1. A fluid temperature adjusting device comprising:
a heater configured to heat a fluid passing through a fluid passageway;
a peltier module including a plurality of peltier elements, the peltier module being configured to heat or cool the fluid passing through the fluid passageway; and
a controller configured to divide a total thermal energy for keeping the fluid at a target temperature into a thermal energy to be supplied from the heater and a thermal energy to be supplied from the peltier module to give the total thermal energy from both the heater and the peltier module to the fluid.
2. The fluid temperature adjusting device according to claim 1,
wherein the controller is configured to change a ratio between an operation amount of the heater and an operation amount of the peltier module depending on a magnitude of the thermal energy to be supplied to the fluid.
3. The fluid temperature adjusting device according to claim 2,
wherein the controller is configured to control the heater and the peltier module so that the operation amount of the peltier module becomes larger than the operation amount of the heater when the total thermal energy to be supplied to the fluid is smaller than a predetermined value.
4. The fluid temperature adjusting device according to claim 1,
wherein the controller is configured to supply power to the heater by a cycle control or a duty control.
5. The fluid temperature adjusting device according to claim 1,
wherein the controller is configured to change the thermal energy to be supplied by each of the peltier module and the heater while keeping a ratio between an operation amount of the peltier module and an operation amount of the heater at a constant value when the thermal energy to be supplied to the fluid changes.
6. The fluid temperature adjusting device according to claim 1,
wherein the controller is configured to monotonously increase a supply amount of the heater and a supply amount of the peltier module.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An exhaust system for a dual-fuel engine that is provided with a first fuel and a different second fuel for combustion, comprising:
an exhaust passageway;
an exhaust treatment component provided in the exhaust passageway, the exhaust treatment component being configured to treat exhaust from combustion of the second fuel and not from combustion of the first fuel;
a thermal enhancement device in communication with the exhaust passageway and located upstream from the exhaust treatment component; and
a controller for activating and deactivating the thermal enhancement device based on switching from the first fuel to the second fuel, wherein the first fuel has a higher sulfur content than the second fuel,
wherein the thermal enhancement device increases a temperature of an exhaust to combust a residual amount of the first fuel present in the exhaust passageway during the switch between the first fuel and the second fuel.
2. The exhaust system of claim 1, wherein the exhaust treatment component is a selective catalytic reduction (SCR) component.
3. The exhaust system of claim 1, further comprising an exhaust by-pass pipe for by-passing the exhaust treatment component.
4. The exhaust system of claim 3, further comprising a valve that is operable to open and close the exhaust by-pass pipe.
5. The exhaust system of claim 3, further comprising a bleed passage in communication between the exhaust passageway and the exhaust by-pass pipe.
6. The exhaust system of claim 1, wherein the thermal enhancement device is activated before the switch, simultaneously with the switch, or immediately following the switch from the first fuel to the second fuel.
7. The exhaust system of claim 1, wherein the thermal enhancement device comprises a burner for combusting residual fuel present in the exhaust passageway prior to the residual fuel entering the exhaust treatment component.
8. The exhaust system of claim 1, wherein the thermal enhancement device is operated for a predetermined amount of time after the supply of the first fuel to the engine is discontinued.
9. The exhaust system of claim 1, wherein the exhaust generated by engine combustion of the first fuel escapes to atmosphere prior to entering the exhaust treatment component and the exhaust generated by engine combustion of the second fuel passes through the exhaust treatment component, wherein after discontinuing the supply of the first fuel to the ending, the residual amount of first fuel that was not combusted by the engine is combusted by the thermal enhancement device and the exhaust from the thermal enhancement device passes through the exhaust treatment component.
10. A method of treating exhaust produced by a dual-fuel engine that is operable to switch between a first fuel and a second fuel, comprising operating a thermal enhancement device that raises an exhaust temperature while switching between the first fuel and the second fuel.
11. The method of claim 10, wherein the first fuel has a greater sulfur content than the second fuel.
12. The method of claim 11, further comprising treating exhaust produced through combustion of the second fuel with an exhaust treatment device.
13. The method of claim 12, wherein the exhaust treatment component is an SCR.
14. The method of claim 13, further comprising expelling exhaust produced through combustion of the first fuel into the atmosphere before treating the exhaust produced through combustion of the second fuel with an exhaust treatment device.
15. The method of claim 14, further comprising operating the thermal enhancement device to combust a residual amount of the first fuel present in the exhaust emitted by the engine and supplying the exhaust from the thermal enhancement device to the exhaust treatment component.
16. The method of claim 11, wherein the thermal enhancement device is operated before switching the fuels, during switching of the fuels, or after switching of the fuels.