introduction of i c engines

INTERNAL COMBUSTION ENGINES

INTERNAL COMBUSTION ENGINESSub Code: ME0441 Credits:(4-0-0) Hrs / Week : 04 CIE : 50% SEE : 50 %

BYEr.VIJAYAKUMARA.MMTech in Thermal EngineeringAssistant ProfessorMechanical Engineering DepartmentThe National Institute of EngineeringMysore-570 008.Karnataka, India

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TEXT BOOKS: 1.I.C. engines by M.L. Mathur and R.P. Sharma, Dhanpat Rai Publications -2012. 2.Internal Combustion Engines by V.Ganeshan, Tata McGraw Hill, 3rd Ed. 2009.3.Fundamentals of Internal Combustion Engines by J.B. Heywood, Tata McGraw Hill, 1988REFERENCE BOOKS:1.Engineering fundamentals of the I.C. Engine by Willard W.Pulkrabek, Year 1998.2.Combustion Engine Process by Lichty Judge, Year 2000.3.A course in I.C.Engines by V.M. Domkundawar, Dhanpathrai Publications -1999. 4.wikipedia.comVIJAYAKUMARA M ME NIE MYSORE2

ObjectivesAfter studying this unit you should be able to knowHow internal combustion engines are classified,Applied Thermal Engineering on which cycles these engines work, How and how many times the piston has to move to and fro to complete a cycle,What fuels are used in these engines and if there are any harmful effects.VIJAYAKUMARA M ME NIE MYSORE3

Introduction:An Engine is a device which transforms the chemical energy of a fuel into thermal energy and uses this thermal energy to produce mechanical work. Engines normally convert thermal energy into mechanical work and therefore they are called heat engines.Heat engines can be broadly classified into :i) External combustion engines ( E C Engines)ii) Internal combustion engines ( I C Engines )

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Heat EnginesHeat EnginesI C EnginesE C EnginesRotaryReciprocatingReciprocatingRotaryOpen cyclegas turbineWankel engineGasoline engineDiesel engineSteam engineStirling engineSteam turbineClosedCycle gas turbineVIJAYAKUMARA M ME NIE MYSORE5

External combustion engines ( E C Engines)

Figure 1 : External Combustion Engine


Internal combustion engines can be classified as Continuous IC engines and Intermittent IC engines.Continuous IC Engines

Figure 2: Continuous IC EnginesIn continuous IC engines products of combustion of the fuel enters into the prime mover as the working fluid.VIJAYAKUMARA M ME NIE MYSORE7

Intermittent Internal Combustion Engine

Fig: Intermittent internal combustion engineVIJAYAKUMARA M ME NIE MYSORE8

ADVANTAGES OF INTERNAL COMBUSTION ENGINES

1. Greater mechanical simplicity.2. Higher power output per unit weight because of absence of auxiliary units like boiler , condenser and feed pump.3. Low initial cost4. Higher brake thermal efficiency as only a small fraction of heat energy of the fuel is dissipated to cooling system.5. These units are compact and requires less space.6. Easy starting from cold conditions.


DISADVANTAGES OF INTERNAL COMBUSTION ENGINES1. I C engines cannot use solid fuels which are cheaper. Only liquid or gaseous fuel of given specification can be efficiently used. These fuels are relatively more expensive.2. I C engines have reciprocating parts and hence balancing of them is problem and they are also susceptible to mechanical vibrations.


HistoryInternal combustion engines date back to 1876 when Otto first developed the spark-ignition engine and 1892 when Rudolf Diesel invented the compression-ignition engine. Since that time these engines have continued to develop as our knowledge of engine processes has increased, as new technologies became available, as demand for new types of engine arose, and as environmental constraints on engine use changed.Internal combustion engines, and the industries that develop and manufacture them and support their use, now play a dominant role in the fields of power, propulsion, and energy.


