Water flows through a horizontal coil heated from the outside by high temperature flue gases. as it passes through the coil water changes state from liquid at 200 kpa and 80 c to vapor at 100 kpa and 125

c. its entering velocity is 3 m s-1 and its exit velocity is 200 m s-1. determine the heat transferred through the coil per unit mass of water. enthalpies of the inlet and outlet streams are 334.9 and 2,726.5 kj kg-1, respectively.

Question

Asia Riley

Physics

31 March, 18:44

Water flows through a horizontal coil heated from the outside by high temperature flue gases. as it passes through the coil water changes state from liquid at 200 kpa and 80 c to vapor at 100 kpa and 125

c. its entering velocity is 3 m s-1 and its exit velocity is 200 m s-1. determine the heat transferred through the coil per unit mass of water. enthalpies of the inlet and outlet streams are 334.9 and 2,726.5 kj kg-1, respectively.

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Londyn · Answer 1

For the steady flow process, the first law is written like

DH + Du2/2 + gDz = Q + Ws

since there is no shaft work, Ws = 0

and flow is horizontal, Dz = 0

Therefore,

DH + Du2/2 = Q

substituting for the quantities,

(2726.5 - 334.9) x 1000 + (200^2 - 3^2) / 2 = Q (in terms of J/kg)

Q = 2411.1 kJ/kg

Heat transferred through the coil per unit mass of water = 2411.1 kJ