Characteristics of a good fuel

A good characteristic of good fuel is depending upon the following factors :

• High calorific value 

A fuel should possess high calorific value since the amount of heat liberated and temperature attained thereby depends upon the calorific value.

• Moderate ignition temperature 

Ignition temperature id the lowest to which the fuel must be pre-heated so that it starts burning smoothly.
Low ignition temperature is dangerous for storage and transport of fuel, hence it can cause fire hazards. While high ignition temperature causes difficulty in igniting the fuel, but fuel is safe during storage and transport. Hence, an ideal fuel should have moderate ignition temperature.

• Low moisture content 

The moisture content of the fuel reduces the heating value and involves a loss of money because it is paid for at the same rate as the fuel. Hence, fuel should have low moisture content.

• Low non-combustible matter content

After combustion, the non-combustible matter content generally in form of ash or clinker.
That also reduces the heating value, besides the additional cost of storage, handling and disposal of the waste products produced.

• The moderate velocity of combustion 

If the rate of combustion id low then the required high temperature may bot be possible, because a part of the heat liberated may get radiated, instead of raising the temperature. While too high combustion rates are also not required.

• Products of combustion should not be harmful 

Gaseous products of combustion should not pollute the atmosphere. 

• Low cost 

A good fuel should be readily available in bulk at a cheap rate.

• Easy to transport 

Fuel must be easy to handle, store and transport at a low cost must be necessary. Solid and liquid fuel can easily be transported but gaseous fuel is costly and can even cause fire hazards.

• Combustion should be easily controllable 

Combustion of the fuel should be easy to start or stop. when it is required. Hence, it must be controllable.

• Should no undergo spontaneous combustion 

Spontaneous ignition can cause fire hazards.

• Storage cost in bulk should be low 
• Should burn in air with efficiency, without a highly smoke
• In case of solid fuel, the size should be uniform so that combustion is regular

VTVT engine technology

In this article we will discuss about the VTVT engine techology. So let first you must know the VTVT full form.

VTVT is a technology which has ability to have independent control of the intake and exhaust valve in an internal combustion engine.

VTVT engine technology gives you class mileage and optimum performance for driving experience.

In this technology the timing of intake and exhaust will be depend upon the engine requirement. The timing of both valve will be programmed in different load criteria that the same as Hyundai do in VVT technology.

Function of lubricants

To supply lubricating oil between the moving parts is simply termed as lubrication.

Any substance introduced between two moving or sliding surface with a view to reducing the frictional resistance between them is called lubricants.

Functions of lubricants :

• It reduces surface deformation, wears, and tear because the direct contact between the rubbing surfaces is avoided.
• It reduces the loss of energy in the form of heat.
• It also acts as a coolant.
• It reduces waste of energy so that the efficiency of a machine is enhanced.
• It reduces the expansion of metal by local frictional heat.
• It avoids the seizure of moving surfaces since the use of lubricant minimizes the liberation of frictional heat.
• It avoids or reduces unsmooth relative motion of the moving or sliding parts.
• It reduces the maintenance and running cost of the machine.
• Sometimes it acts as a seal.

Difference between physical adsorption and chemical adsorption

What is Physical adsorption?

It is one in which the adsorbed molecules are held to the surface of the adsorbent by weak physical or van der Waal's forces.

This types of adsorption are completely reversible.

It is also called physisorption or van der Waal's adsorption.

Example: Adsorption of various gases by charcoal belongs to this type.

What is Chemical adsorption?

It is the force which holds the adsorbed molecules is of valence type.

This type of adsorption is irreversible.

It is also called chemisorption or activated adsorption.

Example: Adsorption of oxygen on tungsten is an example of this type.

Let us have a deep insight into the difference between physical and chemical adsorption. 

Difference :

• Chemical adsorption heat evolved is considerably higher than evolved in physical adsorption.
• The heat of adsorption for physical adsorption is 20-40 kcal/mol while 40-400 kcal/mol for chemical adsorption.
• In physical adsorption, molecules are not tightly retained by the adsorbent while molecules are tightly retained by the adsorbent in case of chemical adsorption.
• Adsorption is appreciable only at a temperature below the boiling point of the adsorbate in case of physical while in chemical it occurs at high temperature.
• Multiplayer adsorption occurs in case of physical adsorption while adsorption leads to at most a monolayer in case of chemical adsorption.
• Forces responsible for physical adsorption are very weak while in the case of chemical adsorption it is quite strong.
• In physical adsorption, the rate of adsorption increases with the increase of pressure or of the adsorbate while in case of chemical adsorption rate of adsorption decrease with the increase of pressure or concentration of adsorbate.
• Physical adsorption involves very small or little activation energy while chemical adsorption generally involves appreciable activation energy.
• The equilibrium is established rapidly in a physical case while the establishment of equilibrium requires time in case of chemical adsorption.
• No surface compound takes place in case of physical adsorption while actual surface compound formation between the adsorbent and adsorbate takes place in chemical adsorption.
• Physical adsorption is very specific in nature while chemical adsorption is highly specific in nature.
• Amount of adsorption on a surfaced is more a function of the adsorbate than the adsorbent in case of physical adsorption while the amount of adsorption is characteristics of both adsorbate and adsorbent in chemical adsorption.

