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Water Evaporator and Condenser Equations

Air conditioner heat loads and evaporator and condenser water flow rates.

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Total heat load:

h = c p ρ q dt

= 500 q dt                                          (1)


h = heat load (Btu/h)

c p = 1 (Btu/lb m o F) for water

ρ = 8.33 (lb m /gal) for water

q = water volume flow rate (gal/min)

dt = temperature difference ( o F)

Evaporator water flow rate can be expressed as

q evap = 24 h evap / dt                                         (2)


q evap = evaporator water flow rate (gallons per minute - gpm)

h evap = air condition load ( 1 refrigeration ton = 1 TONS cond = 12,000 Btu /h = 200 Btu/min = 3,025.9 k Calories /h = 12,661 kJ/h = 3517 kJ/s = 3517 kW = 4713 HP )

Condenser water flow rate can be expressed as

q cond = 30 h cond / dt                                         (3)


q cond = condenser water flow rate (gallons per minute - gpm)

h cond = air condition load, chiller tonnage ( 1 cooling tower ton = 1 TONS evap = 1 TONS cond x 1.25 = 15,000 Btu/h = 3,782 k Calories/h = 15,826 kJ/h )

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Related Topics

  • Air Conditioning

    Air Conditioning systems - heating, cooling and dehumidification of indoor air for thermal comfort.

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