Hello.
I'm about to start on a project about regulating a blower fan after a SetPoint where the customer enters a required Nm³/h, and the blower delivers it. The PV are coming from a Differential Pressure Transmitter measuring over a "constriction-orifice" in the air-supply before it enters the blower. I'm told that I need to take the square-root of the measuring signal, and I will have the air flow for the PV to the regulator. So far so good.
But there are also a measurement of the temperature to compensate for the temperature affecting the volume-flow and this must affect the PV coming from the DP-cell. As I understand it, the normal flow is what defines the volume the air would occupy at a pressure of 101.325 kPa, and a temperature of 0 °C (may be 20°C).
Toady there are an old HW-regulator taking care of the regulating-loop, and the documentation does not show how the temperature affects the PV. I enclose a PDF showing the principle of the regulating loop as I understand it to be.
I would be very happy if someone could show me the direction of how to calculate the temperature compensation in this loop.
Regards From Knut A.B.
I'm about to start on a project about regulating a blower fan after a SetPoint where the customer enters a required Nm³/h, and the blower delivers it. The PV are coming from a Differential Pressure Transmitter measuring over a "constriction-orifice" in the air-supply before it enters the blower. I'm told that I need to take the square-root of the measuring signal, and I will have the air flow for the PV to the regulator. So far so good.
But there are also a measurement of the temperature to compensate for the temperature affecting the volume-flow and this must affect the PV coming from the DP-cell. As I understand it, the normal flow is what defines the volume the air would occupy at a pressure of 101.325 kPa, and a temperature of 0 °C (may be 20°C).
Toady there are an old HW-regulator taking care of the regulating-loop, and the documentation does not show how the temperature affects the PV. I enclose a PDF showing the principle of the regulating loop as I understand it to be.
I would be very happy if someone could show me the direction of how to calculate the temperature compensation in this loop.
Regards From Knut A.B.