Performance Test of Heavy Duty Engine - Report Example

PERFORMANCE TEST OF HEAVY DUTY ENGINE WRITTEN BY SUBMITTED TO DECEMBER 2012 Table of contents Abstract 4 Introduction 5 Apparatus 5 Fuel Conditioning Unit 5 Monitoring of fuel consumption 7 Pressure temperature and humidity control 8 CAHU Components 9 Exhaust emissions 11 Emissions test for heavy vehicles and engine specifications 12 Test procedure 12 Results 14 Relationship between torque and speed 14 Speed versus BMEP 15 Speed versus power 16 BSFC relationship with speed 17 Level of emissions 18 A/F relationship with O2 18 A/F relationship with NOx 19 A/F relationship with CO2 19 A/F relationship with CO 20 Discussions 20 Conclusion 21 References 22 List of Figures List of plates Abstract This report gives the results of the performance of internal combustion engine (JCB DIESELMAX ECOMAX TIER 4 ENGINE 108kW, 129kW 448).The components of the three units of the engine test cells have been described in detail. In this report the test procedure have been described. It was found that the peak power for the engine was around 136kW which was recorded at 1800rpm; the peak torque was 720Nm at 1500rpm. In the test the gas emission was found to conform to theoretical expectation. Introduction The need for performing engine test stems for the need to ensure the engine performs efficiently while in operation. A good choice of the engine will ensure that as the engine is giving the required power it is able to utilize the fuel efficiently. When an engine is operating beyond its optimum level there is likely to be increased productions of emissions beyond the legislative limit. This also may lead to quick deterioration of the engine. The emissions produced by the engine when analyzed can be used as away of establishing if an engine has any form of mechanical problems. In testing of engine cells there is plotting of power, torque and BSFC curves. The levels of emissions is usually given for different level of air fuel ratio. Apparatus Fuel Conditioning Unit The fuel control unit has the ability to combat extreme ambient conditions, control high fuel return line temperature and match specified requirements. The FCU is composed of two elements which are the control enclosure and the process enclosure. The process enclosure components are the Circulating pump Head tank Temperature and level sensors Selector valves Immersion heater It is mandatory that the process enclosure requires one set of feed and return lines in the process water circuit and another set for chilled water; this ensures that the pipe work requirement in the cell is kept low. There are two ways in which temperature in the header tank is maintained or adjusted by a way of directing the intake loop. If the water is to be cooled there will be a diversion into the heat exchanger prior to returning to the header tank. On the other hand, if the water is to be warmed, it will not be passed through the heat exchanger while the heater in the head tanker is on. There is a PRT which is mounted on the header tank which functions to monitor the temperature level of the process water. In the header tank is also a level safety switch which has the ability to send a digital signal to processing unit thus ensuring that the immersion heater will only operate whenever there is sufficient water. Plate 1: Fuel conditioning unit Monitoring of fuel consumption The fuel consumption is effected through the use of FMS-Dynamic fuel consumption Meter which is an instrument that makes it possible to measure continuous and dynamic flow of fuel and the density (CP Engineering Systems Ltd, 2012). Two techniques are put into use in order to determine the fuel being consumed by the engine: Gravimetric fuel measurement and Coriolis flow meter. Both techniques are linked such that there is attainment of benefits for each system. The linking of the two also makes it possible for them to be used in verification of each others performance and operation in the process of calibration. There is a connection of the engine to the gravimetric measurement system via the engine’s feed and return lines while the Coriolis connection is through the supplying port of the gravimetric system so that it measures the make up fuel required so as to maintain the mass of fuel contained in the measurement tank at a level of 500g (i.e. approximately at the 500 grams mark). There is a rotary control valve which makes it possible for the fuel to have its way through the Coriolis meter, into the measurement tank at the desired rate so that the mass can be maintained at 500 grams. In case there is any variation in the mass in the holding tank, above or below the desired level of 500 grams, it will be corrected by using the measurement from the Coriolis meter. A solenoid valve that has been incorporated in the system ensures stoppage into the unit and also into the vent line protection system. The system is also fully