Why carburetor is not used in diesel engine?

• First of all diesel is Non volatile fluid, petrol is volatile fluid..We are using carburetor in petrol engine it premix the air fuel in right proportion..

• During the suction stroke Air gets draw inside..at the time due to the pressure difference between the nozzle and air.. fuel gets vaporize and mix with air..Whereas if we use diesel It cant vaporize ( due to non volatility) hence air fuel mixture will be not good for combustion process..This is the main reason.
• Diesel Engines are desired to function in presence of excess amounts of air to decrease the amount of unburned fuel released (Emissions).It is not possible in carburetor.These are the main reason we are not using the carburetor in diesel engine

Why does a diesel engine have more torque developing capacity than a gasoline engine?

We all have that some question in our mind in automobile field..May be this post will help you about the torque Producing capacity in Diesel and petrol engine

Torque = Force x Perpendicular Distance

What force we are discussing here is gas force which is produced inside the combustion chamber..

gas force = pressure x area

link 1-crankshaft bearing

link 2-crankshaft

link 3-connecting rod

link 4-piston

During the expansion process(power stroke) high amount of pressure is developed,which makes the piston to move downward at high speed..Hence force is acting through the connecting rod(gas force)..Then what is the perpendicular distance?? By this seeing the crank slider diagram we can identify perpendicular distance is crank..

Torque = Gas force ( pressure x area) x perpendicular distance (crank radius)

By above formula,If we increase the pressure area or crank radius we can increase the torque..

In diesel engine..Compression ignition is takes place..During combustion ignition peak pressure will be higher than the petrol engine due to the compression ratio is high..If peak  pressure and area (compression ratio) is higher simultaneously torque will be higher..

This is the main reason we have use diesel engine for commercial vehicle(to carry more load) which will give more torque(force required to rotate the crankshaft)..

Inplant Training in Ashok Leyland Company Ennore

Hi everyone today I am going to share Inplant training Experience in Ashok Leyland Company at ennore,Ennore plant is mainly for the Assembly purpose.

1)FRAME ASSEMBLY:

• It is also the part of the chassis and also the supporting member of the vehicle.
• Mostly frame is assembled by using low carbon steel , because it should withstand some effects during the accident.If it is a brittle material , it will break when the heavy load or force is applied.
• Types of vehicle:

1. Light commercial vehicle
2. Heavy commercial vehicle
3. Passenger type vehicle
4. Multi acting vehicle

Depend on the types frame will be designed.

• There will be several bracket is attached in the frame for several purpose like attach leaf springs,engine mounting etc.
• Front underrun protection device bracket is also used in frame assembly for safety purpose.
• Several cross member also fixed to withstand load.
• For multi acting vehicle,flanges will be provided to withstand heavy load.
• By using several instrument frame is assembled.

2) Chassis Assembly:

• After finishing the frame assembly , chassis assembly is started.
• First of all , rear axle is fitted along air distributor and shake up jaw.
• Then front axle is fitted at the front along with power steering arrangement.
• The exhaust pipe and propeller shaft also connected.
• Propeller shaft is connected by universal joint , because this joint can motion in any direction.
• The engine is placed in the front side at the U-type cross member.It consists of piston,cylinder,fuel pump,two compressor.
• One compressor is used for pressurizing the air,another one is used for pressurizing the oil used for hydraulic forces in steering arrangement
• Along with alternator,fan for radiator is connected by belt,it is automatically run when the engine started and the whole arrangement run by this belt.
• Atlast top portion is fitted.

3) Front axle assembly:

• Axle is mainly used to carry the weight and it is made by forged steel.
• Axle is bow shaped beam.The axle arm is fitted at the both the end.
• The axle arm is fixed by king pin.
• Then the brake drum is fixed.It consists of hub.brake liner,booster for brake,S-Cam.
• In Axle arm,the tie rod is connected between two wheels.It ensure that the both wheel turns in same direction.

