Wednesday, July 25, 2018
Top Ten Reasons Why Diesel Engines are not Used in Bikes?
12:40 PM
We all are bike lovers. We use bike many times in a day. Usually bike is run by petrol. The price of petrol is higher than diesel in many countries. Sometimes we think, why bike is not run by diesel. If there is a diesel bike than we can save some money. Today I am going to tell you some reasons why diesel engines are not used in bikes.
1. Diesel engine has a compression ratio 24:1, which is higher than petrol engine compression ratio of 11:1. Diesel engine must be bigger and of heavy metal in order to handle this high compression ratio. That’s why the diesel engine is heavier than petrol engine and not suitable for small vehicle like motorcycle.
2. Due to high compression ratio, diesel engine produces more vibration and noise as compared to the petrol engine. It is not possible for a light vehicle to handle this high vibration and noise.That’s why diesel engines are not used in motorcycle.
3. Due to high compression ratio and heavy engine, initial price of the diesel engine is more than the petrol engine. And this initial price difference is about 50,000 rupees, which is not suitable for small vehicle.
4. Diesel engine produces approximately 13% more carbon-di-oxide per gallon as compared to the petrol engine. So it makes greater pollution than petrol engine and it is not good to use for environment.
5. Diesel engine works on high pressure, so wear and tear is high in diesel engines. To reduce this wear and tear oil change are frequently required at every 5,000 kilometer instead of 10,000 kilometer in the case of petrol engine.
6. Diesel engine produces more torque but low rpm than petrol engine. So in bikes where we need high speed, it is not suitable.
7. Diesel has high energy per gallon as compare with the petrol. When diesel burns, it produces a large amount of heat which can destroy walls of the cylinder and other parts of the engine. So to reduce this heat, we need a greater surface area and proper cooling system. In order to achieve this greater surface area, the engines are made slightly bigger.
8. Diesel engine uses turbocharger or supercharger to pump more air into the cylinder, which increases its price and size.
9. In diesel engines, injector technology is used to inject fuel into the combustion chamber, which is more expensive than spark plug technology of petrol engine.
10. Diesel engine is very big as compared with the petrol engine and it uses high power starting motor to crank the engine, which is not suitable for motorcycles.
After all these disadvantages some manufactures like Royal Enfield have succeed to manufacture diesel engine bikes and may be, after some years these bikes can replace all petrol bikes.
3. Due to high compression ratio and heavy engine, initial price of the diesel engine is more than the petrol engine. And this initial price difference is about 50,000 rupees, which is not suitable for small vehicle.
4. Diesel engine produces approximately 13% more carbon-di-oxide per gallon as compared to the petrol engine. So it makes greater pollution than petrol engine and it is not good to use for environment.
5. Diesel engine works on high pressure, so wear and tear is high in diesel engines. To reduce this wear and tear oil change are frequently required at every 5,000 kilometer instead of 10,000 kilometer in the case of petrol engine.
6. Diesel engine produces more torque but low rpm than petrol engine. So in bikes where we need high speed, it is not suitable.
7. Diesel has high energy per gallon as compare with the petrol. When diesel burns, it produces a large amount of heat which can destroy walls of the cylinder and other parts of the engine. So to reduce this heat, we need a greater surface area and proper cooling system. In order to achieve this greater surface area, the engines are made slightly bigger.
8. Diesel engine uses turbocharger or supercharger to pump more air into the cylinder, which increases its price and size.
9. In diesel engines, injector technology is used to inject fuel into the combustion chamber, which is more expensive than spark plug technology of petrol engine.
10. Diesel engine is very big as compared with the petrol engine and it uses high power starting motor to crank the engine, which is not suitable for motorcycles.
After all these disadvantages some manufactures like Royal Enfield have succeed to manufacture diesel engine bikes and may be, after some years these bikes can replace all petrol bikes.
Top 5 Cheapest Cars in The World With Price And Mileage
12:26 PM
In this post I am going to tell you the top 5 cheapest cars in the world. This will provides you some idea about which car you should need to buy in minimum possible price. I hope that you will like this.