equipped with features of a standard gravimetric fuel measurement system including bubbles separation from returned fuel with continuous flow operation and measurement and also fuel density readings (Thompson, 2004). Pressure temperature and humidity control In this experiment there was a need to maintain some desired atmospheric conditions. To achieve this, the CAHU was used as it has the ability of generating and replicating various atmospheric conditions and also simulating a varied altitude from the ambient air available. The CAHU has the ability of monitoring, adjusting pressure, temperature and also the humidity (Toyota Motor Sales Inc. ,2012). CAHU Components One of components of the CAHU is the air filter, which filters large particles from the air supply before passing the air to the CAHU cooling coil. This eliminates the possibility of the cooling system being blocked and its efficiency being substantially reduced. Chilled water or glycerol is introduced into the cooling coil at a fixed rate. The cooling coil’s function is to cool the air in the cell. Due to the reduction of temperature of the intake air there is saturation, as a result of which the excess water vapour will condense inside the coil. The water will drain off in the fins in the cooling coil and is then collected in a tank located beneath the coil. The CAHU has a humidifier which is used for addition of steam to achieve the desired level of humidity in the processed air. A component named Steam Lance is used in the introduction of steam to the process air. The 0battery used in the heating will typically have 3 heating elements that can be switched on so as to give a four combination of 0, 2, 4 and 6kW thus giving a varied way of heating the air passing over the elements. The heating elements are mounted in a ducting section where there is processed air and the movement of this air is achieved through use of a fan. The high velocity centrifugal fan used in the system has the ability of raising the combustion air pressure by up to 120mBar (12kPa) over the pressure level at the inlet. The fan is connected to a 4Kw mortar through a belt drive. There is also a secondary cooling coil which is used in the removal of any heat which could have been added through the action of the fan on the processed air. The coil is fed by chilled water supply which has a manual hand operated by pass valve. The air flow is directed to a final delivery plenum where there are two butterfly valves that regulate plenum pressure, with one regulating the inlet flow and another regulating a dump flow to the atmosphere. There is connection of a third outlet port to the engine air intake through an Air Mass Meter. The CAHU has an under–pressure relief valve that allows for potential situation where the fan can fail or the system is blocked. The engine characteristics is such that it will always “demand” air from the CAHU, causing the under pressure valve to open. This makes it possible for the engine to get the air from the atmosphere even if not of the required quality but at least the potential harm to the engine and CAHU is eliminated. The final stage of the system is where the conditioned air is made to pass through an Air Mass Meter with the reading from the meter being fed back into CADETv12 and being logged and this will be the actual mass that will be driven into the engine. Plate 2: Pressure temperature and humidity control equipment photo Exhaust emissions The latest technology exhaust analyzer is capable of measuring the five gases commonly emitted from the engine: HC, CO, CO2, O2 and NOX. All the gases are measured in Enhanced I/M programs. The five gases are usually important tool in trouble shooting (especially CO2 and O2) (Alleman, 2003). By use of an exhaust analyzer it is possible to establish any drivability and emissions concerns (Heywood, J., 1988). This means that this enables one to concentrate in areas which are likely to be causing concern which then saves the time employed in diagnosis. Analysis of emissions HC is measured in PPM by the exhaust analyzer. HC is the presence of fuel which has not undergone combustion which is caused by misfire. When only part of air/fuel charge burn it will be manifested by high level of HC. CO, which is a byproduct, is usually measured in percentage by use of the exhaust analyzer. Without any form of combustion taking place there will be no creation of CO. For fuel injected engine CO is a manifestation that there is a very high delivery of fuel to the engine in comparison to the air which is to be used in the fuel combustion. Nitrogen Oxides (NOX), which is a byproduct of combustion, is usually measured in PPM. A high production of NOX is usually as a result of combustion taking place at very high temperatures. Carbon dioxide is usually measured in parts per hundreds by exhaust analyzer. Presence of this gas is an indication that combustion is complete and efficient