Question Topics :
All Questions
Answer: The course does not deal with engine testing and performance. It deals with the Engine Emissions in depth. You may refer any book on IC engines on this topic e.g., Fergusson and Kirkpatrick, Ganesan, Mathur and Sharma
Answer: Sorry, this course is not designed for meeting needs of GATE exam. Pl see the GATE syllabus and see if you find something useful.
Answer: Smoke results due to mixture being non-uniform and some pockets of the mixture near fuel spray are very rich. In these fuel-rich pockets smoke is formed. In SI engines the mixture is nearly uniform and close to stoichiometric fuel-air ratio, hence no smoke formation.
Answer: Theoritical cycles, yes. Pl refer any standard thermodynamics book. Diesel engine operates at a high CR and lean mixtures . Hence, are more fuel efficient.
Answer: It is a very complex question. Duty cycle of the engine is to be known that will tell the exhaust gas temperature and the pollutant concentration. The guidelines are that for about overall conversion of 85 to 90% size of the converter is about equal to the engine swept volume with precious metal loading of about 1g/litre of catalyst volume. These are baSED ON THE MONOLITH CATALYSTS HAVING 400 TO 600 CPSI.
Answer: During 1990s Cummins of the USA did lot of work on the subject. You can find it in SAE transactions which are available in IIT Madras, IISc Banglore etc. Surely the LHR engine can be simulated for study of interactions of various parameters and their effect on engine performance and emissions.
Answer: Any system that uses hydraulically operated and electrical sensors and actuators for functioning of the system would be called electro-hydraulic system
Answer: Read a standard textbook on IC engines. It is pre-requisite to get benefitted by this course
Answer: The dual-cycle, Otto cycle or Diesel cycle are only the idealized forms of sequence of processes occuring in the working of an IC engine. Heat addition neither takes place at constant volume nor at constant pressure. Both the volume and pressure are changing when the fuel is being burnt and heat is being added to the gases in the cylinder. Using these theoretically idealized processes we may try to do a simple analysis of the engine cycle.These cycles are the first mathematical expression or mathematical models of the IC engines. Now more realistic mathematical models for analysis of real engine cycle are available.
Answer: The answer is Diesel as it operates with at least 40 % excess air, i.e., per unit mass of air inducted less amount of fuel may be burnt in a diesel engine than the petrol engine. I think before getting full benefits of this course one need to know about IC engines. Pick up any standard text book on the subject and study.
Answer: If you go through the course you would get the answer. 3-Way name has been given to the converter as here all the three pollutants viz., CO, HC and NOx can be controlled simultaneously. One may call the oxidation catalytic converter where CO and HC are oxidised at the same time simultaneously, as a 2-way catalyst. But , it is normally called as the oxidation catalyst .
Answer: The student is advised to study any standard text book on IC Engines. In brief, in the conventional petrol engines, a homogeneous mixture of fuel and air is burned. Hence, the fuel should have a low boiling point to evaporate easily and form a homogeneous mixture with air quickly before spark is used to ignite it in the engine. Diesel fuel has a much higher boiling range (170 -380 C) compared to petrol ( 40 -200 C). Second important characteristic of petrol is a high octane number necessary to prevent knocking combustion. A high octane number of fuel is necessary so that a high engine compression ratio is employed for a high engine thermal efficiency. It may be noted that this type of knocking phenomenon is important when a homogeneous fuel-air mixture is being burned by a positive source of ignition like spark. Diesel has a very low octane number. Diesel combstion is a non-homogeneous combustion started by compression ignition and petrol engine type of knocking combustion is not a
Answer: 4-stroke engine has many more components like valves, camshaft, rockers etc which a 2-stroke engine is not required to have. Secondly, 4-stroke engine has one power stroke for every 2 engine revolutions compareed to one power stroke for every engone revolution in a 2-stroke engoine It means that for the same power, a 4-stroke engine has a much higher swept volume/ size compared to a 2-stroke engine and hence a higher weight.
