a)
The rate of heat transfer of air stream.
a)
Answer to Problem 81P
The rate of heat transfer of air stream is
Explanation of Solution
Write the expression to obtain the volume flow rate
Here, diameter is D, and velocity of air is
Write the expression to obtain the mass flow rate of dry air through the cooling section
Here, volume flow rate of air entering the cooling section is
Apply the water mass balance equation to the combined cooling and dehumidification section.
Here, initial and final mass flow rate of dry air is
Apply the water energy balance equation to the combined cooling and dehumidification section.
Here, the amount of energy rate required for cooling coils is
Conclusion:
Refer Table A-4E, “Saturated water – Temperature table”, write the value of saturation pressure of liquid
Refer Table A-5E, “Saturated water – Temperature table”, obtain the properties of water at a temperature of
Refer Fig A-31E, “Psychrometric chart at 1 atm total pressure”, at inlet temperature
Refer Fig A-31E, “Psychrometric chart at 1 atm total pressure”, at exit temperature
Refer Table A-4E, “Saturated water – Temperature table”, write the value of enthalpy at saturation liquid
Substitute 1 ft for D and
Substitute
Substitute
Substitute
Thus, rate of heat transfer of air stream is
b)
The mass flow rate of cooling water.
b)
Answer to Problem 81P
The mass flow rate of cooling water is
Explanation of Solution
Write the expression to obtain the mass flow rate of cooling water
Here, specific heat of water is
Conclusion:
Substitute
Thus, the mass flow rate of cooling water is
c)
The exit velocity of the airstream.
c)
Answer to Problem 81P
The exit velocity is
Explanation of Solution
Apply the conservation of mass of dry air to calculate exit velocity
Conclusion:
Substitute
Thus, the exit velocity is
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Chapter 14 Solutions
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