Dual-purpose heater and fluid flow measurement system
A control system for use in a fluid flow application is provided. The control system includes a heater having at least one resistive heating element. The heater is adapted to heat the fluid flow. The control system further includes a control device that uses heat loss from at least one resistive heating element to determine flow characteristics of the fluid flow.
1. A control system for use in a fluid flow application comprising:
a heater having at least one resistive heating element having a relationship between resistance and temperature defining a non-monotonic curve, the heater operable to heat fluid flow; and
a control device that uses a change in resistance of the at least one resistive heating element to determine mass flow rate of the fluid flow and a temperature of the at least one resistive heating element along the non-monotonic curve between resistance and temperature.
2. The control system according to claim 1 , wherein the mass flow rate is based on flow characteristics selected from the group consisting of temperature of the fluid flow, speed of the fluid flow, geometry of a passageway for the fluid flow, pressure of the fluid flow, density of the fluid flow, and combinations thereof.
3. The control system according to claim 1 , wherein the control device is operable to determine flow characteristics, the flow characteristics are selected from the group consisting of fluid speed, fluid pressure, fluid temperature, fluid turbulence, and combinations thereof.
4. 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.
5. The control system according to claim 1 , wherein the at least one resistive heating element includes a plurality of resistive heating elements provided along a fluid flow pathway, and the control device determines at least one flow characteristic based on the change in resistances of the plurality of resistive heating elements.
6. The control system according to claim 5 , wherein based on the change in resistances of the plurality of resistive heating elements, the control device calculates an average fluid temperature, an average flow speed, or a combination thereof as the at least one flow characteristic.
7. The control system according to claim 5 , 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.
8. The control system according to claim 1 , wherein the control device is operable to receive fluid flow characteristics from the at least one resistive heating element and fluid flow characteristics from an engine control module to determine heater performance of the heater and mass flow measurement performance in the engine control module.
9. The control system according to claim 8 , wherein the control device is operable to determine inconsistencies in the fluid flow characteristics received from the at least one resistive heating element and the engine control module.
10. The control system according to claim 8 , wherein the control device is operable to reduce power to the heater when inconsistencies are determined.
11. The control system according to claim 8 , wherein the control device is operable to reduce engine output when inconsistencies are determined.
12. The control system according to claim 8 , wherein the control device is operable to activate a malfunction indicator lamp when inconsistencies are determined.
13. The control system according to claim 1 , wherein the control device is operable to receive a cooling rate from the at least one resistive heating element, a heating rate from the at least one resistive heating element, and mass flow data from an engine control module.
14. The control system according to claim 13 , wherein the control device is operable to determine if deposits are formed on the at least one resistive heating element based on flow characteristics determined by measurements from the at least one resistive heating element.
15. The control system according to claim 1 wherein the control device determines the temperature of the at least one resistive heating element based on a change in slope of resistance of the at least one resistive heating element along the non-monotonic curve between resistance and temperature.
16. The control system according to claim 1 , wherein the control device determines a temperature of the fluid flow based on the determined temperature of the at least one resistive heat element.
17. The control system according to claim 1 wherein the control device determines the temperature of at least one resistive heating element based on inflection points along the non-monotonic curve between resistance and temperature.
18. The control system according to claim 1 , wherein the control device determines the temperature of the at least one resistive heating element based on incremental changes to power applied to the at least one resistive heating element.
19. The control system according to claim 18 , wherein the control device determines a temperature range of the fluid flow based on the determined temperature of the at least one resistive heat element.