13 Dec 09

Electric Propulsion Systems

By Ahmad Nugroho

Hybrids are designing to apply electric propulsion systems which demonstrate to be really efficient and as well as environmentally friendly. There perhaps several approaches and techniques in order to carry out movement applying electrical power but the main idea is still the same. These arrangements are already operative and will encourage help produce alternate fuel.

What is Electric Propulsion?

Electric propulsion is the speedup of gases in order to produce propellant thrust through electric and magnetic body forces, electric body forces or electric heating. The electric propulsion system is usually integrated in rocket science wherein it manages energy sufficiency to produce a powerful force. An electric propulsion system is an alternative to atomic propulsion system. The total force is less powerful compared to a atomic rocket but still sufficiency to produce effects.

According to a figure of studies, any engine exploited as a main source of such powerful propulsion must produce beat speeds of around 10 to 20 km/s. There are also storable chemical systems applied in rockets with an exhaust speed of around 5 km/s but overall is less efficient.electric propulsion system

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

The 3 Categories of Electric Propulsion

1. 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.

2. 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 acknowledged as ion propulsion technique since ions are mainly used in the process. Electrostatic energy is used to produce propulsion.

The electrons from an atom are stripped off then converted to ions. The ions are accelerated by electrical forces to heat without needing thermal energy producing thrust. The atoms after losing electrons become positively charged.

3. Electromagnetic thrusters produce thrust using electric and magnetic force that interact with charged plasmas like ions and electrons. An example of these is the magnetoplasmadynamic thruster or MPD. The system heats the propellant to a plasma state before being accelerated. A large current is passed by electromagnetic forces through gas in order to ionize the propellant. Plasma is the ionized propellant which is then accelerated by Lorentz force, an electromagnetic force producing thrust.

Effect on Fuel

Decoupling engine speed and power output from the propeller will provide the opportunity to improve propeller efficiency. Since electric forces and electromagnetic forces contribute for support, petrol and diesel propulsion systems in vehicles will diminish the chances of wasting a huge part of power and energy.

The chances of engine overload are eliminated resulting to better fuel economy and better fuel consumption rate. Additionally, there is higher efficiency over longer distances and various speeds and loads.

A study conducted to check how much electric propulsion systems can help diesel and gasoline engines showed that at least 10% fuel savings is attained by simply allowing the engine to move along with the load reducing inefficiencies due to low load with high-velocity. Larger propellers can also save as much as 7% of fuel compared to traditional models.

With the total load split between multiple generators, as much as 20% of fuel can be saved plus another 13% by matching the power produced by the engine to the power required by the propeller. A variable-speed generator will help accomplish this. Overall, 30% to 50% can be saved compared to a very efficient diesel-electric or gasoline-electric system.






10 Sep 09

By Ahmad Nugroho

Human beings have always been and possibly will be dependent on forests to some extent. Trees were there form of homes, their natural world, their mine for food and their shelter from opponents. Forests are greatly significant to man, and other living creatures as well; and unfortunately, it is one of the largest threats that the world is facing today.

Mainly, the problems we have are due to massive deforestation; and at the present moment, we are realistically experiencing the detrimental effects of deforestation and suffering from them at the same time.

Deforestation can be characterized by the great scale depletion of forests. Deforestation transpires when forests are transformed to barren lands and areas for industrialization, for source of human consumption, and other explanations without adequate restoration of the forests. It is rather the undying damage to the vast land areas on earth; and thus should be stopped and halted before the untoward effects become totally inevitable.

Effects Of Deforestation In The Environment

Forests are one of the most organically distinct areas of the world. Millions of plant and animal species inhabit the forests and may or may not have been classified yet. The unique surroundings of these untouched beauties permit the existence of what we call, biodiversity.

Simply, if the forests are to be destroyed wholly, all forms of biodiversities in it will be swept away. There is no probability of getting them back and having to reconstruct again a forest that is as perfect as the ones we have right now. Furthermore, if these places are completely shattered, the prospect to explore other probabilities would be lost forever.

The effects of deforestation on the coming genre ahead can be absolutely inestimable. Thus, the preservation and the protection against extinction of many species can leave the world with many opportunities open for the forthcoming people ahead. Areas such as medicine and other essential inventions can be gaping for future possibilities for the further advancement of humanity.

