PERFORMANCE EVALUATION OF A CONVENTIONAL DIESEL ENGINE RUNNING IN DUAL FUEL MODE WITH DIESEL & LPG

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 6, Issue 11, Nov 2015, pp , Article ID: IJMET_06_11_008 Available online at ISSN Print: and ISSN Online: IAEME Publication PERFORMANCE EVALUATION OF A CONVENTIONAL DIESEL ENGINE RUNNING IN DUAL FUEL MODE WITH DIESEL & LPG Suraj Dev Singh, Chandrabhan Singh Tomar and Ravindra Randa Department of Mechanical Engineering, University Institute of Technology, Rajiv Gandhi Technical University, Bhopal, Madhya-Pradesh, India ABSTRACT Present study evaluates the performance of a compression ignition engine running in dual fuel mode with Liquefied Petroleum Gas and Petroleum Diesel. The LPG was inducted in the engine by Fumigation method at the rate of 0.094, & Kg/hr. Major performance parameters such as Brake power, Brake thermal efficiency, Brake specific fuel consumption etc. were evaluated at different load & different fuel combinations. A reduction of up to 11% in diesel consumption and up to 32% improvement in Brake specific fuel consumption was observed in dual fuel mode. Whereas, brake thermal efficiency didn t improved due to poor utilization of high energy content of LPG. Although the diesel fuel was saved but that came on sacrificing LPG which cost more than saved diesel. It s a loss in terms of cost and performance to use LPG in conventional Diesel engine by fumigation method used in this experiment but the concept of experiment can be advanced to make more subtle dual fuel diesel engine with advance techniques and improved cylinder designs. Cite this Article: Suraj Dev Singh, Chandrabhan Singh Tomar and Ravindra Randa. Performance Evaluation of A Conventional Diesel Engine Running In Dual Fuel Mode with Diesel & LPG, International Journal of Mechanical Engineering and Technology, 6(11), 2015, pp INTRODUCTION For more than a century, internal combustion engines have been relied upon as a principal source of power in a variety of applications. Of those engines, the most widely used are the reciprocating piston engines which are found in automobiles or other forms of transportation, as well as a variety of industrial and consumer applications. Of those variations, Diesel engines have a number of important advantages over gasoline engines. They provide reliability, long life, and good fuel 64 editor@iaeme.com

2 Performance Evaluation of A Conventional Diesel Engine Running In Dual Fuel Mode with Diesel & LPG economy, and are expected to remain the dominant heavy-duty transport power plants for many years. The rapidly depleting petroleum reserves and stringent emission norms have made it mandatory to look for alternate and cleaner sources. Bio-fuels pose a good role as alternate resources but neutral government policies and matters like food security have dominated the yielding of bio-crops and made them much expensive than conventional petro-diesel. So, in the present scenario, we are focusing on methods to improve the performance of CI engine and are trying to minimize the harmful emissions coming out of exhaust which have poisoning effect over the respiratory system along with climate change and global warming effects. A lots of researches are going on in this field to improve performance and reduce emissions by completely burning the diesel inside the combustion chamber, by adding additives to fuel or by modifying the engine to run in the Dual-fuel mode. One of the major problem attached with combustion in conventional diesel engines is that fuel and air doesn t mix homogeneously, a large fraction of fuel exists at very rich fuel-air equivalence ratio due to which incomplete combustion of diesel fuel occurs which results in high Particulate matter (PM) and Furthermore, the fuelrich equivalence ratio can also lead to high flame temperatures residing in a small area in the combustion process, which results in increased NOx emissions. As tougher environmental standards are being enacted for diesel sources, users of diesel engines are looking for ways to lower emissions. One solution is to reduce the amount of diesel injected into the combustion chamber, which reduces the equivalence ratio and works to reduce particulate and NOx emissions. However, it also reduces engine power. Another solution is to partially or completely convert the engine for use with alternative fuels such as, compressed natural gas (CNG), liquid natural fuels (LNF) such as ethanol, and liquid or liquefied petroleum gas (LPG) such as propane. Utilization of such alternative fuels with diesel engines not only provides for more stable and complete combustion and thereby enhanced fuel economy, but also typically results in lower engine emissions. However, alternative fuels, and more particularly gaseous fuels, typically do not have the cetane value required to allow for their ignition through compression. Accordingly, diesel engines must be modified to use such fuels. Methods for converting a diesel engine to consume alternative fuels typically fall into three categories. The first is to convert the engine to a spark-ignited engine; a second is to convert the engine to allow for the direct injection of gaseousfuels into the combustion chamber; and a third is "fogging" or "fumigation" of the gaseous-fuel with all or a portion of the intake air charge entering the engine. As will be appreciated, the second and third methods utilize injected diesel (i.e., pilot diesel) to ignite the gaseous-fuel. In this regard, the combustion of the gaseous-fuel results in more complete combustion of the diesel. Furthermore, the combination of gaseousfuel and diesel allows the engine to produce additional power while less diesel fuel is injected into the cylinders. However, conversion to a spark-ignition system and/or a direct gaseous-fuel injection system for utilizing gaseous-fuels with a diesel engine each typically require substantial modification to the diesel engine. Such modifications may include replacement of cylinder heads, pistons, fuel injection system and/or duplication of many engine components (e.g., injection systems). Accordingly, these systems are typically expensive and often times unreliable. On the other hand, fogging or fumigation type dual-fuel systems require little modification to existing engines. The mixture of gaseous-fuel with the intake air 65 editor@iaeme.com

