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Thermodynamics
A rural hospital requires 14,000 cfm of outdoor air for air conditioning.
The 14,000
cfm of outdoor air is at 95 deg F db and 78deg F wb and has to be cooled and
dehumidified to 54deg F db and 53deg F wb before being distributed to the
hospital rooms.
A refrigeration cycle using R134a as a refrigerant is to be used for this process.
The evaporator will operate at a saturation temperature of 35deg F and the
condenser operates at a saturation temperature of 110 deg F.
A diesel
engine is to be used to power the compressor of the refrigeration cycle.
This engine is to have a compression ratio of 20 and a cutoff ratio of 2.0.
In this area there is a source of biofuel available that has a heating value of
119,000 btu/gallon. You can assume an ideal diesel cycle and an ideal
refrigeration cycle for
your analysis.
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Thermodynamics
A.
What is the cooling capacity required for the refrigeration system?
________________btu/h
A. What is the mass flow of refrigerant required for the vapor compression cycle?
________Lbm/h
A. What is the power input required to operate the refrigeration cycle compressor?
_______Hp
A. What is the COP for this refrigeration cycle? ___________
A. What is the efficiency of the diesel engine cycle? ______________
F.
How many gallons per hour of biofuel
are required to operate this engine in
support of the refrigeration cycle?________________gal/hour
3
Thermodynamics
Diesel Engine,
r = 20,
r
c
= 2
Biofuel, 119,000 btu/gal
Condenser
Evaporator
Compressor
95 deg F db
78% rh
54 deg F db,
53 deg F wb
R134a Air
Conditioning Unit
14,000 cfm
110deg F, Satd liquid
35 deg F Sat’d
Vapor
1
2
3
4
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Thermodynamics
Strategy:
Use psychrometric analysis to find the cooling requirement for air
conditioning system in btu/h or tons.
Analyze refrigeration cycle using the cooling requirement to get the flow rate of
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This note was uploaded on 08/03/2011 for the course EML 3100 taught by Professor Sherif during the Summer '08 term at University of Florida.
 Summer '08
 Sherif

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