Comparison of otto diesel and dual cycles

The operating cycle of an internal combustion engine can be broken down into a sequence of separate processes such as intake, compression, combustion, expansion, and exhaust. The accurate analysis of the internal combustion engine process is very complicated but in this article, we will discuss the comparison between Otto, diesel, and dual cycles.

First, you should know the main factors which are used as the basis for comparison of the cycles :

• Compression ratio
• Peak pressure
• Heat addition
• Heat rejection 
• Network

In order to compare the performance of these cycles some of the variables which we will see above some of the variable factors must be fixed. This analysis will show which cycle is more efficient for a given set of operating conditions.

Now we do it one by one all variables are fixed and then make a comparison.

• Same compression ratio and Heat addition :

Otto cycle has the highest work output and efficiency.

Diesel cycle has the least efficiency.

The dual cycle has the efficiency between the Otto and diesel cycle.

ŋ_Otto > ŋ_Dual > ŋ_Diesel 

• Same compression ratio and Hear rejection :

Otto cycle has the highest work output and efficiency.

The diesel cycle has the least efficiency.

The dual cycle has the efficiency between the Otto and diesel cycle.

ŋ_Otto > ŋ_Dual > ŋ_Diesel 

Same as the same compression ratio and hear addition.

• Same Peak pressure, Peak temperature and Heat Rejection :

Also for the same peak pressure, peak temperature and heat Rejection same as above two.

ŋ_Otto > ŋ_Dual > ŋ_Diesel 

• Same Maximum Pressure and Hear Input and Output :

Also for that case same as above all. because now we all know Otto cycle efficiency is always the highest.

ŋ_Otto > ŋ_Dual > ŋ_Diesel

Explore more information:

1. Comparison of air standard cycle and fuel-air cycles
2. Actual cycles and their analysis 
3. Comparison of air standard and actual cycles

Cam terminology

CAM NOMENCLATURE :

Definitions of terms that used in cam profile nomenclature :

• Base circle :

It is the smallest circle drawn a tangent to the cam profile from the centre.

• Tracepoint :

It is a reference point on the follower to trace the cam profile such as the knife-edge of a knife-edge follower and centre of the roller follower.

• Pitch curve :

It is the curve drawn by the tracepoint assuming that the cam is fixed and the tracepoint of the follower rotates around the cam.

• Pressure angle :

It is the angle between the normal to the pitch curve at a point and the direction of the follower motion.

Pressure angle representing the steepness of the cam profile.

• Pitch point :

It is the point on the pitch curve at which the pressure angle is maximum.

• Pitch circle :

It is the circle passing through the pitch point and concentric with the base circle.

• Prime circle :

The smallest circle drawn a tangent to the pitch curve is known as the prime circle.

Displacement diagram :

As a cam rotates about the axis, it imparts a specific motion to the follower which is repeated with each revolution of the cam. It is enough to know the motion of follower for only one revolution.

The motion of the cam can be represented on a graph the x-axis represents the can rotation and the y-axis represents the displacement of the follower. Now we discuss the follower displacement diagram and its terms :

• The angle of ascent :

It is the angle through which the cam turns during the timing of the follower rising. 

In the above figure angle of ascent represent by Ɵ_ri.

• The angle of dwell :

It is the angle through which the cam turns at the same time follower remains stationary at the highest or the lowest position.

In figure angle of dwell represent for the highest position by Ɵ_d1.

• The angle of descent :

It is the angle through which the cam turns during the timing when the follower returns to its initial position.

In figure angle of descent represent by Ɵ_re.

• Angle of action :

It is the angle through which the cam turns during the time between the beginning of rise and the end of the return of the follower. In fact angle of action is the total angle moved by the cam.

In figure angle of action represent by Ɵ.

For variation of cam types and different types of followers motions there are also different different displacement diagram are made. 

Types of followers

Cam followers are different types they are classified according to :

1. Shape
2. Types of follower motion
3. Location of the line of movement

According to shape :

1. Knife-edge follower
2. Roller follower
3. Mushroom follower 

Let we check it out above follower in details :

• Knife-edge follower :

In knife-edge follower, the connecting end of the follower has a sharp knife-edge so that its called knife-edge follower.