3 Suraj Dev Singh, Chandrabhan Singh Tomar and Ravindra Randa charge is introduced into each cylinder of the engine during the intake stroke. During the compression stroke of the piston, the pressure and temperature of the mixture are increased in the conventional manner. Near the end of the compression stroke, a smaller than normal quantity of diesel fuel from the engine's existing diesel fuel injection system is injected into the cylinder. The diesel ignites due to compression and in turn ignites the mixture of gaseous-fuel and intake air, which in turn, accelerates the flame front of the Diesel Fuel, enhancing the combustion process. As will be appreciated, such fumigation systems may be retrofit onto existing diesel engines with little or no modification of the existing engine. Furthermore, engines using such fumigation systems may typically be operated in a dual-fuel mode or in a strictly diesel mode (e.g., when gaseous-fuel is not available). (1) In our experiment, we will be using this method of fumigation to run the governor controlled constant speed diesel engine in dual fuel mode using Diesel and LPG. For the purpose, we have attached a convergent divergent steel nozzle in the path of air supply to combustion chamber and made a very small hole at the throat of nozzle to accommodate the gas welding torch tip for supplying LPG during operating the engine. The supply of LPG has been varied at 0.094, & Kg/hr, as the engine is governor controlled; the supply of diesel got regulated by engine itself, at every LPG concentration; the Load on the engine was changed and performances were observed. 2. COMPARISON BETWEEN PROPERTIES OF DIESEL AND LPG In the table below, the physiochemical properties of Diesel and LPG are listed. PROPERTIES DIESEL (2) LPG (3,4) NORMAL STATE LIQUID GASEOUS FORMULAE C 12 H 23 C 3 H 8 CALORIFIC VALUE(KJ/KG) LHV: HHV: LHV: HHV: SPECIFIC GRAVITY(RELATIVE TO WATER) O.580(liquid) AUTO IGNITION TEMPERATURE( 0 C) TO FLASH POINT( 0 C) CETANE NUMBER STICHIOMETRIC A/F RATIO (MASS) PEAK FLAME TEMPERATURE( 0 C) BOILING POINT( 0 C) DENSITY(KG/M 3 ) (liquid) (gaseous) It is clear from the table that LPG has a quite low Cetane number which makes it inefficient for self ignition, that s why engine needs some of the Diesel known as pilot fuel to provoke ignition in the combustion chamber. The power is supplied jointly by the combustion of Diesel & LPG. And since LPG has a grater Calorific value, its combustion facilitates in providing required or greater power consuming a lesser quantity of diesel fuel thus improving the fuel economy. With Dual Fuel operation, there is no change to the basic architecture of the diesel engine or to the principle of diesel combustion. The engine itself is virtually unaltered, but for the addition of a gas injection system. The Dual-Fuel in-cylinder 66 editor@iaeme.com

