Energy Balance For An Internal Combustion Engine Engineering Essay

sinew Balance For An Internal burning at the stake Engine Engineering EssayThe main(prenominal) objective of the experiment is to measure the vital force contributions to the diesel railway locomotive, which is treated as a thermodynamics system. The energy contributions that ar not measured may then be estimated from an energy balance.There are two main, unmeasured energy contributions to identify-An energy loss from incomplete burning, in which nigh of the burn down is not burn down completely.An energy loss by heat transfer to the bank line surrounding hot railway locomotive components.IntroductionA petter four stroke diesel engine will be used to investigate the efficiency of a diesel engine. diesel engines areinternal burn enginesdesigned to convert the chemical energy available in the dismiss, 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 motion of th e pistons, known as linear motion, acquires the rotary motion needed to turn the wheels of a car forward.We are already aware of the fact that internal combustion engines consecrate real low efficiencies, but the mark of such experiment is to study where and how the energy is used and lost. This would help us to improve the efficiency of the internal combustion engines where ever possible.TheoryBoth diesel engines and petrol engines convert fuel into energy through a series of small explosions or combustions. The major difference between diesel and petrol engines is the way these explosions happen. In a petrol engine, fuel is mixed with air, compressed by pistons and ignited by sparks from spark plugs. In a diesel engine, however, the air is compressed first, and then the fuel is injected, because as the air is compressed it heats up to around 400C, it is hot enough to ignite fuel.A four stroke diesel engine uses the following cycle (illust estimated in Figure1)Intake stroke Th e intake valve opens, and fresh air (containing no fuel), is drawn into the cylinder, go the piston down.Compression stroke As the piston rises, the air is compressed, causing its temperature to rise. At the end of the compression stroke, the air is hot enough to ignite fuel.Combustion stroke As the piston reaches the top, fuel is injected at just the right moment and ignited, forcing the piston back down.Exhaust stroke The piston moves back to the top, get-up-and-go out the exhaust created from the combustion out of the exhaust valve.Figure 124075-004-613c6f14.gifEq1From the basic steady flow energy equation, using the air-cycle method, we may write-The nourish of dirty dog be approximated, closely, to, Cpe is taken as 1 coulombJ/KgKIt is convenient to replace by in order to make an allowance for the possibility of incomplete combustion.*Where, FL, is the proportion of fuel energy that is not available because of incomplete combustion.Heat transfer, (Qr), is the sum of energy t ransferred to cooling water and energy lost to the surrounding from hot engine components, so we can writeQr = -dot mw Cpw ( Tout Tin ) + QrnReplacing all quantities in Eq1 we getSymbols explained as follows identify of heat energy transfer of systemrate of the work done by the system ( violence)combustion air mass flow ratefuel mass ratespecific enthalpy of products of combustionspecific enthalpy of combustion airspecific heat of water 4190 J/kgKApparatusThe Apparatus used in this experiment is mentioned as followsPetter Diesel Engine A four stroke, single cylinder, 659CC Petter Diesel Engine was used to conduct the experiment. Figure 2 shows the picture of Petter Diesel Engine used in the experiment.Ear Muffles Ear muffles were used to protect the ears from the noisy noise of the diesel engine prolonged exposure to such loud noise without ear protection can lead to hearing impairment.Barometer A Barometer was used to measure the atmospheric hug at the time of experiment. Atmos pheric pressure was needed to calculate the mass flow rate. The Barometer gives readings in mmHg. Figure 3 shows the picture of barometer used in the experiment.IMG_4763.JPGIMG_4767.JPGFigure 2 Figure 3 observational ProcedureThe purpose of this experiment was to investigate the efficiency of a diesel engine. To start with the experiment, all the gauges on the apparatus were pre set to default readings and as a safety precaution all students were provided with ear muffles. Each individual group member was assigned a tax by the module lecturer. My assigned task was to measure the oil and at the same time, time the engine as it consumed the set amount of diesel. Similarly other students were given tasks, which they carried on doing as the experiment progressed.The engine was started and after waiting for the recommended time of ten minutes, all the readings were taken off gauges. A weight of 5kg was already placed onto the torque arm in the beginning starting the engine. Measurements such as fuel flow rate, cooling water flow-rate, spring balance, orifice plate pressure drop, urge on gauge and electric thermometer were taken. electric car thermometer reading is divided into four parts, mentioned as followsExhaust temperatureCooling water inlet temperatureCooling water sales outlet temperatureAir inlet temperatureAfter victorious all the readings, engine was shut down and ear muffles were removed. The readings taken off the gauges were then used to work out the energy balance for an internal combustion engine.ResultsMEASURED PROPERTYVALUEUNITSAtmospheric Pressure764mmHgEngine Speed1500rpmSpring balance reading15NMass on torque arm5KgAmount of Fuel measured20mlTime to consume fuel97SecondsRelative tightness of fuel0.864Orifice plate pressure drop31mmH2OExhaust gas temperature260Degrees CelsiusCooling water inlet temperature69Degrees CelsiusCooling water outlet Temperature75Degrees CelsiusAir inlet Temperature18.5Degrees CelsiusCooling water flow-rate5litres/mi nuteFollowing readings were obtained from the gauges1. Shaft power output= torque* shaft rotational speed= W(kg load -dial reading)*rt*N(rpm)*2/60= (5*9.81)-15*0.4*1500*2/60= 2139.42 Watts= 6.13 10-3 kg/s3. Fuel flow rate == (20 10-3/1000) (864)= Kg/s4. Heat transfer rate to the cooling water = (l/min)/60 * 4.196* (Tout