Question

5. A 15 kg saturated steam has a pressure of 600 kPa and internal energy of 24,725 K. (a) Determine the quality of the saturated steam. (b) Determine the enthalpy of the saturated steam. 6. Air at 600 K flows with 3 kg/s into a heat exchanger and out at 100'C. Determine the amount (kg/s) of water coming in at 100 kPa, 20°C that the air can heat to the boiling point and the heat transfer rate (in kW) from air to the water. The inlet and exit enthalpies for air are 607 kJ/kg and 374 kJ/kg. respectively, and for water are 84 kJ/kg and 2675kJ/kg, respectively.

Answer 1

Sole 6 The values provided in question are :- Inlet Outlet temperature temperatue of of Air To, Air Ta = book = looc = 3731 Inlet outlet temperature of water Twi= 20°c=293 temperature of wales Tea, =loor = 373 mass flow rate of Heat Exchanger air na = 3 kg is frincille - book = Tar i na = 3kg 15 Taza 3731 37346 = Two, - w,=293k Now, Heat given by hot air = Heat absorbed by to Water mala (Thai - Taz) = in Co (Twy Two) Assuming Ca - Specific heat of air = 1ks 1kg K (w - Specific heat of water = 4.18 kg 1 kg k

Now, putting the valus in formula 3x1 [ 600-373] = mw x 4. 18 [373-2357 227x3 =hiw x 4.18 X 80 . mw 22 ax3 4.188 80 - 2.036 Therefore, mass flow rate of water in 2.036 kals. mo or Now , Heat by air to for mula - absorbed water heat tranffer given by is 2 m., С. (Тео) - То, ) 7 2.036 x 448 C 373-2930 Z 680.83 kw There fore Heat transtord by air to water at 200 intel temperature fill out let temperature (boiling point temperature i.e loo'c is 680.83 kW
Mass flow rate of water is 2.036 kg/s And

Heat absorbed or transfered by hot air to water is 680.83 KW.