The last twenty-five years or so have seen an explosive growth in engine research and development as the issues of air pollution, fuel cost, and market competitiveness have become increasingly important.A more successful development-an atmospheric engine introduced in 1867 by Nicolaus A. Otto (1832-1891) and Eugen Langen (1833-1895)-used the pressure rise resulting from combustion of the fuel-air charge early in the outward stroke to accelerate a free piston and rack assembly so its momentum would generate a vacuum in the cylinder.VIJAYAKUMARA M ME NIE MYSORE12

In 1892, the German engineer Rudolf Diesel (1858-1913) outlined in his patent a new form of internal combustion engine. His concept of initiating combustion by injecting a liquid fuel into air heated solely by compression permitted a doubling of efficiency over other internal combustion engines. Much greater expansion ratios, without detonation or knock, were now possibleVIJAYAKUMARA M ME NIE MYSORE13

CLASSIFICATION OF INTERNAL COMBUSTION ENGINES.There are different types of IC engines that can be classified on the following basis.1. According to thermodynamic cyclei) Otto cycle engine or Constant volume heat supplied cycle.ii) Diesel cycle engine or Constant pressure heat supplied cycleiii) Dual-combustion cycle engine2. According to the fuel used:i) Petrol engine ii) Diesel engine iii) Gas engine3. According to the cycle of operation:i) Two stroke engine ii) Four stroke engineVIJAYAKUMARA M ME NIE MYSORE14

4. According to the method of ignition:i) Spark ignition (SI) engine ii) Compression ignition (CI ) engine5. According to the number of cylinders.i) Single cylinder engine ii) Multi cylinder engine6. According to the arrangement of cylinder:i) Horizontal engine ii) Vertical engine iii) V-enginev) In-line engine vi) Radial engine, etc.7. According to the method of cooling the cylinder:i) Air cooled engine ii) Water cooled engineVIJAYAKUMARA M ME NIE MYSORE15

8. According to their applications:i) Stationary engine ii) Automobile engine iii) Aero engineiv) Locomotive engine v) Marine engine, etc.VIJAYAKUMARA M ME NIE MYSORE16

INTERNAL COMBUSTION ENGINE PARTS AND THEIR FUNCTION1. Cylinder :- It is a container fitted with piston, where the fuel is burnt and power is produced.2.Cylinder Head/Cylinder Cover:-One end of the cylinder is closed by means of cylinder head. This consists of inlet valve for admitting air fuel mixture and exhaust valve for removing the products of combustion.3. Piston:- Piston is used to reciprocate inside the cylinder. It transmits the energy to crankshaft through connecting rod.4. Piston Rings:- These are used to maintain a pressure tight seal between the piston and cylinder walls and also it transfer the heat from the piston head to cylinder walls.VIJAYAKUMARA M ME NIE MYSORE17


5. Connecting Rod:- One end of the connecting rod is connected to piston through piston pin while the other is connected to crank through crank pin. It transmits the reciprocatory motion of piston to rotary crank.6. Crank:- It is a lever between connecting rod and crank shaft.7. Crank Shaft:- The function of crank shaft is to transform reciprocating motion in to a rotary motion.8. Fly wheel:- Fly wheel is a rotating mass used as an energy storing device.9. Crank Case:- It supports and covers the cylinder and the crank shaft. It is used to store the lubricating oil.


IC ENGINE TERMINOLOGY


Bore: The inside diameter of the cylinder is called the bore.Stroke: The linear distance along the cylinder axis between the two limiting positions of the piston is called stroke.Top Dead Centre (T.D.C) : The top most position of the piston towards cover end side of the cylinder is called top dead centre. In case of horizontal engine, it is called as inner dead centreBottom Dead Centre (B.D.C):The lowest position of the piston towards the crank end side of the cylinder is called bottom dead centre. In case of horizontal engine, it is called outer dead centre (O.D.C).


Clearance Volume: The volume contained in the cylinder above the top of the piston, when the piston is at the top dead centre is called clearance volume.Compression ratio : It is the ratio of total cylinder volume to clearance volume.


Four-Stroke Petrol Engine OR Four stroke Spark Ignition Engine (S.I. engine)The four-stroke cycle petrol engines operate on Otto (constant volume) cycle shown in Figure . Since ignition in these engines is due to a spark, they are also called spark ignition engines. The four different strokes are:i) Suction strokeii) Compression strokeiii) Working or power or expansion strokeiv) Exhaust stroke.


The construction and working of a four-stroke petrol engine


The construction and working of a four-stroke petrol engine


Four Stroke Diesel Engine (Four Stroke Compression Ignition Engine C.I.Engine)The four stroke cycle diesel engine operates on diesel cycle or constant pressure cycle.Since ignition in these engines is due to the temperature of the compressed air, they are also called compression ignition engines. The construction and working of the four stroke diesel engine is shown in figures shows a theoretical diesel cycle. The four strokes are as follows:


The construction and working of a four-stroke diesel engine




TWO STROKE CYCLE ENGINE

In two stroke cycle engines, the suction and exhaust strokes are eliminated. There are only two remaining strokes i.e., the compression stroke and power stroke and these are usually called upward stroke and downward stroke respectively. Also, instead of valves, there are inlet and exhaust ports in two stroke cycle engines. The burnt exhaust gases are forced out through the exhaust port by a fresh charge which enters the cylinder nearly at the end of the working stroke through the inlet port. The process of removing burnt exhaust gases from the engine cylinder is known as scavenging.VIJAYAKUMARA M ME NIE MYSORE30

Two Stroke Cycle Petrol EngineThe principle of two-stroke cycle petrol engine is shown in Figure . Its two strokes are described as follows:



COMPARISON OF SI AND CI ENGINESSI EngineCI EngineIt works on Otto cycle. A fuel having higher self-ignition temperature is desirable, such as petrol (gasoline).

Air and fuel mixture in gaseous form is inducted through the carburettor in the cylinder during the suction stroke.

The throttle valve of the carburettor controls the quantity of the charge. The quality of the charge remains almost fixed during normal running conditions at variable speed and load. So it is a quantity governed engine.It works on Diesel or Dual combustion cycle. A fuel having lower self-ignition temperature is desirable such as diesel oil.Only air is introduced into the cylinder during the suction stroke and therefore the carburettor is not required. Fuel is injected at high pressure through fuel injectors direct into the combustion chamber.The amount of air inducted is fixed but the amount of fuel injected is varied by regulating the quantity of fuel in the pump. The air-fuel ratio is varied at varying load. So, it is a quality governed engine.


Spark is required to bum the fuel. For this, an ignition system with spark plugs is required. Because of this it is called a spark-ignition (SI) engine.

A compression ratio of 6 to 10.5 is employed.The upper limit is fixed by the anti-knock quality of fuel. The engine tends to knock at higher compression ratios. Part load efficiency is poor, since even at part load the air/fuel ratio is not much varied. In order to improve the part load efficiency of the SI engine, the MPFI technique of fuel supply is used in modem engines. The cost of the petrol is higher than that of the diesel oil.Combustion of fuel takes place on its own with out any external ignition system. Fuel bums in the presence of highly compressed air inside the engine cylinder.A compression ratio of 14 to 22 is employed. The upper limit of compression ratio is limited by the rapidly increasing weight of the engine. Engine tends to knock at lower compression ratios.Part load efficiency is good. As the load decreases, the fuel supply to the engine can also be reduced and lean mixture to the engine is then supplied.The cost of diesel oil is less than that of petrol. Moreover, as fuel is sold on volume basis and diesel oil has higher specific gravity, more weight is obtained in one litre.


Noise and vibration are less because of less engine weight.

The main pollutants are carbon monoxide (CO), oxides of nitrogen (NO.J and hydrocarbons (HC).Noise and vibrations are more because of heavier engine components due to higher compression ratio.

Apart from CO, NOx and HC, soot or smoke particles are also emitted to the atmosphere.


COMPARISON OF FOUR-STROKE AND TWO-STROKE ENGINES


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Actual Valve Timing DiagramThe valve timing of an engine is set to give the best possible performance. This means that the valves must be opened and closed at very precise times. The traditional way of showing exactly when the valve opens and closes is by the use of a valve-timing diagram. As can be seen the valves are opened and closed in relation to the number of degrees of movement of the crankshaft. When comparing the diagrams for the petrol engine of medium and high performance cars, it will be noticed that the high performance car has larger valve opening periods, especially the closing of the inlet valve which is later. VIJAYAKUMARA M ME NIE MYSORE37

This is so that at high operating speeds the increased lag allows as much pressure energy as possible to be generated in the cylinder by the incoming air and fuel charge, prior to its further compression by the rising piston. There is also an increase in the value of valve overlap for the high performance engine. This means that at TDC both inlet and exhaust valves will be open together for a longer period of time giving a better breathing of the engine at these higher engine speeds .


Actual Valve Timing Diagram



Valve timing diagram of 4 stroke petrol engines

IVO Inlet valve OpensIVC Inlet Valve ClosesIS Ignition StartsEVO Exhaust Valve OpensEVC Exhaust Valve ClosesTDC Top Dead CenterBDC Bottom Dead CenterVIJAYAKUMARA M ME NIE MYSORE41



Theoritical & Actual Valve Timing for 4 stroke Diesel Engine



Valve timing diagram of a four stroke engine gives a clear idea about the actual position of the piston during the opening & closing of inlet & exhaust valves. In practice, the events of the four-stroke cycle do not start and finish exactly at the two ends of the strokes - to improve the breathing and exhausting, the inlet valve is arranged to open before TDC and to close after BDC and the exhaust valve opens before BDC and closes after TDC. These early and late opening and closing events can be shown on a valve timing diagram such as Fig.VIJAYAKUMARA M ME NIE MYSORE46


Valve lead :This is where a valve opens so many degrees of crankshaft rotation before either TDC or BDC.Valve lag :This is where a valve closes so many degrees of crankshaft rotation after TDC or BDC.Valve overlap : This is the condition when both the inlet and the exhaust valves are open at the same time during so many degrees of crankshaft rotation.




