© The Institution of Engineering and Technology
In this reported work, the extinction coefficient of water-based nanofluids containing multi-walled carbon nanotubes (MWNCTs) has been experimentally measured. The MWCNTs were dispersed in deionised water with a surfactant, hexadecyltrimethyl-ammonium bromide, and they were homogenised by a bath-type ultrasonicator and a mechanical stirrer. The characteristics of MWCNTs suspended in the nanofluids were examined by transmission electron microscopy and scanning electron microscopy images and their hydrodynamic particle size was measured by a particle size analyser. The extinction coefficient of nanofluids was measured by an in-house developed apparatus at a single wavelength (632.8 nm) based on the Lambert-Beer principle. With the experimentally obtained extinction coefficient, the efficiency of a flat-plate type direct-absorption solar collector (DASC) was theoretically estimated. For this purpose, a modified analytical solution of the DASC efficiency is presented by assuming that the extinction coefficient is not a function of the wavelength. Finally, the efficiency of DASC is demonstrated according to the nanotube volume fractions. The results show that the DASC concept can further improve the efficiency of the conventional flat-plate type solar collectors.
References
-
-
1)
-
11. Sani, E., Barison, S., Pagura, C., et al: ‘Carbon nanohorns-based nanofluids as direct sunlight absorbers’, Opt. Express, 2010, 18, (5), pp. 5179–5187 (doi: 10.1364/OE.18.005179).
-
2)
-
3. Lenert, A., Wang, E.N.: ‘Optimization of nanofluid volumetric receivers for solar thermal energy conversion’, Sol. Energy, 2012, 86, (1), pp. 253–265 (doi: 10.1016/j.solener.2011.09.029).
-
3)
-
2. Otanicar, T.P., Phelan, P.E., Prasher, R.S., Rosengarten, G., Taylor, R.A.: ‘Nanofluid-based direct absorption solar collector’, J. Renewable Sustainable Energy, 2010, 2, (3), p. 033102 (doi: 10.1063/1.3429737).
-
4)
-
7. Taylor, R.A., Phelan, P.E., Otanicar, T.P., Adrian, R., Prasher, R.: ‘Nanofluid optical property characterization: towards efficient direct absorption solar collectors’, Nanosc. Res. Lett., 2011, 6, (1), p. 225 (doi: 10.1186/1556-276X-6-225).
-
5)
-
4. Miller, F.J., Koenigsdorff, R.W.: ‘Thermal modeling of a small-particle solar central receiver’, J. Sol. Energy Eng. – ASME, 2000, 122, (1), pp. 23–29 (doi: 10.1115/1.556277).
-
6)
-
6. Taylor, R.A., Phelan, P.E., Otanicar, T.P., et al: ‘Applicability of nanofluids in high flux solar collectors’, J. Renewable Sustainable Energy, 2011, 3, (2), p. 023104 (doi: 10.1063/1.3571565).
-
7)
-
12. Gan, Y., Qiao, L.: ‘Optical properties and radiation-enhanced evaporation of nanofluid fuels containing carbon-based nanostructures’, Energy Fules, 2012, 26, (7), pp. 4224–4230 (doi: 10.1021/ef300493m).
-
8)
-
9. Lee, S.-H., Jang, S.P.: ‘Extinction coefficient of aqueous nanofluids containing multi-walled carbon nanotubes’, Int. J. Heat Mass. Transfer, 2013, 67, pp. 930–935 (doi: 10.1016/j.ijheatmasstransfer.2013.08.094).
-
9)
-
5. Tyagi, H., Phelan, P., Prasher, R.: ‘Predicted efficiency of a low-temperature nanofluid-based direct absorption solar collector’, J. Sol. Energy Eng. – ASME, 2009, 131, (4), p. 041004 (doi: 10.1115/1.3197562).
-
10)
-
13. Streed, E.R., Hill, J.E., Thomas, W.C., Dawson, A.G., Wood, B.D.: ‘Results and analysis of a round robin test program for liquid-heating flat-plate solar collectors’, Sol. Energy, 1979, 22, (3), pp. 235–249 (doi: 10.1016/0038-092X(79)90139-7).
-
11)
-
10. Veeraragavan, A., Lenert, A., Yilbas, B., Al-Dini, S., Wang, E.N.: ‘Analytical model for the design of volumetric solar flow receivers’, Int. J. Heat Mass Transfer, 2012, 55, (4), pp. 556–564 (doi: 10.1016/j.ijheatmasstransfer.2011.11.001).
-
12)
-
S.A. Kalogirou
.
Solar thermal collectors and applications.
Prog. Energy Combust. Sci.
,
3 ,
231 -
295
-
13)
-
8. Mercatelli, L., Sani, E., Zaccanti, G., et al: ‘Absorption and scattering properties of carbon nanohorn-based nanofluids for direct sunlight absorbers’, Nanosc. Res. Lett., 2011, 6, (1), p. 282 (doi: 10.1186/1556-276X-6-282).
http://iet.metastore.ingenta.com/content/journals/10.1049/mnl.2014.0262
Related content
content/journals/10.1049/mnl.2014.0262
pub_keyword,iet_inspecKeyword,pub_concept
6
6