8. Car pneumatic system

#### 8.1. Proposal of combustion and pneumatic hybrid vehicle

The proposal of the hybrid car driven by combustion and pneumatic engine is shown in Figure 25. During normal driving on the highway or high speed road (outside of the city), the diesel or gasoline engine drives the piston air compressor, which loads the air to the tank. The work done for the air compression is recovered during driving in the city or car acceleration. The system has possibility of filling the air tank during stop in the garage or on special filling stations. The air pressure is controlled by a regulator. Each cylinder or only chosen cylinders are equipped with the air injectors, which are controlled by ECU (electronic control unit). The air injection is applied only in the cities in special regions for the 'zero emission' mode on the distance maximum 10 km or higher and for sudden change of engine load. Some energy for driving of the compressor can be obtained from braking energy (recovering energy) during deceleration of the car. It requires some changing in the electric control system by applying of an electric motor for the piston compressor drive.

#### 8.2. Required amount of air during urban drive

For driving in the city with mean velocity v = 50 km/h, the car with mass m = 1250 kg requires power P about 4 kW. Such value of power can be obtained in the CI pneumatic engine at rotational speed above n = 3500 rpm with air consumption in one cylinder mcycle = 0.12 g/cycle.

The amount of air injection pulses during road distance l = 10 km:

$$i = \frac{60 \cdot l \cdot n}{2 \cdot \nu} = \frac{60 \cdot 10 \cdot 3500}{2 \cdot 50} = 21,000 \text{ cycles} \tag{15}$$

mair ¼ i � mcycle ¼ 21, 000 � 0:12 ¼ 2520 g ¼ 2:520 kg (16)

<sup>350</sup> � <sup>105</sup> <sup>¼</sup> <sup>0</sup>:0062 m3 <sup>¼</sup> <sup>6</sup>:2 l (17)

Modern Pneumatic and Combustion Hybrid Engines http://dx.doi.org/10.5772/intechopen.69689 155

This mass value corresponds to volume of the tank filled with air at pressure 350 bar and

The higher volume is required because during consumption of air by the engine, the air pressure in the tank decreases. The calculations carried out by the authors indicated that a required volume of the tank not greater than 30 l. The required bottle volume of air with

For driving of the car according to drive test NEDC, where mean velocity amounts only 17.8 km/h, the required bottle volumes can be less as shown above. The same bottle volumes are needed for full combustion and pneumatic engine operation, because at 3500 rpm, the engine consumes 0.12 g/cycle. Obtaining of high performance for four-cylinder engine fed by the pressurized air is possible with the total air consumption 0.48 g/cycle. At this rotational speed for only 5 min of the drive, only 4.2 kg of air is needed, which requires the bottle volume

Across the world, some universities and companies successfully manufactured different types of air powered engines (APEs). But generally limited by low working efficiency of the compressed air, low-temperature ice block and critical parts' performance, the APE is still in the development stage. Therefore, precise modelling and simulation cannot only lay a foundation

1. Two-stroke pneumatic engine enables higher values of bmep at lower air pressure (below 150 bar), but at higher air pressure, the four-stroke engine gives the same bmep but indicates lower value of SAC. A higher compression ratio in the four-stroke engine than

2. The two-stroke pneumatic engine indicates smoother work because of existence of expansion process every rotation of the crankshaft and show high power at smaller air pressure, but show also a higher value of SAC. Working parameters of such engine depend mainly on pressure of the injected air, start point and time of duration of air injection, design of

in the two-stroke engine forces of applying of higher pressure of the injected air.

the air valve, way of opening of the air valve and other control parameters.

<sup>p</sup> <sup>¼</sup> <sup>2</sup>:<sup>520</sup> � <sup>287</sup> � <sup>300</sup>

pressure 350 bar for the following road distance at a constant velocity of 50 km/h:

temperature 300 K:

1. 5 km—3.1 l 2. 10 km—6.2 l 3. 15 km—9.3 l 4. 20 km—12.4 l

about 10 l.

9. Summary

<sup>V</sup> <sup>¼</sup> mair ρair

<sup>¼</sup> mairRT

for the design of the APE but also save development costs.

The required mass of air for pneumatic driving:

Figure 25. Scheme of pneumatic system of combustion engine in the car. 1, engine; 2, clutch of compressor drive; 3, piston compressor of high pressure; 4, pressure regulator; 5, high pressure air tank; 6, air common rail; 7, air electromagnetic injector or valve; 8, air high pressure line; 9, ECU; 10, electronic control network.

$$m\_{\rm air} = i \cdot m\_{\rm cycle} = 21,000 \times 0.12 = 2520 \text{ g} = 2.520 \text{ kg} \tag{16}$$

This mass value corresponds to volume of the tank filled with air at pressure 350 bar and temperature 300 K:

$$V = \frac{m\_{air}}{\rho\_{air}} = \frac{m\_{air}RT}{p} = \frac{2.520 \cdot 287 \cdot 300}{350 \cdot 10^5} = 0.0062 \text{ m}^3 = 6.2 \text{ l} \tag{17}$$

The higher volume is required because during consumption of air by the engine, the air pressure in the tank decreases. The calculations carried out by the authors indicated that a required volume of the tank not greater than 30 l. The required bottle volume of air with pressure 350 bar for the following road distance at a constant velocity of 50 km/h:

1. 5 km—3.1 l

8. Car pneumatic system

154 Improvement Trends for Internal Combustion Engines

8.1. Proposal of combustion and pneumatic hybrid vehicle

an electric motor for the piston compressor drive.

