The document discusses the environmental impact of automobile fuel consumption and promotes the use of renewable energy sources like solar, wind, and hydraulic energy. It specifically analyzes the efficiency of an air-powered car using high-pressure compressed air, detailing thermodynamic processes and calculations of energy input and output. The final assessment reveals that the thermodynamic efficiency of the air-powered car is approximately 40%.

1. © Mujeeb-UR-Rahman
Chemical Engineering Department
Chemical Engineering
Thermodynamics

2. MEHRAN UNIVERSITY OF ENGINEERING AND TECHNOLOGY JAMSHORO, PAKISTAN
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Director: Prof. Dr. Muhammad
Shuaib Shaikh
Presenter:
Mujeeb-UR-Rahman 17CH106
Abstract
Nowadays, automobiles consume a large number of fuels. However, the consumption of
fuels is more effective for environment, such as global warming, human life disturbed,
ozone layer depletion and fog and haze, which protects us form direct Sun raises effect
on skin and particulate matter. To avoid such environmental issues, renewable energy
such as solar energy, hydraulic energy, and wind energy has been applied to energy
consumption engines. More energy consumptions the more energy has to create as for
required well. To save the environment from such issues of energy expenditure was
emphasized. The more hazard for environment are the automobiles moving on roads
which exhaust dangerous gases.
So for, the new energy automobiles, such as electric vehicles, hybrid electric vehicles,
pneumatic power vehicles, will be applied. This can effect increase in efficiency more
input consumes into output will low the energy sink exhaust, which will be the less effect
the environment then now as they effects. The electric car exhaust zero-pollution not fully
zero.

3. © Mujeeb-UR-Rahman
Complex Engineering Problem:
An air-poweredcar is powered using high pressure compressed air stored in a tank.
The pressurized tank is connected to air-powered engine. The volume of tank is 0.3m3,
and the initial temperature and pressure of air inside the tank is 20oC and 30MPa,
respectively. Analyze the efficiency of the air-powered Car.

4. © Mujeeb-UR-Rahman
ThermodynamicProcess
For the CAE, the high pressure air at normal temperature could supply the driving force.
The reason of the shaft work is the impulse action and the dynamic action of the high
compressed air.Thermodynamically, the process is considered to the course of the piston-
type air compressor. Intake process are considered constant pressure process, and
expansion process is considered adiabatic process.
The input energy is equal to the amount of energy required to fill the tank with
compressed air. Let’s assume an ideal isothermal (constant temperature) process where
the pressurized sir being pumped into the tank is kept as close as possible to the ambient
air temperature. This minimized the pumping energy required the air into tank. This is
achieved by cooling the pressurized air before it enters the tank. If the air is not
simultaneously cooled as it pumped into the tank it will reach a very high temperature,
which will require a greater pumping energy then cooling air. Air heating due to
compression is a fundamental property of gases (which can be modeled here as ideal gas,
where PV = mRT). If you compress air into a smaller volume, it will tend to heat up.
W1 = p1 (V2 – V1)
Where Wout is the theatrical work done p1 and V2 represent the supply pressure and
volume, respectively, at which the air push down the piston downward movement, V1 is
the clearance of cylinder.
EfficiencyAnalyses
The CAE can be appliedto transform compressed air energy into mechanical energy. The
energy efficiency of CAE can be defined as two approaches .One is the ratioof the output
shaft energy to the input energy of the CAE.
E =
𝑂𝑢𝑡 𝑝𝑢𝑡
𝐼𝑛𝑝𝑢𝑡
× 100
With isothermal pumping of the air into the tank, the (ideal) input energy is, Ein =
P1V1ln(P2/P1), where P1 and V1 is the initial (atmospheric) pressure and initial volume of
the air, respectively, and P2 is the pressure of the air after it's pumped into the tank. From
the ideal gas equation given above, and given an isothermal process, P1V1 = P2V2, where
V2 is the volume of the tank. We can then calculate V1 = 90 m3.

5. MEHRAN UNIVERSITY OF ENGINEERING AND TECHNOLOGY JAMSHORO, PAKISTAN
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Substituting P1 = 0.1 MPa (atmospheric pressure), P2 = 30 MPa, and V1= 90 m3 into the
equation above we calculate Ein = 51.3 MJ (mega joules).
Now, in reality the air heats up somewhat between cooling stages so this "forces" the
compressor to use more than 51.3 MJ to pump air into the tank. A realistic efficiency
factor for multi-stage cooling is 48%. So the actual input energy is Ein = 51.3/0.48 = 107
MJ.
Once in the tank, the air will cool until its temperature reaches the ambient outdoor
temperature. The energy of the air at this point will be 51.3 MJ.
Note that 51.3 MJ is greater than the actual energy that will be extracted from the tank to
power the car. This is due to thermodynamic (physical) losses (a form of thermodynamic
irreversibility).To keep these losses as low as possible it is necessary that the air is heated
up as it expands inside the engine, after exiting the tank. Since air has a tendency to cool
down upon expanding it is best to keep its temperature as high as possible using the
ambient air as a heating source. In other words, we wish to maintain the (expanding) air
temperature as close as possible to its temperature inside the tank. If this could be
accomplished perfectly then the extracted energy will exactly equal 51.3 MJ. But in
realitythis is not the case. The air will unavoidably cool, so to help counteract this, multi -
stage heating is used to heat the expanding air as it exits the tank and goes into the engine.
So the actual output energy is Eout= 51.3×0.84 = 43 MJ.
Therefore, the thermodynamic efficiency of the Air Car is 100× (Eout/Ein) = 40%.