105 6.7 BSFC and BTE variation with speed when using raw biogas fuel for different CR 106 6.8(a) Cylinder pressure variation with crank angle for spark timing when using raw biogas. 7.58 (a) Variation of CO emissions with EGR rate for different spark locations; (b) NOx emission variation with EGR rate for different spark locations. 8.2 a) Two-dimensional geometry of the combustion chamber (only half above the axis) at TDC; (B).
Introduction
- MOTIVATION
- PERFORMANCE IMPROVEMENT METHODS
- Variable compression ratio
- Optimum Ignition timing or spark timing
- Optimum spark plug location
- EMISSION CONTROL NORMS AND METHODS
- Exhaust gas recirculation
- SUMMARY
The ignition timing of the fuel/air mixture is important for the best engine performance. A positive ignition engine that is generally designed and developed based on the fuel used is gasoline.
Literature Review
INTRODUCTON
In this regard, this chapter discusses the research so far carried out by various peoples in the field of variable compression ratio engine development where various mechanisms were incorporated and tried to improve engine performance. These variable compression ratio engine performances for gasoline fuels as well as other liquid and gaseous fuels become extremely important to exploit maximum efficiency with minimum fuel consumption.
VARIOUS PROPOSALS OF VCR MECHANISM
As the piston crown deflects, the cylinder clearance volume increases, lowering the effective compression ratio and reducing peak cylinder pressure. They developed a two-part variable compression ratio cylinder with inner and outer sleeves in which relative movement between the sleeves changes the volume of the combustion chamber and thus changes the CR.
INVESTIGATIONS WITH VARIABLE COMPRESSION RATIO ENGINE Variable compression ratio is the method by which the compression ratio could be altered to
- Liquid fuels in VCR engines
- Findings with gaseous Fuel
- Effect of load a. Combustion
- Effect of speed a. Combustion
- Effect of ignition timing
- Effect of engine compression ratio
- Effect of type of fuel
- Effect of relative air/fuel ratio a. Combustion
- Effect of bore/stroke ratio a. Combustion
- Effect of EGR and Intake air temperature
- Effect of variable spark plug location
Similar to Park et al., (2011), the production efficiency of a four-stroke positive-ignition gas engine generator operating on a biogas-hydrogen mixture with different excess air ratios was evaluated. BSUHC values were lowest at an equivalence ratio of 0.9, but from 0.9 to 1.2, BSUHC starts to increase.
COMPUTATIONAL WORK
The main focus was on the heat transfer to the cylinder wall, the spark timing, the real valve timing and the closing time. The results obtained from the first law analysis of the real cycle, such as the diagram of pressure indicators, efficiency were compared favorably with the corresponding experimental data obtained from a flexible Ricardo engine with variable compression ratio. Engine performance was simulated at each snow to shock ratio keeping the maximum CR as 10. The analysis showed that torque and braking power were increased by 7-54% at low speeds and 7-57% at high speeds compared to the original. the engine.
ANALYTICAL WORK
Ismail and Mehta, (2011) reported the estimation of irreversibility associated with various sub-processes taking place during combustion in a hydrogen fueled spark ignition engine. Hakan and Jehad (2008) developed a computer simulation model of an LPG-powered single-cylinder four-stroke spark-ignition engine with variable stroke length.
SUMMARY OF LITERATURE AND SCOPE OF WORK
But there is room to further increase engine performance while running at best CR if the spark plug (SP) is optimally located. Axial displacement of the spark plug must therefore be for various SI engine fuels.
OBJECTIVES
This study must be performed if the spark plug will be installed inside the auxiliary piston of the new VCR mechanism. A study of variable spark plug location (VSPL) for LPG and crude biogas is performed, followed by a comparison of the results.
ORGANIZATION OF REPORT
Development of a variable spark plug location mechanism incorporated into a new VCR mechanism to investigate the effect of VCR, spark timing and spark plug location of the gaseous fuels investigated. The installation method of this new VCR mechanism on both the HONDA engine and the variable CR engine is presented.
RESEARCH ENGINE TEST RIG
- Spark ignition (SI) engine
- Engine instrumentations
- Engine load
- Engine speed measurement
- Air consumption measurement
- Fuel consumption measurement
- Procedure of experimentation
Now the load is applied on the prony brake dynamometer by increasing the tension in the rope with the rotating lever of the movable spring balance. An alternative fuel such as kerosene can also be tested on the engine without any changes to the existing engine setup.
LARGE CAPACITY SOPHISTICATED VCR TEST FACILITY
- Engine Instrumentation .1 Braking System
- Temperature measurement
- Measurement of fuel consumption
Engine cooling is achieved by circulating water through the jackets of the engine block and cylinder head. The engine crankshaft is connected to a water-cooled eddy current dynamometer (Manufacturer: Saj Test Plant Pvt. Ltd.).
