Thermal mass fluid flow sensor

A flow probe comprising:

• a housing with walls forming a conduit to allow a liquid to flow therethrough, the housing further forming a cavity such that the walls form an inner layer between the conduit and the cavity;
• a thermally-conductive material deposited within the cavity formed by the housing such that a flow of liquid is between opposite portions of the thermally-conductive material and such that the inner layer is between a liquid flowing in the conduit and the thermally-conductive material such that the inner layer prohibits physical contact between the liquid flowing through the conduit and the thermally-conductive material;
• a heating element coupled to an outer portion of the walls with a portion of the heating element penetrating through the walls to be in thermal contact with the thermally-conductive material so that the heating element is not exposed to the conduit;
• a proximal temperature sensor upstream of the heating element, the proximal temperature sensor coupled to an outer portion of the walls with a portion of the proximal temperature sensor penetrating through the walls to be in thermal contact with the thermally-conductive material so that the proximal temperature sensor is not exposed to the conduit;
• a distal temperature sensor downstream of the heating element, the distal temperature sensor coupled to an outer portion of the walls with a portion of the distal temperature sensor penetrating through the walls to be in thermal contact with the thermally-conductive material so that the distal temperature sensor is not exposed to the conduit;
• and
• a controller in communication with the heating element, the proximal temperature sensor, and the distal temperature sensor, the controller configured to:
• control the heating element to apply heat to the thermally-conductive material;
• determine an upstream temperature based at least in part on signals received from the proximal temperature sensor;
• determine a downstream temperature based at least in part on signals received from the distal temperature sensor;
• adjust a heater power provided to the heating element based at least in part on a determined temperature differential between the downstream temperature and the upstream temperature, the adjustment to the heater power being configured to achieve an adjustable targeted temperature differential;
• and
• determine, when the targeted temperature differential has been achieved, a liquid flow rate using the adjusted heater power provided to the heating element, and the achieved targeted temperature differential between the downstream temperature and the upstream temperature.