You can also check it out : 

• Difference between adsorption and absorption

Difference between adsorption and absorption

Absorption is the process in which a fluid is dissolved by a liquid or a solid whereas adsorption is the process in which atoms, ions or molecules from a substance adhere to a surface of the absorbent. Let us have a deep insight into the difference between adsorption and absorption. 

Adsorption :

• It is a phenomenon of concentration or assimilation of gas or a liquid at the surface of a solid or liquid.
• It is a surface phenomenon.
• It is a fast process.
• Equilibrium is attained easily.
• It depends upon the surface area of the adsorbent. 
• It is an exothermic process.
• It is favoured by low temperature.
• It is steadily increasing and reaches equilibrium.
• It is used in Air conditioning, water purification, synthetic resin. 

Examples : 

• Water vapours adsorbed by silica gel.
• NH₃ is adsorbed by charcoal.

Absorption :

• It is a phenomenon in which the substance assimilated is uniformly distributed throughout the body of the solid or liquid.
• It is a bulk phenomenon.
• It is a slow process.
• Attainment of equilibrium takes some time.
• No such effect is there.
• It is an endothermic process.
• It is not affected by temperature.
• It occurs at a uniform rate.
• It is used in cold storage, ice production, turbine inlet cooling, refrigerant. 

Examples :

• Water vapours absorbed by anhydrous CaCl_2.
• NH₃ is absorbed in water forming NH₄OH.

You can also read about the difference between physical adsorption and chemical adsorption.

Disadvantages of hard water

Disadvantages of hard water in Domestic use :

• Washing :

When we use hard water as a washing purpose the using water does not lather freely with soap and it produces sticky precipitates of calcium and magnesium soaps. This cause wastage of a lot of shops is used. 

• Bathing : Bathing

Hard water does not lather freely with shop solution and produces sticky scum on the body.
Thus, cleansing quality of soap is depressed and lots of water is wasted too.

• Cooking :

Due to the presence of dissolved hardness, the boiling point of water is elevated and it producing slats. Therefore, more fuel and time are required for cooking.

• Drinking :

Hard water causes a bad effect on our digestive system and also the possibility of forming calcium oxalate crystals in urinary tracks is increased.

Disadvantages of hard water in Industrial use : 

• Textile industry :

Hard water cannot produce good quality of lathe. It precipitates of calcium and magnesium soaps adhere to the fabrics. These fabrics when dyed do not produce exact shades of colour.

• Sugar industry :

If hard water used in sugar refining it causes difficulties in the crystallization of sugar and the produced sugar may be deliquescent.

• Dyeing industry :

Because of the use of hard water which yields impure shades and gives spots on the fabrics being dyed.

• Laundry :

Hard water is used in laundry causes much of the soap used in washing and may even cause colouration of clothes.

• Concrete making :

It affects the hydration of cement and the final strength of the hardened concrete.

• Pharmaceutical industry : 

If hard water used for preparing pharmaceutical products like drugs or injection may produce certain undesirable products in them.

Disadvantages of hard water in steam generation in boilers :

If hard water directly fed into the boilers it may cause many troubles following below :

• Scale and sludge formation 
• Corrosion 
• Priming and foaming 
• Caustic embrittlement 

What is flywheel

What is Flywheel?

Answer :

• A heavy revolving wheel in a machine which is used to increase the machine's momentum and thereby provide greater stability or a reserve of available power.

A flywheel is a heavy rotating body that acts as a reservoir of energy. 

Flywheel used in an internal combustion engine to control the speed.

The energy is stored in the flywheel in the form of kinetic energy. 

The function of flywheel :

• To store and release energy when needed during the work cycle.
• To reduce the power capacity of the electric motor or engine.
• To reduce the amplitude of speed fluctuations.

Flywheel materials :

Flywheel made by grey cast iron. 

Now recently, flywheels are made of high strength steels and composites in-vehicle applications. 

Graphite-fiber reinforced polymer ( GFRP ) is one of the excellent choices for flywheels fitted on a modern car engine.

