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Cooling Tower Approach & Range Calculator

Cooling towers reject waste heat from industrial processes and chiller systems into the atmosphere through the evaporative cooling of recirculating water.

Warm water entering cooling tower distribution basin.

Cooled water leaving tower cold water basin.

Atmospheric wet-bulb temperature (thermodynamic limit).

Total circulating flow through the tower fill packing.

Ratio of dissolved solids in basin water vs. fresh makeup water.

Calculated Result
5 °C

Cooling Tower Approach

Cooling Range (ΔT)

6 °C

Thermal Approach

5 °C

Tower Effectiveness

54.5 %

Heat Rejection Duty

3,488 kW (992 TR)

Evaporation Loss

4.59 m³/h

Blowdown Loss

1.53 m³/h

Total Makeup Water

6.12 m³/h

Cycles of Concentration

4

Calculation Breakdown

  1. Cooling Range CalculationRange = T_hot_in (35°C) - T_cold_out (29°C) = 6 °C.
  2. Approach Temperature CalculationApproach = T_cold_out (29°C) - T_wet_bulb (24°C) = 5 °C.
  3. Cooling Tower Effectivenessη = Range / (Range + Approach) = 6 / 11 = 54.5%.
  4. Heat Rejection & Water BalanceHeat rejected = 3,488 kW. Evaporation = 4.59 m³/h, Blowdown = 1.53 m³/h for COC = 4.

Thermal & Hydraulic Profile

Interactive visualization based on your current inputs

Value
0.014274155Range (°C)Approach (°C)Effectiveness (%)Evaporation (m³/h)ParameterValue

What Is the Cooling Tower Approach & Range Calculator?

The Cooling Tower Approach & Range Calculator evaluates the thermal and hydraulic performance of industrial open-circuit and closed-circuit evaporative cooling towers.

How Does the Cooling Tower Approach & Range Calculator Work?

Cooling Range is the sensible heat dropped across the tower fill. Approach measures performance margin against local ambient humidity. Water losses are computed from enthalpy balances.

Cooling Tower Approach & Range Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

Approach = T_{cold} - T_{wb}, \quad Range = T_{hot} - T_{cold}, \quad \eta = \frac{Range}{Range + Approach} \times 100\%

Quantifies how close the cooled water approaches the theoretical ambient wet bulb temperature limit.

How to Use the Cooling Tower Approach & Range Calculator

  1. Enter hot inlet water temperature and desired cold outlet basin temperature.
  2. Input local design ambient wet-bulb temperature.
  3. Specify recirculating pump flow rate and water chemistry cycles of concentration.

Step-by-Step Example Calculation

Standard Industrial Cooling Tower Cell

Input Values:

hotWaterTemp:35
coldWaterTemp:29
wetBulbTemp:24
waterFlowRate:500
cyclesOfConcentration:4
Worked Steps: Gives a 6.0 °C range and 5.0 °C approach with 54.5% thermal effectiveness.

Understanding Your Result

Approach: T_cold - T_wb. Smaller approach requires exponentially larger fill volume.

Effectiveness: Percentage of theoretically available cooling achieved.

Evaporation & Blowdown: Hourly water balance for utility sizing.

Factors That Affect the Result

  • Wet-bulb temperature varies seasonally; peak summer design conditions dictate tower footprint sizing.

When Should You Use This Calculator?

  • HVAC chiller plant optimization, power plant condenser cooling, and refinery process water management.

Assumptions & Limitations

  • Assumes steady-state operation and standard sea-level barometric pressure.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Conforms to Cooling Technology Institute (CTI) guidelines.

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