Basics of I.C. Engines
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Questions and Answers

What type of engine uses the combustion of air and fuel inside the cylinder as the direct motive force?

  • Reciprocating engine (correct)
  • External combustion engine
  • Gas turbine
  • Steam engine
  • Which type of engine transfers the products of combustion to a second fluid, which is the working fluid of the cycle?

  • Steam engine
  • Diesel engine
  • Gas engine
  • Closed cycle gas turbine (correct)
  • What type of engine employs the heat of combustion in an external furnace transferred to a gas, usually air, as the working fluid of the cycle?

  • Reciprocating engine
  • Alcohol engine
  • Four-stroke engine
  • Rotary engine (correct)
  • Which type of engine is classified based on the number of strokes per cycle as four-stroke and two-stroke?

    <p>Reciprocating engine</p> Signup and view all the answers

    In which type of engine is the heat of combustion employed to generate steam for useful work?

    <p>Steam engine</p> Signup and view all the answers

    Which type of engine uses a closed cycle system where heat is transferred to gas, usually air, which acts as the working fluid?

    <p>External combustion engine</p> Signup and view all the answers

    What is a common characteristic of two-stroke engines?

    <p>Contains ports arrangement</p> Signup and view all the answers

    In which engines is a spark plug used for ignition?

    <p>Gasoline engines</p> Signup and view all the answers

    What is a distinguishing feature of diesel engines compared to gasoline engines?

    <p>Lower self-ignition temperature</p> Signup and view all the answers

    Which type of cycle is commonly used in SI engines?

    <p>Otto cycle</p> Signup and view all the answers

    What is the compression ratio range for gasoline engines?

    <p>6 to 10.5</p> Signup and view all the answers

    Why is the air-cycle approximation used in internal combustion engine analysis?

    <p>To simplify complex engine problems</p> Signup and view all the answers

    What type of heat addition does the Otto Cycle operate with?

    <p>Isochoric heat addition</p> Signup and view all the answers

    What characteristic leads to the higher maximum efficiency in CI engines compared to SI engines?

    <p>Higher compression ratio</p> Signup and view all the answers

    What is the purpose of a flywheel in an internal combustion engine?

    <p>To maintain constant speed by storing excess energy</p> Signup and view all the answers

    What is the function of a crankshaft in an internal combustion engine?

    <p>To convert reciprocating motion of the piston into rotary motion</p> Signup and view all the answers

    What is the material commonly used for manufacturing connecting rods in internal combustion engines?

    <p>Aluminium alloys</p> Signup and view all the answers

    What defines the top dead centre (TDC) in an internal combustion engine?

    <p>When the piston is farthest from the crankshaft</p> Signup and view all the answers

    What does the compression ratio of an engine refer to?

    <p>The ratio of swept volume to clearance volume</p> Signup and view all the answers

    What is the primary difference between a four-stroke and a two-stroke engine?

    <p>Number of power strokes per revolution</p> Signup and view all the answers

    Which term describes the nominal inner diameter of the working cylinder?

    <p>Cylinder bore</p> Signup and view all the answers

    What role does the crank case play in an internal combustion engine?

    <p>Serves as a sump for lubricating oil</p> Signup and view all the answers

    'Swept volume' in an internal combustion engine refers to:

    <p>&quot;Nominal volume generated by the working piston&quot;</p> Signup and view all the answers

    What is the expansion ratio also known as in the Otto cycle?

    <p>Pressure ratio</p> Signup and view all the answers

    In the air standard efficiency formula for an Otto cycle, what does the term W represent?

    <p>Work done by the system</p> Signup and view all the answers

    What is the characteristic gas constant in terms of specific heat values?

    <p>R = Cp - Cv</p> Signup and view all the answers

    What happens to the specific heat values for air as temperature increases above 1500 K?

    <p>Increases much more rapidly</p> Signup and view all the answers

    What is the reason behind the increase in specific heat with temperature?

    <p>Increase in energy required for motion of atoms within molecules</p> Signup and view all the answers

    What is the value of the difference between Cp and Cv for air at 300 K?

    <p>-0.288 kJ/kg K</p> Signup and view all the answers

    What is the primary difference between an external combustion engine and an internal combustion engine?

    <p>The combustion of air-fuel happens inside the engine cylinder in an internal combustion engine.</p> Signup and view all the answers

    What is a key advantage of internal combustion engines over external combustion engines?

    <p>Lower requirement of water for dissipation of energy</p> Signup and view all the answers

    What is the primary function of a piston in a reciprocating IC engine?

    <p>To convert reciprocating motion into circular motion</p> Signup and view all the answers

    What material is commonly used to make pistons in IC engines due to its heat conducting property?