4 Performance Evaluation of A Conventional Diesel Engine Running In Dual Fuel Mode with Diesel & LPG temperatures and pressures remain within the limits of pure diesel operation, so the converted engine operates within the parameters of the original engine. In a Dual-Fuel engine, however, the diesel fuel injector works like a liquid spark plug. Highly pressurized, it ignites a mixture of compressed gas and air in the cylinder. 3. SPECIFICATIONS OF THE TEST ENGINE The engine used in this experiment is installed at University Institute of Technology, Rajiv Gandhi Technical University, Bhopal. The RGPV engine test contains a complete system for measuring all the parameters relating to the diesel engine performance analysis. The experimental set-up contains mainly a dynamometer to load the engine. Figure below gives a diagram of the experimental system used. Figure 1 Diesel Engine Test Rig Showing Dynamometer Figure 2 Diesel Engine Test Rig Showing Fuel Consumption Meter, Temp. Indicator Etc 67 editor@iaeme.com

5 Suraj Dev Singh, Chandrabhan Singh Tomar and Ravindra Randa Parameter Engine Company and Model Type Cooling System Cylinder Number Bore Stroke Swept volume Compression Ratio (R) Rated Power (P) (kw) Nominal Revolution Details Kirloskar Oil Engine, SV1 Vertical, Totally Enclosed, Compression Ignition, Four Stroke Engine, Water Cooled Single cylinder 87.5 mm 110 mm 662 CC 16.5:1 8 HP 1500 RPM In order to convert the conventional diesel engine into a Dual-Fuel engine, we attached an Inspirator, an LPG fuel injector along with a flow controller to send LPG in a controlled way. For measuring the LPG flow we attached a Hot Wire Anemometer which measures the velocity of LPG in the delivery pipe and when this velocity is multiplied with area of cross section of Pipe, we get the volume flow rate of LPG which can be further converted into mass flow rate by multiplying it to the Density of LPG. For measuring the performance parameters, other devices such as Fuel consumption meter, belt dynamometer, thermocouples, rota meters etc are already attached with the engine test rig. In addition to this, we have supported the engine base with hard rubber dampers to reduce the vibrations. A water tank is used as a reservoir for the cooling of engine and exhaust calorimeter. Figure 3 Inspirator Setup for LPG Introduction 68 editor@iaeme.com

6 Performance Evaluation of A Conventional Diesel Engine Running In Dual Fuel Mode with Diesel & LPG Figure 4 Hot Wire Anemometer for Measuring 4. VELOCITY OF LPG SUPPLY 4.1. LPG Kit We have used a 3 kg gas capacity LPG gas cylinder for the experiment. The gas is supplied through a PVC hose pipe, which hosts a Gas welding torch nozzle at the other end for producing a jet of LPG gas Hot Wire Anemometer A Hot Wire Anemometer is inserted in the PVC pipe between the cylinder and engine to measure the velocity of the gas in the pipe. The velocity obtained is later used for measuring the volume flow rate or mass flow rate for measuring the performance parameters. The volume flow rate is given by s where: = Flow Velocity = Cross-Sectional vector Area/surface When the mass flow rate is known, and the density can be assumed constant, this is an easy way to get. Where: = mass flow rate(kg/s). = density(kg/m3) editor@iaeme.com

