Question

Water at 80 deg. F and 20 psia is heated in a chamber by mixing it with saturated water vapor at 20 psia. If both streams enter the mixing chamber at the same mass flow rate, determine a) the temperature (Ans. approx 230 deg. F) and b) the quality of the exiting steam (Ans. around 0.4).

Answer 1

see explain

Step-by-step explanation:

Given that,

Water pressure P 1 = 20 psia

Water temperature T 1 = 80F

Steam pressure P 2 = 20 psia

Calculating the enthalpy of steam and water at given pressure and temperature by using a steam table

h 1 = 48.07 BTU/lb

h 2 = 1156.20 BTU/lb

The enthalpy of water is determine using the saturated liquid approximation for the given temperature with the data from A -4E. the enthalpy of the vapor is determine from A - 5E for given pressure .the enthalpy of the mixture is determine from the energy balance.

`m_1h_1 + m_2h_2 = m_3h_3\\m_1h_1 + m_2h_2 =2mh_3\\h_3 = (h_1 + h_2)/(2) \\= (48.07 + 1156.2)/(2) \\602.135(btu)/(ibm) \\`

the quality of the mixture is determine from the total enthalpy and the enthaipies of the constituent at the given pressure obtained from A - 5E

`q = (h_3 - h_l_i_q_2_0)/(h_e_v_a_p_2_0) \\ = (602.135 - 196.27)/(959.93) \\ = 0.423`

≅ 0.4

the mixture temperature is simply the saturation temperature for the given pressure obtain from A - 5E

T₃ = 227.92°F

≅ 230°F