Hongming Xu Flashcards
What is an energy carrier?
A substance or a phenomenon that can be used to produce mechanical work or heat or to operate chemical or physical processes. It is any system or substance that contains energy for conversion as usable energy later . Such carriers include springs, electrical batteries, capacitors, pressurized air, dammed water, and hydrogen.
What are primary energy sources?
Primary energy sources are transformed in energy conversion processes to more convenient forms of energy. Examples are coal, oil, natural gas, and wind.
Key features of hybrids
- Hybrids achieve improved efficiencies using several approaches:
- Employ regenerative braking to recover energy that is thrown away
- Downsize or “right-size” the engine or primary power source
- Control the engine or primary power source to operate more efficiently and/or work more often in a more efficient range
- Other vehicle modifications applied to hybrids like aerodynamic improvements, low rolling resistance tires can be applied to CVs too
How does a series hybrid work?
What are the different hybrid drive modes?
- Regenerative braking mode: The engine–generator is turned off and the traction motor is operated as a generator
- Battery charging mode: The traction motor receives no power and the engine–generator is operated only to charge the batteries.
- Hybrid battery charging mode: Both the engine–generator and the traction motor operate as generators in braking to charge the batteries
What are the main advantages of series hybrid systems?
- The engine can be potentially operated within its maximum efficiency region.
- The drive train may not need multi-gear transmission and can be greatly simplified for less cost.
- The speed and torque of each wheel can be independently controlled.
- The control strategy of the drive train may be simple, compared to other configurations, because of its fully mechanical decoupling between the engine and wheels.
What are the main disadvantges of the series hybrid system?
- The energy from the engine changes its form twice to reach its destination—driven wheels (mechanical to electrical in the generator and electrical to mechanical in the traction motor). The inefficiencies of the generator and traction motor may cause significant losses.
- The generator adds additional weight and cost.
- Because the traction motor is the only power plant propelling the vehicle, it must be sized to produce enough power for optimal vehicle performance in terms of acceleration and gradeability
How do parallel hybrid systems work?
Two mechanical powers are added together in a mechanical coupler. The IC engine is the primary power plant, and the batteries and electric motor drive constitute the energy bumper. The power flows can be controlled only by the power plants—the engine and electric motor.
How does a series-parallel hybrid work?
How does a complex hybrid system work?
How does a PEM hydrogen fuel cell work?
H2 gas meets with a catalyst causing it to split into electrons and protons (H+)
The protons travel through the PEM but the electrons have to go around and they produce electricity.
On the other side, the electrons protons and O2 gas combine to make water.
What are the advantages of hydrogen fuel cells?
High efficiency conversion Convert chemical energy directly into electricity without the combustion process, not governed by thermodynamic laws, such as the Carnot efficiency
High power density Relatively compact source of electric power, beneficial in application with space constraints.
Quiet Extremely quiet in operation, good in residential or builtup areas where the noise pollution is undesirable.
How does a solid oxide fuel cell work?
Here the hydrogen losses its electrons and they flow round to produce electricity. The electrons then reduce O2 gas so that it becomes negative. The negataive oxygen ions go through the membraine and meet with protons on the other side to make water.
How does a methanol direct fuel cell work?
What are the three different ways to storge hydrogen?
- 1) compressed hydrogen in a container at ambient temperature,
- 2) cryogenic liquid hydrogen at low temperature, and
- 3) the metal hydride method.
How can you store energy with metal hydrides?
What is the hybrid power train topology?
What is the type 1 arragment of the drivetrain of an electric car?
What is the type 2 arragment of the drivetrain of an electric car?
What is the type 3 arragment of the drivetrain of an electric car?
What is the type 4 arragment of the drivetrain of an electric car?
What is the type 5 arragment of the drivetrain of an electric car?
What is a typical power/torque graph of an electric motor?
What is the typical efficiency graph of an electric motor?
