# GATE2015-3-54

A brick wall $\left(k=0.9\displaystyle{\frac{W}{m.k}}\right)$ of thickness $0.18$ $m$ separates the warm air in a room from the cold ambient air. On a particular winter day, the outside air temperature is $−5^\circ C$ and the room needs to be maintained at $27^\circ C$. The heat transfer coefficient associated with outside air is $20\displaystyle{\frac{W}{m^2k}}$. Neglecting the convective resistance of the air inside the room, the heat loss, in $\displaystyle{\frac{W}{m^2}}$, is

1. $88$
2. $110$
3. $128$
4. $160$

recategorized

## Related questions

One side of a wall is maintained at $400 \: K$ and the other at $300 \: K$. The rate of heat transfer through the wall is $1000 \: W$ and the surrounding temperature is $25^\circ C$. Assuming no generation of heat within the wall, the irreversibility (in $W$) due to heat transfer through the wall is ________
A solid sphere $1$ of radius ‘$r$’ is placed inside a hollow, closed hemispherical surface $2$ of radius ‘$4r$’. The shape factor $F_{2-1}$ is $1/12$ $1/2$ $2$ $12$
Saturated vapor is condensed to saturated liquid in a condenser. The heat capacity ratio is $C_r = \displaystyle{\frac{C_{\text{min}}}{C_{\text{max}}}}$. The effectiveness $(\varepsilon)$ of the condenser is $\displaystyle{\frac{1-\text{exp}[-NTU(1+C_r)]}{1+C_r}} \\$ ... $\displaystyle{\frac{NTU}{1+NTU}} \\$ $1 - \text{exp}(-NTU)$
The ratio of momentum diffusivity $(ν)$ to thermal diffusivity $(\alpha)$, is called Prandtl number Nusselt number Biot number Lewis number
A project consists of $7$ activities. The network along with the time durations (in days) for various activities is shown in the figure. The minimum time (in days) for completion of the project is_________