4.2. Experimental Results of Intake Manifold Using a Nozzle
Figure 6 shows the outputs of an automobile engine with a mileage of 30,000 km when a nozzle was used in the intake manifold. When no nozzle was used, the engine output was 93.11 kW, and the engine output at a nozzle inlet speed of 40 km/h when a 5 mm diameter nozzle was used was 93.6 kW. In addition, when the nozzle inlet speeds were 60, 80, and 100 km/h, the engine outputs were measured to be 94.6, 95.0, and 97.5 kW, respectively. When the nozzle inlet speeds were 40 and 100 km/h, the engine outputs were improved by 0.5% and 4.7%, respectively, compared to when no nozzle was used. This is because the air that flowed into the nozzle from the outside formed vortexes inside the intake manifold. The mixing degree and the oxygen density increased to provide a favorable combustion environment. In addition, when a 2.5 mm diameter nozzle was used, the engine outputs at nozzle inlet speeds of 40, 60, 80, and 100 km/h were 96.9, 97.5, 99.0, and 99.9 kW, respectively. The engine output increased by about 4.1%, 4.7%, 6.3%, and 6.7% at each speed compared to when no nozzle was used. The engine outputs of a vehicle with a mileage of 30,000 km increased by 5.4% and 2.2% on average when the nozzle diameters were 2.5 and 5 mm, respectively, and the engine output when the nozzle diameter was 2.5 mm was 3.1% higher on average than that when the nozzle diameter was 5 mm. The smaller the size of the nozzle inlet, the higher the flow rate of the air flowing into the nozzle, which resulted in an increase in the engine output due to the strong vortexes generated inside the intake manifold.
Figure 7 shows the engine outputs when a nozzle was used in the intake manifold of a vehicle with a mileage of 180,000 km. The output of the old engine for which no nozzle was used was 66.5 kW, a value about 28.5% lower than that of an engine with a mileage of 30,000 km. When a 5 mm diameter nozzle was used, the engine outputs were measured to be 67.0, 67.4, 68.6, and 68.7 kW at nozzle inlet speeds of 40, 60, 80, and 100 km/h, respectively. These values were 0.7%, 1.2%, 3.1%, and 3.3% higher in comparison to engine outputs when no nozzle was used. When a 5 mm diameter nozzle was used, the output of the old automobile engine was improved by about 3.3% in comparison to the case when no nozzle was used. In addition, when a 2.5 mm diameter nozzle was used, the engine outputs were measured to be 67.5, 73.3, 74.4, and 75.4 kW at nozzle inlet speeds of 40, 60, 80, and 100 km/h, respectively, which were improvements of 1.5%, 10.2%, 11.7%, and 13.3%, respectively, in comparison to the case when no nozzle was used. The engine output of the vehicle with a mileage of 180,000 km when a 2.5 mm diameter nozzle was used was 6.9% higher on average than that of the case when a 5 mm diameter nozzle was used. The engine outputs of the vehicles with mileages of 30,000 and 180,000 km at different nozzle inlet speeds increased by 2.2% and 2.1%, respectively, when a 5 mm diameter nozzle was used in comparison to the case when no nozzle was used, and the mileage did not have any significant effect on the degree of improvement in the engine output. On the other hand, when a 2.5 mm diameter nozzle was used, the engine output of the vehicle with a mileage of 180,000 km significantly increased when compared with that of the engine with a mileage of 30,000 km. This is because the nozzle increases the flow speed inside the intake manifold, and the condition approaches perfect combustion as the air density increases due to the inflow of a large amount of outside air. The result of the test showed that, as the effects on these improvements of engine output increased when a nozzle with a smaller diameter of 2.5 mm was used, more significant improvements in the engine output appeared.
To determine the effect of using a nozzle in an intake manifold on the exhaust gas under the engine load condition, exhaust gas was measured in the ASM2525 mode, which measures the exhaust gas of gasoline vehicles that do not exceed 5.5 tons. Although in the ASM2525 mode, exhaust gas is measured on a chassis dynamometer at a driving speed of 40 km/h with a road load of 25%, since actual driving conditions include variables other than driving speed, such as wind, in the present study, the components of the emitted exhaust gas were examined with the same nozzle inlet speeds as those of the engine output test by changing the speed from 40 km/h (11.1 m/s) to 60 km/h (16.7 m/s), 80 km/h (22.2 m/s), and 100 km/h (27.8 m/s).
