468
S. Mohan et al.
Fig. 1 Experimental set-up
The concentrator comprised of two glass receiver tubes, each focused by two
Fresnel lens placed vertically above them, and storage tank is insulated with glass
wool. The Fresnel lens had linear grooves on the surface to concentrate the incoming
solar radiation to the focus of glass tube. The receiver tube used was a concentric
borosilicate glass tube with internal diameter 23 mm and external diameter 25 mm.
The annular space was evacuated in order to decrease the heat loss to the surroundings through convection. Necessary piping arrangement was made to achieve the
circulation of the working fluid. The working fluid from the reservoir is made to flow
through the receiver tube where the photo-thermal conversion takes place. The fluid
from the receiver is sent back to the receiver by employing a pump. A manual solar
tracking was employed for the constant line focus. During experimentation, the heat
transfer fluid was pumped at a constant flow rate into the Fresnel lens concentrator
with the help of a submersible pump kept dipping in the storage tank. The experiments were carried out from 10:00 a.m. to 4:00 p.m., the temperature readings of
the fluid at reservoir were noted by means of a T type thermocouple, and the values
were compared with base fluid.
S. Mohan et al.
Fig. 1 Experimental set-up
The concentrator comprised of two glass receiver tubes, each focused by two
Fresnel lens placed vertically above them, and storage tank is insulated with glass
wool. The Fresnel lens had linear grooves on the surface to concentrate the incoming
solar radiation to the focus of glass tube. The receiver tube used was a concentric
borosilicate glass tube with internal diameter 23 mm and external diameter 25 mm.
The annular space was evacuated in order to decrease the heat loss to the surroundings through convection. Necessary piping arrangement was made to achieve the
circulation of the working fluid. The working fluid from the reservoir is made to flow
through the receiver tube where the photo-thermal conversion takes place. The fluid
from the receiver is sent back to the receiver by employing a pump. A manual solar
tracking was employed for the constant line focus. During experimentation, the heat
transfer fluid was pumped at a constant flow rate into the Fresnel lens concentrator
with the help of a submersible pump kept dipping in the storage tank. The experiments were carried out from 10:00 a.m. to 4:00 p.m., the temperature readings of
the fluid at reservoir were noted by means of a T type thermocouple, and the values
were compared with base fluid.