COLLECTOR EFFICIENCY TESTING – REDUCTION OF TEST DURATION BY USING A 2-NODE COLLECTOR MODEL
Up to now all national and international standards prescribe certain boundary conditions like ambient air velocity, level of solar irradiance, etc. for the efficiency test of solar collectors. Although the boundary conditions vary between standards, one requirement is common for all of them: Only measured data with a positive collector output are allowed to be used to determine the collector efficiency. For outdoor tests, this requirement may lead to long test periods due to unfavourable weather conditions. Against the background of a possible reduction of testing costs and the wish to satisfy the increasing demand for collector tests a reduction of the test duration is a desirable option. One possibility to reduce the test duration is the use of a so called 2-node numerical collector model. In contrast to a 1-node model, the 2-node model takes into account the temperature difference between the absorber and the fluid temperature using two heat capacities Cabs and Cfl as well as a heat transfer capacity rate (UA) combining the two capacities. This differentiation allows for the use of measured data with negative collector output as long as the heat transfer capacity rate is independent of the direction of heat transfer. The paper describes a possible method for efficiency testing of solar thermal collectors using the 2-node collector model.
Stephan Fischer Hans-Müller Steinhagen
Universit(a)t Stuttgart Institute for Thermodynamics and Thermal Engineering (ITW) Pfaffenwaldring 6, 70550 Stuttgart, Germany
国际会议
2007世界太阳能大会(Proceedings of ISES Solar World Congress 2007)
北京
英文
2007-09-18（万方平台首次上网日期，不代表论文的发表时间）