Thermal management system and method for a heat producing system
A vehicle thermal management system includes a temperature control fluid for controlling the temperature of at least a portion of a vehicle system. A pump is configured to pump the temperature control fluid through a heat exchanger to facilitate the transfer of heat between the temperature control fluid and ambient air. A fan is operable to move the ambient air across the heat exchanger to facilitate increased heat transfer. A control system is used to control operation of the pump and the fan. The control system is provided with operation data that includes optimized operating speeds for the pump and the fan to minimize power consumption, while maximizing heat transfer.
1. A thermal management system for a heat producing system, the thermal management system comprising:
a first temperature control fluid for controlling the temperature of at least a portion of the heat producing system;
a first temperature sensor for sensing a temperature of the first temperature control fluid, and outputting a signal related to the temperature of the first temperature control fluid;
a first heat exchanger for transferring heat between the first temperature control fluid and ambient air;
a second temperature sensor for sensing a temperature of the ambient air, and outputting a signal related to the temperature of the ambient air;
a first fan operable to move the ambient air across the first heat exchanger, the first fan being a variable speed electric fan;
a first pump operable to pump the first temperature control fluid through the first heat exchanger, the first pump being a variable speed electric pump; and
a control system operatively connected to the temperature sensors, the first fan, and the first pump and including at least one controller, the control system being programmed with operation data providing optimized operating speeds for combined operation of the first fan and the first pump, each of the optimized operating speeds corresponding to an amount of heat transfer between the first temperature control fluid and the ambient air via the first heat exchanger at a respective ambient air temperature, and each of the optimized operating speeds providing a minimized combined power input into the first fan and the first pump for the corresponding amount of heat transfer, the control system being configured to operate the first fan and the first pump at the optimized operating speeds based at least in part on the operation data and signals received from the temperature sensors.
2. The thermal management system of claim 1 , the heat producing system including an engine in a vehicle, and wherein the control system receives an input related to a speed of the vehicle, and is further configured to operate the first fan and the first pump at the optimized operating speeds based at least in part on the input received.
3. The thermal management system of claim 2 , further comprising a load sensor for sensing a load on the engine and outputting a signal related to the engine load to the control system, and
wherein the control system is further configured to effect transient operation of the first fan and the first pump based at least in part on the sensed engine load, the transient operation occurring immediately following a change in engine load.
4. The thermal management system of claim 1 , wherein the operation data includes at least one equation defining an optimization curve having one of the speed of the first fan and the speed of the first pump as an independent variable, and the other of the speed of the first fan and the speed of the first pump as a dependent variable.
5. The thermal management system of claim 1 , wherein at least some of the operation data includes a lookup table.
6. The thermal management system of claim 1 , wherein the operation data includes data gathered from testing a model of at least a portion of the thermal management system.
7. The thermal management system of claim 1 , further comprising:
a first speed sensor for the sensing the speed of the first pump and outputting a signal related to the speed of the first pump to the control system; and
a second speed sensor for sensing the speed of the first fan and outputting a signal related to the speed of the first fan to the control system, and
wherein the control system is further configured to:
a) determine a temperature error defined as the difference between the sensed temperature of the first temperature control fluid and the first target temperature,
b) determine a current operating point from the operation data based on a sensed speed of at least one of the first fan and the first pump, and
c) determine a new operating point from the operation data based on the current operating point and the magnitude and the sign of the temperature error.
8. The thermal management system of claim 1 , further comprising:
a first electric valve in communication with the control system and operable to prohibit at least some of the first temperature control fluid from passing through the first heat exchanger, and
wherein the control system is further configured to:
a) operate the first pump at a first predetermined pump speed and actuate the first valve to prohibit the first temperature control fluid from passing through the first heat exchanger when the sensed temperature of the first temperature control fluid is below a first temperature set point,
b) actuate the first valve to allow at least some of the first temperature control fluid to pass through the first heat exchanger when the sensed temperature of the first temperature control fluid reaches the first temperature set point, and
c) increase the speed of the first pump to one of the optimized operating speeds when the sensed temperature of the first temperature control fluid reaches a second temperature set point greater than the first temperature set point.
9. The thermal management system of claim 8 , wherein the control system is further configured to prohibit starting the first fan when the speed of the first pump is below a second predetermined pump speed, and to operate the first fan at one of the optimized operating speeds based on the speed of the first pump when the speed of the first pump is at or above the second predetermined pump speed.
10. The thermal management system of claim 1 , the heat producing system including an engine in a vehicle, the thermal management system further comprising:
an exhaust gas cooler in communication with the engine and configured to receive exhaust gas from the engine at a first temperature, and to recirculate the exhaust gas back into the engine at a second temperature lower than the first temperature, and
wherein the first pump is operable to pump the first temperature control fluid through the exhaust gas cooler, thereby facilitating heat transfer between the first temperature control fluid and the exhaust gas.
