CHAPTER 4 VARIABLE COMPRESSION RATIO ENGINE WITH DATA ACQUISITION SYSTEM

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1 57 CHAPTER 4 VARIABLE COMPRESSION RATIO ENGINE WITH DATA ACQUISITION SYSTEM 4.1 GENERAL The variable compression ratio engine was developed by Legion brothers, Bangalore, India. This chapter briefly discusses the experimental set up with data acquisition system, engine specifications, eddy current dynamometer, various sensors used for this experiment, measurement of air flow, measurement of fuel flow, measurement of water flow, engine speed, measurement of temperature, measurement of cylinder pressure and measurement of exhaust gas emissions. 4.2 EXPERIMENTAL SETUP The schematic diagram of the experimental setup of variable compression ratio engine is shown in Figure 4.1. The photographic view of the experimental setup is shown in Figure 4.2. The experiments are conducted on a four-stroke, naturally aspirated, water cooled, single cylinder variable compression ratio multi fuel engine. Details of the engine specifications are shown in Table 4.1. An air cooled eddy current dynamometer has been directly coupled to the engine output shaft using a tyre coupling. The engine and air cooled eddy current dynamometer are coupled using a tyre coupling while the output shaft of the dynamometer is fixed to a strain gauge type load cell for measuring the load applied to the engine. The specifications of the eddy current dynamometer are shown in Table 4.2. Accuracy of the

2 58 measurements and percentage of uncertainties are given in Table 4.3. Engine Test Express software (V5.76) is used in this system and the data collected during the experiments are stored in an excel file which is transferred into significant numerical information by using DASTEP (Version 8) device and stored in the computer. The photographic view of the VCR set up in the engine and eddy current dynamometer is shown in Figures 4.3 and 4.4. Figure 4.1 Schematic diagram of the experimental setup Figure 4.2 Photographic view of VCR engine experimental setup

3 59 Table 4.1 Specifications of the variable compression ratio engine Make Legion brothers Compression Ratio Variable from 5:1 to 22:1 Number of cylinders Single Method of cooling Water Cooled Spark timing Variable from 0-70deg Fuel Multi-fuel BHP 3 to 5 Hp Speed 1400 to 1500 rpm Bore 80mm Stroke 110mm Type of ignition Compression Ignition Method of loading Eddy Current Dynamometer Method of starting Manual Crank Start Lubrication Forced Temperature Sensor K type Chromel and Alumel type thermocouples Table 4.2 Specifications of eddy current dynamometer Type Cooling Load measurement method Maximum speed BHP Coupling type PowerMag Air Strain gauge 3000 rpm 5HP Direct

4 60 Table 4.3 Accuracy of the measurements and uncertainties of results Sl.No Parameter/Instrument Range Accuracy Percentage Uncertainties 1 Engine speed 2 Temperature rpm ± 2 rpm o C ±1 o C ±1.0 ±0.1 3 Pressure 0-100bar ±0.5bar ±0.1 4 Load 0-100kg ±0.1kg ±0.2 5 Fuel measurement - ±0.2cm 3 ±1.5 6 Manometer - ±1mm ±1.0 7 Crank angle encoder - ±1 o ±0.2 8 NO X ppm ±15 ppm ±0.2 9 HC ppm ±1 ppm ± CO 0-10% ±0.01 ±0.1 Figure 4.3 Photographic view of VCR lever

5 61 Eddy current Dynamometer Figure 4.4 Photographic view of Eddy current dynamometer setup 4.3 MEASUREMENT OF AIR FLOW AND FUEL FLOW Various pressure sensors are used to measure the pressure difference between orifice plates. The differential pressure sensor provides a proportional voltage output with respect to difference in pressure. Signal conditioning is standalone for each sensor. The range of air flow is 0-99m 3 /hr. Fuel consumption is measured using optical sensors. These optical sensors detect any liquid and give output signals. The system consists of a burette fitted with two optical sensors, one at the top and the other at the bottom. The time taken for fuel consumption for a fixed volume is calculated. The range of fuel flow is 0-99 kg/hr. 4.4 MEASUREMENT OF ENGINE SPEED A non contact type PNP sensor is used to measure the engine speed. A PNP sensor gives a pulse output for each revolution of the crank shaft. The frequency of the pulse is converted into voltage output and connected to the computer. The range of the sensor is rpm.

6 MEASUREMENT OF WATER FLOW An acrylic body rota meter is used to measure water flow with a range LPH for engine cooling and LPH for calorimeter cooling. 4.6 MEASUREMENT OF LOAD Torque is measured using a load cell transducer. The transducer is a strain gauge base. The output of the load cell is connected to the load cell transmitter. The output of the load cell transmitter is connected to the USM port through the interface card. 4.7 MEASUREMENT OF TEMPERATURE A shell tube gas to liquid heat exchanger is used as calorimeter for conducting the heat balance. The measurement of temperature at different points in calorimeter is shown in Table 4.4. K type sensors are used for the measurement of temperatures at various points in the calorimeter. The photographic view of the calorimeter is shown in Figure 4.5. Table 4.4 Location of sensors in calorimeter Type Range ( o C) K Signal conditioning / transmitter Location Inlet water temperature in calorimeter K Outlet water temperature in calorimeter K Inlet exhaust gas temperature in calorimeter K Standalone Outlet exhaust gas temperature in calorimeter K Inlet water temperature to the engine cylinder K K Ambient temperature Outlet water temperature from the engine cylinder