7 Suraj Dev Singh, Chandrabhan Singh Tomar and Ravindra Randa The above formulae can also be used to calculate the mass flow rate if the Volume flow rate and density are known Inspirator An Inspirator is a device, similar to Venturi tube and an Orifice plate, which mixes a fuel gas with atmospheric air in a precise ratio to regulate burn characteristics. Only the pressure of the fuel gas is used to draw in and mix the air. They are the most simple and common type of mixing device commonly used in gas stoves and furnaces. Burners using an inspirator are considered to be naturally aspirated. In an inspirator there are 2 tubes. The first is a fuel gas pipe with an Orifice at the end where the gas comes out. Then in front of this there is another section of tubing with a larger diameter that the gas blows into. Usually (but not always) this second piece of tubing is tapered so that it starts getting narrower downstream from the orifice. Then, at a certain point, it stops getting narrower and either straightens out or starts getting larger again. This gives the fuel and air time to mix. The fuel/air ratio is determined by the ratio of the diameter of the orifice to the diameter of the mixing tube. In our experiment, we have used a gas welding torch nozzle of hole diameter of 0.1 mm as an orifice to supply fuel gas to engine. It supplies gaseous fuel at the throat of Venturi or Inspirator after which the diameter of Venturi starts increasing and gaseous fuel and air mix homogeneously and burn completely and give their full power to engine for running minimizing the quantity of liquid fuel to be used by the engine for producing the required power at that speed and load. 5. RESEARCH METHODOLOGY As discussed earlier, we are using Diesel, & the Diesel-LPG fuel mix to run our engine and LPG is been mixed by Fumigation technique. As our engine is governor controlled, it takes the Diesel fuel in accordance with its need. We provide LPG in a controlled way in different concentrations with help of a control valve and hot wire anemometer and observe the diesel fuel consumption in every step. We observe performance parameters in every case & try to determine the suitability of Diesel- LPG mix for improved performance in dual fuel mode. At first we start the engine and switch on every accessory such as water supply, temperature indicators and let the engine run for 20 minutes so that it can achieve its steady state. In the first set we run the engine on pure diesel fuel purchased from a Petrol Pump. We, initially run the engine at Zero load at take readings of all the parameters required for our performance and emission results. Following parameters are to be noted:- 1. Air Velocity in the air passage(m/s) 2. Fuel consumption(ml/minute) 3. Temperatures T 1 = Temperature of the water entering into the engine jacket. T 2 = Temperature of the water coming out from the engine jacket. T 3 = Temperature of the Exhaust gases entering into the exhaust calorimeter. T 4 = Temperature of the Exhaust gases coming out from the exhaust calorimeter. T 5 = Temperature of the water entering into the Exhaust Calorimeter. T 6 = Temperature of water coming out from the Exhaust calorimeter. 4. Load on the engine applied by the Belt Dynamometer.(Kg.) 70 editor@iaeme.com

8 F.C. (Kg/hr.) Performance Evaluation of A Conventional Diesel Engine Running In Dual Fuel Mode with Diesel & LPG 5. Water flow to the engine Jacket and To the Exhaust Calorimeter.(Liter per Minute) 6. After noting down all the parameters, we apply a load of 1 Kg on the engine and let it run for 15 minutes to achieve the steady state and then point down all the parameters again. 7. In the same manner, we increase the load to 2 kg than 4 kg and than 8 Kg and note down all the parameters like before. 8. The results of the experiment are tabulated. These are our reference values. 9. In the next phase, we introduce LPG with the Diesel and note down the readings. In this stage, we have to take reading of one additional parameter i.e. LPG fuel consumption. We measure the LPG gas velocity with the help of a Hot Wire Anemometer and then covert it into volume flow rate as discussed in earlier sections to measure its quantity in m 3 /s or mass flow rate in Kg/s or Kg/hr. The results are noted down in the same fashion as Pure Diesel. 10. We repeat this process with different LPG concentration of 0.094, & Kg/hr. 11. After all the values are obtained, these values are scrutinized for the preparation of final results and for comparing the performance parameters. 6. RESULTS AND DISCUSSION The results are then tabulated and calculated thus for the results and then plotted in the terms of line graphs. 5 different graphs have been plotted and discussed. 1. Fuel consumption v/s Load Fuel Consumption Vs Load Diesel Diesel + LPG at 0.1 m/sec Diesel + LPG at 0.2 m/sec Diesel + LPG at 0.3 m/sec LOAD (Kgs) Graph 1 Fuel consumption vs Load Fuel consumption increases with increase in load as for maintaining the RPM of engine more brake power is required which is harnessed by burning more fuel at higher load. The graph shows the consumption of liquid diesel fuel only in case of dual fuel operation. Now looking at the plot of neat diesel fuel, it rises a little during initial increase in loading from 0 to 2 kg but falls a little on subsequent loadings to editor@iaeme.com

