Non-intrusive thermal power monitor and method

A non-intrusive thermal power measuring apparatus for determining thermal power added to or taken from a fluid stream by a thermal power source or thermal power sink comprising:

• (a) reference heat application means for applying a known amount of heat to a fluid passing through a fluid carrying conduit and for obtaining a signal representative of the known amount of heat;
• (b) a first temperature sensor for measuring a fluid temperature on one side of the reference heat application means with respect to the direction of fluid flow and generating a first electrical signal in response thereto and as a function of the measured temperature, the first temperature sensor including a probe and means on such probe to permit its attachment to the conduit at least ten conduit diameters upstream of the heat application means;
• (c) a second temperature sensor for measuring the fluid temperature on the opposite side of the heat application means with respect to the direction of fluid flow and generating a second electrical signal in response thereto and as a function of such measured temperature, the second temperature sensor including a probe and means on such probe to permit its attachment to the conduit at least ten conduit diameters downstream of the heat application means;
• (d) a third temperature sensor for measuring fluid temperature at the opposite side of said power source or thermal power sink with respect to either of the first or second temperature sensors and generating an electrical signal representative of and a function of the temperature measured thereby;
• (e) thermal power determining means including means for subtracting the first signal from the second signal to obtain a temperature differential signal, dividing the temperature differential signal into the signal representative of the known amount of heat to derive a heat capacity rate of the fluid, using the third temperature signal to obtain an unknown source or sink temperature difference signal, and multiplying that temperature difference signal by the heat capacity rate to determine the thermal power contribution provided by the unknown thermal power source or sink.

An improved, non-intrusive meter for determining the energy or power contribution to a fluid stream from a source or sink comprising:

• (a) a heater adapted for attachment to a line through which the fluid stream is passing, the heater including an electrical heating element, insulation backing the heater element to prevent heat loss to the environment, and means for attaching the heater to the line;
• (b) a first temperature sensor including a temperature probe adapted to be attached to the line upstream from the heater to obtain a first temperature signal, the first temperature sensor having insulation to isolate its probe from the environment;
• (c) a second temperature sensor including a temperature probe adapted to be attached to the line downstream of the heater and upstream from the source or sink to obtain a second temperature signal, the second temperature sensor having insulation to isolate its probe from the environment;
• (d) a third temperature sensor including a temperature probe adapted to be attached to the line downstream from the source or sink to obtain a third temperature signal, the third temperature probe having insulation to isolate its probe from the environment;
• (e) means for providing a signal representative of an amount of energy or power supplied by the heater to the stream;
• (f) means to obtain a first temperature difference signal across the unknown source of the second and third temperature signals;
• (g) means to obtain a second temperature difference signal across the heater of the first and second temperature signals;
• and
• (h) means for multiplying the energy or power signal by the first temperature difference signal across the unknown source or sink and dividing that product by the second temperature signal difference across the heater to obtain the energy or power contribution or drain to the fluid stream from the source or sink.

A method for non-intrusively measuring the amount of thermal power contribution to or from a fluid stream flowing in a conduit, the method comprising:

• (a) supplying or removing a known amount of heat to a flowing fluid stream by or from a reference heat means without intrusion into the fluid stream and obtaining a reference electrical signal thereof;
• (b) measuring a first temperature of the fluid stream at least ten conduit diameters from the reference heat means without intrusion into the fluid stream and generating a first electrical signal in response thereto;
• (c) measuring a second temperature of the fluid stream without intrusion into the fluid stream on the opposite side of the reference heat means and at least ten conduit diameters from such heat means and generating a second electrical signal in response thereto;
• (d) taking the difference between the first and second electrical signals to provide a temperature differential signal across the reference heat means;
• (e) measuring a third temperature of the fluid stream with respect to an unknown thermal power source which adds thermal power to the stream or an unknown thermal power sink which removes thermal power from the fluid stream and generating a third electrical signal in response thereto;
• (f) electrically determining the heat capacity rate from the temperature differential signal and the reference signal of the amount of heat provided by or removed by the reference heat means;
• and
• (g) determining the amount of thermal power added to or removed from the fluid stream by the unknown source or sink using the third electrical signal and the heat capacity rate.