Q$3[16$ marks$]$

A rectangular tube, $30mm50mm,$ carries water at a rate of $2k\frac{g}{s}.$ Determine the length required to heat water from $30C$ to $50C$ if the wall temperature is maintained at $60C.$ Use the following properties of water at $N\frac{s}{m},k=0\mathrm{.}634\frac{W}{m}K.,Cp=4174\frac{J}{k}gK).$

laminar Flow$)$ turbulent Flow$)$