9 BSFC (Kg/KW.hr.) Suraj Dev Singh, Chandrabhan Singh Tomar and Ravindra Randa and 8 kg and stabilizes and shows a linear gradual increment from kg/hr. at no load to kg/hr. at full load. The other three plots of varying LPG flow rates of 0.094, & Kg/hr indicate the decrease in diesel consumption with increase in LPG flow rate; although LPG flow rates of & Kg/hr show very little difference at all loads and kg/hr. shows highest diesel consumption in dual fuel league. 2. Brake specific fuel consumption vs Load BSFC Vs Load LOAD (Kgs) Diesel Diesel + LPG at 0.1 m/sec Diesel + LPG at 0.2 m/sec Diesel + LPG at 0.3 m/sec Graph 2 Brake specific fuel consumption vs Load BSFC states that how much amount of fuel is consumed for generation of per unit brake power. It is governed by the quality of the combustion of fuel. As brake power varies with load thus BSFC also changes with load. The graph shows the consumption of diesel, and only diesel in dual fuel mode for generating per unit brake power. It is apparent that BSFC for neat diesel is worst at all loads. In dual fuel mode, diesel with 0.1 m/s LPG flow rate shows poor BSFC than other two dual fuel operational modes but better BSFC than neat diesel. BSFC for & Kg/hr LPG flow rates operation are nearly similar and overlap each other. BSFC at 1 kg load for diesel was 1.53 kg/kwhr which reduced to a mere 1.03 kg/kwhr. in dual fuel mode with LPG flow rate of Kg/hr. The LPG being the gas facilitates in smoother and complete burning of diesel fuel and thus reduces the BSFC. In all cases BSFC reduces with increase in load and thus increased break power. It is because of higher HC emission and incomplete burning of fuel at low loads. LPG induction helps in reducing the ignition delay and reduces the BSFC thus improving the performance. e.g. at top load of 8 kg, the BSFC of diesel is at 0.31 kg/kwhr while diesel with Kg/hr LPG flow rate show improved BSFC of 0.21 m/s i.e.32.25% reduction is observed editor@iaeme.com

10 BSEC Performance Evaluation of A Conventional Diesel Engine Running In Dual Fuel Mode with Diesel & LPG 3. Brake specific energy consumption vs Load 30 BSEC Vs Load Diesel Diesel + LPG at 0.1 m/sec Diesel + LPG at 0.2 m/sec Diesel + LPG at 0.3 m/sec LOAD (Kgs) Graph 3 Brake specific energy consumption vs load Brake specific energy consumption shows the required energy of the fuel for generating per unit of brake power. In this graph total energy content of the fuels in dual fuel mode has been taken in account. Neat Diesel shows lowest BSEC at all loads. The highest BSEC was observed in Dual fuel mode with LPG flow rate of 0.3 m/s. Other two flow rates of 0.1 and 0.2 m/s of LPG flow show very similar characteristics. The high energy content of LPG is not completely utilized thus resulting in higher BSEC. At lower loads this difference is apparent while at higher loads this difference is very minor and can be ignored. 4. Brake thermal efficiency vs Load Diesel Diesel + LPG at 0.1 m/sec Diesel + LPG at 0.2 m/sec Diesel + LPG at 0.3 m/sec Graph 4 Brake thermal efficiency vs load Brake thermal efficiency is a dimensionless number which indicates the extent to which energy given by the fuel is converted to brake power i.e. net work output. Here in this graph it is represented in percentage. The poorest BTE is observed in dual fuel mode at LPG flow rate of kg/hr followed by O.189 kg/hr and then kg/hr editor@iaeme.com

