Relationship Between Fan RPM, Power Consumption, and Airflow Efficiency

Hi Guys,

I just want to ask if there is a relation between fan RPM and the fan power consumption.
Because in some specifications I see, Power consumption is not consistently increasing as you increase the Fan RPM.

If we lower the RPM , will we still achieve the same airflow?
if we always set at low RPM, will it take longer time to transfer heat?
Then If it takes longer time, will the power consumption then get bigger and not smaller?

Please correct me if I'm wrong,

Thanks for your time

An engine's or electric motor's (in your case with the fan) output power is expressed as its torque multiplied by its rotational speed of the axis (and your rpm is a measurement for that rotational speed). Power is pretty much dependent on the Torque and rpm of which are both measured as quantities of engine output.

Lowering your RPM (Revolutions per minute) may cause some changes with your airflow. By heat, do you mean the amount of heat produced at the motor? The amount of time that your fan is working is also proportional to amount of power being consumed since energy is continually consumed to keep the motor running.

Thank you for your comments.

To clarify this problem, the heat I was referring to is the heat being transferred in a heat exchanger system. I was thinking if the airflow was reduce it will take longer time to transfer the heat from inside to outside.

The reason I'm asking this is that I have a project to design a heat exchanger.
However , the fan spec we used has a power consumption of 145W, but customer only requires 95W per fan.
The problem is we already ordered it and we are looking for solutions.
Is it possible to lower the power consumption from 145 to 95W?

Thanks