1. Bajaj RE60
Price: Rs 1.0-1.5 lakh
Mileage:
Mileage:
- Highway: 35 kmpl
- City: 24 kmpl
2. Tata Nano
Price: Rs 1.42-2.66 lakh
Mileage:
Mileage:
- Highway: 25.4 kmpl
- City: 22.2 kmpl
3. Maruti 800
Price: Rs 2.16-2.39 lakh
Mileage:
Mileage:
- Highway: 18 kmpl
- City: 13 kmpl
4. Maruti Alto 800
Price: Rs 2.5-3.66 lakh
Mileage:
Mileage:
- Highway: 22.7 kmpl
- City:17 kmpl
5. Hyundai EON
Price: Rs 2.93-3.95 lakh
Mileage:
Mileage:
- Highway: 21 kmpl
- City: 15 kmpl
Types of Wind Turbines – Horizontal Axis and Vertical Axis Wind Turbines
7:53 AM
In this article we will learn about different types of wind turbines with their advantages and disadvantages and difference between them. Basically the turbines are used to convert the wind energy into electrical energy with the help of a generator. It extracts the energy from the wind and converts it into mechanical energy and then this mechanical energy is used to derive a generator and we get electricity. So let’s begin our journey to learn about types of wind turbines.
Types of Wind Turbines
The wind turbines are basically divided into two types. Before discussing about wind turbine types in detail, I want to tell you about what is wind turbine?
What is Wind Turbine?
It is a mechanical machine that converts kinetic energy of the fast moving winds into electrical energy. On the basis of axis of rotation of the blades, it is divided into two parts.
1. Horizontal axis wind turbine (HAWT)
2. Vertical axis wind turbine (VAWT)
1. Horizontal Axis Wind Turbine (HAWT)
It is a turbine in which the axis of rotation of rotor is parallel to the ground and also parallel to wind direction.
They are further divided into two types
(i) Upwind turbine
(ii) Downwind turbine
(i) Upwind Turbine
The turbine in which the rotor faces the wind first are called upwind turbine.
- Today most of the HAWT is manufactured with this design.
- This turbine must be inflexible and placed at some distance from the tower.
- The basic advantage of this turbine is that, it is capable of avoiding wind shade behind the tower.
- It requires yaw mechanism, so that its rotor always faces the wind.
(ii) Downwind Turbine
The turbine in which the rotor is present at the downside of the tower is called downwind turbine. In these types of wind turbines, the wind first faces the tower and after that it faces the rotor blades.
- Yaw mechanism is absent in this turbine. The rotors and nacelles are designed in such a way that the nacelle allows the wind to flow in a controlled manner.
- It receives some fluctuation in wind power because here the rotor passes through the wind shade of the tower. In other words the rotor is present after nacelle of the tower and this create fluctuation in the wind power.
Advantages and Disadvantages of HAWTs
The various advantages and disadvantages of the horizontal axis types of wind turbines are:
Advantages
- It has self-starting ability. It does not require any external power source to start.
- It has high efficiency as compared with the HAWT.
- Capable of working in high wind speed condition.
- In the case of slow wind condition, its angle of attack can be varied to get maximum possible efficiency.
- Since all blades of this turbine work simultaneously, so it is capable of extracting maximum energy form the wind.
Disadvantages
- Its initial installation cost is high.
- It requires large ground area for its installation.
- Because of its giant size of blades and towers, it becomes difficult to transport it to the sites.
- High maintenance cost.
- Creates noise problem.
- It cannot be installed near human population.
- It is not good for the bird’s population. They are killed by its blades rotation.
2. Vertical Axis Wind Turbine (VAWT)
It is a turbine in which the axis of rotation of the rotor is perpendicular to the ground and also perpendicular to the wind direction.
- It can operates in low wind situation.
- It is easier to build and transport.
- These types of Wind turbines are mounted close to the ground and are capable of handling turbulence in far better way as compared with the HAWT.
- Because of its less efficiency, it is used only for the private purpose.
VAWTs are further classified as
(i) Darrieus turbine
(ii). Giromill turbine
(iii) Savonius turbine
(i) Darrieus Turbine
Darrieus turbine is type of HAWT. It was first discovered and patented in 1931 by French aeronautical engineer, Georges Jean Marie Darrieus. It is also known as egg beater turbine because of its egg beater shaped rotor blades.
- It consists of vertically oriented blades which are mounted on a vertical rotor. It is not a self-starting turbine and hence a small powered motor is required to start its rotation.
- First the Darrieus turbine is rotated by using a small powered motor. Once it attains sufficient speed, the wind flowing across its blades generates lift forces and this lift forces provides the necessary torque for the rotation. As the rotor rotates, it also rotates the generator and electricity is produced.
