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Electric Propulsion Systems

January 6th, 2009 | No Comments | Posted in Hybrid System

Electric Propulsion Systems

Hybrids are planning to use electric propulsion systems which prove to be very efficient and also environmentally friendly. There may be various approaches and methods in order to accomplish movement using electric power but the main idea is still the same. These systems are already working and will further help develop alternate fuel.

What is Electric Propulsion?

Electric propulsion is the acceleration of gases in order to produce propulsive thrust through electric and magnetic body forces, electric body forces or electric heating. The electric propulsion system is usually incorporated in rocket science wherein it manages energy enough to produce a powerful thrust. An electric propulsion system is an alternative to nuclear propulsion system. The total thrust is less powerful compared to a nuclear rocket but still enough to produce effects.

According to a number of studies, any engine used as a primary source of such powerful propulsion must produce exhaust velocities of around 10 to 20 km/s. There are also storable chemical systems used in rockets with an exhaust velocity of around 5 km/s but overall is less efficient.

Propulsion systems that do not require energy through chemical reactions are still needed. There are electric propulsion thrusters able to produce exhaust velocities of around 10 to 20 km/s which increases payload and reduces propellant mass. The consequences however, are less powerful thrusters consuming larger quantities of power.

The 3 Categories of Electric Propulsion

Electro thermal propulsion is when the propellant is electrically heated then isentropically expanded through a C/D or convergent/divergent nozzle. The system works as electrical energy heats propellants that produce gases as a result. The gases are sent through the C/D nozzle creating thrust. Catalyzed hydrazine or another neutral gas is used in thrusters like arc jets and resistojets.

Arc jets can also be used to heat the propellants via an electrical arc discharge. The arc in the arc jet is a beam of electrons produced from the cathode tip then gathers at the anode. Since an arc jet has a cathode and an anode, a constrictor is also present which is a narrow pathway between the two charges.

Electrostatic thrusters are also called ion thrusters. These use an ionized propellant accelerated through electric fields applied directly like gridded ion thrusters and Hall thrusters. The technique of propulsion is also known as ion propulsion technique since ions are mainly used in the process. Electrostatic energy is used to produce propulsion.

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A Brief Guide to Hybrid Vehicles

January 6th, 2009 | 2 Comments | Posted in Hybrid System

A Brief Guide to Hybrid Vehicles

Hybrid vehicles were the stuff of dreams centuries ago. Nobody ever thought that creating a vehicle independent from fuel was possible. Fortunately with the continuing development of hybrid technology, more efficient and practical vehicles have been created. In the recent years the campaign for global warming has brought the attention of the public. Hybrid cars are now becoming steadily popular available in different types from compact sedans to SUVs.

Environmental issues are not the only reason that has made the public favor hybrid cars. Rising gas prices is also one of the major reasons why people prefer hybrid cars than conventional ones. Its also practical in suburban environments where you don’t really need horsepower but gas mileage.

Hybrid vehicles

There are  different types of hybrid vehicles. They can vary from the simplest wheelbarrows to ships. No matter what form they are, these vehicles help in reducing greenhouse and noise emissions. Although these vehicles are expensive due to their unique structures, developments will continue to provide more alternatives to the public. These cars may not compare to conventional ones with a 200 horsepower but why would you need that if you only need 20 in the streets?

The simplest hybrid would be the single wheeled vehicles. These are wheelbarrows famously depicted with sails. This can be seen in Chinese sailing carriages.

The next is two wheeled vehicles. These are usually cycle type vehicles. The best example would be the Moped and electric bicycles. They are powered by an electric motor or an internal combustion engine in combination with the rider’s muscles. This concept was also used in the 1800’s by motorcycles. The electric bicycle can either be a parallel or a series hybrid.

Hybrid vehicles are not just limited to private cars. There are also hybrid power trains used by heavy vehicles. There are diesel or turbo electric buses, railway locomotives, heavy duty vehicles, hydraulic machinery and ships.

In ships a diesel engine drives the electric generator or hydraulic pump which in turn powers one or more hydraulic or electric motors. Sails and engines were early forms of hybrids which may be used again due to rising fuel costs.

More developments are continually being made in hybrid structures and systems for efficiency. Today buying a hybrid car is expensive but it will be beneficial in the long run. It does not just save fuel costs but also removes pollution that can harm the health of the people and take whatever it is left of the environment.

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