- Air consumption
- P- θ Measurement
- Exhaust gas measurement
- Raw biogas chromatography
- Ignition timing variation
- LPG fuel supply system
- Raw biogas fuel supply system
- Experimental Design and Procedure
- The baseline test
- The EGR Test
- SUMMARY
Raw biogas produced by biomethanization method varies in the composition of gases, which is highly influenced by surrounding environment and atmospheric conditions as discussed in chapter 1. The percentage of methane and carbon dioxide in raw biogas obtained through gas chromatography analyzer (GFM406). The test is carried out by first running the engine with petrol as fuel. The maximum braking torque is already set in the ECU software for petrol.
Design and Development of VCR Mechanism
VARIABLE COMPRESSION RATIO INTERNAL COMBUSTION ENGINE In general, the variable compression ratio has been obtained by altering the geometric
The ball screw (3) is made to rotate within the bearings fixed within the secondary cylinder head (1). During the calibration of new VCR mechanism, as per procedure mentioned in APPENDIX-A, displacement of the secondary piston is measured.
COMPONENTS OF VCR MECHANISM
- Secondary Piston
- Ball screw and ball nut
- Secondary cylinder head
- Piston rings
Important dimensions of the secondary piston to be designed are as shown in Fig. The secondary piston height (Eq-4.6) is the height of the piston depends on the spark plug length(hsp) and length of spark plug cap(hcap) , ball screw height inside the secondary piston (hscrew), ball screw nut (hthreadd).
ATTACHMENT OF NOVEL VCR MECHANISM ON THE HONDA ENGINE The VCR mechanism designed and developed for two different engines having different
- New engine head
The design of the new engine head installed on the engine equipped with the new VCR mechanism is as shown in Figure 4.16. The design of the new engine head installed on the engine equipped with the new VCR mechanism is shown in Figure 4.16.
METHOD OF ATTACHMENT OF NOVEL VCR MECHANISM ON THE LARGE VCR ENGINE
- Simultaneous use of two VCRs
(c) the new VCR mechanism fixed over engine; (d) assembly of engine head with new video recorder; (e) the space consumed on the convention engine; (f) the inner structure of the engine head which accommodates intake, exhaust valve and third secondary piston is very precisely arranged; (g) the secondary piston displacement of 5 mm inside combustion chamber; (h) the secondary piston displacement of 2 mm inside combustion chamber; (i) the secondary piston displacement of 0 mm inside combustion chamber. 4.19, for CR10 the depth 12.2 mm is available to move the secondary piston inside combustion chamber.
METHOD OF VARYING SPARK PLUG LOCATION IN LARGE VCR ENGINE
Fig.4.22 Spark plug adjustment in used spark ignition engine, (C) Spark plug in new position with 5 mm inner chamber[SP3]; (D) Spark plug in new position with 10 mm inner chamber[SP4]. Some of those spark plug sites, such as 2 mm extension inside the combustion chamber, represent SP2 (Fig 4.22-B), 5 mm travel inside is considered to be SP3 (Fig 4.22-C) and SP4 assumes 10 mm spark plug depth in space. volume (Fig 4.22-D) of the engine are as shown in Fig.4.22. This VCR lift mechanism without spark plugs can be.
Weight to size assessment of novel VCR mechanism
SUMMARY
Novel VCR Mechanism Analysis using Honda Engine
NOVEL VCR RESULTS USING HONDA ENGINE
- Effect of speed for original engine
- Effect of speed on performance parameters with novel VCR mechanism
Basic tests are initially performed on the engine at the original compression ratio of 4.8 specified by the engine manufacturer using gasoline and kerosene as fuel (Figure 5.1) at predetermined ignition timing settings. At a fixed compression ratio for a given fuel, the thermal efficiency of the brakes decreases with increasing speed (Fig. 5.1-c) and (Fig. 5.1-d).
SUMMARY
Apart from this fact, the BSFC for a given speed decreases with increasing compression ratio for gasoline up to CR equal to 5.02. As CR increases, cylinder pressure increases causing more homogeneous and complete combustion of the charge.
Studies with Alternative SI Engine Fuels
INTRODUCTION
In addition, the combustion of raw biogas is different from the combustion of gasoline fuel in positive ignition engines due to the difference in their composition and calorific value. The calorific value of crude biogas fuel is very low compared to gasoline (Ibrahim and Bari, 2009; Porpatham, 2007, Borah, 2015).
GASEOUS FUEL OPTIMUM SPARK TIMING ANALYSIS .1 Performance analysis
- Effect of ignition timing
- Effect of compression ratio
- Combustion Analysis .1 Effect of ignition timing
- Effect of compression ratio
Figure 6.3(d) Variation of mean gas temperature (MGT) with crankshaft angle for ignition timing using LPG fuel. Figure 6.4 (c) Variation of mass fraction burned (MFB) with crank angle for different ignition times using biogas crude fuel for different CRs.
