I am interested in discovering a method to relate air flow to temperature reduction efficiency.

The purpose of this is in application to atmospheric water generation.

The apparatus will involve a fan (with a CFM rating), a long coil that will be externally cooled, and the temperature it is cooled to with perhaps another post processing stage. That would involve the narrow diameter pipe opening into a larger diameter "dew point chamber" or a way to cool the air further by narrow to wider expansion.

All of the condensed water will be collected into a collection reservoir.

So, the question is: How can I relate the CFM (cubic feet per minute) of air flow, the diameter of the pipe, the length of the pipe, the temperature of the pipe, the diameter of the expansion chamber --> the amount of water collected?

I am not an engineer. I am a simple person with aspirations to design a viable atmospheric water generator. I do not want to discuss energy requirements. I only want to discuss the variables I have outlined.

EDIT: I understand the idea of relative humidity vs. water available to "mine" from the air via condensation. My question pertains to the apparatus itself and how the variables relate. My concern is a high air flow will only have a certain rate of cooling based upon the length, diameter, and temperature of the pipe. My goal is to develop, with someone's kind help, a sort of formula for determining the temperature of the starting air (ambient) and the output temperature based on the variables.

Thank you, my fellow smart humans!


1 Answer 1


This is a straightforward calculation for an engineer trained in the art of what is called HVAC (heating/ventilation/air conditioning) engineering but a full outlining of the solution process would require you to grasp many new physics concepts (most of which are not simple), an unfamiliar dictionary of engineering jargon, and the mastery of coupled algebraic equations. As such it is beyond the scope of what can be dealt with here. I would recommend that you partner up with an HVAC engineer to help you with this project.

  • $\begingroup$ Ya, I guess it is also pretty specific to design and method of refrigeration $\endgroup$
    – Michael S.
    Dec 9, 2018 at 20:40

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