This ppt contains thermal cycles if engines

1. MEASUREMENT OF
EXHAUST EMISSION

2. CO MEASUREMENT

3. CONSTRUCTION:
 Infrared source : An infrared lamp is connected .
 Sample Chamber : The gas sample flows through this chamber.
 Reference Chamber : Filled with non absorbing gas for comparison
 Detector : This detects the intensity of the filtered infrared light.
 Diaphragm : Shows the relative pressure between the sample cell
and the reference cell.

4. WORKING:
1. An infrared (IR) light source emits a broad spectrum of infrared
radiation.
2. The IR light passes through a chamber containing the gas sample.
3. Different gas molecules absorb specific wavelengths of IR
radiation, depending on their molecular structure.
4. The target gas will absorb radiation at a specific wavelength unique to it.
5. An optical filter allows only the specific wavelength absorbed by the
target gas to pass through.
6. The filtered light reaches an infrared detector that measures the intensity
of the remaining radiation.
7. The amount of IR radiation absorbed is proportional to the concentration
of the target gas in the sample.

5. NOX MEASUREMENT:

6. CONSTRUCTION:
 Converter : Converts NO2 sample gas to NO
 Crome Generator : The oxygen is ionized to O3
 Reaction Chamber : Where NO and O3 will mix and react
 Detector : Usually a Photo Multiple Tube(PMT) is used which is
sensitive to certain wavelength
 Amplifier : Amplifies the signal from PMT and converts the signal
into the concentration reading for NOx

7. WORKING:
1. The sample gas is typically drawn into the analyzer through a
sampling line.
2. The sample gas is which contains nitrogen dioxide is converted to
nitric oxide.
3. The sample gas is mixed with ozone in a reaction chamber.
4. The reaction between NO and O3 produces excited NO2*, which
emits light.
5. The intensity of the light is measured by a photodetector.
6. The amplifier converts the signal from the photodetector into a
concentration reading for NO.

8. OXYGEN/AIR-FUEL RATIO ANALYZER :

9. CONSTRUCTION:
Based on the principle of galvanometric cell:
 Cathode : Poly tetra fluoro ethylene membrane with gold coating.
 Anode : Silver coil.
 Electrolyte : Potassium chloride gel.
 The anode and cathode are dipped in KCl.

10. WORKING:
 Potential applied across electrodes-> oxygen diffuses through the
membrane-> oxygen is reduced electromagnetically->current flows.
 This current is directly proportional to partial pressure of oxygen
In the sample

11. SMOKE EMISSION:
 Controlled volume of exhaust gases is drawn through the filter paper
and change in its reflectance is related to smoke level.
0 – Clean Filter Paper.
10 – Filter paper that doesn’t reflect any light.
 The calibration of intermediate values Can be checked by placing a
perforated piece of non-reflecting paper over filter paper.

12. PARTICULATES:
 Exhaust particulates are defined materials that can be
collected on the filter paper maintain that 325K.
STEPS:
 Sample of exhaust is drawn of an cooled by dilution with air.
 The filter is weighed before and after use and mass of the
particulates is evaluated.

13. EMISSION CONTROL
METHODS

14. Thermal Converters:
 Secondary reactions occur much more readily and completely
if the temperature is high.
 Thermal converters are high-temperature chambers through which
the exhaust gas flows.
 They promote oxidation of the CO and HC which remain in the
exhaust.
CO + 1/2 O2 → CO2

15.  Consider,
Cx Hy + z O2 → xCO2 + y H2O
 The above reaction needs a temperature above 600
◦
C for at least
50 milliseconds to substantially reduce HC.
 It is therefore necessary for a thermal converter to be effective, it
should operate at a high temperature.

16. PROBLEMS IN THERMAL CONVERTER:
 In automobiles this creates two very serious problems,
1.In modern, low-profile, aerodynamic automobiles, space in the engine
compartment is very limited, and fitting in a large, usually insulated thermal
converter chamber is almost impossible.
2. Secondly, because the converter must operate above 700 ◦C to be efficient,
even if it is insulated the heat losses create a serious temperature problem in the
engine compartment.
Even though HC and CO emissions can be reduced by oxidation, NOx emissions
cannot be reduced using a thermal converter.

17. CATALYTIC CONVERTERS:
 Catalytic converters are chambers mounted in the flow system
through which the exhaust gases pass through.
 These chambers contain catalytic material, which promotes the
oxidation of the emissions contained in the exhaust flow.
 Generally, they are called three-way converters because they are
used to reduce the concentration of CO, HC, and NOx in the
exhaust.

18.  Usually a stainless steel container. Inside the container
is a porous ceramic structure through which the
exhaust gas flows.

19. RECENT DEVELOPMENT IN
CONTROLLING EMISSION

20. RECENT DEVELOPMENT/METHODS:
 Improved Combustion Technologies : Direct injection, Variable
valve timing, and Turbocharging to improve combustion efficiency.
 Emission Control Systems : Advanced exhaust gas recirculation
(EGR) systems, selective catalytic reduction (SCR), diesel particulate
filters (DPF).

21. EGR(Exhaust gas recirculation) :
 It works by recirculating a portion of an engine’s exhaust gas back
to the engine cylinders. EGR works by recirculating a portion of an
engine's exhaust gas back to the engine cylinders.
SCR(Selective catalytic reduction):
 It works by means of converting nitrogen oxides, with the aid of
a catalyst into diatomic nitrogen and water.

22. RECENT DEVELOPMENT/METHODS IN
INDIA:
 Bharat Stage VI (BS-VI) Emission Standards : India
transitioned to BS-VI emission standards nationwide in April
2020, which are equivalent to Euro 6 standards.
 FAME-India (Faster Adoption and Manufacturing of (Hybrid &)
Electric Vehicles in India): It is a government scheme launched
in 2011 as a part of the National Mission on Electric Mobility.

23. COMPARISON OF CYCLES

24. COMPARISON OF THE OTTO, DIESEL
AND DUAL CYCLES
 The important variable factors which are used as the basis for
comparison of the cycles
 Compression ratio.
 Peak Pressure…….
 Heat Addition…....
 Heat Rejection…..
 Net Work………….

25. 1. Same Compression Ratio and Heat Addition

26. .
 It is seen from the T-s diagram for the same heat input, the heat
rejection in Otto cycle (area 5146) is minimum and heat rejection in
Diesel cycle (514`6`) is maximum.
 Consequently Otto cycle has the highest work output and
efficiency.

27. 2. Same Compression Ratio and Heat Rejection

28.  QS is heat supplied in Otto cycle.
 Q’S is heat supplied in the Diesel cycle.
 From the T-s diagram it is clear that QS > Q’S
 Heat supplied in the Otto cycle is more than that of the Diesel
cycle.
 Hence, it is evident that, the efficiency of the Otto cycle is greater
than the efficiency of the Diesel cycle.

29. 3. Same Peak Pressure, Peak Temperature and
Heat Rejection

30.  It is evident from T-S Diagram that Q’S > QS
 The Diesel cycle efficiency is greater than the Otto cycle efficiency
when both engines are built to withstand the same thermal and
mechanical stresses.

31. 4. Same Maximum Pressure and Heat Input

32.  It is evident from the figure that the heat rejection for Otto
cycle (area 1564 on T-s diagram) is more than the heat
rejected in Diesel cycle (156’4’).
 Hence Diesel cycle is more efficient than Otto cycle for the
condition of same maximum pressure and heat input.
NOTE:
 Diesel cycle has higher compression ratio V1/V2 than that of
Otto cycle V1/V2 .
 Cycle which is having higher efficiency allows maximum
expansion