    <p>Aluminium alloy</p> Signup and view all the answers

    Which component of the IC engine provides an air-tight seal to prevent leakage of burnt gases into the lower portion?

    <p>Piston rings</p> Signup and view all the answers

    In a multi-cylinder engine, how are cylinders typically cast?

    <p>In one block known as a cylinder block</p> Signup and view all the answers

    What is the role of a cylinder head in an IC engine?

    <p>To cover the top end of the cylinder and house components like valves or injectors</p> Signup and view all the answers

    What type of rings are housed in circumferential grooves on the outer surface of a piston in an IC engine?

    <p>Compression and exhaust rings</p> Signup and view all the answers

    What converts the reciprocating motion of the piston into circular motion of the crankshaft in an IC engine?

    <p>'U' shaped connecting rod</p> Signup and view all the answers

    What is a significant difference between compression ignition engines and spark ignition engines?

    <p>Compression ignition engines rely on fuel injected into the cylinder just before ignition.</p> Signup and view all the answers

    What does the thermal efficiency of the Otto cycle depend on?

    <p>Compression ratio and ratio of specific heats</p> Signup and view all the answers

    In the Otto cycle, when isentropic processes 1?2 and 3?4 are considered, what is the relationship between T4/T3 and T1/T2?

    <p>T4/T3 = T1/T2</p> Signup and view all the answers

    What factor can increase the efficiency of the Otto cycle according to the given text?

    <p>Increasing the compression ratio</p> Signup and view all the answers

    Which parameter has no direct impact on the thermal efficiency of the Otto cycle based on the information provided?

    <p>Pressure ratio</p> Signup and view all the answers

    What is the expression for the net work output in an Otto cycle as per the given equations?

    <p>(p3V3 - p4V4/x - 1) - (p2V2 - p1V1/x - 1)</p> Signup and view all the answers

    What does the thermal efficiency of the Otto cycle primarily rely on?

    <p>Temperature differences at different points in the cycle</p> Signup and view all the answers

    What is the relationship between T2 and T1 in the process 1?2 with constant specific heats?

    <p>T2 = T1(v1/v2)^(-1)</p> Signup and view all the answers

    What is the consequence of expansion at constant specific heats instead of variable specific heat in the process 3' 4''?

    <p>T4'' is higher than T4'</p> Signup and view all the answers

    What happens to the maximum temperature and pressure in internal combustion engines due to heat transfer to the cooling medium?

    <p>Maximum temperature and pressure decrease</p> Signup and view all the answers

    At what temperature does dissociation of CO2 into CO and O2 start occurring?

    <p>Around 1000°C</p> Signup and view all the answers

    What inhibits the dissociation of CO2 into CO and O2 in gases?

    <p>Presence of CO and O2</p> Signup and view all the answers

    What chemical process occurs when dissociation takes place?

    <p>Disintegration</p> Signup and view all the answers

    How does dissociation affect the maximum temperature in exhaust gas mixtures?

    <p>Reduces it</p> Signup and view all the answers

    Which mixture ratio results in maximum brake power output according to the text?

    <p>Stoichiometric mixture</p> Signup and view all the answers

    What effect does dissociation have on the p-V diagram of the Otto cycle?

    <p>Reduces the maximum pressure reached</p> Signup and view all the answers

    What is the main reason for dissociation effects being less pronounced in a Compression Ignition (CI) engine compared to a Spark Ignition (SI) engine?

    <p>Heterogeneous mixture presence</p> Signup and view all the answers

    How do friction losses affect engine efficiency?

    <p>Cause a loss of energy</p> Signup and view all the answers

    Which of the following is a common type of loss in Internal Combustion (IC) engines that contributes to environmental pollution?

    <p>Incomplete Combustion</p> Signup and view all the answers

    What happens during process 2?3 in the Otto cycle?

    <p>Heat supplied reversibly at constant volume</p> Signup and view all the answers

    Which loss is caused by combustion gases leaking past the piston rings into the crankcase?

    <p>Blowby Losses</p> Signup and view all the answers

    How do accessory losses impact engine performance?

    <p>Contribute to additional losses</p> Signup and view all the answers

    What is the primary purpose of isentropic compression in the Otto cycle?

    <p>Compression of air</p> Signup and view all the answers

    Why is efficient heat management crucial in Internal Combustion (IC) engines?

    <p>To minimize heat losses</p> Signup and view all the answers

    How does incomplete combustion affect Internal Combustion (IC) engines?

    <p>Results in unburned hydrocarbons and carbon monoxide emission</p> Signup and view all the answers

    What effect does reassociation have on the expansion process in an Internal Combustion (IC) engine?

    <p>Results in a different path of expansion</p> Signup and view all the answers

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