AL-2497 -- Testing of Solar Collectors According to ASHRAE Standard 93-77 PDF

A proposed procedure for testing and rating solar collectors based on thermal performance was published by the National Bureau of Standards (NBS) in 1974 [1-3]. The procedure prescribed that a series of outdoor steady-state tests be conducted to determine the near-solar-n06n efficiency of the collector over a range of temperature conditions. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has recently adopted ASHRAE Standard 93-77 [4]. It is similar to the original NBS procedure but calls for additional tests to determine the collector time constant as well as an incident angle correction factor that can be applied to the near-solar-noon efficiency to determine collector performance both early in the morning and late in the day.

Two test facilities have been built at NBS in accordance with ASHRAE Standard 93-77, one for modular water-cooled collectors and the other for air heaters. The purpose of this paper is to describe the recently adopted test procedure, provide a description of the facility at NBS, and to give results of a complete series of tests made according to the Standard on several commercially available collectors.