ME 412 Heat Transfer Laboratory
Fall 2004
Refrigeration Experiment
MSU Chilled Water Plant Tour
Worksheet
Name:
Solution Key
Signature of TA to Verify Attendance:
(50 pts)
1. What devices in an absorption refrigeration system replace the compressor of a
conventional vapor/compression refrigeration system?
Generator and Absorber (Maybe Steam) (2 pts each)
2. Describe the four (4) fluid streams within a Trane absorption unit.
Steam into the generator, Cooling Tower Water into the absorber and condenser
Chilled Water into the evaporator, Lithium/Bromide-Water Solution as refrigerant
(2 pts each)
3. How does a cooling tower operate?
Water evaporates from the hot water stream into the air, cooling the water stream
due to evaporative heat loss. (10 pts)
4. What is the rated capacity of the chilled water plant in tons of refrigeration,
Btu/hr, and kW?
10,790 tons of refrigeration, 129.5 MBtu/hr, 37,950 kW (1 pt each)
5. Given the chilled water flow rate (from the pump) and the entering and exiting
temperatures of the chilled water stream for one of the absorption units,
calculate the actual cooling load (in tons of refrigeration) the unit is providing.
QL = mCWCp(Tin - Tout), for unit #6 T = 14F, for VCW = 2143 gpm, but mCW = 
VCW
3
evaluate properties at average temperature (52.5F), Cp = 4.819 kJ/kgK,  = 1000 kg/m
mCW = (1000)(2143)/(60)/(264.17) = 135.2 kg/s,
QL = (135.2)(4.189)(14)/(1.8)/(3.517), QL = 1252 tons (10 pts)
6. Determine the Carnot cycle COP for the absorption cycle used at the MSU
chilled water plant.
(COP)Carnot = 1/(TH/TL - 1), TH = 112F = 572R, TL = 40F = 500R
(COP)Carnot = 1/(TH/TL - 1) = 1/(572/500 - 1) = 6.94 (5 pts)
7. Using the Carnot cycle COP and assuming a cooling load of 1250 tons,
determine the required mass flow rate of steam in kg/s.
(COP)AC = QL/Qgen, Qgen = mstmhfg(@244F), hfg(@118C) = 2208 kJ/kg
QL = (1250)(3.517) = 4396 kW, mstm = (4396)/(6.94)/(2208) = 0.29 kg/s (10 pts)