How to evaluate the optical efficiency of a solar collector?

As already stated, the evaluation of the optical efficiency requires measuring the heat captured by the collector while keeping the collector itself at a temperature very close to the ambient. However, only a small amount of solar heat can be collected when the collector has a restricted collection area.

Do solar devices need optical efficiency?

This fact justifies the requirement for experimental investigation of optical efficiency for all solar devices. This assignment typically entails evaluating the instantaneous efficiency of a solar collector when the absorber and surrounding temperatures are equal.

What is optical efficiency?

The optical efficiency is the ratio of solar radiation flux q rec reaching the absorber to the incoming solar power q s = I S c that impinges the aperture area of the collector. The direct measure of the optical efficiency is not possible because of the difficulties to assess q rec.

Does mass flow rate affect optical efficiency of a solar collector?

However, this strategy's fundamental disadvantage is that a lack of adequate mass flow rate value might impact heat transmission and lead to misleading results. The significance of this study is to design a more robust and repeatable methodology to assess the optical efficiency of a solar collector.

What is concentrating solar power (CSP)?

Concentrating Solar Power (CSP) systems receive and concentrate solar radiation to heat a working fluid at medium–high temperatures. As a result, optical efficiency is a central quantity for these systems because it expresses the potentiality with which a solar device traps solar radiation to convert it into heat for practical applications.

Does transient heating of a solar collector improve optical efficiency?

The significance of this study is to design a more robust and repeatable methodology to assess the optical efficiency of a solar collector. Consequently, this aim proposes the transient heating of the empty collector as an indicator to deduce its optical efficiency, thus avoiding measuring the fluid temperature increase.