In shortTotal capacity is calculated from the enthalpy difference between inlet and outlet air. The sensible part comes from the temperature difference and the latent part from dehumidification. Water flow is Q / (1.163·ΔT).
Result
Preliminary calculation: This tool is for quick sizing and information. In real projects, load calculation, selection and commissioning require engineering calculations and a site survey. Results are approximate values.
Formulas
Q_total = ṁ_air × [ (h1 − h2) − (w1 − w2)·4.186·T_condensate ]Q_sensible = ṁ_air × (1.006 + 1.86·w1) × (T1 − T2)Q_latent = Q_total − Q_sensible, V̇_water = Q / (1.163 × ΔT_water)The condensate quantity is determined by the difference in inlet and outlet humidity ratio. The drip pan and trap under the air handling unit should be sized for this quantity.
- For the target outlet air temperature, coil row count and water temperature are selected together
- If coil velocity is too high, droplet carry-over occurs
- A dirty coil reduces capacity; cleaning should be done periodically
Frequently asked questions
What is latent load?
It is the heat removed when moisture is taken out of the air (condensation). Sensible load is the heat that lowers the temperature.
Why does the condensate quantity matter?
It must be known for the sizing of the drip pan, trap and drain line, and for hygiene.
What does the water flow depend on?
On the total capacity and the selected water ΔT; as ΔT gets smaller, flow rate and pump load increase.