Thermal Engg II (Unit I - Quiz 2)

Nozzle efficiency is given by

•  $\frac{h_1-h_{3s}}{h_1-h_3}$  

•  $\frac{h_1-h_3}{h_1-h_{3s}}$  

•  $\frac{h_1-h_3}{h_{1s}-h_3}$  

•  $\frac{h_{1s}-h_3}{h_1-h_3}$  

In the figure shown,

• Frictional loss in divergent portion

• Frictional loss in convergent portion

• No frictional loss

• Frictional loss in both in convergent and divergent portion

During expansion of steam in a nozzle as shown in figure, the condition of steam at throat i.e. at state 2 is

• Wet

• Saturated

• Supersaturated

• Superheated

 $\frac{mv_2}{V_2}$  With respect to the nozzle shown, this equation gives ____________ (Note m - mass flow rate)

• Area of nozzle at throat

• Area of nozzle at exit

• Area of nozzle at inlet

• None of the above

When inlet velocity is considered in a nozzle, the following equation can be used to calculate the velocity at throat

• $44.72\ \sqrt{h_1-h_2}$

• $44.72\sqrt{h_{01}-h_2}$

• $44.72\sqrt{h_2-h_1}$

• $44.72\sqrt{h_2-h_{01}}$

During expansion of steam through a nozzle as shown in figure, the condition of steam at throat is

• Superheated

• Wet

• Saturated

• Supersaturated

During expansion in a convergent - divergent nozzle, the enthalpy of steam under isentropic conditions:

at inlet section 1-1 is 3100 kJ/kg;

at throat section 2-2, 2900 kJ/kg and

at exit section 3-3, 2700 kJ/kg

If there is a frictional loss of 15 % of overall enthalpy drop in divergent portion, What would be the enthalpy at exit.

• 2770 kJ/kg

• 2640 kJ/kg

• 2760 kJ/kg

• 2670 kJ/kg

During expansion in a convergent - divergent nozzle, the enthalpy of steam under isentropic conditions:

at inlet section 1-1 is 3100 kJ/kg;

at throat section 2-2, 2900 kJ/kg and

at exit section 3-3, 2700 kJ/kg

If there is a frictional loss of 50 kJ in divergent portion, What would be the enthalpy at exit.

• 2650 kJ/kg

• 2750 kJ/kg

• 2950 kJ/kg

• 2850 kJ/kg

In the figure, superheated steam at state 1, after reaching state a, expands under supersaturated condition. The temperature of steam at state b is

• Equal to $T_{sat}$ at $p_2$

• Greater than $T_{sat}$ at $p_2$

• Less than $T_{sat}$ at $p_2$

• None of the above

The degree of supersaturation is

• $\frac{p_b}{p_{b_{sat}}}$

• $\frac{p_{b_{sat}}}{p_b}$

• $\frac{p_2}{p_b}$

• $\frac{p_b}{p_2}$