3.1. Experimental studies on using nanofluids in FPSCs
The effect of using an multi-walled carbon nanotube
(MWCNT)/water nanofluid as the heat transfer fluid on
the efficiency of a 2-m2 FPSC was investigated experimentally
by Yousefi et al. (2012a). MWCNTs were used that
had outer diameters in the range of 10–30 nm and weight
fractions of 0.2% and 0.4%. Triton X-100 was selected as
the surfactant (Rastogi et al., 2008). They used an aluminum
frame, a copper absorber plate with a selective
coating, copper header and riser tubes with 22 and
10 mm diameters, respectively, and a 4-mm float glass
cover to build the solar collector. An electrical pump was
used to circulate the fluid in the forced-convection test
setup (Fig. 3). Also, the solar system had a 41-l tank with
an internal heat exchanger to absorb the heat from the solar collector.