An electric cable 1.2 cm OD has to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (ho = 8.7 wim2°C) at 18°C. Calculate: (i) the heat dissipation from bare pipe (cable),...

An electric cable 1.2 cm OD has to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (ho = 8.7 wim2°C) at 18°C. Calculate: (i) the heat dissipation from bare pipe (cable), (ii) the maximum heat dissipating, and (iii) the critical thickness of insulation assuming a cable surface tamperature of 70°C.