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Energy Balance For An Internal Combustion Engine Engineering Essay

The chief aim of the experiment is to mensurate the energy parts to the Diesel engine, which is treated as a thermodynamics system. The energy parts that are non measured may so be estimated from an energy balance.

There are two chief, immeasurable energy parts to place: –

An energy loss from uncomplete burning, in which some of the fuel is non burned wholly.

An energy loss by heat transportation to the air environing hot engine constituents.


A Petter four stroke Diesel engine will be used to look into the efficiency of a Diesel engine. Diesel engines are internal burning engines designed to change over the chemical energy available in the fuel, into mechanical energy. This mechanical energy moves the Pistons up and down inside cylinders. The Pistons are connected to a crankshaft, and the up-and-down gesture of the Pistons, known as additive gesture, creates the rotary gesture needed to turn the wheels of a auto forward.

We are already cognizant of the fact that internal burning engines have really low efficiencies, but the intent of such experiment is to analyze where and how the energy is used and lost. This would assist us to better the efficiency of the internal burning engines where of all time possible.


Both diesel engines and gasoline engines convert fuel into energy through a series of little detonations or burnings. The major difference between Diesel and gasoline engines is the manner these detonations happen. In a gasoline engine, fuel is assorted with air, compressed by Pistons and ignited by flickers from flicker stoppers. In a Diesel engine, nevertheless, the air is compressed foremost, and so the fuel is injected, because as the air is compressed it heats up to around 400 & A ; deg ; C, it is hot plenty to light fuel.

A four shot Diesel engine uses the undermentioned rhythm ( illustrated in Figure1 ) :

Intake shot — The consumption valve opens, and fresh air ( incorporating no fuel ) , is drawn into the cylinder, traveling the Piston down.

Compression shot — As the Piston rises, the air is compressed, doing its temperature to lift. At the terminal of the compaction shot, the air is hot plenty to light fuel.

Combustion shot — As the Piston reaches the top, fuel is injected at merely the right minute and ignited, coercing the Piston back down.

Exhaust shot — The Piston moves back to the top, forcing out the fumes created from the burning out of the exhaust valve.

Figure 1


Eq1From the basic steady flow energy equation, utilizing the air-cycle method, we may compose: –

The value of can be approximated, closely, to:

, Cpe is taken as 1100J/KgK

It is convenient to replace by in order to do an allowance for the possibility of uncomplete burning.

*Where, FL, is the proportion of fuel energy that is non available because of uncomplete burning.

Heat transportation, ( Qr ) , is the amount of energy transferred to chilling H2O and energy lost to the environing from hot engine constituents, therefore we can compose:

Qr = -dot mw Cpw ( Tout – Tin ) + Qrn

Replacing all measures in Eq1 we get:

Symbols explained as follows:

rate of heat energy transportation of system

rate of the work done by the system ( power )

burning air mass flow rate

fuel mass rate

specific heat content of merchandises of burning

specific heat content of burning air

specific heat of H2O 4190 J/kgK


The Apparatus used in this experiment is mentioned as follows:

Petter Diesel Engine: A four shot, individual cylinder, 659CC Petter Diesel Engine was used to carry on the experiment. Figure 2 shows the image of Petter Diesel Engine used in the experiment.

Ear Muffles: Ear muffles were used to protect the ears from the loud noise of the Diesel engine ; drawn-out exposure to such loud noise without ear protection can take to hearing damage.

Barometer: A Barometer was used to mensurate the atmospheric force per unit area at the clip of experiment. Atmospheric force per unit area was needed to cipher the mass flow rate. The Barometer gives readings in mmHg. Figure 3 shows the image of barometer used in the experiment.


Figure 2 Figure 3

Experimental Procedure

The intent of this experiment was to look into the efficiency of a Diesel engine. To get down with the experiment, all the gages on the setup were pre set to default readings and as a safety safeguard all pupils were provided with ear muffles. Each single group member was assigned a undertaking by the faculty lector. My assigned undertaking was to mensurate the oil and at the same clip, clip the engine as it consumed the set sum of Diesel. Similarly other pupils were given undertakings, which they carried on making as the experiment progressed.

The engine was started and after waiting for the recommended clip of 10 proceedingss, all the readings were taken off gages. A weight of 5kg was already placed onto the torque arm before get downing the engine. Measurements such as fuel flow rate, chilling H2O flow-rate, spring balance, orifice home base force per unit area bead, velocity gage and electric thermometer were taken.

Electric thermometer reading is divided into four parts, mentioned as follows:

Exhaust temperature

Cooling H2O recess temperature

Cooling H2O mercantile establishment temperature

Air recess temperature

After taking all the readings, engine was shut down and ear muffles were removed. The readings taken off the gages were so used to work out the energy balance for an internal burning engine.




Unit of measurements

Atmospheric Pressure



Engine Speed


revolutions per minute

Spring balance reading



Mass on torsion arm



Sum of Fuel measured



Time to devour fuel



Relative denseness of fuel


Orifice home base force per unit area bead



Exhaust gas temperature


Degrees Celsius

Cooling H2O recess temperature


Degrees Celsius

Cooling H2O mercantile establishment Temperature


Degrees Celsius

Air recess Temperature


Degrees Celsius

Cooling H2O flow-rate



Following readings were obtained from the gages:

1. Shaft power output= torque* shaft rotational velocity

= W ( kg burden -dial reading ) *rt*N ( revolutions per minute ) *2?/60

= ( 5*9.81 ) -15*0.4*1500*2?/60

= 2139.42 Watts

= 6.13 10-3 kg/s

3. Fuel flow rate =

= ( 20 10-3/1000 ) ( 864 )

= Kg/s

4. Heat transportation rate to the chilling H2O = { ( l/min ) /60 } * 4.196* ( Tout – Tin )

= *4.196* ( 75-69 )