This type of follower is quite simple in construction.

It produces great wear of the surface at the point of contact and considerable thrust exist so its use is limited.

• Roller follower :

In roller follower, the connecting end of the follower is a roller so that is called roller follower.

Wear rate is greatly reduced because of rolling motion between contacting surfaces of the cam and follower.

At low speed, the follower has a pure rolling action but at high speeds, some sliding also occurs.

Roller followers are commonly used where more space is available in the large stationary gas or oil engines and aircraft engines.

In case of a steep rise, a roller follower jams the cam and therefore it is not preferred.

• Mushroom follower :

A mushroom follower is also two types :

1. Flat-faced follower
2. Spherical follower

• Flat-faced follower :

In flat-faced follower connecting end of the follower is perfectly flat-faced so that is called flat-faced follower.

The thrust at the bearing exerted is less as compared to another follower.

In this follower, high surface stresses and wear are quite high due to deflection and misalignment.

This types of follower are mostly used in an automobile.

• Spherical follower :

In spherical follower connecting end of the follower is spherical in shape so its called spherical follower.

In flat-faced follower, high surface stress is produced to minimize these stress the follower is machined to spherical shape.

According to follower movement :

1. Reciprocating follower 
2. Oscillating follower 

• Reciprocating follower :

In this type, the cam rotates and the follower reciprocates or translates in the guides of the cam.

This is also called translating follower.

• Oscillating follower :

In this type, cam makes the rotary motion and follower is pivoted at the suitable point on the frame and oscillating as the cam makes a rotary motion.

According to the location of the line of movement :

• Radial follower :

In this type of follower, the line of movement of the follower passes through the centre of rotation of the cam. 

• Offset follower :

In this type of follower, the line of movement of the roller follower is offset from the centre of rotation of the cam.

You may also check different types of the cam.

Types of cam

Cams are classified according to the following terms :

• Shape
• Follower movement
• Manner of the constraint of the follower 

According to shape :

1. Wedge and flat cams
2. Radial or Disc cams
3. Spiral cams
4. Cylindrical cams
5. Conjugate cams
6. Globoid cams
7. Spherical cams

Now explain the above types of cams in details : 

• Wedge and flat cams :

A wedge cam has a wedge W has a translational motion.

The follower F can either translate or oscillate.

In that type of cam, spring is usually, used to maintain the contact between the cam and the follower.

The cam is stationary and the follower constraint or guide G causes the relative motion of the cam and the follower.

• Radial or Disc cams :

  

A cam in which the follower moves radially from the centre of rotation of the cam is known as a radial cam.

Radial cams are very popular due to their simplicity and compactness.

• Spiral cams :

A spiral cam is a face cam in which a groove is cut in the form of a spiral. The spiral groove consists of teeth which mesh with a pin gear follower. 

The use of such cam is limited as the cam has to reverse the direction to reset the position of the follower. It is mainly used in computers.

• Cylindrical cams :

In a cylindrical cam, a cylinder which has a circumferential contour cut in the surface rotates about its axis. For this cam follower motion can be two types :

• A groove is cut on the surface of the cam and a roller follower has a constrained oscillating motion.
• An end cam in which the end of the cylinder is the working surface. 

Cylindrical cams are also known as barrel or drum cams.

• Conjugate cams :

A conjugate cam is a double-disc cam, the two discs being keyed together and are in constant touch with the two rollers of a follower. 

Thus, the follower has a positive constraint. 

Such cam is preferred when the requirements are low wear, low noise, better control of the follower, high speed and high dynamic loads.

• Globoid cams :

A globoid cam can have two types of surfaces, convex or concave. 

A circumferential contour is cut on the surface of rotation of the cam to import the motion to the follower which has an oscillatory motion.

Such types of the cam are used in limited to moderate speeds and where the angle of oscillation of the follower is large.

• Spherical cams :

In spherical cam, the follower oscillates about the axis perpendicular to the axis of rotation of the cam.