Difference between herringbone and double helical gears

Herringbone and double helical gears are constructed by combining two identical helical gears of the same pitch circle diameter, module, and a number of teeth, but both gears have an opposite hand of a helix. This offers an advantage of balancing the axial thrust in both the direction by developing opposite thrust reaction providing higher power transmission capacities. 

What is herringbone gear?

No gap is provided between two halves so teeth with left-hand helix touch the teeth with right-hand helix. Its manufacturing is difficult and requires a dedicated machine. 

What is double helical gear?

Small relief gap is provided between two halves so teeth with left-hand helix do not touch the tooth with right-hand helix. Its manufacturing is comparatively easy as it can be cut by hobbing, shaping and even by milling. 

Let us have a deep insight into the difference between herringbone and double helical gears. 

Difference :

• In the case of double helical gears, there is a groove between two helical gears, while herringbone gears are called a gear without a groove.
• A double helical gear is cut on a single gear blank, by a hob with a tool run-out groove between the hands of helices whereas herringbone gear is cut by two cutters, which reciprocate 180⁰ out of phase to avoid clashing. 
• Both the gears allow higher helix angle because there is no thrust force and angle of helix is about to 20⁰ to 45⁰.
• Herringbone gear has less axial strength thus can be used where space is limited whereas double-helical gear requires more axial space due to the presence of relief gap. 

Double helical gear advantages and disadvantages

Advantages of double helical gear :

• They develop opposite thrust reactions thus cancel out the thrust force within the gear itself.
• The net axial force that acts on the bearings is zero.
• Power transmitting capacity is very high.
• By using this high pitch line velocities can be attained.

Disadvantages of double helical gear :

• A double helical gear is expensive as compared to helical gear.
• Balancing of thrust forces depends upon the equal distribution of load between the right and left parts of the gear. Therefore, a high degree of precision is required to locate double-helical gears axially on the shaft.
• No external forces are present.

Where does LPG comes from?

Where does LPG come from?

• Natural gas processing 
• Petroleum refining

LPG comes from drilling oil and gas wells because above both processes are comes during drilling oil and gas wells.

LPG is not made or manufactured separately it is found in combination with other hydrocarbons naturally during the two processes mentioned above.

About 60% of LPG is produced from natural gas and the other 40% during the petroleum refining.

LPG is separated from unprocessed natural gas using refrigeration and LPG is extracted from heated crude oil using a distillation tower.

LPG is stored as a liquid under pressure in gas bottles or in a tank.

Hyundai VTVT full form

What is the full form of VTVT?

Answer: 

• Variable Timing Valve Train

What does VTVT mean?

Hyundai has the technology applied to there Hyundai models are mentioned below :

• Hyundai Verna 
• Hyundai i10
• Hyundai i20 

Explore more information: 

• CNC full form

• VMC full form

• SFC full form

• CRDI full form

• TDI full form

• PDI full form

• ESC full form

• LASER full form

• ARAI full form

• VTVT full form

• DFI full form

• GVWR full form

• HVAC full form

• IHP full form

• ISFC full form

• KPL full form

• OHV full form

• FHP full form

• LPG full form

• EBD full form

• BHP full form

• BMEP full form

• BSFC full form

• CDI full form

• CI Engine full form

• CV full form

• NHTSA full form

• IMEP full form

• ESC full form

• 4WD full form

• CNG full form

• TC full form

• VDB full form

• VVT full form

• 2WD full form

• FPEG full form

• Kph full form

• CC full form

• CCVTI full form

• CVTI full form

• LCV full form

• HCV full form

• ASFS full form

• APDV full form

• SAE full form

• MUV full form

• SUV full form

• XUV full form

• DTSI full form

• MPFI full form

• ABS full form

• SOHC full form

• DOHC full form

Spur gear backlash

In this article, we have discussed the backlash of the spur gear. so let us know first 
What is the backlash ?

• Backlash is defined as the amount by which the width of tooth space exceeds the thickness of the engaging tooth measured along the pitch circle.

Backlash is the play a vital role in spur gear designing it plays between the missing teeth and it occurs only when teeth are in mesh.

Why provide backlash?

• Backlash compensates for machining errors 
• Backlash compensates for thermal expansion of teeth.
• Backlash prevent the mating teeth from jamming together.

Methods to provide backlash :

• The centre distance between mating gears is slightly increased.
• The teeth of the gear are cut slightly thinner.

The magnitude of backlash is depended upon the diametral pitch or module and the centre distance.

The magnitude of backlash is very small for gear trains used in precision equipment and instruments.

