Practice Problems for Test $2$

Problems

$5-29$ Air at $1$ atm and $27C$ blows across a large concrete surface $15$ m wide maintained at $55C.$ The flow velocity is $4\mathrm{.}5\frac{m}{s}.$ Calculate the convection heat loss from the surface.

$10-5$ Water at the rate of $68k\frac{g}{m}in$ is heated from $35$ to $75C$ by an oil having a specific heat of $1\mathrm{.}9k\frac{J}{k}g*C.$ The fluids are used in a shell$-$and$-$tube exchanger with the water making one shel pass and the oil making two tube passes. The oil enters the exchanger at $110C$ and leaves at $75C.$ The overall heat$-$transfer coefficient is $320\frac{W}{m}2*C.$ Calculate the heat$-$exchanger area.