Effects Of Deforestation In The Society

Much of the effects of deforestation weigh on the indigenous people bracket; this is because they form the largest inhabitants of the forests plus they earn a living from there too. All other groups affected such as hunters and agriculturists have been greatly tormented by the influx of colossal devastation of the forests. All forms of reproductions which people benefit form these land areas have been stopped; and thus, the whole world also suffered from its inescapable effects.

Indigenous people will become homeless if their form of habitation is taken away from them. The natives of every country would be fleeing to live somewhere else, thus bringing another set of problem for the world to absorb. Since they would assumingly transfer to rural and urban areas, their chances of living are narrowed because unlike city inhabitants, these people know less of the busy and buzzing world.

Overall, the terrible effects of deforestation cannot be compensated by the plans of further world development. No matter what great importance industrialization may bring, we must also consider that nature serves us in far better ways than buildings and other facilities you can see in urbanized areas.

Nature knows how to get back at us, and we can inevitably wait for more disastrous effects if humans to do not stop destroying it.






10 Sep 09

By Ahmad Nugroho

Hybrid electric vehicles are means of transportation that incorporates the use of an electric system in the main engine. Since gasoline engines have caused a variety of environmental pollutants, people are now starting to rely on electric power which has zero emission and are more fuel efficient. Here is an overview about hybrid electric vehicles.

What is a Hybrid Electric Vehicle?

A hybrid electric vehicle or HEV is a vehicle that is a combination of a rechargeable energy storage system or RESS and a traditional propulsion system. It saves more fuel and also covers more distance compared to battery electric vehicles since charging is done through a variety of methods instead of a lone external source. The propulsion power systems of various hybrid electric engines may be composed of the same parts or subsystems.

Usual hybrid electric models have an ICE or internal combustion engine as well as electric batteries that support the main electric motors. The mechanisms of the HEV have improved significantly with the discovery of regenerative braking wherein kinetic energy can be stored. Fuel is conserved more and emission is minimized as much as possible. Drivers get to cover longer ranges as well without worrying about speed and performance.

The combustion engine too can generate electric power through a spinning electrical generator. The energy either provides power directly to the motor or recharges the battery. The internal combustion engine automatically shuts down when idling but immediately restarts as necessary. The engine is also considerably smaller which is more efficient.

Do HEVs Still Use Gas and Diesel?

Gasoline engines will most likely remain in the hybrid vehicle scene for years to come since it generates power like no other discovered or affordable material can. Petroleum gasoline is considered as the main fuel source but can be mixed with different concentrations of ethanol from other energy sources. HEVs use up around 15% bioethanol like other internal combustion engines but manufacturers are currently finding ways to improve ratios for increased fuel efficiency and decreased emission.

There are diesel electric engines wherein a diesel engine is mainly used to provide power. Diesel can prove to be more efficient than gasoline although speed and noise may not be its best features. Diesel can be better-performing and can provide power for long periods of time without wearing much.

Gas mileage is also better due to its high torque while using biodiesel. The need for petroleum is minimized depending on the type used. Although diesel are usually known to drive bigger transportations like trucks, SUVs and vans, hybrid diesel-electric vehicles have also appeared in smaller versions like sedans and other passenger cars.

Hybrid Electric Vehicle Types

Hybrid diesel-electric motorcycles have been created having a top speed of around 800 mph with a very affordable retail price of $500. Several known automobile manufacturers have also joined the bandwagon like Honda, Ford, General Motors, Mazda, Nissan and Toyota. These big names are currently innovating to continuously provide well-performing vehicles with all the advantages.

HEVs have been very specific in being made available for future taxicab models. Since these vehicles are usually on the go all day long, fuel and emission can be improved through automatic engine shutdown, regenerative braking and idling. There are plug-in models in which taxicabs can conveniently recharge batteries at designated stands throughout the city. Plug-in hybrid electric models are also available in the form of sedans and mini-cars.

Hybrid-electric buses and trucks are also circulating due to the many advantages offered. The diesel engine is smaller which means that it is more efficient. There is also a 1.9-liter diesel engine instead of the 7.0, emitting less harmful gases. Emission reduction has been reported to be around 30% while fuel efficiency is around 40%. Some hybrid-electric buses have gas turbine generators. More efforts are exerted to convert other means of transportation like trains.

Several other types of HEVs are available today and are being used in various projects. The military uses diesel-electric hybrid trucks which has a fuel cell auxiliary power and diesel electric unit. The United States Army began using hybrid electric drives for all vehicle systems and subsystems. Other notable trucks have also found their purpose in commercial sectors, scientific projects and mining endeavors.