Answer: You are advised to read any standards IC engine text book. In short reply is given here.As the engine speed increases engine friction also increases resulting in a lower brake thermal efficincy at high engine speeds. At lower motorcycle speeds the bike operates at a lower gear ratio and hence the engine runs at a higher speed. Interaction of several parameters such as engine friction, volumetric efficiency and combustion efficiency results in best engine thermal efficiency in middle range of engine speed and hence the best economy range corresponds to the range shown on your bike.
Answer: PLease read some book on engineeering thermodynamics.
Answer: Any engine modification that would reduce combustion temperatures and also reduce oxygen content in the combustion zone will tend to reduce formation of NOx. Retarding of spark timing (SI engine)or retarding of injection timing (CI Engines) reduces combustion temperatures and hence are used to reduce NOx emissions. In SI engines, reduction of compression ratio also lowers NOx. However, CR should not be reduced too much otherwise it will result in poor fuel economy. In SI engines charge stratification is employed to reduce NOx formation. In addition to injection timing retardation in CI engines, any parameter that will reduce ignition delay would generally result in reduction of NOx emissions as the peak combustion pressure and temperatures would reduce with decrease in ignition delay. Injection rate shaping and control also can help. A high CR, turbocharging reduce ignition delay. You are advised to study the other modules of the course and you will get more details on this.
Answer: This course is designed for the readers who have taken a basic course on IC Engines. Please refer to any text book on IC Engines e.g., Ganesan,Mathur and RP Sharma etc. for your question.
Answer: Knocking is due to autoignition of fuel-air mixture resulting in very high rate of pressure rise and pressure oscillations in the combustion chamber, In SI engine this happens when the last fraction of mixture called as endgas autoignites before the flame reaches it. In CI engines,the combustion itself starts because of autoignition of fuel. If too much fuel autoignites right when the combustion starts high rates of oressure rise result causing noisy combustion in CI engines. This is diesel knock. The cause of both types of knock is autoignition of fuel. The difference is its timing during cycle . Also in SI engine it is not desirable while in CI engines it is in a way part of usual combustion process.
Answer: In large low speed 2-stroke diesel engines, intake ports but exhaust valves are used. For small , high speed 2-stroke engines time available for valve opening/closing is too small. Hence, use of valves is not practical. Also uset of valves and their driving mechanism increases cost and complexity of engine,
Answer: Look in NPTEL. Otherwise, there are many text books, Refer those books.
Answer: For IC Engines, IC Engine Fundamentals by J B Heywood, McGraw Hill
Answer: Recovery of any waste energy in principle would improve fuel efficiency. Go ahead invent the storage system and use it wherever heat is required for heating or preheating.
Answer: search internet
Answer: This question does not relate to this course. Take a good book of automobile engineering. Find the road horse power requirement of vehicle as a function of vehicle speed. From the performance characteristics of the engine ( engine power -speed - SFC charts), you can calculate from engine SFC the vehicle FE. If you know SFC of engine and road horse power the relation you can easily work out.
Answer: Yes, an optimum design has to be worked out for acceptable performance of turbocharger and adequate amount of EGR,
Answer: The main requirements are: (i) Rapid fuel-air mixing (ii) Prevent impingement of injection spray on combustion chamber walls (ii) High enough compression ration for easy engine cold start (iii) Compact to have low surface/volume ratio to reduce heat loss (iv)low engine emissions (iv) High engine efficiency. An optimim combination of injection configuration and air motion is employed. Swirl and squish type of air motion are generated through design of intake valve port and combustion chamber. High engine speeds require a more intensive air motion i.e., high air swirl and squish. Hence high speed engine combustion chamber bowl in pistion is having a smaller diameter and more depth. For more details read the references given in the course e.g., IC Engines : Combustion and Emissions by B P Pundir, IC Engine Fundamentals by J. B. Heywood.
Answer: Question is not clear.I have not talked about any such test in the course.
Answer: Do you mean distributor type of injection pumps? Yes, these were used in passenger cars until relatively low injection pressures of up to 500 bars were used. Now these are not used as pressures of above 1000 bars are mostly used. The common rail (CRDI) injection systems are becoming as standard FI for diesel engines..
Answer: Exhaust gas contains alrge amonts of triatomic gases like CO2 and H2O which have higher value of Cp than O2 and N2 (main components of air)