7 63 Calorimeter Figure 4.5 Photographic view of the calorimeter setup 4.8 MEASUREMENT OF CYLINDER PRESSURE The combustion pressure sensor is mounted on the cylinder head. Optimized piezoelectric sensor with sensitivity of ± 0.5% is used for continuous monitoring of combustion pressure. The crank angle encoder consists of 14 analog inputs (12-16 bits depending on speed) with a rotational speed of maximum 12000min -1 using pin connector. The specifications of crank angle encoder are given in Table 4.5. The sensor used for measurement of cylinder pressure is very precise and an optimized piezoelectric sensor (Type KISTLER 6613CA) is used for continuous measurement of cylinder pressure of the engine. The photographic view of the sensor is given in Figure 4.6. The sensor is connected to the charge amplifier with a robust integrated high temperature Viton cable. Good linearity and long term stability ensure reliable and repeatable measurements over a long period of time. The technical specifications of the sensor are given in Table 4.6.

8 64 Figure 4.6 Pressure sensor type KISTLER 6613CA Table 4.5 Technical specifications of the crank angle encoder General specifications Pulse count (ppr) 360 Electrical specifications Operating voltage 5V DC ±5% No load current supply Max 70mA Output Output type Pulse Operating current Max.per channel20ma Output frequency Max.200MHz Rise time 100ns Connection Connector Type 9416, 12-pin, type 9416L, 12-pin Ambient conditions Operating temperature 253 to 333K Storage temperature 233 to 343K Mechanical Specifications Rotational speed Max 12000min -1 Moment of Inertia 25gcm 2 Starting torque 1.5Ncm

9 65 Table 4.6 Technical specifications of the sensor Pressure range 0-100bar Type Piezoelectric Cooling Air cooled Calibration at 200 o C 0-100bar Sensitivity (±0.5%) 25mv/bar Frequency range Hz Linearity ±1%FSO Shock 2000g Operating temperature range 240 o C max Sensitivity shift ±2,5% (200±150 o C) ±1% (200±50 o C) Supply voltage 7to32 VDC Supply current 6mA Mounting torque of sensor 15Nm 4.9 DATA ACQUISITION SYSTEM Windows based software is used for data measurement, auto zoom graphs and digital display of data in the system. Further, it stores indefinite number of graphs with facilities to export data to an excel sheet. This system can calculate P-θ diagram, mass fraction burned angle, heat release rate and combustion pressure and store them in an excel file. The calorific value and viscosity are measured by bomb calorimeter and redwood viscometer respectively. K type sensors with a range of o C and o C are used to measure the gas temperature at various points in calorimeter. All the measured parameters from the sensor are connected to the computer.

10 MEASUREMENT OF EMISSION A MN model, MARS portable gas analyzer used for measuring the exhaust gas emissions is shown in Figure 4.7. Specifications of the exhaust gas analyzer are given in Table 4.7. The probe of the analyzer is inserted into the exhaust pipe of the engine before taking the measurements. Figure 4.7 Photographic view of the exhaust gas analyzer After the engine achieves steady state condition, the exhaust emissions are measured. Nitrogen oxides, carbon monoxide and hydrocarbon are measured for different blends of methyl ester of cottonseed oil with standard diesel and analysis is done for different compression ratios. In this analyzer, the zero setting function sets the sensor to zero using span gas. The smoke density is measured by AVL smoke meter. The computerized data acquisition system collects the data that is used to analyze engine performance, combustion characteristics and emission of exhaust gases.

11 67 Table 4.7 Specifications of the exhaust gas analyzer Gas measured Measuring range Resolution CO 0 10 % Volume 0.01% HC ppm 1 ppm O % Volume 0.01% NO x ppm 1 ppm The following Table 4.8 contains the emission standards for the Euro emission standards for heavy duty diesel engines. In this smoke emission is given in m -1. Table 4.8 Euro union emission standards for heavy duty diesel engines, g/kwh Tier Exhaust gas emissions CO HC NO X Smoke Euro I Euro II Euro III Euro IV Euro V Euro VI EXPERIMENTAL METHODOLOGY The present study is carried out to analyse the effect of higher compression ratios and biodiesel on the engine performance, combustion and

12 68 emission characteristics of COME as a biodiesel in a VCR engine. The various phases of work adopted to analyse the VCR engine are a) By fuelling the engine with base line diesel fuel b) By fuelling the engine with COME-diesel blends c) By fuelling the engine with COME-diesel-ethanol blends d) By varying the CR at maximum load e) By varying the load at fixed maximum CR The following experiments are carried out to meet out the objective a) To conduct the experiment using COME as a fuel and compare the result with neat diesel b) To conduct the experiment by using biodiesel for various blend proportions B15, B30, B45, B60, B75, B90 and B100 respectively c) To conduct the experiment by varying the load with various blend proportions of COME diesel blends (B15, B30, B45, B60, B75, B90 and B100) at fixed maximum CR 22:1 d) To conduct the experiment by varying the CR (18:1 to 22:1) with various blend proportions of COME diesel blends (B15, B30, B45, B60, B75, B90 and B100) at fixed maximum load e) To conduct the experiments by varying the CR at maximum load conditions and by varying the blend proportions at maximum CR using COME-diesel-ethanol blends. The above experimental investigations are carried out in the VCR engine setup with that five trails have been made for every test run.

13 SUMMARY The VCR engine with detailed experimental setup, various sensors used for the measurements, the role of data acquisition system and exhaust gas analyser is discussed in this chapter. Using the setup, experiments are conducted to study the performance, combustion and emission characteristics of the VCR engine for all fuels tested.