(ii) Giromill Turbine:
It is similar to the Darrieus turbine but the difference is that, it has H-shaped rotor. It works on the same principle of Darrieus turbine.
- This turbine has H- shaped rotor. Here Darrieus design which has egg beater shaped rotor blades are replaced by straight vertical blades attached with central tower with horizontal supports. It may consists of 2-3 rotor blades.
- Giromill turbine is cheap and easy to build as compared with Darrieus turbine. It is less efficient turbine and requires strong wind to start. Same as darrieus types of wind turbines, it is also not self- starting and requires small powered motor to start. It is capable of working in turbulent wind conditions.
(iii) Savonius Turbine
Savonius turbine is HAWT.It was first discovered in 1922 by a Finnish Engineer Sigurd Johannes Savonius. It is one of the simplest turbine among all known turbines.
- It is a drag-type device and consists of two or three scoops. If we look it from above than it looks ‘S’ shape in cross section. The scoops of these turbines have curvature shape and because of that, it experiences less drag when it moves against the wind instead of moving with the wind.
- Since it is a drag-type machine, it is capable of extracting very less amount of wind power as compared with other similar sized lift-type turbines.
Advantages and Disadvantages of Vertical Axis Wind Turbine
Advantages
- It is simple in design and easy to construct and transport.
- It can be easily installed to desired location.
- It requires less ground area for its installation.
- Initial installation cost is very less as compared with the HAWT.
- It can work in turbulent wind condition.
- It is omni-directional and hence do not need to track winds.
- They are smaller in size and hence can be used for domestic or private purpose easily.
- They have low maintenance cost as compared with the HAWT.
Disadvantages
- It is less efficient. The efficiency of this turbine is about 30-35%.
- They are not self-starting. A small powered motor is needed to start it.
- Guy wires may required to support this turbine.
Difference between Horizontal Axis Wind Turbine and Vertical Axis Wind Turbine
S.no
|
Horizontal Axis Wind Turbine
|
Vertical Axis Wind Turbine
|
1.
|
In HAWTs, the axis of rotation of the rotor is Horizontal to the ground.
|
In VAWTs the axis of rotation of the rotor is perpendicular to the ground.
|
2.
|
Yaw mechanism is present.
|
Absence of Yaw mechanism.
|
3.
|
It has high initial installation cost.
|
It has low initial installation cost.
|
4.
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They are big in size.
|
They are small in size.
|
5.
|
Its efficiency is high.
|
It has low efficiency.
|
6.
|
It requires large ground area for installation.
|
It requires less ground area for installation.
|
7.
|
High maintenance cost.
|
Low maintenance cost as compared with HAWT.
|
8.
|
They are self-starting.
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They are not self-starting.
|
9.
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They are unable to work in low wind speed condition.
|
They are capable of working in low wind speed condition.
|
10.
|
Difficult in transportation.
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Easy in transportation.
|
11.
|
They are mostly used commercially.
|
They are mostly used for private purpose only.
|
12.
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It cannot be installed near human population.
|
It can be installed near human population.
|
13.
|
It is not good for the bird’s population.
|
It is good for the bird’s population.
|
What is Governor in Automobile? How Does it Works?
7:08 AM
Governor is a mechanical device which is used to regulate
the mean speed of the engine, when there are variations in the load. When load
on the engine varies, the configuration of the governor changes and it controls
the supply of the fuel to the engine. How does it controls the supply, this
question arises in our mind, so let’s find out what happens in the governor’s
configuration when load varies on the engine.
the mean speed of the engine, when there are variations in the load. When load
on the engine varies, the configuration of the governor changes and it controls
the supply of the fuel to the engine. How does it controls the supply, this
question arises in our mind, so let’s find out what happens in the governor’s
configuration when load varies on the engine.
When load on the engine increases, its speed decreases, so
it becomes necessary to increase the supply of the working fluid (ex petrol or diesel)
to the engine. On the other hand when the load on the engine decreases, the
governor’s speed increases, so it requires to decrease the supply of the fuel.
it becomes necessary to increase the supply of the working fluid (ex petrol or diesel)
to the engine. On the other hand when the load on the engine decreases, the
governor’s speed increases, so it requires to decrease the supply of the fuel.
