A $6$ m long and $8$ cm diameter horizontal hot $4$ yaterpipe passes through a large room whose temperature is $20C.f$ the outer surface temperature of the pipe is $70C,$ determine the rate of heat loss from the pipe by natural convection. The properties of $ai{r}_{at}45C$ are, $K=0\mathrm{.}02699\frac{W}{m}K,Pr=0\mathrm{.}7221,v={1\mathrm{.}749}^{**}{10}^{-5}\frac{m^2}{sec},$ dse correlation $=[0\mathrm{.}6+(\frac{A}{B}){]}^2$ Where, $A=0\mathrm{.}387(Gr.Pr{)}^{(\frac{1}{6})}$ and $B=[1+(\frac{0\mathrm{.}559}{P}r{)}^{(\frac{9}{6})}{]}^{(827)}$

$[8]$