Tin)= *4.196*(75-69)= 2.098 kJ/s5. Heat transfer to exhaust gases= (6.24= 1.70 kJ/s6. Energy BalanceFuel Energy Input = mf*LCV= (1.7810-4) x (43106)= +7654WShaft Power Output= + 2139.42WCooling Water Heat Transfer= +2098WExhaust Heat Transfer = +1700WEnergy Transfer =Qm-mf *FL= -7654+2139.42+2098+1700= -1716.58WEfficiency = n= effectual work outputfuel energy input=2139.42 x 1007654=27.95% (Useful Work)Energy to surroundings = (Heat supplied in fuel Useful work done Energy to coolant Energy to exhaust)= 7.66 2.14 2.10 1.68= 1.74KWPercentage energy to coolant = Energy to coolant 100Heat supplied in fuel= x 100= 27.41%Percentage to exhaust = Energy to exhaust 100Heat supplied in fuel= x 100= 21.93%Percentage loss to the surrounding = Energy to surroundings 100Heat supplied in fuel= x 100= 22.71%pie chart.jpgFigure 5Figure 4DiscussionEngine efficiency refers to an engines ability to transform the available energy from its fuel into useful work. The new petrol combustion engine operates at an average of roughly 20 to 30 pct engine efficiency. The remaining 70 to 80 percent of the energy is lost to the surroundings in form of exhaust heat, mechanical sound energy and friction.Diesel engines are a bit more(prenominal) efficient. Thediesel engineuses high compression to ignite its fuel. This higher compression compensates for the engines heat losses and results in roughly 40 percent engine efficiency. This engine efficiency is save observed by direct injection diesel engines (discussed later). Rest 60 percent energy, like the petrol engine is lost to the surroundings.The Petter diesel engine which was the subject of this experiment showed a poor overall efficiency compared to an average diesel engine. The overall efficiency of the Petter diesel engine was only 27.95 percent. The rationality for such poor efficiency was that most of the energy was lost to surrounding, but that doesnt mean that the engine cannot me made more efficient.See Figure 4 and 5 for the distribution of energy lost and utilised.There are many ways to improve the efficiency of a diesel engine, some are discussed belowTurbochargers The purpose of a turbocharger is to compress the air flowing into the diesel engine, this lets the engine squeeze more air into a cylinder and more air means that more fuel can be added basically a turbocharger converts waste energy from an engines exhaust gases into compressed air, which it pushes into the engine. This allows the engine to burn more fuel producing more power and improves the overall efficiency of the combustion process, hence making the engine more efficient. However, the only disadvantage of a turbo charger is that, if it is in a cars engine it would take a few second to respond as the driver presses the pedal, this phenomenon is known as lag. Turbocharger suffers from lag because it takes a few moments before the exhaust gases reach a upper that is sufficient to drive the impeller/turbine.Direct Injection With direct injection, the diesel fuel is directly injected into the cylinder i.e. fuel is mixed with air inside the cylinder, allowing for better sway over the amount of fuel used, and varies depending on demand. This makes the engine more fuel efficient. Before direct injection, the fuel was mixed with air in the cars intake manifold. varying Valve Timing Valves open and close to allow air and fuel to enter cylinders and for the products of combustion to exit. Different valve timings produce different results (more power and or better fuel economy). Many modern engines can vary valve timing, allowing the default low RPM depart of the engine to have more economical timing , and the higher RPM range to go for max power.Cylinder Deactivation Internal Combustion Engines, with this feature can simply deactivate some cylinders when less power is required, temporarily reducing the total volume of the engine cylinders and so burning less fuel. This feature is mostly found on V6 and V8 engines.Super Charger Superchargers increase the intake of air into the combustion chamber. This means, more air into the combustion chamber and with more air, more fuel can be added, and more fuel means a bigger explosion and greaterhorsepower. Adding a supercharger is a good way to increase the power of a normal-sized engine and thus making it more efficient. Superchargers also create better fuel efficiency by increasing the amount of oxygen available to an engines combustion chambers, because superchargers increase the power of the engine by utilising more oxygen, they do not require a larger engine and therefore also increase fuel efficiency by allowing cars to be lighter . The biggest disadvantage of superchargers however, is that they steal some of the engines horsepower. A supercharger can consume as much as 20 percent of an engines total power output but also generates as much as 46 percent additional horsepower. Since, it generates more power than it requires, it is generally thought to be good option to increase engines efficiency.ConclusionDiesel engines are a form of Internal Combustion Engines. They are very inefficient if working on their own. Generally about 25-30 percent energy is used in work and the rest is lost to surroundings. The efficiency of a diesel engine can be enhanced by at least 10-15 percent if combine with the modern technological devices, such as turbochargers and superchargers. Other clever techniques can also be used to improve the fuel efficiency and overall engine efficiency of the engine, such as direct injection, variable valve timing and cylinder deactivation.Unfortunately, from the very beginning the focus on an internal combustion engine has been on producing more power rather than providing a better fuel economy, but nowadays due to growing awareness of environment and rising oil prices, engineers have shifted their attention on to producing more fuel efficient engines. For example, BMW is researching on ways to increase the fuel efficiency of a conventional engine by 10-15 percent by looking torecover and reuse heat energylost through the exhaust and that absorbed by the engine cooling system. With such initiatives we can see a future of more efficient and more environmentally friendly engines.