11. The thermal management system of claim 1 , the heat producing system including an engine and a transmission in a vehicle, and wherein the first temperature control fluid is used to control at least one of a temperature of the transmission and a temperature of the engine.
12. The thermal management system of claim 11 , further comprising:
a second temperature control fluid for controlling the temperature of recirculated exhaust gas entering the engine;
a third temperature sensor for sensing a temperature of the second temperature control fluid, and for outputting a signal related to the temperature of the second temperature control fluid to the control system;
a second heat exchanger for transferring heat between the second temperature control fluid and the ambient air;
a second fan in communication with the control system and operable to move the ambient air across the second heat exchanger;
an exhaust gas cooler in communication with the engine and configured to receive exhaust gas from the engine at a first temperature, and to recirculate the exhaust gas back into the engine at a second temperature lower than the first temperature; and
a second variable speed electric pump in communication with the control system, the second pump being operable to pump the second temperature control fluid through the second heat exchanger and through the exhaust gas cooler, thereby facilitating heat transfer between the second temperature control fluid and the exhaust gas, and
wherein the control system is programmed with operation data providing optimized operating speeds for combined operation of the second fan and the second pump, each of the optimized operating speeds for the second fan and the second pump corresponding to an amount of heat transfer between the second temperature control fluid and the ambient air via the second heat exchanger at a respective ambient air temperature, and each of the optimized operating speeds for the second fan and the second pump providing a minimized combined power input into the second fan and the second pump for the corresponding amount of heat transfer, the control system being configured to operate the second fan and the second pump at the optimized operating speeds based at least in part on the operation data for the second fan and the second pump and signals received from the second and third temperature sensors, thereby effecting heat transfer between the second temperature control fluid and the ambient air to drive the temperature of the second temperature control fluid toward a second target temperature.
13. The thermal management system of claim 11 , further comprising:
a first electric valve in communication with the control system and operable to prohibit at least some of the first temperature control fluid from passing through the first heat exchanger;
a first temperature control loop including the first heat exchanger, the first electric valve, and the first pump, the first temperature control loop being configured to facilitate heat transfer between the first temperature control fluid and the transmission;
a second temperature control loop including a second temperature control fluid, a second heat exchanger for facilitating heat transfer between the second temperature control fluid and the ambient air, and a second fan operable to move the ambient air across the second heat exchanger, the second temperature control loop being in selective communication with the first temperature control loop, thereby facilitating mixing of the first and second temperature control fluids, the second temperature control loop being configured to facilitate heat transfer between the second temperature control fluid and the engine.
14. The thermal management system of claim 13 , wherein the first valve is operable to allow selective fluid communication between the first and second temperature control loops, the thermal management system further comprising:
a second electric valve in communication with the control system and operable to allow selective fluid communication between the first and second temperature control loops; and
a third temperature control loop including at least a portion of the first and second temperature control loops, and resulting from at least partial opening of the first and second valves, the third temperature control loop being configured to facilitate heat transfer between the engine and the transmission.
15. The thermal management system of claim 14 , the transmission including transmission oil, the thermal management system further comprising a third heat exchanger configured to facilitate heat transfer between the first temperature control fluid and the transmission oil, and
wherein the second and third temperature control loops include the third heat exchanger.
16. A method for managing thermal characteristics of a heat producing system, the heat producing system including a first cooling loop, the first cooling loop including a first temperature control fluid for controlling the temperature of at least a portion of the heat producing system, a first heat exchanger for transferring heat between the first temperature control fluid and ambient air, a first fan for moving the ambient air across the first heat exchanger, and a first pump for pumping the first temperature control fluid through the first heat exchanger, the method comprising:
determining coefficients of performance for combined operation of the first fan and the first pump, each of the coefficients of performance being defined as a ratio of the amount of heat transfer between the first temperature control fluid and the ambient air via the first heat exchanger during operation of at least one of the first fan and the first pump to the combined power input into the first fan and the first pump at a respective ambient air temperature;
determining a temperature of the first temperature control fluid;
determining a temperature of the ambient air;
comparing the temperature of the first temperature control fluid to a first target temperature;
operating at least one of the first fan and the first pump based at least in part on the coefficients of performance and the comparison of the temperature of the first temperature control fluid to the first target temperature, thereby effecting a change in the temperature of the first temperature control fluid toward the first target temperature.
17. The method of claim 16 , further comprising:
determining maximum coefficients of performance for corresponding operating speeds of the first fan and the first pump, each of the maximum coefficients of performance corresponding to a minimum combined power input into the first fan and the first pump for a corresponding amount of heat transfer at a respective ambient air temperature, and
wherein the operation of at least one of the first fan and the first pump is based at least in part on the maximum coefficients of performance.
