Abstract
ABSTRACT Detailed comparative measurements have been performed on collectors with a Teflon film or a honeycomb structure as the secondary glazing. The results indicate that a replacement of the Teflon film by a 30 mm honeycomb in a large area flat collector in Sweden, operating at a temperature of around 70°C, will increase the performance by around 40–50 kWh/m 2 or 10–15% on an annual basis. This is estimated from laboratory optical transmittance measurements and hot-box heat loss measurements, and also confirmed by outdoor collector measurements of daily efficiency. The improved efficiency is a result of a strong reduction in the U L -value of 0.7–1.1 W/m 2 °C, combined with only a small decrease in the solar transmittance of 1–2 %.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