4)Rear axle Assembly:

• It is slightly different from front axle assembly.
• In this additionally differential arrangement is placed for rear wheel drive.
• First of all,hub is attached after that break drum arrangement is fixed.
• After that two bearing is fixed inside the brake drum arrangement for the fine rolling action.
• Then the half shaft is placed inside the differential arrangement at the both end.

5)Engine assembly:

• In engine,engine case and flywheel is made by cast iron,piston is made by aluminium alloys,crank and cam is made by forged steel.
• The piston is placed in the engine case,the piston is connected to crank shaft by connecting rod.The small end of connecting rod is connected to piston and big end is connected to crank shaft.
• The fuel injector is placed above the cylinder.
• The cam is connected to crankshaft for the valve mechanism,the cam converts rotational motion into reciprocating motion for valve.
• For fuel injecting purpose,fuel pump is used,it transfer the fuel into the fuel injector.
• Turbo charger is fixed at the exhaust,another end is connected to inlet.It will increase the efficiency by transfer the inlet air quickly using compressor.
• Atlast alternator and fan for radiator is connected by belt.

Turbocharger and Supercharger

Main Principle:
                           It is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power.It is an Forced Induction method(It is the process of delivering compressed air to the intake of an internal combustion engine. A forced induction engine uses a gas compressor to increase the pressure, temperature and density of the air. An engine without forced induction is considered a naturally aspirated engine.

Main Difference:

                          The key difference between a turbocharger and a supercharger is its power supply. Something has to supply the power to run the air compressor. In a supercharger, there is a belt that connects directly to the engine. It gets its power the same way that the water pump or alternator does. A turbocharger, on the other hand, gets its power from the exhaust stream. The exhaust runs through a turbine, which in turn 
spins the compressor

Turbocharger:

Advantages:

• Significant increase in horsepower.
• Power vs size: allows for smaller engine displacements to produce much more power relative to their size.
• Better fuel economy: smaller engines use less fuel to idle, and have less rotational and reciprocating mass, which improves fuel economy.
• Higher efficiency: turbochargers run off energy that is typically lost in naturally-aspirated and supercharged engines (exhaust gases), thus the recovery of this energy improves the overall efficiency of the engine.
• It is most suitable for the diesel engine.Because turbocharger will operate at higher exhaust flow rate spontaneously for diesel engine low torque will be produce at higher RPM If we install turbocharger it will give more power.

Disadvantages:

• Turbo lag: turbochargers, especially large turbochargers, take time to spool up and provide useful boost.
• Boost threshold: for traditional turbochargers, they are often sized for a certain RPM range where the exhaust gas flow is adequate to provide additional boost for the engine. They typically do not operate across as wide an RPM range as superchargers.
• Power surge: in some turbocharger applications, especially with larger turbos, reaching the boost threshold can provide an almost instantaneous surge in power, which could compromise tyre traction or cause some instability of the car.
• Oil requirement: turbochargers get very hot and often tap into the engine’s oil supply. This calls for additional plumbing, and is more demanding on the engine oil. Superchargers typically do not require engine oil lubrication.

Supercharger:

Advantages:

• Increased horsepower: adding a supercharger to any engine is a quick solution to boosting power.
• No lag: the supercharger’s biggest advantage over a turbocharger is that it does not have any lag. Power delivery is immediate because the supercharger is driven by the engine’s crankshaft.
• Low RPM boost: good power at low RPM in comparison with turbochargers.
• Price: cost effective way of increasing horsepower.

Disadvantages:

      

• Less efficient: the biggest disadvantage of superchargers is that they suck engine power simply to produce engine power. They’re run off an engine belt connected to the crankshaft, so you’re essentially powering an air pump with another air pump. Because of this, superchargers are significantly less efficient than turbochargers.
• Reliability: with all forced induction systems (including turbochargers), the engine internals will be exposed to higher pressures and temperatures, which will of course affect the longevity of the engine. It’s best to build the engine from the bottom up to handle these pressures, rather than relying on stock internals.

Thermodynamic Process

Here we going to discuss about the some of the Thermodynamic process.First lets discuss about the what is thermodynamic process.

