Saturated refrigerant 134a vapor at 40°C is condensed as it flows through a tube at a rate of 0.2 kg/s. The condensate leaves the tube as saturated liquid at 40°C. The rate of heat transfer from the tube is

Question

Quizplus · Accepted Answer

Solved by EES Software. Solutions can be verified by copying-and-pasting the following lines on a blank EES screen. 
T1=40 "C"
 m_dot=0.2 "kg/s"
h_f=ENTHALPY(R134a,T=T1,x=0)
h_g=ENTHALPY(R134a,T=T1,x=1)
h_fg=h_g-h_f 
Q_dot=m_dot*h_fg
"Some Wrong Solutions with Common Mistakes:"
W1_Q=m_dot*h_f "Using hf"
W2_Q=m_dot*h_g "Using hg"
W3_Q=h_fg "not using mass flow rate"
W4_Q=m_dot*(h_f+h_g) "Adding hf and hg"

Saturated Refrigerant 134a Vapor at 40°C Is Condensed as It