When the speed of the governors increases, its sleeve moves in
upward direction, which is connected to a throttle valve through a bell crank
lever. This upward motion of the sleeve operates the valve to decrease the supply
of the fuel. And when the speed of the governor decreases due to the increase
in the load, the sleeve move downward, this made the valve to open to a larger
extent and increases the fuel supply.
upward direction, which is connected to a throttle valve through a bell crank
lever. This upward motion of the sleeve operates the valve to decrease the supply
of the fuel. And when the speed of the governor decreases due to the increase
in the load, the sleeve move downward, this made the valve to open to a larger
extent and increases the fuel supply.
How Refrigerator Works ?- Easiest Explanation
7:02 AM
What is a Refrigerator?
A refrigerator commonly called as fridge is defined as a machine which is used to maintain or keep the food materials at low temperature and prevents their spoilage. The food materials kept at low temperature spoils or degrade gradually and can remain fresh for longer time. The refrigerator generally keeps the perishable items at a lower temperature range.
Working Principle of Refrigerator
It works on the principle of thermal equilibrium i.e. when a cold body comes in contact with a hot body than the heat flows from hot body to cold body until they will not attain the same temperature. In the same way a liquid (called as refrigerant) at low temperature is allow to pass through the fridge compartment. As the refrigerant comes in contact with the air, it takes the heat from it and lowers its temperature. This process keeps continue and the temperature inside the fridge lowers down and keeps the food or perishable items at lower temperature and stops or slows down their spoilage time and can be stored for weeks or months.
Main Components
A refrigerator has the following five main components
- Refrigerant: Isobutane, CFCs, ammonia.
- Compressor: Compresses the vapor and maintains the flow of refrigerant in the cycle.
- Condenser Coil: Cools the high pressure vapor and changes it into high pressure liquid.
- Expansion device or throttling device: Expands the high pressure liquid, reduces its temperature and pressure.
- Evaporator coil: Takes the heat from the air inside the fridge and makes it cool.
Lets discuss the function of each component in detail
1. Refrigerant
It is also called as coolant and is the working fluid for the refrigerator. It takes the heat from inside of the refrigerator and transports it to the outside. Most commonly used refrigerant in the refrigerator are isobutane (used in modern fridges), CFCs and ammonia (toxic gas and not used in modern fridge)
2. Compressor
It circulates the refrigerant during the working of the fridge. It compresses the refrigerant gas and increases its temperature and pressure. Compressor is the heart of the fridge, without it its working is not possible.
3. Condenser Coil
It is present outside at the back of the refrigerator. It has grill tube and looks like radiator. Its main purpose is to cools the hot and high pressure gases from the compressor. When the hot gases pass through the condenser coil, it gets cool down by the cool air of the room and gets converted into high pressure liquid.
4. Expansion Device or Throttling Device
As its names indicated it expands the high pressure liquid refrigerant and reduces its temperature and pressure. The temperature drops to 20 degree Celsius and pressure to 0.6 bar.
5. Evaporator Coil
Evaporator coil is present inside the fridge. It takes the heat from the air inside the fridge and makes it cool. And this cool air inside the fridge takes the heat from the food materials and lowers their temperature.
How Refrigerator Works?
1. The high pressure and high temperature (80-90 degree Celsius) refrigerant vapor from the compressor enters into the condenser. In the condenser the vapor gets cooled down and changes into liquid.
How condenser cools the liquid?
Since the condenser coil is exposed to the room temperature and when the hot high pressure vapor inside the condenser coil is comes in contact with room air, It gets cooled and changes into high pressure liquid.
2. Now this high pressure liquid has a temperature of 45 degree Celsius and pressure of 8 bar and passes to the throttling device where it expands and its pressure and temperature drops to .6 bar and 20 degree Celsius and partially gets converted into vapor.
3. The partially converted vapor-liquid refrigerant passed to the evaporator coil and it absorbs the heat from the air inside the refrigerator and completely gets converted into vapor. Here refrigerant cools the inside air of the fridge by absorbing its heat. In the evaporator the temperature of the refrigerant do not changes. The cool air inside the fridge is used to maintain the food items at lower temperature.
4. Form evaporator the low pressure vapor enters into the compressor. The compressor compresses the vapor to high pressure. But as the pressure of the gas increases it also increases its temperature. And this high pressure and high temperature vapor enters into the condenser to repeat the cycle.
The cycle that is used in the working of the refrigerator is called vapor compression cycle.
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