= 2.098 kJ/s

5. Heat transportation to wash up gases

= ( 6.24

= 1.70 kJ/s

6. Energy Balance:

Fuel Energy Input = mf*LCV

= ( 1.78×10-4 ) ten ( 43×106 )

= +7654W

Shaft Power Output= + 2139.42W

Cooling Water Heat Transfer= +2098W

Exhaust Heat Transfer = +1700W

Energy Transfer =Qm-mf *FL

= -7654+2139.42+2098+1700

= -1716.58W

Efficiency = n=useful work end product

fuel energy input

=2139.42 x 100


=27.95 % ( Useful Work )

Energy to environ = ( Heat supplied in fuel – Useful work done – Energy to coolant – Energy to wash up )

= 7.66 – 2.14 – 2.10 – 1.68

= 1.74KW

Percentage energy to coolant = Energy to coolant – 100

Heat supplied in fuel

= x 100

= 27.41 %

Percentage to wash up = Energy to wash up – 100

Heat supplied in fuel

= x 100

= 21.93 %

Percentage loss to the environing = Energy to environ – 100

Heat supplied in fuel

= x 100

= 22.71 %

pie chart.jpg

Figure 5

Figure 4


Engine efficiency refers to an engine ‘s ability to transform the available energy from its fuel into utile work. The modern gasoline burning engine operates at an norm of approximately 20 to 30 per centum engine efficiency. The staying 70 to 80 per centum of the energy is lost to the milieus in signifier of exhaust heat, mechanical sound energy and clash.

Diesel engines are a bit more efficient. The Diesel engine uses high compaction to light its fuel. This higher compaction compensates for the engines heat losingss and consequences in approximately 40 per centum engine efficiency. This engine efficiency is merely observed by direct injection Diesel engines ( discussed subsequently ) . Rest 60 per centum energy, like the gasoline engine is lost to the milieus.

The Petter Diesel engine which was the topic of this experiment showed a hapless overall efficiency compared to an mean Diesel engine. The overall efficiency of the Petter Diesel engine was merely 27.95 per centum. The ground for such hapless efficiency was that most of the energy was lost to environing, but that does n’t intend that the engine can non me made more efficient.

See Figure 4 and 5 for the distribution of energy lost and utilised.

There are many ways to better the efficiency of a Diesel engine, some are discussed below:

Turbochargers: The intent of a turbocharger is to compact the air fluxing into the Diesel engine, this lets the engine squeezing more air into a cylinder and more air means that more fuel can be added ; fundamentally a turbocharger converts waste energy from an engine ‘s exhaust gases into tight air, which it pushes into the engine. This allows the engine to fire more fuel bring forthing more power and improves the overall efficiency of the burning procedure, therefore doing the engine more efficient. However, the lone disadvantage of a turbocharger is that, if it is in a auto ‘s engine it would take a few 2nd to react as the driver presses the pedal, this phenomenon is known as slowdown. Turbocharger suffers from slowdown because it takes a few minutes before the fumes gases reach a speed that is sufficient to drive the impeller/turbine.

Direct Injection: With direct injection, the Diesel fuel is straight injected into the cylinder i.e. fuel is assorted with air inside the cylinder, leting for better control over the sum of fuel used, and varies depending on demand. This makes the engine more fuel efficient. Before direct injection, the fuel was assorted with air in the auto ‘s consumption manifold.

Variable Valve Timing: Valves open and close to let air and fuel to come in cylinders and for the merchandises of burning to go out. Different valve timings produce different consequences ( more power and or better fuel economic system ) . Many modern engines can change valve timing, leting the default low RPM scope of the engine to hold more economical timing, and the higher RPM scope to travel for max power.

Cylinder Deactivation: Internal Combustion Engines, with this characteristic can merely deactivate some cylinders when less power is required, temporarily cut downing the entire volume of the engine cylinders and so firing less fuel. This characteristic is largely found on V6 and V8 engines.

Super Charger: Superchargers increase the consumption of air into the burning chamber. This means, more air into the burning chamber and with more air, more fuel can be added, and more fuel means a bigger detonation and greater HP. Adding a supercharger is a good manner to increase the power of a normal-sized engine and therefore doing it more efficient. Superchargers besides create better fuel efficiency by increasing the sum of O available to an engine ‘s burning Chamberss, because superchargers increase the power of the engine by using more O, they do non necessitate a larger engine and hence besides increase fuel efficiency by leting autos to be lighter. The biggest disadvantage of superchargers nevertheless, is that they steal some of the engine ‘s HP. A supercharger can devour every bit much as 20 per centum of an engine ‘s entire power end product but besides generates every bit much as 46 per centum extra HP. Since, it generates more power than it requires, it is by and large thought to be good option to increase engines efficiency.


Diesel engines are a signifier of Internal Combustion Engines. They are really inefficient if working on their ain. By and large about 25-30 per centum energy is used in work and the remainder is lost to milieus. The efficiency of a diesel engine can be enhanced by at least 10-15 per centum if combined with the modern technological devices, such as turbochargers and superchargers. Other clever techniques can besides be used to better the fuel efficiency and overall engine efficiency of the engine, such as direct injection, variable valve timing and cylinder inactivation.

Unfortunately, from the really get downing the focal point on an internal burning engine has been on bring forthing more power instead than supplying a better fuel economic system, but presents due to turning consciousness of environment and lifting oil monetary values, applied scientists have shifted their attending on to bring forthing more fuel efficient engines. For illustration, BMW is researching on ways to increase the fuel efficiency of a conventional engine by 10-15 per centum by looking to retrieve and recycle heat energy lost through the fumes and that absorbed by the engine chilling system. With such enterprises we can see a hereafter of more efficient and more environmentally friendly engines.

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