11 Exhaust Gas Temp. ( 0 C) Suraj Dev Singh, Chandrabhan Singh Tomar and Ravindra Randa BTE is less at low loads and improves at higher loads. Neat Diesel shows best BTE at all loads. The cause of poor BTE in case of dual fuel operation is high calorific value of LPG, which increases overall energy input to the engine thus reducing BTE at all loads. With increasing concentration of LPG gas, diesel fuel is substituted by a little amount but the energy provided by LPG increases greatly thus reducing BTE. 5. Exhaust gas temperature vs load EGT Vs Load Diesel Diesel + LPG at 0.1 m/sec Diesel + LPG at 0.2 m/sec Diesel + LPG at 0.3 m/sec LOAD (Kgs) Graph 5 Exhaust gas temperature vs Load EGT is an important parameter in engine performance check, it is an indication of how hot the combustion process is in the cylinders, and the amount of "afterburning" that is occurring in the exhaust manifold. EGT is also directly related to the air/fuel ratio. The richer the air/fuel ratio in a diesel, the higher the EGT will be. Two things can create a rich mixture under heavy loads or at full throttle: the first is too much fuel, and the second is not enough air. That seems simple enough, but it's the second part, not enough air, could get an engine in trouble. Anything that restricts intake airflow, or intake air density, limits the air mass or amount of oxygen that gets to the cylinders for supporting the combustion of fuel. This could include: a dirty or restrictive air cleaner, a partially blocked air intake, high outside air temperature, high altitude, restricted airflow to or through the radiator or intercooler, and high water temperature. Looking at the graph, it is obvious that with increase in load the EGT increases, but the increment is not linear. Higher EGT s were observed in dual fuel modes, the causes of it may be less air for combustion in the combustion chamber and high heating value of LPG gas. In a surprising way, in dual fuel mode, LPG flowing at 0.3 m/s shows lesser temperature than other two dual fuel modes only at highest load of 8 kg. It may be due to excess LPG unburned which cooled the EG. Neat diesel shows better and lower EGT s than all other fuels except at low loads it is little more than the diesel+lpg 0.1m/s, but otherwise it is lower at all other loads. The highest temperature reached in neat diesel case was C while the overall highest EGT observed was C in case of diesel+lpg 0.2 m/s editor@iaeme.com

12 Performance Evaluation of A Conventional Diesel Engine Running In Dual Fuel Mode with Diesel & LPG 7. CONCLUSION A comprehensive experimental work on the performance measurement of diesel engine and to convert it into dual fuel engine with the help of LPG kit has been carried out successfully. Following important outcomes derived from the experiment. 1. Fuel consumption was reduced in dual fuel mode. At no load, neat diesel consumption was reduced by 9.09%, 24.24% & 25.49% in dual fuel mode at LPG induction rates of 0.094, & Kg/hr respectively. While At top load of 8 kg s this reduction falls to 5%, 6.67% & 10.72% respectively. To support the load while maintaining the speed requires more fuel thus fuel consumption increases. 2. Brake specific fuel consumption also reduced in dual fuel mode, BSFC in dual fuel mode of & Kg/hr LPG flow rate are quite similar. BSFC in case of neat diesel at top load was 0.31 kg/kwhr while in case of dual fuel (LPG flow of 0.2 m/s) it was 0.21 kg/kwhr. Thus, we are able to save 0.1 kg/kwhr of diesel. 3. BSEC and BTE didn t got improved in dual fuel modes, although low LPG flow rates give comparable results but increased concentration of LPG in successive stages worsen the BTE. The higher calorific value of LPG and lower utilization of it causes to reduce BTE by increasing the overall non utilized energy input to the engine. This can be overcame by using advance techniques such as electronically timed and controlled injection of fuel to determine the needed quantity of fuel in engine, exhaust gas recirculation to utilize unburned HC, glow plugs for reducing the ignition delay at higher speeds and loads etc. but it is still unsure that they will improve BTE to great extent. 4. Exhaust gas temperature increased in dual fuel modes. The high heating value of LPG is the main cause behind it. Better cooling systems in which the cooling fluid quantities are also changeable are needed to employ dual fuel systems in diesel engines to keep the EGT in limit at higher loads. High temperature inside the combustion chamber may also harm the engine parts and reduce the mechanical strength it is very essential to take care of cooling inside the combustion chamber. 5. The cost of cooking LPG used in experiment is 455 INR per 14.2 kg i.e INR per kg maximum while the Diesel cost is INR per litre which when converted to kg comes to INR per kg (taking diesel density as 850 kg/m 3 ). The price of diesel is just double the LPG and it seems that there may be a saving in cost in using LPG in diesel engine. Taking the case of no load in which nearly 26% diesel fuel was saved while using diesel+ LPG at flow rate Kg/hr, in neat diesel operation, kg/hr fuel was used which costs INR/hr., when LPG at Kg/hr was inducted, only kg/hr fuel was used which costs INR/hr that means 5.25 INR were saved but for this sake kg/hr of LPG was used which costs 9.06 INR/hr, it is apparent that saving done in diesel was overcame in expense done on LPG and we incur a loss off 3.81 INR/hr. If we take the case of full load of 8 kg s then this loss is increased to around 5 INR/hr. Taking the case of LPG flow rate of Kg/hr, at no load, this loss is 1.13 INR/hr. which remains same at full load also. At LPG flow rate of Kg/hr, at no load, the loss is INR/hr and at full load it is increased to INR/hr. that means in every case, mixing LPG with Diesel doesn t show any profit cost wise or performance wise if seen the thermal efficiency. 6. There are other problems to consider as well - The unmodified Diesel engine was relatively slow-revving, producing its maximum torque at lower RPM than a similar Petrol version. This is not the case when it is converted to run on Diesel and LPG mix. The revised engine has to'rev' more when running on Diesel / LPG mix because its maximum torque will have been moved higher up the rev. band. This can bring new problems of reliability and longevity. The crankshaft, bearings and connecting rods (to mention but a few components) were all designed to rev. at a lower rate editor@iaeme.com

