14 Study on Thermal Performance of the Collector of the Solar Membrane Distillation System

In this paper, against the application background of brackish water desalination and seawater, the solar powered membrane distillation technology is applied to deal with brackish water desalination in the west of China, and this research work has laid the foundation for application of the solar membrane distillation system. The thermal performance and the structural characteristics of the glass evacuated solar collector tube with an inserted heat pipe have been compared with all-glass evacuated collector tube in this paper. The results in comparison with average heat loss coefficient, daily average efficiency and instantaneous efficiency by experiment have also been discussed. The result of theoretic analysis and experiment investigation showed that the daily average efficiency of the solar collector with an inserted heat pipe is higher than that of all-glass evacuated collector and the average heat loss coefficient is opposite. Meanwhile, its instantaneous efficiency is almost 15% higher than that of all-glass evacuated collector. Comparing with all-glass evacuated collector, the tube with an inserted heat pipe has small heat capacity, thermal inertia, appropriate anti-freezing capability, safety and steady running in pressure-containing, so this collector has better characteristic in high temperature efficiency and heat preservation. This research has laid the foundation for application of the solar membrane distillation system.