flow rate and the extinction coefficient of the nanofluid. They alter the efficiency by 9.2% and 6.2%. Finally, the article briefly notes the technical and economic features of the DASC operation.