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It is proposed to coat a 1 mm diameter wire with enamel paint (k = 0.1 W/mK) to increase heat transfer with air. If the air side heat transfer coefficient is 100 W/m²K, the optimum thickness of enamel paint should be
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- 0.25 mm
- 0.5 mm
- 1 mm
- 2 mm
Correct Option: B
Critical radius of insulation,
| rc = | = | = 0.001 = 1 mm | ||
| h | 100 |
Radius of min = 0.5 mm.
∴ Thickness of coating = 1 – 0.5 = 0.5 mm.
