Figure 4 Pre-data period and data period (t = time constant).
Related Figures (12)
Fig. 1. The experimental setup. The specifications of the flat-plate collector. Table 1 Fig. 2. Prepared Al2O3 nanofluid solutions (a) With Triton X-100 surfactant (b) Without Triton X-100 surfactant. Fig. 3. The schematic of the experiment. where 79, is the collector outlet fluid temperature after time f, To, is the collector outlet initial fluid temperature and T; is the collector inlet fluid temperature. t*: time constant of the flat-plate solar collector. FRU, and Fr(t«) of the flat-plate collector at various mass flow rates. Table 2 Fig. 5. Experimental data for water as working fluid. All the presented data were divided into several test runs (each test run was chosen 60 min). Each test run was divided in into several test periods in a quasi-steady state condition. The Fig. 6. The efficiency of the flat-plate solar collector at several mass flow rates. maximum variations in ambient, inlet and outlet temperatures in each test period are 0.7 °C, 0.4 °C, and 0.6 °C respectively, while in global radiation, it is 21 W/m?. The above phrase revealed that the data presented here satisfy the necessities presented in ASHRAE Standard 93-86. Values of FrU; and Fr(ta) for AlgO3 nanofluid and water in 3 Lit/min mass flow rate. Table 3 Fig. 7. The efficiencies of solar collector for AlgO3 nanofluid without surfactant and for water. Fig. 8. The efficiency of the flat-plate solar collector for 0.4 wt% Al2O3 nanofluid with and without surfactant. Fr(ta) and FRU, values of solar collector for each mass flow rate. Table 4 on the Eq. (6) and these values, adding surfactant to the Al203 nanofluid has a positive effect on the performance of the flat-plate solar collector. Fig. 9. The efficiency of the flat-plate solar collector with Al,03 nanofluid as base fluid for various mass flow rates.
