Experiments on heat transfer from spheres to liquids have been carried out in the range of 2.0×10
-4<Re<900, 7.0<Pr<2.4×10
4 and 5.7×10
-3<Gr<10
7 for combined convection. A sphere, 46.03 mm in diameter, composed of eleven copper segments, and two brass spheres (19.03 and 9.534 mm in diameter) have been used. Test liquids used were 0.96%, 2.59%, 2.62% CMC aqueous sol. and 0.69%, 0.97%, 1.07% MC (methylcellulose) aqueous sol. The experimental data are summarized by the following relation:
Nu
m-2 = [{(126Re+57Re
3/2)Pr
1/3/(1+52Re
1/2+100Re)}
3/2 + (0.44Gr
1/4Pr
1/4)
3/2]
2/3(μ
b/μ
s)
1/4 where μ
b is the viscosity at the bulk liquid temperature t
b and μ
s is the viscosity at the sphere surface temperature t
s. This equation has been shown to represent measured values of Nu
m within an average deviation of 13.6 per cent.
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