Calculating Cooling Loads

Calculating Cooling Loads Calculating chiller and cooling tower refrigeration in tons Sponsored Links

Cooling towers tons pairs the water-cooled chiller tons and the water-cooled condenser tons.

Chiller Refrigeration Tons A water-chiller refrigeration ton is defined as: 1 refrigeration ton = 1 TONScond = 12,000 Btu/h = 3,025.9 k Calories/h = 12,661 kJ/h 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: 288,000 BTU/24 hr = 12,000 BTU/hr Converting Btu to Tons of Refrigeration

Btu per hour

Tons of Refrigeration

6000

1/2

12000

1

18000

1 1/2

24000

2

30000

2 1/2

36000

3

42000

3 1/2

48000

4

54000

4 1/2

60000

5

Cooling Tower Tons A cooling tower ton is defined as: 1 cooling tower ton = 1 TONSevap = 1 TONScond x 1.25 = 15,000 Btu/h = 3,782 k Calories/h = 15,826 kJ/h The equivalent ton on the cooling tower side actually rejects about 15,000 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 (1,500 pound/hour) of water 10°F, which amounts to 15,000 Btu/hour, or a chiller coefficient-ofperformance (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/gal) q (60 min/h) dt = 500 q dt

(1)

where h = heat load (Btu/h) cp = 1 (Btu/lbm oF) for water ρ = 8.33 (lbm/gal) for water q = water volume flow rate (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 gal/min) (10 oF) / 12,000 = 0.42 ton