Figure 8a shows the changes in HC emissions from the engine with a mileage of 30,000 km at different nozzle inlet speeds in the ASM2525 mode. The HC value of the engine with a mileage of 30,000 km was 0.01483 g/kg when no nozzle was used, and when a 5 mm diameter nozzle was used, the HC value was 0.01459 g/kg at a nozzle inlet speed of 40 km/h, showing a decrease of about 1.6%. In addition, under the same conditions, the HC values decreased to 0.01265, 0.01174, and 0.009 g/kg at nozzle inlet speeds of 60, 80, and 100 km/h, respectively, and when the nozzle inlet speed was 100 km/h, the HC value decreased by 39.3% in comparison to the case when no nozzle was used. In addition, when a 2.5 mm diameter nozzle was used, the HC values showed a decreasing trend to 0.0113, 0.0107, 0.0094, and 0.008 g/kg at nozzle inlet speeds of 40, 60, 80, and 100 km/h, respectively, and when the nozzle inlet speed was 100 km/h, the HC value decreased by 45.8% in comparison to the case when no nozzle was used. The values of HC emitted from the engine with a mileage of 30,000 km decreased by 17.1% on average when a 2.5 mm diameter nozzle was used compared to the case when a 5 mm diameter nozzle was used.
Figure 8b shows the changes in HC emissions from the engine with a mileage of 180,000 km at different nozzle inlet speeds in the ASM2525 mode. The HC value of the engine with a mileage of 180,000 km was 0.0218 g/kg when no nozzle was used, and when a 5 mm diameter nozzle was used, the HC values decreased to 0.0198, 0.0176, 0.0164, and 0.01342 g/kg at nozzle inlet speeds of 40, 60, 80, and 100 km/h, respectively. In particular, when the nozzle inlet speed was 100 km/h, HC emissions decreased by 38.4% in comparison to the case when no nozzle was used. In addition, when a 2.5 mm diameter nozzle was used, the HC values were 0.0162, 0.0146, 0.0124, and 0.0108 g/kg at nozzle inlet speeds of 40, 60, 80, and 100 km/h, respectively, and when the nozzle inlet speed was 100 km/h, HC emissions decreased by 50.5% in comparison to the case when no nozzle was used. The result of the test showed that the amount of HC emitted from the engine with a mileage of 180,000 km was 24.8% less than that in the 5 mm case on average. The values of the HC emitted from both engines with mileages of 30,000 and 180,000 km decreased more when the nozzle diameter was 2.5 mm than when it was 5 mm. In addition, when the nozzle diameter was 5 mm, the HC values emitted from engines with mileages of 30,000 and 180,000 km at different nozzle inlet speeds decreased by 39.3% and 38.4%, respectively, showing similar degrees of decrease regardless of the engine mileage. On the other hand, when the diameter of the nozzle was 2.5 mm, the values of the HC emitted from engines with mileages of 30,000 and 180,000 km at different nozzle inlet speeds decreased by 45.8% and 50.5%, respectively, showing a greater decrease in the case of the vehicle with a mileage of 180,000 km. This is because the use of the nozzle brings in more outside air and increases the flow rate of the air flowing in through the nozzle. Such effects were more significant when the diameter of the nozzle was 2.5 mm. These effects improve the combustion performance by providing a uniform combustion environment inside the cylinder through improvements in the turbulent combustion speed and the degree of mixing resulting from the high-speed flow.
Figure 9a shows the results of measuring the CO gas emitted from the engine with a mileage of 30,000 km at different nozzle inlet speeds in the ASM2525 mode. The CO emission value was 0.046% when no nozzle was used, and when a 5 mm diameter nozzle was used, the CO emission value at a nozzle inlet speed of 40 km/h decreased to 0.043%. The CO emission values were 0.036%, 0.032%, and 0.03% at nozzle inlet speeds of 60, 80, and 100 km/h, respectively, and CO emissions at a nozzle inlet speed of 100 km/h decreased by 34.8% in comparison to the case when no nozzle was used. When a 2.5 mm diameter nozzle was used, the CO emissions were 0.04%, 0.034%, 0.026%, and 0.024% at nozzle inlet speeds of 40, 60, 80, and 100 km/h, respectively, and when the nozzle inlet speed was 100 km/h, the CO emission value decreased by 47.8% in comparison to the case when no nozzle was used. The values of the CO emitted from the engine with a mileage of 30,000 km when the nozzle diameter was 2.5 mm decreased by 12.8% on average in comparison to the case when the diameter of the nozzle was 5 mm.