Variable valve timingVariable valve timing is a development that has been enabled by the use of electronic control which permits valve timing to be changed while the engine is operating, to suit low speed, intermediate speed and high speed operation. The variations in inlet valve timing are approximately as follows:Low speed inlet valves opened later to improve idling performance;Intermediate speed inlet valves opened a few degrees earlier to take advantage of manifold design and thus improve cylinder filling and performance.High speed a larger degree of early opening of the inlet valves.

The amount of variation in the timing may be limited to approximately 10

The aim of the system is to reduce harmful exhaust emissions and improve engine performance.VIJAYAKUMARA M ME NIE MYSORE51

Valve timing diagram of 4- stroke single cylinder diesel engine.IVO - 25 before TDCIVC - 30 after BDCEVO - 45 before BDCEVC - 15 after TDCFVO - 15 before TDCFVC - 25 after TDCVIJAYAKUMARA M ME NIE MYSORE52

Valve timing diagram of 4- stroke single cylinder petrol engine.(low speed)IVO - 10 before TDCIVC - 20after BDCEVO - 25 before BDCEVC - 5 after TDCValve timing diagram of 4- stroke single cylinder petrol engine.(high speed)IVO - 10 before TDCIVC - 50 after BDCEVO - 45before BDCEVC - 20 after TDCVIJAYAKUMARA M ME NIE MYSORE53

Port timing diagram of 4- stroke single cylinder petrol engineEPO - 45before TDCEPC - 45 after BDCTPO - 35 before BDCTPC - 35 after TDCVIJAYAKUMARA M ME NIE MYSORE54

Fuel air cycle and Actual cycle Air - standard cycle is based on several assumptions Consequently the performance levels are higher Ex: Thermal efficiency of an SI engine with Comp. Ratio 8:1 is 56% whereas actual is 28%.

Deviation from actual performance attributed to a small extent to progressive burning of fuel, incomplete combustion, valve operation etc.

Main reason is the assumptions made.


Fuel air cycleThe gases contain fuel, air, water vapour and residual gas Fuel - Air ratio varies during operation Consequently CO2, water vapour etc. change Specific heats increase with temp. Fuel, air, do not completely combine chemically at high temp. (1600K) leads to presence of CO, H2, H and O2 at equilibrium condition No. of molecules present after combustion depend and on pressure and temperature after combustion.VIJAYAKUMARA M ME NIE MYSORE56

Fuel air cycle assumptions

No chemical change in fuel or air prior to combustion Subsequent to combustion charge is always in chemical equilibrium No heat exchange between cylinders and gas (Adiabatic), compression and expansion are frictionless Fluid motion is ignored For constant volume fuel cycle, Fuel completed vapourised and mixed with air Instant burning at TDC (constant vol)VIJAYAKUMARA M ME NIE MYSORE57

Fuel air cycle - Composition of gas

Air fuel ratio changes during operation Consequently the composition in exhaust changes (O2, CO and water vapour) Fresh charge mixes with the burnt gases Amount of burnt gases in the cyl. depends on load and speed

All these are considered in fuel air cycle



Fuel air cycle Variable specific heats

When temperature rises larges fraction of heat is required to produce motion of atoms within molecules

This is does not contribute to temperature rise

Consequently final temp and pressure will be lower



Fuel air cycle DissociationDisintegration of combustion products at high temp. Deemed as reverse process of combustion During dissociation heat is absorbed During combustion heat is released At 1000 C, CO2 will be CO, O2 and little of H2OCO2 + Heat < =>2 CO + O2 at 1000 C H2O + Heat < => 2 H2 + O2 at 1300C Heat released consequent to reversal at the end of power stroke dissipates into exhaust (not as power) Dissociation not pronounced in CI due to excess air


Fuel air cycle No. of moles

No. of molecules depends on fuel air ratio, type/extent of combustion Pressure depends on no. of molecules and consequently on work