A thermodynamic process is a passage of a thermodynamic system from an initial state to a final state.In general, in a thermodynamic process, the system passes through physical states which are not describable as thermodynamic states, because they are far from internal thermodynamic equilibrium.

Isobaric Process:

                             

An isobaric process occurs at constant pressure. An example would be to have a movable piston in a cylinder, so that the pressure inside the cylinder is always at atmospheric pressure, although it is

isolated from the atmosphere.From diagram we can see that from A to B pressure remains constant.

Isochoric Process:

An isochoric process is one in which the volume is held constant, meaning that the work done by the system will be zero. It follows that, for the simple system of two dimensions, any heat energy transferred to the system externally will be absorbed as internal energy. An isochoric process is also known as an isometric process or an isovolumetric process. An example would be to place a closed tin can containing only air into a fire. To a first approximation, the can will not expand, and the only change will be that the gas gains internal energy.From diagram we can see that from A to B Volume is constant

Isothermal process:

An isothermal process occurs at a constant temperature. An example would be to have a system immersed in a large constant-temperature bath. Any work energy performed by the system will be lost to the bath, but its temperature will remain constant.

Adiabatic Process:

An adiabatic process is a process in which there is no energy added or subtracted from the system by heating or cooling. For a reversible process, this is identical to an isentropic process. The system is thermally insulated from its environment and that its boundary is a thermal insulator. If a system has an entropy which has not yet reached its maximum equilibrium value, the entropy will increase even though the system is thermally insulated. Under certain conditions two states of a system may be considered adiabatically accessible

Isentropic Process:

An isentropic process occurs at a constant entropy. For a reversible process this is identical to an adiabatic process. If a system has an entropy which has not yet reached its maximum equilibrium value, a process of cooling may be required to maintain that value of entropy.

Polytropic process:

A polytropic process is a thermodynamic process that obeys the relation:

where P is the pressure, V is volume, n is any polytropic index, and C is a constant. This equation can                 be used to accurately characterize processes of certain systems, notably the compression or expansion of a gas, but in some cases, liquids and solids.

isentropic process and polytropic process difference:
1. isentropic is reversible adiabatic process.polytropic process is one of the proces of thermodynamic.
2. isentropic perform . but polytropic perform  ,pv reletion. here p is pressure in pascal. v= volume meret cube. and y=adiabatic index,and n= polytropic index.
3. isentropic process only work transfer no heat transfer. but in polytropic heat and work both can be transfer.
4.polytropic index "n" always less then adiabatic index "y",but greater then 1.

Relationship to ideal processes[edit]

For certain values of the polytropic index, the process will be synonymous with other common processes. Some examples of the effects of varying index values are given in the table.

Variation of polytropic index 

Polytropic index	Relation	Effects
	—	Negative exponents reflect a process where the amount of heat being added is large compared to the amount of work being done (i.e. the energy transfer ratio > γ/(γ-1)). Negative exponents can also be meaningful in some special cases not dominated by thermal interactions, such as in the processes of certain plasmas in astrophysics.
	(constant)	Equivalent to an isobaric process (constant pressure)
	(constant)	Equivalent to an isothermal process (constant temperature)
	—	A quasi-adiabatic process in which the heat flow and work flow are in opposite directions (positive K), such as in vapor compression refrigeration during compression, where the elevated vapour temperature resulting from the work done by the compressor on the vapour leads to some heat loss from the vapour to the cooler surroundings. Also a "polytropic compression" process like gas through a centrifugal compressor where heat loss from the compressor (into environment) is greater than the heat added to the gas through compression.
	—	is the isentropic exponent, yielding an isentropic process (adiabatic and reversible). It is also widely referred as adiabatic index, yielding an adiabatic process (no heat transferred). However the term adiabatic does not adequately describe this process, since it only implies no heat transfer.[3] Only a reversible adiabatic process is an isentropic process.
	—	Normally polytropic index is greater than specific heat ratio (γ) within a "polytropic compression" process like gas through a centrifugal compressor. The inefficiencies of centrifugal compression and heat added to the gas outweigh the loss of heat into the environment. Also a quasi-adiabatic process in which the heat flow and work flow are in the same direction (negative K), such as in an internal combustion engine during the power stroke, where heat is lost from the hot combustion products, through the cylinder walls, to the cooler surroundings, at the same time as those hot combustion products do work on the piston.
	—	Equivalent to an isochoric process (constant volume)

