Question

A 2.2-mm-diameter and 10-m-long electric wire is tightly wrapped with a 1-mm-thick plastic cover whose thermal conductivity is k0.15 W/m-K. Electrical measurements indicate that a current of 13 A passes through the wire and there is a voltage drop of 8 V along the wire. If the insulated wire is exposed to a medium at T 30°C with a heat transfer coefficient of h 24 W/m2 K, determine the temperature at the interface of the wire and the plastic cover in steady operation. Also determine if doubling the thickness of the plastic cover will increase or decrease this interface temperature Electrical wire Insulation 10 m

Answer 1

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P.4 where Q=Yate of heat transfer Phrough Weelectri cal powe lost rom E 8x13 Outer diameter of electric elve win sho 2-2 2 CSI Scanned with CamScanner D,-4-2 x 10-3 m

2s 2 CS Scanned with CamScanner

P.6 due toconduc tn is Un (p-la) Cs Scanned with CamScanner

フ anste, e ihte, are Cover kelvin fmal) k=1a+173-15 (celšius k 30% +173.IS とこ303: IS Here s Scanned with CamScanner

P8 34.96824 k = T-303-1s k T, ะ 343.ilk -0.ir w)m'と 2 0.00 2.5 m Cs Scanned with CamScan ner

-) Ç9, if doubling.rheれickness-f the plutic rodius of intulathion. and deuree he nterhce temperature Scanned with CamScanner