Effect of dissociation on temp wrt air fuel ratio

Rich mixture : Presence of CO and O2 in burnt gas tend to prevent dissociation

Lean mixture : Nearly no dissociation due to low temp. Stoichiometric : Dissociation pronounced

Reduction to the tune of 300 C





Fuel air cycle - Merits Fairly accurate estimate possible 85% of the actual efficiency Peak pressure and Exhaust temp. estimate can be reasonably close to actual engine Influence of many variables on engine performance understood better


Actual cycle

Deviates largely from Air- standard cycle and fuel-air cycle Efficiency is much lower than Air standard cycle


Actual cycle( Conditions common to Fuel Air cycle) Air and fuel mixture combines with products of combustion of previous cycle Change in chemical composition of working substance Variation of specific heats with temp. Change in composition, temp., and actual amount of fresh charge because of residual gases


Actual cycle (Conditions Exclusive, Responsible for the difference between Actual cycle and Fuel-air cycle Progressive combustion (not instantaneous) Heat transfer to and from working medium Exhaust blow-down (loss of work due to early EVO) Gas leakage, fluid friction


Actual cycleMajor influencing factors:Time loss factor- loss due to time required for mixing of air and fuel as also for combustionHeat loss factor loss of heat from gases to cylinder wallsExhaust blow-down factor loss of work due to early EVO in the power stroke



Performance Parameters(a) Power and Mechanical Efficiency.(b) Mean Effective Pressure and Torque.(c) Specific Output.(d) Volumetric Efficiency.(e) Fuel-air Ratio.(f) Specific Fuel Consumption.(g) Thermal Efficiency and Heat Balance.(h) Exhaust Smoke and Other Emissions.(i) Specific Weight.VIJAYAKUMARA M ME NIE MYSORE74

Power and Mechanical EfficiencyThe main purpose of running an engine is to obtain mechanical power.Power is defined as the rate of doing work and is equal to the product of force and linear velocity or the product of torque and angular velocity. Thus, the measurement of power involves the measurement of force(or torque) as well as speed. The force or torque is measured with the help of a dynamometer and the speed by a tachometer.The power developed by an engine and measured at the output shaft is called the brake power (bp) and is given by,P=2NT/60where, T is torque in N-m and N is the rotational speed in revolutions per minute.VIJAYAKUMARA M ME NIE MYSORE75

The total power developed by combustion of fuel in the combustion chamber is, however, more than the bp and is called indicated power (ip). Of the power developed by the engine, i.e. ip, some power is consumed in overcoming the friction between moving parts, some in the process of inducting the air and removing the products of combustion from the engine combustion chamber.VIJAYAKUMARA M ME NIE MYSORE76

Indicated Power IC Engine TestingIt is the power developed in the cylinder and thus, forms the basis of evaluation of combustion efficiency or the heat release in the cylinder.IP= pim LANk/60where, pm = Mean effective pressure, N/m2,L = Length of the stroke, m,A = Area of the piston, m2,N = Rotational speed of the engine, rpm (It is N/2 for four stroke engine) andk = Number of cylinders.Thus, we see that for a given engine the power output can be measured in terms of mean effective pressure.VIJAYAKUMARA M ME NIE MYSORE77

The difference between the ip and bp is the indication of the power lost in the mechanical components of the engine (due to friction) and forms the basis of mechanical efficiency; which is defined as follows :Mechanical efficiency=bp/ipThe difference between ip and bp is called friction power (fp).fp = ip bp Mechanical efficiency= bp /(bp+fp)VIJAYAKUMARA M ME NIE MYSORE78

Mean Effective Pressure and TorqueMean effective pressure is defined as a hypothetical/average pressure which is assumed to be acting on the piston throughout the power stroke. Therefore,Pm=ip 60 / LANkwhere, Pm = Mean effective pressure, N/m2,Ip = Indicated power, Watt,L = Length of the stroke, m,A = Area of the piston, m2,N = Rotational speed of the engine, rpm (It is N/2 for four stroke engine) andk = Number of cylinders.VIJAYAKUMARA M ME NIE MYSORE79

If the mean effective pressure is based on bp it is called the brake mean effective pressure (bmep Pmb replace ip by bp), and if based on ihp it is called indicated mean effective pressure (imep). Similarly, the friction mean effective pressure (fmep) can be defined as,fmep = imep-bmep The torque is related to mean effective pressure by the relationP=2NT/60IP= pim LANk/60By equation2NT/60= bemp.A.L.Nk/60T=( bemp.A.L.k) / 2


