Cooling Tower Thermal Rating and Upgrade — online
Predict cold water for any weather, flow, load or fan condition — and compare fill, fan and extra-cell upgrades with payback.
Yellow cells are inputs; orange cells are choices; blue cells choose the unit. Select or hover over an input to see its help in the box below the toolbar. The sheet is the same as the Excel tool (USD 49) — the Guide, method and references are in the Excel file.
What this cooling tower thermal rating and upgrade calculator does
Know what your tower will do next summer, and which upgrade actually pays. Predict cold water for any weather, flow, load or fan condition — and compare fill, fan and extra-cell upgrades with payback.
- Merkel rating. Design KaV/L and fill characteristic from your design point; predicted cold water at any wet-bulb, flow, load or fan power.
- Four cases at once. For example design, summer peak, extra flow and one fan off.
- Fan-off and stopped cells. Natural-draft air through a stopped cell and mixed cold water by mass balance.
- Upgrade options. High-efficiency fill, bigger fans or an extra cell — colder water, extra heat load and payback for each.
- Measured-test check. Capability from a measured test by the characteristic-curve approach.
- Predicted curves. Cold water against wet-bulb for 90/100/110 % flow, ready to print.
What you enter
- Tower characteristic from
- Design water flow (whole tower)
- Design hot water temperature
- Design cold water temperature
- Design inlet wet-bulb temperature
- Design L/G (water ÷ dry-air mass flow)
- Fill characteristic exponent n
- Site barometric pressure
- Design fan power per cell
- Air through a stopped-fan cell (% of design air)
- Process cold-water limit (highest acceptable)
- Electricity price
- Operating time
- Value of 1 °C colder cold water
What you get
- Design range (hot − cold)
- Design approach (cold − wet-bulb)
- Design heat rejected
- Tower characteristic KaV/L at design (Merkel)
- Characteristic coefficient C (as designed)
- Test L/G (from flow and fan power)
- Test KaV/L (Merkel)
- Characteristic coefficient C (from the test)
- Tower capability (test C ÷ design C)
- KaV/L used for predictions (at design L/G)
- Range
- Hot water temperature
- Cold water temperature (predicted)
- Approach to wet-bulb
Related
- Free quick calculator — a simpler free version for a fast estimate.
- Calculation guide — the equations behind this tool, with a worked example.
- Cooling Tower Thermal Rating and Upgrade Excel tool — USD 49, keep the workbook and its Guide.
- All 40 online tools
Questions
Is the cooling tower thermal rating and upgrade calculator free?
You can enter and check all your data free. The full results, findings and printable sheet are unlocked with a 3-run pack (USD 9), a monthly subscription to all 40 online tools (USD 15) or a yearly one (USD 99).
Are the results the same as the Excel tool?
Yes. The online tool runs the formulas of the Cooling Tower Thermal Rating and Upgrade Excel workbook, checked cell by cell against the Excel file.
Which units can I use?
SI, US customary and British units — choose the unit next to each input.