Heat flows through a composite slab, as shown below. The depth of the slab is $$1$$ $$m.$$ the $$k$$ values are in $$W/m. K.$$ The overall thermal resistance in $$K/W$$ is

Heat is being transferred by convection from water at $${48^ \circ }C$$ to a glass plate whose surface that is exposed to the water is at $${40^0}C.$$ The thermal conductivity of water is $$0.6$$ $$W/mK$$ and the thermal conductivity of glass is $$1.2$$ $$W/mK.$$ The spatial gradient of temp in the water at the water glass interface is
$$dT/dy = 1 \times {10^4}\,\,K/m.$$

The heat transfer coefficient $$h$$ in $$W/{m^2}K$$ is

Heat is being transferred by convection from water at $${48^ \circ }C$$ to a glass plate whose surface that is exposed to the water is at $${40^0}C.$$ The thermal conductivity of water is $$0.6$$ $$W/mK$$ and the thermal conductivity of glass is $$1.2$$ $$W/mK.$$ The spatial gradient of temp in the water at the water glass interface is
$$dT/dy = 1 \times {10^4}\,\,K/m...$$

The value of the temperature gradient in the glass at the water-glass interface in $$K/m$$ is

It is proposed to coat a $$1mm$$ diameter wire with enamel paint $$\left( {k\,\,\,\, = 0.1W/m} \right.$$ - $$\left. K \right)$$ to increase heat transfer with air. If the air side heat transfer co-efficiency is $$100$$ $$W/{m^2}K,$$ the optimum thickness of enamel paint should be