Posted tagged ‘help’

SOLAR POWER IN CARS

September 10, 2011

solar-auto-carsSolar energy is one of the many renewable sources of energy that is used for fueling vehicles, running consumer products and for the efficient running of homes and business establishments. Solar power is harnessed with the help of solar cells and solar panels which are placed in the item that has to be powered.

The solar car is something that is envisioned to materialize in the future, with some countries already having solar cars racing across countries.
With this, it is proven that it is viable to indeed produce and manufacture solar power cars in bulk, in the near future so that everyone will soon own a solar power car.

Of course, once solar power cars are manufactured, it does not implicate that all other fuel sources for cars on highways will be removed. All that is done in solar power cars is the supplementation of traditional fuel with solar energy so that you save not only on your economy, but also save the environment in more ways than one every year.

The solar power cars that are used in races today run only on solar power, and thus look odd in appearance. This is because these cars are designed in such a way that they can collect maximum solar energy with which it is possible for the car to gain the required speed and desired efficiency.

The solar cells used in solar power cars are large, and usually cover the entire vehicle. However in case of commercial uses, solar cells are much smaller and designed so that the vehicle not only looks attractive, but is also efficient in its functioning. Solar cars can be used for short commutes in town as these cars can work only on solar energy.

The batteries found in the vehicle stores excess solar power so that this power can be used when solar power is not available on demand like on cloudy days and at nighttime. The engines found in these solar power cars are very much like the engines found in electric cars found today. In addition to this, the cars are lightweight, so that solar power can be used more efficiently.

At present, there are many types of solar power cars in the development stage today, which are also available for sale. However as these cars are in the developmental stage, the car is not available to the general public. With so many benefits found in solar power cars, its cost will not be much higher than the cost of the traditionally powered vehicles of today.

Another benefit of solar power cars is there is no hassle of stopping at gas stations for gas nor is there the need of getting worried of rising gasoline costs. With a solar power car, you save on the money that you would have otherwise have needed for buying fuel to run your car. In addition to this, with solar power cars you will be doing your bit in stopping global warming problems as there are no fuel emissions from solar power cars.

CONVEYOR

August 23, 2011

Conveyor Take-up Arrangement:

01-belt conveyor-take up arrangement-screw take up-take up pulley-automatic take up device-fixed take up device-manual take up-self adjusting take up devices


All belt conveyors require the use of some form of take-up device for the following reasons:

  • To ensure adequate tension of the belt leaving the drive pulley so as to avoid any slippage of the belt
  • To ensure proper belt tension at the loading and other points along the conveyor
  • To compensate for changes in belt length due to elongation
  • To provide extra length of belt when necessary for splicing purpose.

Usually there are two types of take up arrangements.

  • Fixed take up device that may be adjusted periodically by manual operation
  • Automatic take up devices for constant load type

In a screw take up system the take up pulley rotates in two bearing blocks which may slide on stationery guide ways with the help of two screws. The tension is created by the two screws which are tightened and periodically adjusted with a spanner. It is preferable to use screws with trapezoidal thread t decrease the effort required to tighten the belt.

01-hydraulic take up device-pneumatic take up device-electrical take up device-self adjusting take up device-automatic take up device

The main problem with the use of manual take-up is that it requires a vigilant and careful operator to observe when take up adjustment is required. Perfect tension adjustment with this system is also not possible. For this reason these devices are used only in case of short conveyors of up 60 m length and light duty.

In automatic take up arrangement the take up pulley is mounted on slides or on a trolley which is pulled backwards by means of a steel rope and deflecting pulleys. The carriage travels on guide ways mounted parallel to the longitudinal axis of the conveyor, i.e., horizontally in horizontal conveyors and at an incline in inclined conveyors. Hydraulic, pneumatic and electrical take up devices are also used.

Automatic take-up has the following features:

  • It is self adjusting and automatic
  • Greater take-up movement is possible.

MECHANICAL ENGG QUESTIONS

August 22, 2011

1. What is the importance of the Thermodynamics in the field of Mechanical Engineering?
All the mechanical engineering systems are studied with the help of thermodynamics. Hence it is very important for the mechanical engineers.

2. How many Laws of Thermodynamics are there?
There are three laws of the thermodynamics.

First Law: Energy can be neither created nor destroyed. It can only change forms.In any process in an isolated system, the total energy remains the same.


Second Law: When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium in itself, but not in equilibrium with each other at first, are at some time allowed to interact, breaking the isolation that separates the two systems, and they exchange matter or energy, they will eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated systems is less than or equal to the entropy of the final exchanging systems. In the process of reaching a new thermodynamic equilibrium, entropy has increased, or at least has not decreased.

Third Law: As temperature approaches absolute zero, the entropy of a system approaches a minimum.

3. State Laws of conservation of energy?
According to the laws of conservation of energy, “energy can neither be created nor be destroyed. It can only be transformed from one form to another.”

4. Is the boiler a closed system?
Yes definitely the boiler is a closed system.

5. What is Carnot engine?
It was being designed by Carnot and let me tell you that Carnot engine is an imaginary engine which follows the Carnot cycle and provides 100% efficiency.

6. Which formula forms a link between the Thermodynamics and Electro chemistry?
Gibbs Helmholtz formula is the formula which forms the link between the thermodynamics and electromagnetism.

∆Hs/R = [∂ lnp /∂ (1/T)]x

where: x – mole fraction of CO2 in the liquid phase
p – CO2 partial pressure (kPa)
T – temperature (K)
R – universal gas constant
α – mole ratio in the liquid phase (mole CO2 per mole of amine)

7. Which is the hardest compound known?
Diamond.

8. What is Hess Law?
According to the Hess law the energy transfer is simply independent of the path being followed. If the reactant and the product of the whole process are the same then same amount of energy will be dissipated or absorbed.


9. Which has more efficiency: Diesel engine or Petrol engines?
Off course Diesel engine has the better efficiency out of two.