a review - Acta Technica Corviniensis

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ACTA TECHNICA CORVINIENSIS – Bulletin of Engineering 1 9 0.9 8.5 Volumetric Efficiency (Fraction) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 48 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 Engine Speed (RPM) test model Figure 5. Values of volumetric efficiency in gasoline engine at various speeds IMEP [bar] 8 7.5 7 6.5 6 Model Test 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 Engine Speed [RPM] Figure 8. Indicated mean effective pressure for CNG engine at various speeds 10 46 9.5 cylinder pressure [bar] 44 42 40 38 36 IMEP [bar] 9 8.5 8 34 7.5 32 30 Model Test 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 7 Model Test 1500 2500 3500 4500 5500 6500 Engine Speed [RPM] Engine Speed [RPM] Figure 6. Values for maximum pressure cylinder CNG engine at various speeds Figure 9. The mean effective pressure for the gasoline engine at various speeds 105 60 100 55 95 50 90 Pressure [Bar] 45 40 35 Torque [N.M] 85 80 75 70 30 65 Test Model 25 20 Model Test 1500 2500 3500 4500 5500 6500 Engine Speed [RPM] Figure 7. Values for maximum pressure cylinder gasoline engine at various speeds Heat transfer model in cylinder Woschni model is used to calculate the heat transfer rate from the cylinder. With the energy release, some of the air-fuel mixture into energy used and the amount of additional heat is wasted. To ensure the accuracy of calculating the heat transfer rate and the strain energy release rate must be calculated at and this was done with great care in the previous section. Therefore, the pressure inside the cylinder to model and test moments, mean effective pressure for the test model must be equal. Figures (8) and (9) for both CNG and gasoline hybrid engine have indicated them. Torque [N.M] 60 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 Engine Speed [RPM] Figure 10. CNG engine brake torque at various speeds 105 100 95 90 85 80 75 70 65 60 Test Model 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 Engine Speed [RPM] Figure 11. Gasoline engine brake torque at various speeds 104 2013. Fascicule 2 [April–June]
ACTA TECHNICA CORVINIENSIS – Bulletin of Engineering After ensuring the same indicatedr mean effective pressure for test and model, if the mechanical efficiency of the test and model are consistent with each other, then be concluded that the heat transfer rate is modeled correctly. Moreover, figures (10) and (11) are shown the brake torque model and test for both CNG and gasoline engines and fuel-burning natural gas. Select the appropriate turbocharger After calibrating the exact model, in the figures (4) and (5) is seen to be the volumetric efficiency of the CNG engine is lower that gasoline engine and therefore we should compensate the loss by a technique and also increase the volumetric efficiency as possible and even for this reason, the turbocharger is used to compensate this loss and increasing the volumetric efficiency. Most of overfeeding is done in the engines made and the purpose overfeeding is to increase the power and torque versus speed range. The problem of the overfeeding engine is to achieve the maximum output power, and in combination with maximum strength, improving the low-speed torque is reduced to postpone Turbo Lag [8]. To achieve this goal, careful planning and consideration of turbine engine components are required harmonized. We should change some of the design parameters to converting XU-7 natural breathing engine to an overfeeding engine, of course some parameters such as engine geometry and runner do not changed and should enter the codeand no optimization on any of these parameters. These changes will be discussed. In general, the following points should be noted for the choice of a turbocharged engine: A) The selected turbocharger engine torque for different speeds increased to the desired value. B) The turbocharger is chosen as small as possible. As turbocharger is smaller so its launching is faster, and increasing or decreasing its speed will be faster with high or low load , as a result the delay will be lower in the performance turbocharger (turbo lag). Inertia turbocharger is much smaller than it would be there and a further delay in performance will be resolved. C) much less of a turbocharger to the combustion gases is used to increase the torque, the better. However, the turbine control valve (waste gate) will open more and more gases are discharged to the atmosphere. Or in other words, as the combustion gases flow through the turbine is less, so turbocharger will have a higher response rate. D) the turbocharger engine must be carefully selected that the selected compressor turbocharger and turbine will work with high efficiency and all functional parts and engine turbine and compressor are working in the area. This points do not reach to the surge line. E) the maximum turbocharger shall not exceed the maximum speed as the manufacturer made. [15] Some tips for choosing the turbocharger to the engine XU-7 has been taken into consideration. Two turbocharger engines XU-7 is considered to be there and the analysis results will be shown that which of the turbocharger is suitable for the engine and the turbochargers are mady by the Company IHIthat the characteristics of the turbine and its compressor are presented in Table 3. Table 3: turbine and compressor for both turbochargers Turbine Compressor turbocharger b RHF4HTTW14P12 f4c109a turbocharger a RHF4HTTW14P12 f4c93f Some engine design parameters such as timing of inputs and outputs valves, valve lift curve, and ignition timing and etc have been changed in conversion of a normal breathing engine to an overfeeding engine. Thus, the first of these changes and then overfeeding is appropriate.The optimum choice of two turbochargers must be found that would allow the engine to increase torque. The results for both turbocharger models (b) and (a) is shown in figure (12). Brake Torque [N.M] 180 160 140 120 100 80 60 40 20 0 Turbocharger-b Turbocharger-a 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 Engine Speed [RPM] Figure 12. Torque values of the overfeeding engine with two turbochargers at full load state As the two diagrams show that the turbocharger (a) can be a limit engine torque; although in the diagram (28), the turbocharger (b) can not provide the desired torque. So the first reason for being better turbocharger (a) of the turbocharger (b) to provide the desired torque. Generally due to the exhaust of combustion energy is low at low speeds thus, selecting the proper turbocharger and engine torque at low speeds, in order to increase the torque is very important; compressor efficiency model has been calculated in both turbochargers (a) and (b). Efficiency [%] 80 75 70 65 60 55 50 45 40 35 30 Compressor a Compressor b 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 Engine Speed [RPM] Figure 13. Comparing the compressor efficiency for two turbochargers at various speeds and at full load state The efficiency for both compressors at different speeds in is shown in figure (13). As the digaram showed the turbocharger compressor efficiency (a) is 2013. Fascicule 2 [April–June] 105
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ACTA TECHNICA CORVINIENSIS - BULLET
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ACTA TECHNICA CORVINIENSIS - Bullet
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offset or angled extensions from su
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There are two process trees at crea
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ROLE OF METAMODELING Detailed resea
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economy, packaging and knock limita
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satisfy constraints. This technique
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metamodel driven conceptual design
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[90.] Jian Deng, 2006, Structural r
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The wire movement is reported to th
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Figure 5 presents the cross-recepta
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RESULTS AND DISCUSSION. Electrochem
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REFERENCES [1.] Velisek, J.; Cejpek
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October 2008 (6.200 BAR) Figure 1.
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Figure 5. High pressure connection
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Table 2: Ranges of variables select
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which solves the problem of mobile
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Page 56 and 57: CONCLUSIONS Based on the discussed
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