Nitrogen enters a steady-flow heat exchanger at 150 kPa, 10°C, and 100 m/s, and it receives heat in the amount of 120 kJ/kg as it flows through it. Nitrogen leaves the heat exchanger at 100 kPa with a velocity of 200 m/s. Determine thejvlach number of the nitrogen at the inlet and the exit of the heat exchanger.

Step 1 </p>

Nitrogen enters a steady flow heat exchanger with velocity 100 m/s and leaves with velocity 200 m/s. The temperature in the inlet is 100C and we need to find out the temperature in the outlet .

Internal energy qin =120 KJ/kg

The gas constant of nitrogen R =0.2968 KJ/kg K

The specific heat of nitrogen, cp =1.040 KJ/kg K

Step 2</p>

The speed of the nitrogen at the inlet

C1 =

C1 =

C1 =342.9 m/s

Step 3</p>

The mach number at the inlet

Ma1 ==

Ma1 =0.292

Step 3</p>

To find out the speed at the outlet the T value is unknown so it can find out by using the steady flow balance equation.

qin =cp(T2 -T1)+

120 KJ/kg =(1.040)(T2 -100)+

120=(1.040)(T2 -100C)+15

120-15=(1.040)(T2 -100C)

=(T2 -100C)

100.96=(T2 -100C)

T2 =100.96+100C

T2 =1110C

T2 =384 K