Pool boiling characteristics of multiwalled carbon nanotube (CNT) based nanofluids over a flat plate heater
✍ Scribed by R. Kathiravan; Ravi Kumar; Akhilesh Gupta; Ramesh Chandra; P.K. Jain
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 789 KB
- Volume
- 54
- Category
- Article
- ISSN
- 0017-9310
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✦ Synopsis
This paper is mainly concerned about the pool boiling heat transfer behavior of multi-walled carbon nanotubes (CNTs) suspension in pure water and water containing 9.0% by weight of sodium lauryl sulphate anionic surfactant (SDS). Three different concentrations of 0.25%, 0.5% and 1.0% by volume of CNT dispersed with water and water containing 9.0% by weight of sodium lauryl sulphate anionic surfactant (SDS) were prepared and boiling experiments were conducted over a stainless steel flat plate heater of size 30 mm 2 and 0.44 mm thickness. The test results exhibit that the addition of carbon nanotubes increases boiling heat transfer coefficients of the base fluids. At a given heat flux of 500 kW/m 2 , the enhancement of heat transfer coefficient was found to be 1.5, 2.6 and 3.0 times of water corresponding to 0.25%, 0.5% and 1.0% concentration of CNT by volume in water, respectively. In water-CNT-surfactant nanofluid, it was found that 0.5% of CNT concentration gives the highest enhancement of 1.7 compared with water. In both water and water-surfactant base fluids, it was observed that the enhancement factor for 0.25% of CNT first increases up to the heat flux of 66 kW/m 2 and then decreases for higher heat fluxes. Further, the overall heat transfer coefficient enhancement in the water-CNT nanofluids is approximately two times higher than that in the water-CNT-surfactant nanofluids. With increasing heat flux, however, the enhancement was concealed due to vigorous bubble generation for both water-CNT and water-CNTsurfactant nanofluids. Foaming was also observed over the liquid-free surface in water-CNT-surfactant nanofluids during the investigation. No fouling over the test-section surface was observed after experimentation.