This type of cam is in the form of a spherical surface.

According to follower movement :

• Rise-Return-Rise ( R-R-R)
• Dwell-Rise-Return-Dwell ( D-R-R-D )
• Dwell-Rise-Dwell-Return-Dwell ( D-R-D-R-D )

The motion of the followers is distinguished from each other by the dwells they have.

Now the question arises in your mind is what is dwell?

A dwell is zero displacements or the absence of motion of the follower during the motion of cam.

Now explain the above types of cams in details : 

• Rise-Return-Rise ( R-R-R ) :

In this type of cam, there is an alternate rise and return of the follower with no periods of dwells.

In this type of cam follower has a linear or an angular displacement.

• Dwell-Rise-Return-Dwell ( D-R-R-D ) :

In this type of cam there is rise and return of the follower after a dwell.

This type of cam are more frequently used than the R-R-R cam types.

• Dwell-Rise-Dwell-Return-Dwell ( D-R-D-R-D ) :

In this type of cam dwelling of the cam is followed by rise and return.

This type of cam is most widely used cam types.

According to manner of constraint of the follower :

1. Pre-loaded Spring Cam
2. Positive-drive Cam
3. Gravity Cam

Introduction of cam and Follower

In this article, we have to see some basic knowledge about the cam and follower and about cam mechanism. Let we know first what is cam?

A cam is a mechanical member used to impact desired motion to a follower by direct contact.   
                                                                   OR

Cam is the part of a machine in sliding or rolling contact with a rotating cam and given motion by it.

The cam may be rotating or reciprocating whereas the follower may be rotating, reciprocating or oscillating. Now the question may arise that what is a follower?

Cam drives the mating element in mechanical linkage of motion is called FOLLOWER.

There are many different types of the cam are widely used in automobile, automatic machines, internal combustion engine, machine tools, printing control mechanisms etc.

Cams are manufactured by die-casting, milling or by punch-press.

A cam and the follower combination belong to the category of a higher pair. 
In that mechanism :

• A driver member is known as the cam.
• A driven member is known as a follower.
• A frame that can support the cam and guides the follower.

LPG autoignition temperature

What is the autoignition temperature of LPG?

Answer:

• Autoignition temperature of LPG Propane is 470 ⁰C or 878 ⁰F
• Autoignition temperature of LPG Butane is 405 ⁰C or 761 ⁰F

The autoignition temperature decreases as the pressure or oxygen concentration increases.

LPG flame temperature

What is the flame temperature of LPG?

Answer :

• LPG flame temperature is 1980 ⁰C

When LPG is burned properly, the flame colour is blue but sometimes the colour is yellow or red it indicates incomplete combustion.

That property is a consideration while LPG Liquefied petroleum gas is used in mainly automobile vehicle as a fuel or as rural heating. 

Some important facts about LPG

LPG important facts: 

1. LPG full form is Liquefied Petroleum Gas or Liquid Petroleum Gas.
2. LPG is a group of flammable hydrocarbon gases that are liquefied through the use of pressure and commonly used as fuel mostly in an automobile.
3. LPG comes from natural gas processing and while refining petroleum.
4. Propane, butane and isobutane or a mixture of all of this gas es all are fall under LPG gas label.
5. LPG is used for heating, cooking, hot water and vehicles and also used in refrigeration as refrigerant, aerosol propellants and petrochemical feedstock.
6. LPG is mainly stored as a liquid in steel vessels ranging from small gas bottles to the large gas cylinders and storage tank.
7. Sometimes LPG is also called as WET GAS because of its liquidity.
8. It also called NHL means natural gas-liquid.
9. LPG gases are compressed into a liquid at relatively low pressure.
10. Propane does not occur alone naturally.
11. Commercially available LPG is mostly derived mainly from fossil fuels.
12. Real LPG Explosions are Really Rare.
13. LPG is NOT Coal Seam Gas (CSG).
14. LPG is a Renewable Energy Source.

What does LPG stands for?