GASEOUS FUELS WITH AND WITHOUT EGR
- LPG analysis without EGR
- Performance Analysis
- Combustion Analysis
- Emission Analysis (A) Effect of compression ratio
- RAW BIOGAS ANALYSIS WITHOUT EGR .1 Performance Analysis
With the increase in speed, the load on the engine is reduced, so the uneven combustion at low compression and temperature results in reduced cylinder pressure (Fig. 6.5-c). The average gas temperature is the flag of complete combustion by converting the chemical energy. to heat energy after combustion. This is due to an increase in exhaust gas temperature with an increase in speed for all CRs. The gaseous fuel has a relatively shorter combustion time.
Effect of compression ratio
Fig.6.8 (a) Cylinder pressure variation with crank angle to spark timing using raw biogas fuel for different CR. Fig.6.8 (b) NHRR variation with the crank angle of spark timing using raw biogas fuel for different CR.
Effect of speed
- Combustion Analysis A. Effect of compression ratio
- Emission Analysis
- Gaseous fuels LPG analysis in presence of EGR
- Experiments using LPG fuel for optimum spark timing with EGR
Fig.6.9 (b) Variation of combustion duration with spark timing speed using raw biogas fuel for different CR. Fig.6.9 (c) Peak MGT variation with spark timing speed using raw biogas fuel for different CR.
Effect of spark advance
- Performance Analysis in presence of EGR
However, the spark advance of 46.0 bTDC is the result of repeated tests with the engine using LPG at an EGR rate of 40% for CR10. The similar trend is also observed in CR9 and CR8, where spark timing needs to be advanced with an increase in EGR. speed (Fig.6.11-a). The nature of the BTE variation is very close to that of the braking torque at constant speed, as shown in Figure 6.11(c). The BTE at EGR0 is 26.69% with CR10 at an MBT timing of 26.0 bTDC.
Effect of EGR
- Combustion Analysis in presence of EGR
Figure 6.17 (e) Variation of MGT with crankshaft angle for different levels of raw EGR using LPG fuel for 90%. Figure 6.17 (f) Variation of MBT with crankshaft angle for different raw EGR level using LPG fuel at 50%.
Effect of EGR
Fig.6.17 (c) NHRR variation with crank angle for different untreated EGR rates using LPG fuel for 90%. Fig.6.17 (d) Variation of cylinder pressure with crank angle for various degrees of untreated EGR using LPG fuel for 50% WOT.
Effect of CR
- Emission Analysis of LPG fuel in presence of EGR
- Raw biogas fuel performance analysis with EGR
The variation of NOx with speed for different EGR rates is as shown in Fig. Further increasing the EGR rate to 20%, NOx is 75 ppm showing a 35% reduction with respect to EGR0.
Effect of EGR
- Raw biogas fuel with full and part throttle position
- SUMMARY
Thus, it reduces the combustion temperature and thus net heat released is reduced which affects the thermal efficiency of the engine (Bedoya et al., 2013; Sahoo, 2011). The effects of treated EGR for experimental conditions of. Similar findings are also reported by author Huang and Crooks, 1998. The variation of nitrogen oxide (NOx) with EGR Rate is shown in Fig.
Novel VCR SI Engine using Gaseous Fuels
INTRODUCTION
NOVEL VARIABLE SPARK PLUG LOCATION RESULTS
- Biogas performance under variable spark location concept
- Performance analysis for change in spark plug location
- Combustion Analysis for change in spark plug location
- Emission analysis for spark plug location
- LPG fuel for variable spark plug location
- Performance Analysis using LPG fuel for different spark locations
The effect of a change in spark plug location on the thermal efficiency of the engine is shown in Figure. The cylinder pressure variation with crank angle for different spark plug locations is plotted as shown in Figure 1.
COMBINED EFFECT OF NOVEL VCR AND VSPL MECHANISM .1 Biogas fuel performance under novel VCR and VSPL
- Performance Analysis
- Combustion Analysis
- Emission Analysis
- LPG fuel performance with Novel VCR added with VSPL .1 Performance Analysis
- Combustion Analysis
- Emission Analysis
Figure 7.22 presents the cylinder pressure variation with CA for different CR combined with VSPL. The burn duration was found to be minimal for CR10.48. The mean gas temperature (MGT) for the combustion of raw biogas fuel in the SI engine is shown in Figure 7.25.
GASEOUS FUEL PERFORMANCE WITH EGR UNDER INFLUENCE OF VCR AND VSPL
- Biogas run SI engine performance with EGR under influence of VCR and VSPL
- Performance Analysis
- Combustion Analysis
The variation of BTE with EGR rate for different spark locations while keeping CR10 constant is shown in Figure 7.37. This can be seen in Figure 7.38, which shows the variation of BSFC with EGR rate for different SP locations.