The backlash and variation in centre distance have no effect on tooth action or velocity ratio.

Application of rolling contact bearing

Rolling contact bearings are used in the following applications.

• Machine tool spindles 
• Automobile front and rear axles 
• Rope sheaves 
• Crane hooks
• Hoisting drums
• Gearboxes 

Application of sliding contact bearing

Sliding contact bearings are used in the following applications :

• Centrifugal pumps 
• Large size electric motors 
• Steam and gas turbine
• Crankshaft bearings in petrol and diesel engine 
• Concrete mixtures
• Rope conveyors 
• Marine industries in installation 

Difference between LPG and CNG

LPG full form Liquefied petroleum gas is a mixture of propane and butane liquefied at 15⁰C and a pressure of 1.7 to 7.5 bar While CNG full form Compressed Natural Gas which is mainly methane compressed at a pressure of 200 to 245 bar.

Now you need to select the best option that would serve as your best friend in your daily activities. So now we have discussed the difference between LPG and CNG that help you decided in which the best for you.

Basic Difference between LPG and CNG:

Abbreviation:

LPG - Liquefied petroleum gas

CNG - Compressed natural gas

Gas:

LPG - Artificial in nature.

CNG - It is natural gas.

Constituents:

LPG - Composed of propane and butane. 

CNG - Major component is methane.

Source:

LPG - Automatically generated while natural gas extraction and also while crude oil refining process.

CNG - Obtained from natural gas, condensate wells, oil well, coal bed methane wells.

Safety:

LPG - It is difficult to get disperse so that the risk of fire is more.

CNG - Easily disperses so that the risk of ignition is minimized.

Environmental Effect:

LPG - Release gas like CO₂ which is greenhouse gas serves as a great cleaner comparing to gasoline.

CNG - Release the minimum amount of greenhouse gases.

Uses:

LPG uses - Heating and cooking in homes, refrigeration, industrial, agricultural, catering, and automobile fuel.

CNG uses - Alternative of gasoline in Automobile.

Properties:

LPG Properties -

• It is highly inflammable.
• It is heavier than air.
• Leakage will accumulate in low lying areas and settle down to the floor.

CNG properties - 

• It is highly inflammable.
• It is lighter than air.
• Disperses quickly during leakage.

Some key difference between LPG and CNG:

• LPG has a higher energy content than CNG.
• LPG density is greater than CNG.
• There is a number of hydrocarbon gases that fall into the category of LPG while in CNG just two most common properties propane and butane are used.
• LPG needs more oxygen as compared to CNG.

LPG requires oxygen to gas ratio - 25 to 1

CNG requires oxygen to gas ratio - 10 to 1 

Explore more information: 

1. Advantages and disadvantages of LPG
2. Which gas present in LPG?
3. What does LPG stand for? 
4. What are the uses of LPG?
5. What is the full form of LPG?
6. LPG acronyms and Abbreviations
7. Difference between petrol and diesel oil

Which gas is present in LPG?

Which gas is present in LPG?

Answer :

LPG is not just made by a single gas it constitutes many flammable hydrocarbon gases. 

• In LPG Propane, Butane (n-butane) and isobutane (i-butane), as well as the mixture of these gases, are present.

LPG as Propane :

Propane is flammable hydrocarbon gas it liquefied by using pressurization.

The chemical formula of propane is C₃H₈. There are 3 carbon and 8 hydrogen atoms in a propane molecule.

LPG as Butane :

Butane is also flammable hydrocarbon gas it liquefied by using pressurization.

The chemical formula for butane is C₄H₁₀. There are 4 carbon and 10 hydrogen atoms in a butane molecule.

LPG as Isobutane :

Isobutane is an isomer of butane.

Isobutane has the same chemical formula but different physical properties.

Isobutane is converted from butane and its process is isomerization.

So for different LPG gases have different physical properties and formulas.

What is notch sensitivity

What is Notch sensitivity ?

Answer :

• A measure of a reduction in strength of metal caused by presence of stress or a notch.

Advantages of cast iron

Cast iron is an iron and carbon alloy that contains more than 2% of carbon. Cast iron is classified on the basis of the distribution of carbon content in their microstructure.

1. Grey cast iron
2. Malleable cast iron
3. Ductile cast iron

Let us have a deep insight into the advantages of cast iron in this article. 

Advantages of cast iron :

• It is available in large quantities and is produced on a mass scale.
• The tooling required for the casting process is relatively simple and inexpensive results the cost of cast iron components is less.
• Without costly machining operations, cast-iron components can be given any complex shape.
• Cast iron has a higher compressive strength.
• Cast iron has an excellent ability to dampen vibrations, making it an ideal choice for guides and frames for machine tools.
• Cast iron has greater wear resistance even under boundary lubrication conditions.
• The mechanical properties of cast iron parts do not change between room temperature and 350 degrees.
• Cast iron parts have low notch sensitivity.