18. The method of claim 17 , wherein the comparison of the temperature of the first temperature control fluid to the first target temperature includes determining the difference between them, thereby defining a temperature error, the method further comprising:
determining a current operating speed for at least one of the first fan and the first pump;
determining a current maximum coefficient of performance based on at least one of the current operating speed of the first fan and the first pump; and
operating at least one of the first fan and the first pump based on the current maximum coefficient of performance and the magnitude and the sign of the temperature difference.
19. The method of claim 18 , the cooling loop further including a first electric valve operable to prohibit at least some of the first temperature control fluid from passing through the first heat exchanger, the method further comprising:
operating the first pump at a first predetermined pump speed and actuating the first valve to prohibit the first temperature control fluid from passing through the first heat exchanger when the determined temperature of the first temperature control fluid is below a first temperature set point,
actuating the first valve to allow at least some of the first temperature control fluid to pass through the first heat exchanger when the determined temperature of the first temperature control fluid reaches the first temperature set point, and
increasing the speed of the first pump to a speed corresponding to one of the maximum coefficients of performance when the determined temperature of the first temperature control fluid increases to at least a second temperature set point.
20. The method of claim 19 , further comprising:
prohibiting starting the first fan when the speed of the first pump is below a second predetermined pump speed; and
operating the first fan at a speed corresponding to one of the maximum coefficients of performance based on the speed of the first pump when the speed of the first pump is at or above the second predetermined pump speed.
21. A thermal management system for a vehicle, the vehicle including an engine and a transmission containing transmission oil, the thermal management system comprising:
a transmission temperature control loop for controlling a temperature of the transmission, the transmission temperature control loop including a first pump operable to pump a first temperature control fluid through the transmission temperature control loop, a first radiator for transferring heat between the first temperature control fluid and ambient air, a first fan operable to move the ambient air across the first radiator, a first valve operable to control the amount of the first temperature control fluid passing through the first radiator, and a heat exchanger in fluid communication with the first radiator for transferring heat between the first temperature control fluid and the transmission oil;
an engine temperature control loop for controlling a temperature of the engine, the engine temperature control loop including a second pump operable to pump a second temperature control fluid through the engine temperature control loop, a second radiator for transferring heat between the second temperature control fluid and the ambient air, a second fan operable to move the ambient air across the second radiator, and a second valve operable to control the amount of the second temperature control fluid passing through the second radiator;
a first conduit disposed between the engine temperature control loop and the second valve, the second valve being further operable to facilitate mixing of the first and second temperature control fluids;
a second conduit disposed between the engine temperature control loop and the transmission temperature control loop;
a third valve operable control flow through the second conduit, thereby facilitating mixing of the first and second temperature control fluids; and
a control system including at least one controller, the control system being configured to operate at least the first fan, the first pump, and the first and third valves.
22. A thermal management system for a vehicle, the vehicle including an engine and a transmission containing transmission oil, the thermal management system comprising:
a transmission temperature control loop for controlling a temperature of the transmission, the transmission temperature control loop including a first pump operable to pump a first temperature control fluid through the transmission temperature control loop, a first radiator for transferring heat between the first temperature control fluid and ambient air, a first fan operable to move the ambient air across the first radiator, a first valve operable to control the amount of the first temperature control fluid passing through the first radiator, and a first heat exchanger in fluid communication with the first radiator for transferring heat between the first temperature control fluid and the transmission oil;
an engine temperature control loop for controlling a temperature of the engine, the engine temperature control loop including a second pump operable to pump a second temperature control fluid through the engine temperature control loop, a second radiator for transferring heat between the second temperature control fluid and the ambient air, a second fan operable to move the ambient air across the second radiator, and a second valve operable to control the amount of the second temperature control fluid passing through the second radiator;
a second heat exchanger in fluid communication with the first and second radiators for transferring heat between the first temperature control fluid and the second temperature control fluid; and
a control system including at least one controller, the control system being configured to operate at least the first fan and the first valve.
23. A thermal management system for a heat producing system, the thermal management system comprising:
a temperature control fluid for controlling the temperature of at least a portion of the heat producing system;
a temperature sensor for sensing a temperature of the temperature control fluid, and outputting a signal related to the sensed temperature;
a first heat exchanger capable of receiving at least some of the temperature control fluid for transferring heat between the temperature control fluid and ambient air;
a first fan operable to move the ambient air across the first heat exchanger;
a first pump operable to pump the temperature control fluid through at least the first heat exchanger;
a second heat exchanger capable of receiving at least some of the temperature control fluid for transferring heat between the temperature control fluid and the ambient air;
a second fan operable to move the ambient air across the second heat exchanger, the second fan being a variable speed electric fan;
a control system including at least one controller, the control system being operatively connected to at least the temperature sensor and the second fan, and configured to operate the second fan based at least in part on signals received from the temperature sensors; and
a second pump operable to pump the temperature control fluid through the second heat exchanger and operatively connected to the control system, the control system being further configured to operate the second pump to control the flow of the temperature control fluid through the second heat exchanger based at least in part on signals received from the temperature sensor.