A new performance evaluation method for solar thermosyphon systems

摘要

The thermal performance of a solar thermosyphon system for water heating depends on its design characteristics and manufacturing quality. For product improvement and quality control purposes, standardized tests are performed and system characteristic parameters are determined through statistical analysis of measured data. A number of national and international test methods are currently available. However, the characteristic parameters derived from these tests are dependent on the relative sizes of the major components, such asmass of water in system in relation to the collector aperture area. The methods are therefore not good enough to serve for direct system comparison purpose. This article introduces a new evaluation method based on M/A_c = 75 kg/m2 and 50% system efficiency at zero reduce temperature. The four characteristic parameters, namely a_(eff),u_(eff),u_(50) and PF_(50), are independent of the M/A_c ratio, and by analyzing the four characteristic parameters, we can assess not only the solar thermosyphon system performance, but also the direction for system performance improvement.