Hi science community,
I am attempting to calculate the efficiency of an oil cooler that takes the form of a counterflow shell and tube heat exchanger.
In the shell is the oil which is being cooled from around 70*C to 40*C
In the tubes is pure Ammonia (R-717 refrigerant) which enters as a liquid and leaves as a gas.
I am very confused by the phase-change in the Ammonia.. do I use the heat of vaporization to find the Heat generation (Q_dot). (With this equation: Q_dot = m_dot * h_fg)?
I have been attempting to use this formula to find the efficiency:
Q_dot = e * C_min * (T_hot_in - T_cold_in)
with e being the efficiency.
Am I on the right track at all??