Quasistatic process:

A quasistatic process is a thermodynamic process that happens slow enough for the system to remain in internal equilibrium. An example of this is quasistatic compression, where the volume of a system changes at a rate slow enough to allow the pressure to remain uniform and constant through out the system

UNITS

Units: It is the measurement of Physical quantity.It is one of the important factor in Engineering

                     field.It is mainly classified into two units.

                               1)Fundamental units

                               2)Derived units

Fundamental units:

               It is the base unit for all physical quantity.There are seven base units are kilogram,candela,metre,second,ampere,kelvin and mole.Most probably fundamental units are denoted as Length(L),Mass(M) and Time(t).

Derived units:

                               The units which is derived from the Fundamental units are called Derived units 

e.g., Volume, area,velocity,pressure.

System of units:

                               There are four types of system of units,which are commonly used and universally

recognised.

                               1)C.G.S units

                               2)F.P.S  units

                               3)M.K.S units

                               4)S.I. units

C.G.S units :

                               In this system,fundamental units of Length,mass,time are centimetre,gram and time.It is also known as absolute units(not depend on arbitrary units)

F.P.S units :

                           In this system,fundamental units of length,mass and time are foot,pound and second respectively.

M.K.S units:

                                 In this system,fundamental units of length,mass and time are mass,kilogram and second respectively.It is also known as engineer's units.

International System of Units(S.I. units):

                                 When Maxwell first introduced the concept of a coherent system, he identified three quantities that could be used as base units: mass, length and time. Giorgi later identified the need for an electrical base unit. Theoretically any one of electric current,potential difference, electrical resistance, electrical charge or a number of other quantities could have provided the base unit, with the remaining units then being defined by the laws of physics. In the event, the unit of electric current was chosen for SI. Another three base units (for temperature, substance and luminous intensity) were added later.It is the most widely used system of measurement.The seven base units are metre,kilogram,second,ampere,kelvin,mole and candela.

Important units:

SI Units and Symbols used in the Guide Subject Physical Quantity Symbol Name Unit Mechanics Mass m, M kilogram kg Linear position Length, Distance Radius x, r  l, d R meter m Time t,  second s Linear angle, Angular position ,  radian rad Spherical angle steradian sr Area A - m2 Volume V - m3 Moment of inertia I - kg*m2 Density - kg/m3 Linear velocity v, u, c - m/s Angular velocity ,  - rad/s Linear momentum p - kg*m/s Angular momentum L - kg*m2/s Linear acceleration a - m/s2 Angular acceleration - rad/s2 Force F newton N=kg*m/s2 Torque - N*m Impulse I - N*s Work Energy W E joule J=N*m Power P watt W=J/s Dynamic viscosity - Pa*s Electricity and Magnetism Current I ampere A Charge Q, q, e coulomb C=A*s Current density j - A/m2 Volume charge density - C/m3 Surface charge density - C/m2 Linear charge density - C/m Electric potential Voltage emf V volt V=J/C Electric field E - N/C, V/m Electric flux - V*m Electric moment pe - C*m Resistance R, r ohm =V/A Specific resistance - *m Capacitance C farad F=C/V Specific conductivity - (*m)-1 Magnetic field B tesla T=N/(A*m) Magnetic flux weber Wb=T*m2=V*s Inductance Mutual-inductance L M henri H=Wb/A Magnetic moment pm - A*m2 Polarization P - C/m2 Magnetization I - A/m Thermodynamics Temperature T kelvin K Substance quantity M mole mol Pressure P - Pa Heat Q - J Heat capacity Entropy C S - J/K Specific heat c - J/(kg*K) Molar heat cm - J/(mol*K) energy flux j - W/m2 Surface tension - N/m Stress Elasticity modulus E pascal Pa=N/m2 Oscillations and Waves Wavelength - m Wave number k - m-1 Frequency f hertz Hz Energy density - J/m3 Energy flux J - J/m2 Intensity I - J/(m2*s) Reactance Impedance X Z ohm =V/A Optics Focal length f - m Luminous intensity I candela cd Luminous flux lumen lm=cd*m2 Illuminance E lux lk=lm/m2 Brightness L - cd/m2 Linear absorption coefficient - m-1 Quantum Physics Mass absorption coefficient - m2/kg Radioactive activity A becquerel Bq=s-1 Absorbed dose D gray Gy=J/kg