with the level of this gas approaching 15.5% (theoretical perfect level) in case there is near perfect combustion. Air fuel ratio and the spark timing are some of the factors that may affect the CO2 level. Just like the case of CO and CO2, O2 is also measured as a percentage. The level of O2 production is dependant on the closeness of air/fuel ratio to stoichiometry with a lean mixture causing an increase in the concentration levels of the gas. Misfire may also cause an increase in O2 level as because of it passing unused. Emissions test for heavy vehicles and engine specifications Heavy vehicles (40 tonnes and above) emission testing require testing to be done in engine test cells where the engine is operated over the European Stationary Cycle (ESC) and the European Transient Cycle (ETC) (Clark, 2005). In the ESC test it is a requirement for the engine to be run at specified speed and load points in a set period of time. The exhaust is then collected and usual steps, just like the vehicle based tests, are used in the analysis of the gases. In this test the JCB DIESELMAX ECOMAX TIER 4 ENGINE 108kW, 129kW 448 was used. The manufacturer gives the BMEP of the engine as 14.8 to 18.2. The engine can give an out put power range of 108kW to 129kW. Test procedure This experiment involved the testing of the engine on a dynamometer in a sequence of steady state modes. The engine was required to be operated within a prescribed time in each of the mode, such that the engine speed and the load changes were complete within 20 seconds. Also it was ensured that the specified speed was within  rpm while the specified torque was to be in  range of the maximum torque at the speed at which the test was being conducted. The measurement of the gas emissions was taken for each mode and an average taken over the cycle by use of a set of weighting factors and then the final emission results were expressed in g/kWh. Plate 3:DIESELMAX ECOMAX TIER 4 ENGINE 108kW, 129kW 448. Results This section gives the graphical representation of the results obtained in the experiment. The results are given in form of line graphs. The results which have been presented include Torque versus speed Speed versus BMEP Speed versus power BSFC relationship with speed Relationship between air/fuel emitted gases Relationship between torque and speed Figure 1 gives the relationship between the torque and the engine speed. The highest torque of 720 Nm is given at an engine speed of 1500rpm. The lowest torque before the peak torque was 614 Nm at the speed of 1000 rpm. After the peak the torque reduced to 628 Nm at the speed of 2000 rpm. Figure 1 Speed versus BMEP The relationship between the brake mean effective pressure (BMEP) and the speed in rpm was as shown in figure 2. From this figure it is clear that the highest value of BMEP was recorded at an engine speed of 1500 rpm. The smallest BMEP value before the peak was 16 at 1000 rpm while after the peak value the BMEP value reduced to 16.4 at 2000 rpm. Figure 2 Speed versus power Figure 3 clearly shows that the peak power of 136 kW was recorded at engine speed of 1800rpm, the power output then reduced to 120kw at 2000rpm. The lowest power was recorded before achieving the peak power was 62 kW which was recorded at the 1000 rpm speed. Figure 3 BSFC relationship with speed Specific fuel consumption of the engine is a measure of the torque which is delivered by the engine putting into consideration the amount of fuel consumed by the engine. The brake specific fuel consumption (BSFC) is measured after the parasitic losses have been deducted. From figure 4 it can be seen that BSFC values are high at lower speed. This can be attributed to the fact that there is more fuel consumption for the same torque because there is increased time for losing heat from the working fluid to the cylinder walls. At speed beyond 1500rpm the BSFC is expected to increase due to increased friction losses attributed to the high speed. Figure 4 Level of emissions A/F relationship with O2 The amount of O2 emitted, increased with an increase in air fuel ratio. The O2 level then became constant at about air/fuel ratio of 100. This can be explained by the fact that when the air fuel increases it reaches a point where there is enough for complete combustion and thus any excess will cause the O2 to be emitted as an exhaust gas. There may be emission of varied level of O2 at the same level of air/fuel ratio due to other factors. This could be because of misfire where the O2 is not consumed even though there is no complete combustion of the fuel. A/F relationship with NOx The level of NO and NOX was found to be high at low A/F values. The level of the gases (NO and NOX) reduced rapidly as the A/F values increase to about 50. Beyond the A/F value of 50 the NO and NOX values remained constant. This could be an indication that at high A/F values the temperatures are very high and this favours the