The meaning of LPG is either liquefied petroleum gas or liquid petroleum gas.

LPG stands by many names and this can something be confusing.

LPG also called sometimes LPG gas, Propane, LP Gas, BBQ Gas, Autogas or Camping Gas.

LPG is a mixture of hydrocarbon and flammable mixture.

LPG is refined petroleum gas used as a green replacement fuel in the converted vehicle because the emission is less in LPG engine as compared with petrol and diesel used as fuel.

LPG used as fuel in heating operation, automobile, rural heating and as a refrigerant in refrigeration.

Milling machine operation

The different operations performed in a milling machine are following below.

1. Plain Milling 
2. Face Milling 
3. Side Milling 
4. Straddle Milling 
5. Angular Milling 
6. Gang Milling 
7. Form Milling 
8. Profile Milling 
9. End Milling 
10. Saw Milling 
11. Milling keyways, Grooves, and slots
12. Gear Cutting 
13. Helical Milling 
14. Cam Milling 
15. Thread Milling 

• Plain milling:

It is the operation of production of a plain, flat or horizontal surface parallel to the axis of rotation of a plain milling cutter.

The operation is also called slab milling.

To perform this operation, the work and the cutter are mounted properly on the machine. The depth of cut is adjusted by rotating the vertical feed screw of the table and the machine is started after selecting the proper speed and feed. 

• Face milling:

This operation is performed by a face milling cutter rotated about an axis perpendicular to the work surface. The operation is carried in a plain milling machine and the cutter is mounted on a stub arbour to produce a flat surface. Hence the face milling operation is done.

• Side milling:

It is the operation of production of a flat vertical surface on the side of a workpiece by using a side milling cutter. 

• Straddle milling:

The straddle is the operation of production of flat vertical surfaces on both sides of the workpiece by using two side milling cutters mounted on the same arbour. This operation is very commonly used to produce square or hexagonal surfaces. 

• Angular milling:

The angular milling is the operation of the production of an angular surface on a workpiece other than at right angles to the axis of the milling machine spindle. The angular groove may be single or double angle but may be of varying included angle according to the type and shape of the angular cutter used.

• Gang milling:

It is the operation of machining many surfaces of a workpiece simultaneously by feeding the table against a number of cutters having same or different diameters mounted on the arbour of the machine.

• Form milling:

It is the operation of producing irregular contours by using form cutter. The irregular contour may be convex, concave or any other shape. After machining, the formed surface is checked by a template gauge. The cutting speed for form milling is 20% to 30% less than that of the plain milling.

• Profile milling :

It is the operation of reproduction of an outline of a template or complex shape of a master die on a workpiece. An end mill is one of the most widely used milling cutters in profile milling work.

• End milling:

It is the operation of production of a flat surface which may be vertical, horizontal or at an angle in reference to the table surface. An end mill cutter is used for this operation. The end milling cutters are also used for the production of slots, grooves or keyways.

The vertical milling machine is most suitable for end milling operation.

• Saw Milling:

It is the operation of the production of narrow slots or grooves on a workpiece by using a sawmilling cutter. 

It can be also be performed for complete parting-off operation.

• Milling keyways, grooves, and slots:

It is the operation of production of keyways, grooves and slots of varying shapes and sizes can be performed in a milling machine by using a plain milling cutter, a plain slitting saw, an end mill or by a side milling cutter.

The open slots can be cut by a plain milling cutter or by a side milling cutter.

The closed slots can be cut by using end mills.

Dovetail slots or T-slots is manufactured by using a special type of cutters.

A woodruff key is produced by using a woodruff key slot cutter.

Standard keyways are cut on shafts by using a side milling cutter or end mills.

The cutter is exactly at the centre line of the workpiece and then the cut is taken.

• Gear cutting:

It is the operation performed in a milling machine by using a form-relieved cutter. The cutter may be a cylindrical type or end mill type. The cutter profile corresponds exactly with the tooth space of the gear. 

• Helical milling:

It is the operation of the production of helical flutes or grooves around the periphery of a cylindrical or conical workpiece.