Because of these advantages, it has widely used in to make cookware components and many other applications. 

Difference between thermoplastic and thermosetting plastic

What is Thermoplastics?

A thermoplastic is a polymeric material which softens when heated and hardens upon cooling.

What is Thermosetting plastics?

Thermosetting plastic is a polymeric material, which once having cured or hardened by a chemical reactions does not soften or melt upon subsequent heating.

Thermoplastic and thermosetting are both two different classes of polymers, which are differentiated based on their behaviour in the presence of heat.  

Main difference : 

The main difference is thermoplastic materials have low melting points, therefore they can be remoulded or recycled by exposing it to heat whereas thermosetting plastic can withstand high temperatures without losing its rigidity, therefore they cannot be reformed, remoulded or recycled by applying heat. 

Let us have a deep insight into the difference between thermoplastic and thermosetting plastic. 

Difference between thermoplastic and thermosetting plastic :

• Thermoplastic softens with heat while not softens with the heat in case of the thermosetting plastic.
• A thermoplastic material has a linear polymer chain while a thermosetting plastic material consists of a cross-linked polymer chain.
• A thermoplastic is 2 dimensional with no crosslinks whereas thermosetting plastic is 3 dimensional with multiple cross-links. 

• The thermoplastic material can be softened, hardened or softened repeatedly by the application of heat while thermosetting plastic material once set and hardened it can't be remelted or reshaped.
• The thermoplastic material can be recycled while not possible to recycle in the thermosetting plastic.
• Thermoplastic components are environment-friendly while thermosetting plastic components after their useful life create a problem.
• Thermoplastic materials are flexible because of molecules in the linear chain while thermosetting materials are more rigid because of molecules in cross-linked.
• Thermoplastic is processed by injection moulding, extrusion process, blow moulding, thermoforming process and rotational moulding while thermosetting plastic is processed by compression moulding, reaction injection moulding.
• Thermoplastic is synthesised by addition polymerization while thermosetting plastic is synthesised by condensation polymerization.
• Thermoplastic is lower in molecular weight while thermosetting plastic is higher in molecular weight.
• Thermoplastic can be reshaped and reused while thermosetting plastic can not.

Example of thermoplastic materials :

• Polyethene
• Polypropylene
• Polyvinylchloride ( PVC )
• Polystyrene
• Polytetrafluoroethylene ( PTFE )
• Nylon

Example of thermosetting plastic materials :

• Aminos
• Polyesters
• Phenolics 
• Epoxies 
• Phenol-formaldehyde

Difference between physical properties :

• Melting point is low in thermoplastic while high in a thermosetting plastic.
• Tensile strength is low in thermoplastic while high in a thermosetting plastic.
• Thermal stability is low in thermoplastic while high in a thermosetting plastic.
• Stiffness and brittleness are low in thermoplastic while high in a thermosetting plastic.
• Rigidity and durability are also low in thermoplastic while high in a thermosetting plastic.
• Thermoplastic is soluble in some organic solvents while thermosetting plastic is insoluble in organic solvents.

Tensile test

A tensile test is one of the simplest and basic tests and determines the value of a number of parameters concerned with mechanical properties of materials like strength, ductility, toughness.

Some other information can be obtained by this test are following below :

• Proportional limit
• Elastic limit
• Modulus of elasticity
• Yield strength
• Ultimate tensile strength
• Modulus of resilience
• Modulus of toughness
• Percentage elongation
• Percentage reduction in area

The specimen used in a tensile test is illustrated in the figure below :

The shape and dimensions of this specimen are standardized and confirm to 

IS 1608:1972. 

The cross-section of the specimen can be circular, rectangular or square.

The standard gauge length is given by l₀.

Procedure :

In the tensile test, the specimen is subjected to axial tensile force, which continues increasing and corresponding to that deformation is measured.

The specimen is mounted on the machine and gripped in the jaws. It is subjected to tensile stress which is increased by increments. After each increment, the amount by which the gauge length l₀ increases and deformation of gauge length are measured by an extensometer.

This procedure of measuring the tensile force and corresponding deformation continued till fracture. 

This results of a tension test are expressed by means of a stress strain diagram.

Uniaxial tensile testing is the most commonly used for obtaining the mechanical characteristics of isotropic materials. For anisotropic materials, such as composite materials and textiles, biaxial tensile testing is required.