Chapter 7, Problem 7.81P

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…

Question 18 Air enters a horizontal, constant-diameter heating duct operating at steady state at 290 K, 1 bar, with a volumetric flow rate of 0.23 m³/s, and exits at 325 K, 0.95 bar. The flow area is 0.04 m². Assuming the ideal gas model with k = 1.4 for the air, determine: (a) the mass flow rate, in kg/s, (b) the velocity at the inlet and exit, each in m/s, and (c) the rate of heat transfer to the air, in kW. Part A Determine the mass flow rate, in kg/s. kg/s m₁ = Part B Determine the velocity at the inlet and exit, each in m/s. V₁ = V₂ = Q m/s Part C Determine the rate of heat transfer to the air, in kW. = m/s KW

Refrigerant 22 in a refrigeration system enters one side of a counter-flow heat exchanger at 12 bar, 28°C. The refrigerant exits at 12 bar, 20°C. A separate stream of R-22 enters the other side of the heat exchanger as saturated vapor at 2 bar and exits as superheated vapor at 2 bar. The mass flow rates of the two streams are equal. Stray heat transfer from the heat exchanger to its surroundings and kinetic and potential energy effects are negligible. Determine the entropy production in the heat exchanger, in kJ/K per kg of refrigerant flowing. What gives rise to the entropy production in this application? Show state point 1 and 2, then 3 and 4 on a T-s diagram, show the process from 1 to 2 and from 3 to 4. ,(2) 12 bar 20°C 12 bar (1) 28°C (4) 2 bar (3) 2 bar sup. vapor sat. vapor

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

Question 14 kg/s

Figure shows a cooling tower operating at steady state. Warm water from an air-conditioning unit enters at 49°C with a mass flow rate of 0.5 kg/s Dry air enters the tower at 21 ° C, 1 atm with a volumetric flow rate of 1.41 m/s. Because of evaporation within the tower, humid air exits at the top of the tower with a mass flow rate of 1.64 kg/s. Cooled liquid water is collected at the bottom of the tower for return to the air-conditioning unit together with makeup water. Determine the mass flow rate of the makeup water, in kg/s. Humid air = 1.64 kg/s Cooling tower 4 Air conditioning unit Warm water inlet m = 0.5 kg/s Fan T,= 49°C Spray heads Dry air T, = 21°C P3 I bar (AV), = 1.41 m'/s Pump Return water Liquid 72 = 27°C %3D Makeup water

46. Air modeled as an ideal gas enters a well-insulated diffuser operating at steady state at 307 K with a velocity of 80 m/s and exits with a velocity of 25 m/s. For negligible potential energy effects, determine the exit temperature, in K. Use cp = 1.006 kJ/kg-K. a. 301 C. 319 b. 313 d. Answer is not among the choices

Steam enters a counterflow heat exchanger operating at steady state at 0.05 MPa with a quality of 0.9 and exits at the same pressure as saturated liquid. The steam mass flow rate is 1.7 kg/min. A separate stream of air with a mass flow rate of 100 kg/min enters at 30°C and exits at 60°C. The ideal gas model with c, = 1.005 kJ/kg-K can be assumed for air. Kinetic and potential energy effects are negligible. Determine the temperature of the entering steam, in °C. For the overall heat exchanger as the control volume, what is the rate of heat transfer, in kW. Step 1 Your answer has been saved. See score details after the due date. Determine the temperature of the entering steam, in °C. T1 = 81.317 °C Attempts: 1 of 1 used Step 2 For the overallI heat exchanger as the control volume, what is the rate of heat transfer, in kW. kW Save for Later Attempts: 0 of 1 used Submit Answer

Twenty m3/hr of air at 600 kPa, 330 K enters a well-insulated, horizontal pipe having a diameter of 1.2 cm and exits at 120 kPa. Assume steady state and use the ideal gas model for the air. Also assume constant specific heat, c, = 1.007 kJ/kg-K for air at 330 K. Determine the mass flow rate, in kg/s, and the exit velocity, in m/s. Step 1 Determine the mass flow rate, in kg/s. i kg/s Save for Later Attempts: 0 of 1 used Submit Answer Step 2 The parts of this question must be completed in order. This part will be available when you complete the part above.