high generation of NO and NOX. A/F relationship with CO2 The CO2 concentration was found to remain low when the A/F values ranged from 20 to 40. At A/F values of about 44 and 98 the CO2 value went beyond 2.5. For A/F of above 140 it was observed that the CO2 drops to values 1.1 just as low as those recorded in the 20 to 40 A/F values. The low values of CO2 associated with the reach fuel mixture (20 to 40 A/F) is attributed to the fact that at this level of A/F there is more production of CO at the expense of CO2 due to incomplete combustion. At the A/F of 43 and 98 the high CO2 value can be attributed to complete combustion of fuel, thus high generation of CO2. The low CO2 concentration in the last stage is attributable to the high dilution of the CO2 as a result of excess air even though there is complete combustion of fuel. A/F relationship with CO The CO concentration was very high at low A/F values of 44 and lower. At A/F values of 98 the CO values was at a low of about 23. This could be attributed to the fact that at this level of A/F there is complete combustion and thus there is more production of CO2 and very little production of CO. The increased CO values at A/F values of 140 and above may be attributed to low heat energy that is not enough to ensure complete combustion. Discussions The performance of the engine has been found to be similar to what has been reported in other literature. The trend in terms of power and torque outputs for most conventional engines indicate that the two variables will tend to increase with increasing speed to a certain pick point followed by a reduction beyond certain speeds. The engine torque will always have its peak point at a much lower speed that the power peak. It is always the intention of the designer to have the transmission systems to operate within a narrow band of speed levels so as to ensure that the engine operate at high efficiency and gives maximum torque and power. Friction losses are one of the reasons that cause power, torque and overall efficiency of the engine to drop beyond certain speeds. As the speed of the engine is increased it will reach a point where there is substantial power loss which leads to the reduction in the parameters. Thermal loss is the other way that the engine losses power. Both the friction losses and thermal losses have been found to increase with the reduction in the engine size. A small engine size has a high surface to volume ratio, which translates to a high loss of heat, which inhibits combustion. At high speed the combustion process is required to take place within a very short time. The time the fuel mixture is allowed to stay in the combustion chamber determines the efficiency of the engine and power and torque output. Heavy fuels require more time for complete combustion of fuels when compared to lighter fuels. This is a clear indication that engines with lighter fuels will operate much efficiently at higher speeds as compared to those with heavy fuels. At a very high speed of operation there is not complete combustion of the fuel and thus here is reduced power production in addition to the increased power loss due to friction. At very high speeds there will also be generation of CO due incomplete combustion process. Conclusion From the experiment many of the outcomes have been seen to coincide with the theoretical expectations. The graph of torque seems to match that of BMEP with the peak values on both graphs being at the same speed values. It was noted that the maximum power was occurring at higher speed than the maximum torque. The BSCF slope was expected to rise at higher speed but this was not seen in the graph. This is an indication that the engine needs to have adjusted to higher speed (beyond 1500rpm recorded in this experiment) for a clear picture to be seen. The gas emission curves fitted within the expected theoretical expectation. References Alleman, T.L. and McCormick, R.L.(2003), “Fischer-Tropsch Diesel Fuels – Properties and Exhaust Emissions: A Literature Review”, SAE Technical Paper No. 2003- 01-0763. Alleman, T.L., et al (2005) “Final Operability and Chassis Emissions Results from a Fleet of Class 6 Trucks Operating on Gas-to-Liquid Fuel and Catalyzed Diesel Particle Filters”, SAE Technical Paper No. 2005-01-3769. AVL and Diesel Net. Legislative Emissions Measurement Clark, R.H., et al (2005). “Fuels and Lubricant Base Oils from Shell Gas to Liquids (GTL)”, SAE Technical Paper No 2005-01-2191. CP Engineering Systems Ltd (2012). Dynamic Fuel Weigher. Heywood, J. (1988) “Internal Combustion Engine Fundamentals”, McGraw-Hill, May, M.P.et al (2001)“Development of Truck Engine Technologies for Use with Fischer-Tropsch Fuels”, SAE Technical Paper No. 2001-01-3520. Thompson, N.et al 2004.“Fuel Effects on Regulated Emissions From Advanced Diesel Engines and Vehicles”, SAE Technical Paper No. 2004-01-1880. Toyota Motor Sales Inc. (2012). Emissions. Read More

