Question

a tube-within-a-tube heat exchanger operating at steady state is composed of one pipe containing
Refrigerant 134a and another pipe containing an ideal gas with constant specific heat at constant
pressure of 1.2 kJ/(kg∙K). The refrigerant 134a enters the heat exchanger in a saturated liquid state
and exits the heat exchanger in a saturated vapor state. The temperature and mass flow rate of the
refrigerant 134a are -20° C and 3 kgs/s, respectively, at both its inlet and outlet. The ideal gas enters
the heat exchanger with a temperature of 140° C. The mass flow rate of the ideal gas is 2 kg/s.
Determine the temperature in °C of the ideal gas exiting the heat exchanger. Assume the heat
exchanger is well-insulated and neglect kinetic and potential energy changes.

Answer 1

It is given that heat exchanger is well insulated and the main thing to note here that mass flow rate different for refrigerant and temperature difference is quite high so we will also get a low value of temperature fot ideal gas exit temperature.

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