Dual-purpose heater and fluid flow measurement system
A control system for use in a fluid flow application includes a heater and a control device. The heater has at least one resistive heating element and the heater is operable to heat fluid. The control device determines at least one flow characteristic of a fluid flow based on a heat loss of the at least one resistive heating element and determines a mass flow rate of the fluid based on the at least one flow characteristic and a property of the at least one resistive heating element. And the property of the at least one resistive heating element includes a change in resistance of the at least one resistive heating element under a given heat flux density.
1. A control system for use in a fluid flow application having a fluid flow pathway, the control system comprising:
a heater having at least one resistive heating element, the heater operable as a primary heater to heat and influence a temperature of fluid provided in the fluid flow pathway and operable to measure an electrical characteristic of the at least one resistive heating element, wherein the electrical characteristic includes a resistance of the at least one resistive heating element; and
a controller configured to:
calculate a heat flux based on a change in resistance of the at least one resistive heating element;
determine at least one flow characteristic of the fluid flowing in the fluid flow pathway based on the heat flux; and
determine a mass flow rate of the fluid based on the at least one flow characteristic.
2. The control system according to claim 1 , wherein the at least one resistive heating element includes a plurality of resistive heating elements provided along the fluid flow pathway, and the controller is configured to determine the at least one flow characteristic based on heat loss of the plurality of resistive heating elements.
3. The control system according to claim 2 , wherein based on the heat loss of the plurality of resistive heating elements, the controller is configured to calculate an average fluid temperature, an average flow speed, or a combination thereof as the at least one flow characteristic.
4. The control system according to claim 2 , wherein the at least one flow characteristic is selected from the group consisting of fluid speed, fluid pressure, fluid temperature, fluid turbulence, and combinations thereof.
5. The control system according to claim 2 , wherein the controller is configured to determine calculate the heat flux for each of at least two of the plurality of resistive heating elements.
6. The control system according to claim 5 , wherein the controller is configured to calculate the heat flux for each of the at least two resistive heating elements using at least one of known fluid properties, known dimensions of the at least two resistive heating elements, and known dimensions of a flow channel adjacent the at least two resistive heating elements.
7. The control system according to claim 6 , wherein the controller is configured to calculate the heat flux for each of the at least two resistive heating elements using a calculated pressure at each of the at least two resistive heating elements.
8. The control system according to claim 7 , wherein the controller is further configured to re-calculate a temperature and a fluid flow rate at each of the at least two resistive heating elements as a function of the calculated pressure at each of the at least two resistive heating elements.
9. The control system according to claim 7 , wherein the controller is further configured to recalculate a temperature and a fluid flow rate at each of the at least two resistive heating elements as a function of a difference in calculated pressures between the at least two resistive heating elements.
10. The control system according to claim 7 , wherein the controller is further configured to re-calculate a temperature and a fluid flow rate at each of the at least two resistive heating elements as a function of the calculated pressure at each of the at least two resistive heating elements and as a function of a difference in calculated pressures between the at least two resistive heating elements.
11. The control system according to claim 1 , wherein the at least one flow characteristic is selected from the group consisting of fluid speed, fluid pressure, fluid temperature, fluid turbulence, and combinations thereof.
12. The control system according to claim 1 , wherein the heater further comprises ceramic insulation surrounding the at least one resistive heating element and a metal sheath surrounding the ceramic insulation.
13. The control system according to claim 1 , wherein the controller is further configured to receive the at least one flow characteristic from the at least one resistive heating element and flow characteristics from an engine control module to determine heater performance of the heater and mass flow measurement performance in the engine control module.
14. The control system according to claim 13 , wherein the controller is further configured to determine inconsistencies between the at least one flow characteristic received from the at least one resistive heating element and the flow characteristics received from the engine control module.
15. A control system for use with a vehicle exhaust system having an exhaust gas flow pathway, the control system comprising:
a heater having at least one resistive heating element, the heater being operable as a primary heater to heat and influence a temperature of an exhaust gas provided in the exhaust gas pathway and operable to measure an electrical characteristic of the at least one resistive heating element, wherein the electrical characteristic includes a resistance of the at least one resistive heating element; and
a controller configured to:
calculate a heat flux based on a change in resistance of the at least one resistive heating element;
determine at least one flow characteristic of the exhaust gas flowing in the exhaust gas flow pathway based on the heat flux; and
determine a mass flow rate of the exhaust gas based on the at least one flow characteristic,
wherein the at least one flow characteristic is selected from the group consisting of exhaust gas flow speed, exhaust gas pressure, exhaust gas temperature, exhaust gas turbulence, and combinations thereof.
16. The control system according to claim 15 , wherein the at least one resistive heating element includes a plurality of resistive heating elements provided along the exhaust gas flow pathway, and the controller is configured to determine the at least one flow characteristic based on heat loss of the plurality of resistive heating elements.
17. The control system according to claim 16 , wherein the controller is configured to calculate the heat flux for each of at least two of the plurality of resistive heating elements.
18. The control system according to claim 17 , wherein the controller is configured to calculate the heat flux for each of the at least two resistive heating elements using at least one of known exhaust gas properties, known dimensions of the at least two resistive heating elements, and known dimensions of an exhaust pipe adjacent the at least two resistive heating elements.
19. The control system according to claim 18 , wherein the controller is configured to calculate the heat flux for each of the at least two resistive heating elements using a calculated pressure at each of the at least two resistive heating elements.
20. The control system according to claim 19 , wherein the controller is configured to re-calculate a temperature and a fluid flow rate at each of the at least two resistive heating elements as a function of the calculated pressure at each of the at least two resistive heating elements.