To achieve this, the CAHU was used as it has the ability of generating and replicating various atmospheric conditions and also simulating a varied altitude from the ambient air available. The CAHU has the ability of monitoring, adjusting pressure, temperature and also the humidity (Toyota Motor Sales Inc. ,2012). CAHU Components One of components of the CAHU is the air filter, which filters large particles from the air supply before passing the air to the CAHU cooling coil. This eliminates the possibility of the cooling system being blocked and its efficiency being substantially reduced.

Chilled water or glycerol is introduced into the cooling coil at a fixed rate. The cooling coil’s function is to cool the air in the cell. Due to the reduction of temperature of the intake air there is saturation, as a result of which the excess water vapour will condense inside the coil. The water will drain off in the fins in the cooling coil and is then collected in a tank located beneath the coil. The CAHU has a humidifier which is used for addition of steam to achieve the desired level of humidity in the processed air.

A component named Steam Lance is used in the introduction of steam to the process air. The 0battery used in the heating will typically have 3 heating elements that can be switched on so as to give a four combination of 0, 2, 4 and 6kW thus giving a varied way of heating the air passing over the elements. The heating elements are mounted in a ducting section where there is processed air and the movement of this air is achieved through use of a fan. The high velocity centrifugal fan used in the system has the ability of raising the combustion air pressure by up to 120mBar (12kPa) over the pressure level at the inlet.

The fan is connected to a 4Kw mortar through a belt drive. There is also a secondary cooling coil which is used in the removal of any heat which could have been added through the action of the fan on the processed air. The coil is fed by chilled water supply which has a manual hand operated by pass valve. The air flow is directed to a final delivery plenum where there are two butterfly valves that regulate plenum pressure, with one regulating the inlet flow and another regulating a dump flow to the atmosphere.

There is connection of a third outlet port to the engine air intake through an Air Mass Meter. The CAHU has an under–pressure relief valve that allows for potential situation where the fan can fail or the system is blocked. The engine characteristics is such that it will always “demand” air from the CAHU, causing the under pressure valve to open. This makes it possible for the engine to get the air from the atmosphere even if not of the required quality but at least the potential harm to the engine and CAHU is eliminated.

The final stage of the system is where the conditioned air is made to pass through an Air Mass Meter with the reading from the meter being fed back into CADETv12 and being logged and this will be the actual mass that will be driven into the engine. Plate 2: Pressure temperature and humidity control equipment photo Exhaust emissions The latest technology exhaust analyzer is capable of measuring the five gases commonly emitted from the engine: HC, CO, CO2, O2 and NOX. All the gases are measured in Enhanced I/M programs.

The five gases are usually important tool in trouble shooting (especially CO2 and O2) (Alleman, 2003). By use of an exhaust analyzer it is possible to establish any drivability and emissions concerns (Heywood, J., 1988). This means that this enables one to concentrate in areas which are likely to be causing concern which then saves the time employed in diagnosis. Analysis of emissions HC is measured in PPM by the exhaust analyzer. HC is the presence of fuel which has not undergone combustion which is caused by misfire.

When only part of air/fuel charge burn it will be manifested by high level of HC. CO, which is a byproduct, is usually measured in percentage by use of the exhaust analyzer.

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