It is performed by swivelling the table to the required helix angle and then by rotating and feeding the work against the rotary cutting edges of a milling cutter.

• Cam milling:

It is the operation of the production of the cam in a milling machine by the use of a universal dividing head and a vertical milling attachment. The cam blank is secured at the end of the dividing head spindle and an end mill is held in the vertical milling attachment. The axis of the cam blank and the end mill spindle should always remain parallel to each other when setting for cam milling.

• Thread milling:

It is the operation of the production of threads by using a single or multiple thread milling cutter. The operation is performed in special thread milling machines to produce accurate threads in small or large quantities.

This operation required three driving motions in the machine.

• For the cutter
• For the work 
• For the longitudinal movement of the cutter

Read related posts:

1. Milling machine introduction
2. Difference between turning and milling
3. Working principle of milling machine
4. Milling machine safety precautions
5. Milling machine parts
6. Lubrication used in milling machine
7. Types of milling cutter
8. Uses of milling machine
9. What is a milling machine?
10. Milling machine uses

Type of milling cutter

Different types of milling cutters are used in milling operation performed on a milling machine. so let we know first what is milling cutters?

The milling cutter is revolving tools having one or many cutting edges of identical form equally spaced on the circumference of the cutter. The cutting elements are called teeth which intermittently engages the work piece and remove material by relative movement of the work piece and cutter. 

Types of milling cutters :

1. According to constructional features of the cutter :

• Solid cutter
• Tipped solid cutter
• Inserted teeth cutter

2. According to the relief characteristics of the cutter teeth :

• Profile relieved cutter
• Form relieved cutter

3. According to the methods of mounting the cutter :

• Arbor type cutter
• Shank type cutter
• Facing type cutter

4. According to the direction of rotation of the cutter :

• Right-hand rotational cutter
• Left-hand rotational cutter

5. According to the direction of a helix of the cutter teeth :

• Parallel or straight teeth cutter
• Right-hand helical cutter
• Left-hand helical cutter
• Alternate helical teeth cutter

6. According to the purpose or use of cutter :

• Standard milling cutter
• Special milling cutter 

There are many other different types of standard milling cutters. They are classified below : 

1. Plain milling cutter 

• Light duty plain milling cutter
• Heavy-duty plain milling cutter
• Helical plain milling cutter

2. Side milling cutter 

• Plain side milling cutter
• Staggered teeth side milling cutter
• Half side milling cutter
• Interlocking side milling cutter

3. Metal slitting saw 

• Plain metal slitting saw
• Staggered teeth metal slitting saw

4. Angle milling cutter

• Single angle milling cutter
• Double angle milling cutter

5. End mill

• Taper shank end mill
• Straight shank end mill
• Shell end mill

6. T-slot milling cutter

7. Woodruff key slot milling cutter

8. Fly cutter

9. Formed cutter

• Convex milling cutter
• Concave milling cutter
• Corner rounding milling cutter
• Gear cutter
• Thread milling cutter

10. Tap and reamer cutter

Read related posts:

1. Milling machine introduction
2. Difference between turning and milling
3. Working principle of milling machine
4. Milling machine safety precautions
5. Milling machine parts
6. Lubrication used in milling machine
7. Uses of milling machine
8. What is a milling machine?
9. Milling machine uses
10. Milling machine operation

The size of drilling machine

Size of a drilling machine :

The drilling machine size varies with the different types of the machine being considered.

A portable drilling machine is specified by the maximum diameter of the drill that it can hold.

The sensitive and upright drilling machines are specified by the diameter of the largest piece that can be centred under the spindle. This is a case of a 600 mm size upright drilling machine, the spindle placed at a distance is slightly greater than 300 mm from the front face of the column.

The size of the radial drilling machine is specified by the diameter of the column and length of the arm. Other particulars such as maximum drilling radius, minimum drilling radius, spindle speeds and feeds etc. 

To specify a drilling machine fully further particulars such as the maximum size of drill that the machine can operate, table diameter, the maximum spindle travel, numbers of spindle speeds and feeds available.