13 Suraj Dev Singh, Chandrabhan Singh Tomar and Ravindra Randa These components will suffer much higher stresses (stress increases at the square of RPM) at the increased RPM necessary to get sufficient torque when running on LPG. Mechanical breakdown may result in far less time, whilst increased wear and reduced component life are certain. Given the low overall savings achieved (to date) and the cost of the adaption (often equal to that of an injected Petrol engine conversion) many miles would have to be covered before any real savings are realised whilst reliability has been reduced. This does not seem to be an economically viable alternative. 7. One more benefit of using LPG is that Diesel engine becomes quieter and more responsive when using the LPG / Diesel mix. The classic Diesel 'Knock' can be greatly reduced. The main reason for increased smoothness and reduced noise (vibration) is that the LPG element begins its combustion before the Diesel fuel does, a result of 'detonation' due to the compression ratio being so high. The engine may also get up to its optimum temperature more quickly, whilst harmful emissions like Particulates and Carbon Monoxide can be reduced. These all appear to be benefits but a new set of problems arises when LPG is used to increase performance of an engine that wasn't designed to rev to the new, higher levels. As a result of this apparent improvement in performance, one of the best attributes of the Diesel engine (relative longevity and reliability) is dramatically reduced by the Diesel / LPG adaption. 8. Thus as a conclusion, the fumigation method used in this experiment does not appear to be an attractive or useful alternative for the average diesel engine. The economic benefits are not supportive in favor of the mixing of LPG with diesel. On a purely running cost reduction basis adapting the conversion technology for average diesel engine does not appear to be a viable option. 8. SCOPE OF FUTURE WORK Although there are many problems encountered in running a diesel engine in dual fuel mode with LPG, several researches are going on all over the world to eliminate these problems. LPG is quite cheaper than Diesel and if total energy of its can be utilized to run the diesel engine without harming its reliability and longevity, it would be a great boon. To improve the performance of a dual fuel engine, a turbocharger to provide more air (or oxygen) for the combustion, must be installed. It will help in complete combustion of fuel and will reduce exhaust gas temperature thus improving the engine life. Apart from that, precise electronic control system must be installed to watch the combustion patterns and needs in combustion chambers and for providing best ratio of diesel and LPG. A good exhaust gas recirculation system monitored electronically must be employed to engine to utilize any unburned HC. Some advance additives and catalyst might be added to fuel for smoother and efficient combustion. The concept of present work might be employed with some modifications and with other fuels such as CNG and Natural gas. ACKNOWLEDGMENT The authors wish to acknowledge the support rendered by University Institute of Technology, Bhopal in preparation of this Manuscript. REFERENCES [1] [2] [3] [4] editor@iaeme.com