Inward-flowing fraction of absorbed solar radiation for Venetian blinds.

摘要

A test apparatus and method for determining the inward-flowing fraction of absorbed solar energy was successfully evaluated for use with any calorimeter. Electrical heating of the shade layer can be used to calculate {dollar}Nsb{lcub}S{rcub}{dollar} under specific test conditions. Input powers of about 250 W per m{dollar}sp2{dollar} of projected blind area produced precise results under all circumstances. Lower power inputs resulted in increased data uncertainty. Results were dependent on the interior/exterior temperature gradient. Realistic test conditions would be advisable. Results indicate that the exterior air film coefficient did not have any significant effect on results. Wind speed should be controlled to accepted standard test conditions as dictated by the ASHRAE HOF.; A predictive model found in the literature was also evaluated. Measured and calculated radiative and convective heat transfer coefficients were input to the model and compared with test data. Results showed that the model was an excellent predictor of both inward-flowing fraction and solar heat gain. As such, calorimetric testing may be unnecessary if heat transfer coefficients can be determined for all cases. Therefore, further development in this area is needed. Particularly, convective heat transfer coefficients between the glass and the interior air require closer analysis.; More testing is required for various complex fenestration systems. This testing would include both inward-flowing fraction and heat transfer coefficient measurements. A major problem encountered during this analysis was the lack of measured inward-flowing fraction data. In addition, full validation of the model requires further work, especially in regard to the effects of the interior/exterior temperature gradient.