Use the calculator below to estimate either (1) the liquid water (condensate/moisture) carried with wet steam from total steam flow and steam quality, or (2) the condensate produced when saturated steam condenses to meet a heat load. Select the appropriate tab for your known inputs.

Condensate Flow Rate Calculator

From Heat Load
From Steam Flow

How much condensate does this heat load produce?

Condensate Flow Rate
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Condensate Flow Rate Formulas

This page includes two common ways to estimate condensate flow rate, depending on what you mean by “condensate” and what data you have: (1) the liquid water (moisture) fraction carried with wet steam based on steam quality, and (2) the condensate generated by a heat load when saturated steam condenses.

\begin{aligned}
CFR &= SF\left(1-\frac{SQ}{100}\right) \\
CFR &= \frac{Q}{h_{fg}}
\end{aligned}

Variables:

  • CFR is the condensate (liquid water) mass flow rate (e.g., lb/hr, kg/hr)
  • SF is the total wet-steam mass flow rate (e.g., lb/hr, kg/hr)
  • SQ is the steam quality, x, expressed as a percent vapor by mass (0–100%)
  • Q is the heat load (e.g., Btu/hr or kW)
  • hfg is the latent heat of vaporization of saturated steam at the selected pressure (Btu/lb)

For the steam-quality method, multiply the total wet-steam flow by the liquid fraction (1 − x). For the heat-load method, divide the heat load by the saturated-steam latent heat (this assumes condensation of saturated steam and does not account for superheat or subcooling).

What is Condensate Flow Rate?

Condensate flow rate is the mass flow rate of liquid water (condensate) in a steam system. Depending on context, it may refer to (a) liquid water carried with wet steam (moisture present because the steam quality is less than 100%), or (b) condensate produced when steam gives up heat and condenses in equipment such as heat exchangers and coils. Steam quality (vapor mass fraction) is only used in case (a); for case (b), condensate depends primarily on the heat removed from the steam (latent heat).

How to Calculate Condensate Flow Rate?

The following steps outline how to calculate the Condensate Flow Rate.

  1. Choose a method: use Steam Quality (Moisture) if you have wet-steam flow and quality, or Heat Load if you know the heat duty and saturated steam pressure.
  2. For the steam-quality method, determine the total wet-steam flow (SF) in a mass flow unit (e.g., lb/hr).
  3. Determine the steam quality (SQ), which is the percent vapor by mass (0–100%).
  4. Compute CFR using the appropriate formula: CFR = SF × (1 − SQ/100) (steam-quality moisture) or CFR = Q / hfg (condensing saturated steam from a heat load).
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

steam flow (SF) = 500 lbs/hr

steam quality (SQ) = 90% (so the liquid water/moisture portion is CFR = 500 × (1 − 0.90) = 50 lbs/hr)