Specific OutputSpecific output of an engine is defined as the brake power (output) per unit of piston displacement and is given by,Specific output=Bp /A L= Constant bmep rpm The specific output consists of two elements the bmep (force)available to work and the speed with which it is working. Therefore, for the same piston displacement and bmep an engine operating at higher speed will give more output.It is clear that the output of an engine can be increased by increasing either speed or bmep. Increasing speed involves increase in the mechanical stress of various engine parts whereas increasing bmep requires better heat release and more load on engine cylinder.VIJAYAKUMARA M ME NIE MYSORE81

Volumetric EfficiencyVolumetric efficiency of an engine is an indication of the measure of the degree to which the engine fills its swept volume. It is defined as the ratio of the mass of air inducted into the engine cylinder during the suction stroke to the mass of the air corresponding to the swept volume of the engine at atmospheric pressure and temperature. Alternatively, it can be defined as the ratio of the actual volume inhaled during suction stroke measured at intake conditions to the swept volume of the piston.Volumetric efficiency, v =Mass of charge actually sucked in / Mass of charge corresponding to the cylinder intake P and T conditionsVIJAYAKUMARA M ME NIE MYSORE82

The amount of air taken inside the cylinder is dependent on the volumetric efficiency of an engine and hence puts a limit on the amount of fuel which can be efficiently burned and the power output.For supercharged engine the volumetric efficiency has no meaning as it comes out to be more than unity.Fuel-Air Ratio (F/A)Fuel-air ratio (F/A) is the ratio of the mass of fuel to the mass of air in the fuel-air mixture. Air-fuel ratio (A/F) is reciprocal of fuel-air ratio. Fuel-air ratio of the mixture affects the combustion phenomenon in that it determines the flame propagation velocity, the heat release in the combustion chamber, the maximum temperature and the completeness of combustion.VIJAYAKUMARA M ME NIE MYSORE83

Relative fuel-air ratio is defined as the ratio of the actual fuel-air ratio to that of the stoichiometric fuel-air ratio required to burn the fuel supplied. Stoichiometric fuel-air ratio is the ratio of fuel to air is one in which case fuel is completely burned due to minimum quantity of air supplied.Relative fuel-air ratio, FR =(Actual fuel-Air ratio)/(Stoichiometric fuel -Air ratio)Brake Specific Fuel ConsumptionSpecific fuel consumption is defined as the amount of fuel consumed for each unit of brake power developed per hour. It is a clear indication of the efficiency with which the engine develops power from fuel.This parameter is widely used to compare the performance of different engines.VIJAYAKUMARA M ME NIE MYSORE84

Thermal Efficiency and Heat BalanceThermal efficiency of an engine is defined as the ratio of the output to that of the chemical energy input in the form of fuel supply. It may be based on brake or indicated output. It is the true indication of the efficiency with which the chemical energy of fuel (input) is converted into mechanical work. Thermal efficiency also accounts for combustion efficiency, i.e., for the fact that whole of the chemical energy of the fuel is not converted into heat energy during combustion.Brake thermal efficiency = bp / mf Cvwhere, Cv = Calorific value of fuel, kJ/kg, andmf = Mass of fuel supplied, kg/sec.


The energy input to the engine goes out in various forms a part is in the form of brake output, a part into exhaust, and the rest is taken by cooling water and the lubricating oil.The break-up of the total energy input into these different parts is called the heat balance. The main components in a heat balance are brake output, coolant losses, heat going to exhaust, radiation and other losses.Preparation of heat balance sheet gives us an idea about the amount of energy wasted in various parts and allows us to think of methods to reduce the losses so incurred.VIJAYAKUMARA M ME NIE MYSORE86

Exhaust Smoke and Other EmissionsSmoke and other exhaust emissions such as oxides of nitrogen, unburned hydrocarbons, etc. are nuisance for the public environment. With increasing emphasis on air pollution control all efforts are being made to keep them as minimum as it could be.Smoke is an indication of incomplete combustion. It limits the output of an engine if air pollution control is the consideration.Exhaust emissions have of late become a matter of grave concern and with the enforcement of legislation on air pollution in many countries; it has become necessary to view them as performance parameters.VIJAYAKUMARA M ME NIE MYSORE87

Specific Weight

Specific weight is defined as the weight of the engine in kilogram for each brake power developed and is an indication of the engine bulk. Specific weight plays an important role in applications such as power plants for aircrafts.VIJAYAKUMARA M ME NIE MYSORE88

introduction of i c engines

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