8.2. Required amount of air during urban drive

The required mass of air for pneumatic driving:

The amount of air injection pulses during road distance l = 10 km:

<sup>i</sup> <sup>¼</sup> <sup>60</sup> � <sup>l</sup> � <sup>n</sup>

injector or valve; 8, air high pressure line; 9, ECU; 10, electronic control network.

The proposal of the hybrid car driven by combustion and pneumatic engine is shown in Figure 25. During normal driving on the highway or high speed road (outside of the city), the diesel or gasoline engine drives the piston air compressor, which loads the air to the tank. The work done for the air compression is recovered during driving in the city or car acceleration. The system has possibility of filling the air tank during stop in the garage or on special filling stations. The air pressure is controlled by a regulator. Each cylinder or only chosen cylinders are equipped with the air injectors, which are controlled by ECU (electronic control unit). The air injection is applied only in the cities in special regions for the 'zero emission' mode on the distance maximum 10 km or higher and for sudden change of engine load. Some energy for driving of the compressor can be obtained from braking energy (recovering energy) during deceleration of the car. It requires some changing in the electric control system by applying of

For driving in the city with mean velocity v = 50 km/h, the car with mass m = 1250 kg requires power P about 4 kW. Such value of power can be obtained in the CI pneumatic engine at rotational speed above n = 3500 rpm with air consumption in one cylinder mcycle = 0.12 g/cycle.

Figure 25. Scheme of pneumatic system of combustion engine in the car. 1, engine; 2, clutch of compressor drive; 3, piston compressor of high pressure; 4, pressure regulator; 5, high pressure air tank; 6, air common rail; 7, air electromagnetic

<sup>2</sup> � <sup>50</sup> <sup>¼</sup> <sup>21</sup>, 000 cycles (15)

<sup>2</sup> � <sup>ν</sup> <sup>¼</sup> <sup>60</sup> � <sup>10</sup> � <sup>3500</sup>


For driving of the car according to drive test NEDC, where mean velocity amounts only 17.8 km/h, the required bottle volumes can be less as shown above. The same bottle volumes are needed for full combustion and pneumatic engine operation, because at 3500 rpm, the engine consumes 0.12 g/cycle. Obtaining of high performance for four-cylinder engine fed by the pressurized air is possible with the total air consumption 0.48 g/cycle. At this rotational speed for only 5 min of the drive, only 4.2 kg of air is needed, which requires the bottle volume about 10 l.

#### 9. Summary

Across the world, some universities and companies successfully manufactured different types of air powered engines (APEs). But generally limited by low working efficiency of the compressed air, low-temperature ice block and critical parts' performance, the APE is still in the development stage. Therefore, precise modelling and simulation cannot only lay a foundation for the design of the APE but also save development costs.


3. Higher injection pressure of the air increases bmep as well as increases the value of SAC. The engine at full load shows a decrease of bmep and an increase of SAC with growing of rotational speed at the same injection pressure.

national subsides or financial support from industry, the research work in scientific institutions will not be possible. Now the passenger cars are equipped only with four-stroke engine. For that reason, the research work should be carried out on pneumatic four-stroke engine and hybrid pneumatic and combustion engines of the same type. A wider use of considered engines requires also an engagement of the industry. Research work under development of pneumatic and hybrid engines will be focused on further simulation and adaptation of production engines for the pneumatic feeding and testing them on laboratory stands also in dynamic modes. Correlation of simulation and experimental results will give a more precise

Modern Pneumatic and Combustion Hybrid Engines http://dx.doi.org/10.5772/intechopen.69689 157

model of the pneumatic engine.

CAI Controlled auto-ignition

CI Compression ignition SI Spark ignition CA Crank angle TDC Top dead centre BDC Bottom dead centre ATDC After top dead centre BTDC Before top dead centre WOT Wide opening throttle ECU Electronic control unit bmep Brake mean effective pressure imep Indicated mean effective pressure bsfc Brake specific fuel consumption SAC Specific air consumption AMPC Air mass per cycle Λ Air excess ratio

HCCI Homogeneous charge compression ignition

ATAC Active thermo-atmosphere combustion

Abbreviations

Author details

Wladyslaw Mitianiec

Address all correspondence to: wmitanie@usk.pk.edu.pl

Cracow University of Technology, Cracow, Poland


In this chapter, we presented only chosen aspects of clean pneumatic and hybrid combustion and pneumatic piston engines for application in transportation based on the own works. The presented experimental and theoretical works of other researchers indicate the needs of alternative and more ecological driving sources.
