Fabrication and testing of a Non-Glass Vacuum-Tube Collector for Solar Energy Utilization

An evacuated tubular solar collector was fabricated from acrylics for improved resistance to shattering. A plasmatron was employed to apply a thin gas-barrier coating to the surfaces of the plastic tube to prevent/alleviate gas infiltration. Experiments were conducted to investigate the effect of vacuum level on the performance of the non-glass vacuum-tube solar collector. A finned heat pipe was inserted in the evacuated tube for solar energy collection and heat transfer to a water tank. Time variations of temperatures on the heat pipe surface and in the water tank were recorded and analyzed for different degrees of vacuum in the collector. A comparison between the steady-state temperatures of the non-glass collector and a commercial glass vacuum-tube collector was made to assess the feasibility of the use of evacuated plastic tubes for solar energy collection.