                                     

                                   

(Most Important) Unit Conversions

• length
• area
• volume
• mass
• pressure
• energy
• power
• temperature
• radioactivity
• scientific notation

Length

• 1 (statute) mile (mi) = 1.6093 kilometer (km)
• 1 (nautical) mile (mi) = 1.8520 kilometer (km)
• 1 foot (ft) = 0.3048 meter (m)
• 1 yard = 0.9144 meter (m)
• 1 inch (in) = 2.54 centimeter (cm)
• 1 angstrom (A) = 10^-8 centimeter (cm) = 10^-10 meter (m)

Area

• 1 square kilometer (km²) = 10⁶ square meters (m²) = 100 hectares (ha)
• 1 hectare (ha) = 10,000 square meters (m²)
• 1 acre (ac) = 4047 square meters (m²) = 0.4047 hectare (ha)

Volume

• 1 milliliter (ml) = 1 cubic centimeter (cm³)
• 1 cubic meter (m³) = 1000 liters (L)
• 1 (US) quart (qt) = 0.9461 liter (L)
• 1 (US) gallon (gal) = 3.7854 liter (L)
• 1 (US) pint = 0.4723 liter (L)
• 1 (US) fluid ounce = 29.6 milliliter (ml)

Mass

• 1 metric ton (m.t.) = 1000 kilograms (kg)
• 1  pound (lb) = 0.4535924 kilogram (kg)
• 1 ounce (oz) = 28.3495 grams (g)

Pressure

• 1 pascal (Pa) = 1 newton/square meter (N/m²) = 1 Kg m^-1 s^-2
• 1 bar = 0.98692 atmosphere (atm) = 10⁵ pascals (Pa)
• 1 pound per square inch (psi) = 68.97 millibars (mb) = 6897 pascals (Pa)

Energy

• 1 joule (J) = 1 newton meter (Nm)
• 1 calorie (cal) = 4.184 joule (J)
• 1 kilowatt hour (kWh) = 3.6 x 10⁶ joules (J) = 8.60 x 10⁵ calories

Power (energy per unit time)

• 1 watt (W) = 1 joule per second (J/s) = 14.34 calories per minute (cal/min)

Temperature

• from Fahrenheit to Celsius: C = (F - 32) x 5/9
• from Celsius to Fahrenheit: F = (C x 9/5) + 32
• from Celsius to Kelvin: K = C + 273.15

Radioactivity

• 1 Curie (Ci) = 3.7x10¹⁰ Becquerel (Bq)
• 1 Gray (Gy) = 1 J/kg tissue = 100 rad

Commonly used prefixes...

Scientific notation

Prefix...........	Exponent	Examples of exponential usage:
peta (P)	15	amount of CO2 in atmosphere (as C)- 750 Pg (or Gt)
tera (T)	12
giga (G)	9	pool sizes: amount of water in ocean - 1.37 x 109 km3
mega (M)	6	rates: flow of Anatarctic Circumpolar Current - 200 x 106 m s-1
kilo (k)	3	distance New York - Albany ~ 350km
hecto (h)	2	atmospheric pressure: ~1012.5 hPa (=1012.5 mbar)
base unit	0
milli (m)	-3	typical amount of medicine ~1ml
micro (m)	-6
nano (n)	-9	wavelength of violet light ~400nm
pico (p)	-12	size of atom ~10pm
femto (f)	-15	detection limit of gas chromatographs for SF6 : ~1 fmole/L