evaluated the characteristics of water-inglass
evacuated tube solar water heating systems including assessment
of the circulation rate through single ended tubes. A
numerical model of the heat transfer and fluid flow inside a single
ended evacuated tube have been developed assuming no interaction
between adjacent tubes in the collector array. For a specific
collector configuration, circulation flow rate through the tubes is
influenced by two factors, namely the radiation intensity falling
onto the absorber surface and the temperature of the storage tank.
Flow measurement using Particle Image Velocimetry (PIV) has
been undertaken to validate the numerical model. It was found
that the circumferential heat distribution to be an important
parameter influencing the flow structure and circulation rate
through the tube. It was also reported that a separate correlation
needs to be developed if a concentrating reflector is incorporated
into the collector.