Expert Q&A 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 -20°C and a quality of 20% and exits at state 2 as saturated vapor at -20°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. Sketch states 1 and 2 on a T-s diagram, including the liquid-vapor dome. b. Describe the heat transfer inside the heat exchanger (what is transferring heat to what?) Determine the specific enthalpy of each state, in kJ/kg. d. Determine the mass flow rate of ammonia, in kg/s. Determine the rate of exergy destruction within the heat exchanger, in kW. f. Devise and evaluate an exergetic efficiency for the heat exchanger.

Expert Q&A 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 -20°C and a quality of 20% and exits at state 2 as saturated vapor at -20°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. Sketch states 1 and 2 on a T-s diagram, including the liquid-vapor dome. b. Describe the heat transfer inside the heat exchanger (what is transferring heat to what?) Determine the specific enthalpy of each state, in kJ/kg. d. Determine the mass flow rate of ammonia, in kg/s. Determine the rate of exergy destruction within the heat exchanger, in kW. f. Devise and evaluate an exergetic efficiency for the heat exchanger.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter7: Forced Convection Inside Tubes And Ducts

Section: Chapter Questions

Problem 7.49P

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