Modeling and Thermal Parametric Analysis of U-pipe Evacuatesd Tube Solar Collectors for Four Different Climates in Iran

Authors

Abstract

In this study, the thermal performance of collectors with analytic and quasi-dynamic method is evaluated based on energy balance equations for each part of the U-pipe evacuated tube solar collector. Using this approach, the effect of different parameters such as tube size, overall heat loss coefficient, absorber tube absorptivity, mass flow rate, and air layer thermal resistance on the thermal performance of the collector were analyzed. The results show that collector efficiency is increased with an increase in the length of the tube for a fixed tube diameter, but this increase is very small if the length of the tube increases more than two meters. Under the same conditions, collector efficiency increases with an increase in tube diameter for a fixed tube length. An optimum flow rate is obtained for different climate condition in which collector efficiency is maximum. It shows different values for different climates. A correlation is obtained for optimum flow rate based on average annual total solar radiation.

Keywords


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