Air at ${20}^{o}C$ C and I atm flows over a flat plate at 40 m/s. The plate is 80 cm long and is maintained at ${60}^{o}C$. Properties of air at ${40}^{o}C$ are Pr = 0.7, K = 0.02733 W/mK, $C_p=1.007\frac{kJ}{kgK}\mu =1.906\times {10}^{-5}\frac{kg}{m-s}and\rho =1.128kg/m^3.$
The avergae heat transfer coefficient is ___$Use\overline{Nu}=P{r}^{\frac{1}{3}}(0.036R_e^{0.8}-871)$.

Q. Air flows over a heated plate at a velocity of 50 m/s. The local skin friction coefficient at a point on a plate is 0.004. The following properties for air are, $density=0.88kg/m^3,viscosity=2.286\times {10}^{-5}kg-m/s,specificheat=1.001kJ/kgK,$ thermal conductivity of air = 0.035 W/mK and use St.$P{r}^{1/3}=C_{fx}/2.$

The local heat transfer coefficient is

Q. Air flows over a heated plate at a velocity of 50 m/s. The local skin friction coefficient at a point on a plate is 0.004. The following properties for air are, $density=0.88kg/m^3,viscosity=2.286\times {10}^{-5}kg-m/s,specificheat=1.001kJ/kgK,$ thermal conductivity of air = 0.035 W/mK and use St.$P{r}^{1/3}=C_{fx}/2.$

The average heat transfer per unit area if the temperature differences is ${60}^{o}C$ and the flow is assumed to be laminar

Q. Lubricating oil at a temperature of ${60}^{o}C$ enter 1 cm diameter tube with velocity of 3m/s. the tube surface is maintained at ${40}^{o}C$ and the properties of oil are
$\rho =865Kg/m^3$, $\mu =0.0216N-s/m^2,$
$K=0.140W/m^{o}C,C_P=1780J/K{g}^{o}C$

The heat transfer coefficient for the lubricating oil is

Q. Gas at atmospheric pressure and ${40}^{o}C$ flows with a velocity is 5m/s over a 2m long flat plate whose surface is kept at a uniform temperature of ${120}^{o}C$. The average heat transfer coefficient $\left(inW/m^{2o}C\right)$ over the 2m length of the plate if the properties of gas at mean film temperature are
Kinematic viscosity = $2.107\times {10}^{-5}{m}^2/s,$
Thermal conductivity = 0.03025 W/mK,
Prandtl number = 0.6965.
Average Nussult number = Nu = $0.664R{e}^{0.5}$.
$P{r}^{0.3}....ForLaminarflow$
Average Nussult number = Nu = 0.0375
$R{e}^{0.8}.P{r}^{0.3}....$For turbulent flow

Q. The thermo-physical properties of air at 60${}^o$C are:
Density = 1.06 kg/m${}^3$; Cp = 1.008 kJ/kgK;
Thermal conductivity = 0.028 W/mK and Dynamic viscosity = 18.97 x 10${}^{-6}$ Ns/m${}^2$ .
The Prandtl number of air at 60${}^o$C is