) Water flows through a horizontal coil heated from the outside by high-temperature flue gases. As it passes through the coil the water changes state from liquid at 250 kPa and 70 to vapor at 150 kPa and 120 . Its entering velocity is 5 and its exit velocity is 220 . Determine the heat transferred through the coil per unit mass of water.

Respuesta :

Explanation:

Formula for steady flow energy equation for the flow of fluid is as follows.

    [tex]m[h_{1} + \frac{V^{2}_{1}}{2}] + z_{1}g] + q = m[h_{1} + \frac{V^{2}_{1}}{2} + z_{1}g] + w[/tex]

Now, we will substitute 0 for both [tex]z_{1}[/tex] and [tex]z_{2}[/tex], 0 for w, 334.9 kJ/kg for [tex]h_{1}[/tex], 2726.5 kJ/kg for [tex]h_{2}[/tex], 5 m/s for [tex]V_{1}[/tex] and 220 m/s for [tex]V_{2}[/tex].

Putting the given values into the above formula as follows.

     [tex]m[h_{1} + \frac{V^{2}_{1}}{2}] + z_{1}g] + q = m[h_{1} + \frac{V^{2}_{1}}{2} + z_{1}g] + w[/tex]  

     [tex]1 \times [334.9 \times 10^{3} J/kg + \frac{(5 m/s)^{2}}{2} + 0] + q = 1 \times [2726.5 \times 10^{3} + \frac{(220 m/s)^{2}}{2} + 0] + 0[/tex]

                q = 6597.711 kJ

Thus, we can conclude that heat transferred through the coil per unit mass of water is 6597.711 kJ.