The process of cooling is called refrigeration. Refrigeration or cooling capacity can be measured in tons.
A water-chiller refrigeration ton is defined as:
A water-chiller refrigeration ton is defined as:
1 Refrigeration Ton (RT) = 1 TONScond = 12000 Btu/h = 200 Btu/min = 3025.9 k Calories/h = 12661 kJ/h = 3.517 kW
1 kW = 0.2843 Refrigeration Ton (RT)
A ton is the amount of heat removed by an air conditioning system that would melt 1 ton (2000 lbs.) of ice in 24 hours. The heat required to melt 1 lb of ice at 32 oF to water is 144 Btu.
1 Ton Refrigeration = (2000 lb) (144 Btu/lb) / (24 hr)
= 12000 Btu/hr
Converting between Btu/h and Tons of Refrigeration
| Btu/h | Refrigeration Ton | kW |
|---|---|---|
| 6000 | 1/2 | 1.76 |
| 12000 | 1 | 3.52 |
| 18000 | 1 1/2 | 5.28 |
| 24000 | 2 | 7.03 |
| 30000 | 2 1/2 | 8.79 |
| 36000 | 3 | 10.6 |
| 42000 | 3 1/2 | 12.3 |
| 48000 | 4 | 14.1 |
| 54000 | 4 1/2 | 15.8 |
| 60000 | 5 | 17.6 |
Cooling Tower Tons
A cooling tower ton is defined as:
1 cooling tower ton = 1 TONSevap = 1 TONScond x 1.25 = 15000 Btu/h = 3782 k Calories/h = 15826 kJ/h = 4.396 kW
The equivalent ton on the cooling tower side actually rejects about 15000 Btu/h
due to the heat-equivalent of the energy needed to drive the chiller's
compressor. This equivalent ton is defined as the heat rejection in
cooling 3 U.S. gallons/minute (1500 pound/hour) of water 10°F, which amounts to 15000 Btu/hour, or a chiller coefficient-of-performance (COP) of 4.0 - a COP equivalent to an energy efficiency ratio (EER) of 13.65.Heat Load and Water Flow
A water systems heat load in Btu/h can be simplified to:h = cp ρ q dt
= (1 Btu/lbm oF) (8.33 lbm/US gal) q (60 min/h) dt
= 500 q dt (1)
where
h = heat load (Btu/h)
cp = specific heat, 1 (Btu/lbm oF) for water
ρ = 8.33 (lbm/US gal) for water
q = water volume flow rate (US gal/min)
dt = temperature difference (oF)
Example - Water Chiller Cooling
Water flows with 1 gal/min and 10oF temperature difference. The ton of cooling load can be calculated as:Cooling load = 500 (1 US gal/min) (10 oF) / 12000
= 0.42 ton
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