The size of a lathe

Size of lathe machine expressed in following ways that illustrated below :

• The height of the centres measured from the lathe bed.
• The swing diameter over the bed. It is the largest diameter of work that will revolve without touching the bed and is twice the height of the centre measured from the bed of the lathe.
• The length between centres. This is the maximum length of work that can be mounted between the lathe centres.
• The swing diameter over the carriage. This is the largest diameter of work that will revolve over the lathe saddle and is always less than the swing diameter over the bed.
• The maximum bar diameter. This is the maximum diameter of bar stock that will pass through hole of the head stock spindle.
• The length of the bed. This is the approximate floor shape occupied by the lathe.

Ion beam machining

Ion beam machining is generally a surface finishing process in which the material removal takes place by sputtering of ions.
It is also called the etching process. This is a different process from electric discharge, electron beam, laser beam and plasma arc machining. 

Working Principle :

This process is very simple. It consists of bombarding the work with accelerated ions which collide with the surface atoms of the work. Each bombarding ions, as a result of collisions, dislodges surface layer.
It consists of an electron gun discharging free electrons into a chamber filled with argon gas. The gas is ionized by electrons. The top of the chamber is known as ion-beam generating apparatus. At the other end, the workpiece is fixed to a table which can be oscillated and rotated so that different points on the work surface can be subjected to an ion beam.

Accuracy :

• Etching rates vary up to 2000 Å per min.
• Accuracy of the etching process is considerably high mainly due to the small amount of material removal.
• Tolerances in the vicinity of + 50  Å  to - 50  Å  are possible.

Applications of IBM :

• It is applied mostly in micro-machining of electronic components.
• Typical materials that can be etched included glass, alumina, quartz, crystal, silica, agates, porcelains, numerous metals, cermets and oxides.
• It is also be used to deposit materials such as platinum, tungsten and silicon oxide insulators on another material substrate.

Advantages of IBM :

• IBM is almost universal.
• No chemical reagents or etching are required.
• Etching rates are easily controlled.
• There is no undercutting as with another chemical etching process.

Disadvantages of IBM :

• IBM is relatively expensive.
• Etching rates are slow.
• No heat is generated so there is little possibility of some thermal or radiation damage.

Difference between nuclear fission and nuclear fusion

Nuclear energy is released by nuclear reactions one is called nuclear fission and another is nuclear fusion. They both involve the disintegration and combination of the elemental nucleus. An atom divides into two or more smaller or lighter atoms is called nuclear fission. Nuclear fusion occurs when two or more atoms join or fuse together to form a large or heavy atom. 

Let us have a deep insight into the comparison between nuclear fission and fusion.

Nuclear fission :

• It is a process of breaking a heavy nucleus with some projectiles into two or more light fragments, with the liberation of a large amount of energy.
• A huge amount of energy required to combine small atoms.
• In this process the emission of radioactive rays possible.
• This process takes place spontaneously at an ordinary temperature.
• The mass number and an atomic number of the daughter elements are considerably lower than that of the parent nucleus.
• This process gives rise to chain-reaction.
• During nuclear fission, neutrons are emitted.
• Nuclear fission can be performed under controlled conditions.
• Fission is used in nuclear power plants.
• Uranium is used as a fuel in power plants.
• Example - Atomic bomb
• Never occurs in natural source in normal cases. 

Nuclear fusion :

• It is a process of fusing two light nuclei into a single nucleus, with the liberation of a large amount of energy.
• Require less energy to divide the atom.
• Does not emit any kind of radioactive rays.
• This process takes place at a very high temperature ( nearly at about >100000 K ).
• The mass number and an atomic number of the product is higher than the starting elements.
• This process does not give rise to chain-reaction.
• During nuclear fusion, positrons are emitted.
• Nuclear fusion cannot be performed under controlled conditions.
• Fusion is an experimental technology for producing power.
• Hydrogen isotopes such as Deuterium and Tritium are the primary fuel used in experimental fusion power plants.
• Example - the Hydrogen bomb
• Happens in a natural source like stars and sun.