An experimental investigation on the effect of MWCNT-H2O nanofluid on the efficiency of flat-plate solar collectors

In this study the effect of MWCNT nanofluid, as absorbing medium, on the efficiency of a flat-plate solar collector was investigated experimentally. The weight fraction of CNTs was 0.2% and 0.4%. The effect of Triton X-100 as a surfactant on the stability of nanofluid was studied. The tests were performed in different mass flow rates of nanofluid from 0.0167 to 0.05 kg/s. ASHRAE standard was used to perform the tests. Results show that by increasing the weight fraction from 0.2% to 0.4%, there is a substantial increase in the efficiency. Also, using the surfactant causes an increase in the efficiency.

► The efficiency of collector for 0.2 wt% MWCNT nanofluid is lower than that for water.
► The FRUL value for MWCNT nanofluid is greater than that for water by 9.3%.
► The efficiency of collector for 0.4 wt% MWCNT nanofluid is higher than that for water.
► By adding Triton X-100 there is an efficiency increase for solar collector.
► For small values of Ti-TaGT, the efficiency increases by increasing the mass flow rate.