Question

Steam at an initial enthalpy of 100 kJ/kg and inlet velocity of 100 m/s, enters an insulated horizontal nozzle. It leaves the nozzle at 200 m/s. The exit enthalpy (in kJ/kg) is

• A. 85

Answer 1

The correct option is A 85

Applying steady flow energy equation between section 1 and 2
$h_1+\frac{V_1^2}{2}+g{z}_1+q=h_2+\frac{V_2^2}{2}+g{z}_2+w$

where $q=0$ insulated nozzle
$z_1=z_2$ horizontal nozzle
$w=0$ always for nozzle
$h_1+\frac{V_1^2}{2000}=h_2+\frac{V_2^2}{2000}$
where $h_1$ and $h_2$ are in kJ/kg and $V_1$ and $V_2$ are in m/s

$\therefore$ $100+\frac{(100{)}^2}{2000}=h_2+\frac{(200{)}^2}{2000}$
$100+5=h-2+20$
or $h_2=85kJ/kg$