Chapter 5, Problem 5.21CU

I need help going through the process to solve this problem, I think I have a general idea, but want to make sure I am doing it correctly. A counterflow heat exchanger operates at steady state while being well-insulated from the surroundings with air and ammonia flowing in separate streams. Ammonia enters at state 1 with -30°C and a quality of 30% and exits at state 2 as saturated vapor at -30°C. Air enters at state 3 with pressure 1 bar and temperature 295 K and exits at state 4 with pressure 1 bar and temperature 265 K. The flow rate of air is 10 kg/s. Ignore kinetic and potential energy effects, and take the dead state as 1 bar and 300 K. a. Describe the heat transfer inside the heat exchanger (what is transferring heat to what?) b. Determine the specific enthalpy of each state, in kJ/kg. c. Determine the mass flow rate of ammonia, in kg/s. d. Determine the rate of exergy destruction within the heat exchanger, in kW.e. Devise and evaluate an exergetic efficiency for the heat…

Oil enters a counterflow heat exchanger at 600 K with a mass flow rate of 10 kg/s and exits at 350 K. A separate stream of liquid water enters at 20°C, 5 bar. Each stream experiences no significant change in pressure. Stray heat transfer with the surroundings of the heat exchanger and kinetic and potential energy effects can be ignored. The specific heat of the oil is constant, c = 2 kJ/kg · K. If the designer wants to ensure no water vapor is present in the exiting water stream, what is the minimum mass flow rate for the water, in kg/s?

Oil enters a counterflow heat exchanger at 525 K with a mass flow rate of 10 kg/s and exits at 350 K. A separate stream of liquid water enters at 20°C, 5 bar. Each stream experiences no significant change in pressure. Stray heat transfer with the surroundings of the heat exchanger and kinetic and potential energy effects can be ignored. The specific heat of the oil is constant, c= 2 kJ/kg · K. If the designer wants to ensure no water vapor is present in the exiting water stream, what is the minimum mass flow rate for the water, in kg/s? mwater,min = i kg/s