Figure 9b comparatively shows the changes in the CO emitted from the engine with a mileage of 180,000 km at different nozzle inlet speeds in the ASM2525 mode. The CO emission value was 0.17% when no nozzle was used, and when a 5 mm diameter nozzle was used, the CO emission value at a nozzle inlet speed of 40 km/h slightly decreased to 0.167%. The CO emission values were 0.163%, 0.14%, and 0.097% at nozzle inlet speeds of 60, 80, and 100 km/h, respectively, and CO emissions at a nozzle inlet speed of 100 km/h decreased by 42.9% in comparison to the case when no nozzle was used. When a 2.5 mm diameter nozzle was used, the CO emissions were 0.15%, 0.1%, 0.093%, and 0.073% at nozzle inlet speeds of 40, 60, 80, and 100 km/h, respectively, and when the nozzle inlet speed was 100 km/h, the CO emission value decreased by 57.1% in comparison to the case when no nozzle was used. This result is similar to that of the HC test, and the values of the CO emitted from the nozzle with a smaller diameter of 2.5 mm decreased in comparison to the case when the diameter of the nozzle was 5 mm. In addition, when a 5 mm diameter nozzle was used, the values of the CO emitted from the engines with mileages of 30,000 and 180,000 km decreased by 34.8% and 42.9%, respectively, and when the nozzle diameter was 2.5 mm, the decreases were 47.8% and 57.1%, respectively, which shows that the CO reduction effect was greater in the old engine with a mileage of 180,000 km. This is because, similar to the result of the HC test, the airflow speed is higher in the nozzle with a smaller diameter of 2.5 mm, which improves the degree of mixing to form a uniform combustion environment and increase the oxygen concentration, thereby improving the combustion performance.
Figure 10a shows changes in the NO
x emitted from the engine with a mileage of 30,000 km in accordance with changes in nozzle inlet speeds in the ASM2525 mode. The NO
x emission level was 0.0598 g/kg when no nozzle was used, and when a 5 mm diameter nozzle was used, NO
x emissions at a nozzle inlet speed of 40 km/h decreased by 13.4% to 0.0518 g/kg. The NO
x emission values were 0.0444, 0.0388, and 0.0276 g/kg at nozzle inlet speeds of 60, 80, and 100 km/h, respectively, and NO
x emissions at a nozzle inlet speed of 100 km/h decreased by 53.8% in comparison to the case when no nozzle was used. In addition, when a 2.5 mm diameter nozzle was used, the NO
x emissions were 0.0478, 0.0334, 0.0242, and 0.0168 g/kg at nozzle inlet speeds of 40, 60, 80, and 100 km/h, respectively, and when the nozzle inlet speed was 100 km/h, the NO
x emission value decreased by 71.9% in comparison to the case when no nozzle was used. The results of the test showed that the values of the NO
x emitted from the engine with a mileage of 30,000 km when the nozzle diameter was 2.5 mm decreased by 27.7% on average in comparison to the case when the diameter of the nozzle was 5 mm.
Figure 10b shows the changes in the NO
x emitted from the engine with a mileage of 180,000 km at different nozzle inlet speeds in the ASM2525 mode. The NO
x emission value was 0.1477 g/kg when no nozzle was used, and when a 5 mm diameter nozzle was used, the NO
x emission value at the nozzle inlet speed of 40 km/h decreased by 0.005 to 0.1403 g/kg. The NO
x emissions were 0.13, 0.1193, and 0.1077 g/kg at nozzle inlet speeds of 60, 80, and 100 km/h, respectively, and NO
x emissions at the nozzle inlet speed of 100 km/h decreased by 27.1% in comparison to the case when no nozzle was used. In addition, when a 2.5 mm diameter nozzle was used, the NO
x emissions were 0.1333, 0.1217, 0.1043, and 0.0927 g/kg at nozzle inlet speeds of 40, 60, 80, and 100 km/h, respectively, and when the nozzle inlet speed was 100 km/h, NO
x emissions decreased by 37.2% in comparison to the case when no nozzle was used. In both engines with mileages of 30,000 and 180,000 km, the NO
x values when the nozzle diameter was 2.5 mm decreased by 18.4% on average in comparison to the case when the nozzle diameter was 5 mm, which shows that the use of a nozzle with a smaller diameter had the effect of reducing NO
x. In addition, when the nozzle diameter was 5 mm, the NO
x emitted from the engines with a mileage of 30,000 and 180,000 km at different nozzle inlet speeds decreased by 53.8% and 27.1%, respectively, which shows that the NO
x reduction effect was greater in the engine with a mileage of 30,000 km. In addition, when a 2.5 mm diameter nozzle was used, the NO
x emitted from the engines with mileages of 30,000 and 180,000 km at different nozzle inlet speeds decreased by 71.9% and 37.2%, respectively, which shows that the NO
x reduction effect was greater in the engine with a mileage of 30,000 km. In general, NO
x values show an increasing trend when the HC and CO values decrease in an engine depending on the driving condition, and, in the present study, HC, CO, and NO
x all showed decreasing trends. This is because the generation of NO
x is predominantly affected by the temperature inside the engine, and the use of a nozzle has the effect of reducing the combustion temperature by bringing in low-temperature outside air.
The present study confirms that the application of a nozzle with a simple structure to introduce external air to the intake manifold improves engine output and effectively reduces exhaust gases (HC, CO, and NOx). In addition, the greater the mileage of the vehicle, the greater the effect. Thus, the use of nozzles in old vehicles can increase engine performance, reduce harmful emissions, and improve vehicle life.