Evaporator Size Calculator

Plan coil size using airflow, temperatures, and moisture conditions. Compare loads with clear results instantly. Export reports, study formulas, and graph performance trends easily.

Calculator Inputs

The page stays in a single-column flow, while the input controls use a responsive 3-column, 2-column, and 1-column grid.

Reset

Example Data Table

This sample case uses the default values preloaded in the calculator.

Airflow Entering Air Leaving Air Evap. Temp U Value Total Load Area with Safety Estimated Coil Size Rows
8,500.00 m³/h 30.00 °C / 60.00% 14.00 °C / 92.00% 7.00 °C 55.00 W/m²·K 89.50 kW 135.51 m² 1.23 × 0.77 m 15

Formula Used

1) Humidity Ratio

W = 0.62198 × Pv / (Patm − Pv)
Here, Pv is the vapor partial pressure from dry bulb temperature and relative humidity.

2) Air Enthalpy

h = 1.006T + W(2501 + 1.86T)
This estimates moist-air enthalpy in kJ/kg dry air.

3) Total Cooling Load

Qtotal = ṁdry × (hin − hout)
It gives the evaporator load in kW.

4) Sensible Cooling Load

Qsensible = ṁdry × 1.006 × (Tin − Tout)
Latent load equals total load minus sensible load.

5) Log Mean Temperature Difference

LMTD = (ΔT1 − ΔT2) / ln(ΔT1 / ΔT2)
Where ΔT1 = Tin − Tevap and ΔT2 = Tout − Tevap.

6) Required Coil Area

A = (Q × 1000) / (U × LMTD)
A safety factor is then added for practical selection.

7) Face Area

Aface = V̇ / Face Velocity
This helps estimate frontal dimensions and coil proportions.

How to Use This Calculator

Step 1

Enter the design airflow in cubic meters per hour. Use the project supply air value planned for the evaporator section.

Step 2

Fill in entering and leaving air dry bulb temperatures and relative humidity values. These conditions define sensible and latent performance.

Step 3

Enter the evaporating temperature, overall heat transfer coefficient, and design face velocity. These directly affect coil area and frontal size.

Step 4

Set the safety factor, aspect ratio, surface enhancement factor, and daily operating hours. These improve practical sizing and energy visibility.

Step 5

Press the calculate button. The results appear immediately below the header and above the form, including graph, summary table, and export options.

Frequently Asked Questions

1) What does this calculator estimate?

It estimates evaporator cooling load, coil area, frontal face area, approximate width and height, coil rows, moisture removal, and daily cooling energy for construction cooling applications.

2) Why is entering and leaving humidity needed?

Humidity affects latent cooling. Without it, the calculator cannot estimate enthalpy change accurately, and total evaporator size may be underestimated.

3) What is the U value in this tool?

The U value is the overall heat transfer coefficient. It combines coil, fin, and air-side transfer behavior into one practical sizing input.

4) Why is a safety factor included?

A safety factor gives additional coil area beyond the theoretical minimum. It helps cover fouling, selection margins, and real installation conditions.

5) What does estimated coil rows mean?

It is a planning estimate based on required transfer area, face area, and the entered surface enhancement factor. Final manufacturer selection may differ.

6) Can I use this for retrofit work?

Yes. It is useful for retrofit checks, concept design, and quick comparisons. Final procurement should still be confirmed with detailed equipment data.

7) What if the results look too large?

Check airflow, evaporating temperature, U value, and leaving conditions first. Large loads or small temperature differences can increase required coil area significantly.

8) Do the CSV and PDF buttons export the results?

Yes. After calculation, both buttons export the summary results. They also include the performance table used for the graph.

Related Calculators

Room BTU calculatorCoil bypass factor calculatorCooling tonnage calculatorsubcooling calculatorkw to btu calculator

Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.