Internal Combustion Engine Theory Quiz
45 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the indicated horsepower (I.P) calculated in kilowatts?

  • 10.78 kw
  • 17.07 kw (correct)
  • 52.06 kw
  • 14.22 kw
  • What is the formula used to calculate brake power (B.P)?

  • B.P = T × ω (correct)
  • B.P = Q.f / Q.w
  • B.P = m.f × C.V
  • B.P = I.P - Q.st
  • How much heat is lost to the cooling water (Q.w) in kilowatts?

  • 853.4 kj/min
  • 14.22 kw (correct)
  • 52.06 kw
  • 10.78 kw
  • What is the total mass of dry exhaust gases (in kg/sec)?

    <p>0.03678 kg/sec</p> Signup and view all the answers

    What is the heat lost to radiation in kilowatts?

    <p>9.31 kw</p> Signup and view all the answers

    What is the purpose of the intake stroke in a four-stroke Otto cycle engine?

    <p>To draw the fuel-air mixture into the cylinder</p> Signup and view all the answers

    Who is considered the inventor of the modern internal combustion engine?

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

    In the Otto cycle, what initiates combustion in the cylinder?

    <p>A spark from the spark plug</p> Signup and view all the answers

    During which stroke of the Diesel cycle is the fuel injected into the cylinder?

    <p>Compression stroke</p> Signup and view all the answers

    What is a potential problem that can occur if the initial pressure in an Otto cycle engine is too high?

    <p>Auto-ignition causing knock</p> Signup and view all the answers

    How does the Diesel engine differ from the Otto engine in terms of ignition?

    <p>Diesel engines use compression to auto-ignite the fuel.</p> Signup and view all the answers

    What does the term 'four-stroke engine' refer to?

    <p>The complete cycle of an engine involving four different strokes</p> Signup and view all the answers

    What key role does the intake manifold play in the functioning of an engine?

    <p>To distribute the air mixture to individual cylinders</p> Signup and view all the answers

    What occurs during the delay period in a compression ignition engine?

    <p>Fuel is injected but does not ignite immediately.</p> Signup and view all the answers

    What are the two parts into which the ignition delay period can be divided?

    <p>Chemical delay and physical delay.</p> Signup and view all the answers

    Which of the following factors affects the rate of vaporization of fuel droplets in a compression ignition engine?

    <p>Droplet diameter, velocity, pressure, and temperature of air.</p> Signup and view all the answers

    Which stage follows the ignition delay in the combustion process of a C.I. engine?

    <p>Rapid combustion.</p> Signup and view all the answers

    What is the range of ignition delay for low-compression ratio direct injection (DI) diesel engines?

    <p>0.6 to 3 ms.</p> Signup and view all the answers

    Which of these is NOT a requirement for good atomization during fuel injection?

    <p>Increased fuel viscosity.</p> Signup and view all the answers

    During which phase does the fuel continue to burn even after injection ceases?

    <p>After burning.</p> Signup and view all the answers

    Which process occurs first during the ignition delay period after fuel injection?

    <p>Fuel spray atomization and mixing with air.</p> Signup and view all the answers

    What does the relative efficiency or efficiency ratio (ηr) represent?

    <p>The ratio of actual thermal efficiency to the ideal cycle's thermal efficiency</p> Signup and view all the answers

    Which of the following factors influences volumetric efficiency?

    <p>Engine speed</p> Signup and view all the answers

    What is the ideal air to fuel ratio (A/F ratio) in spark-ignition engines for optimal performance?

    <p>14.7:1</p> Signup and view all the answers

    How does a lean air/fuel mixture affect engine performance?

    <p>It reduces the tendency for knock to occur</p> Signup and view all the answers

    What happens when the air/fuel mixture becomes too weak?

    <p>The combustion becomes incomplete</p> Signup and view all the answers

    Which component is NOT typically included in a heat balance sheet for engine performance analysis?

    <p>Heat loss due to oil consumption</p> Signup and view all the answers

    What does a compression ratio indicate in an engine?

    <p>The ratio of the cylinder's volume at bottom dead center to its volume at top dead center</p> Signup and view all the answers

    Which of the following describes the effect of a rich air/fuel mixture on engine performance?

    <p>It leads to higher unburnt fuel levels and reduced efficiency</p> Signup and view all the answers

    What does the brake specific fuel consumption (bsfc) measure?

    <p>The efficiency of fuel conversion into brake power</p> Signup and view all the answers

    How is the indicated specific fuel consumption (isfc) defined?

    <p>The ratio of fuel mass injected to indicated work done</p> Signup and view all the answers

    What does a lower specific fuel consumption indicate about engine efficiency?

    <p>It suggests higher engine efficiency</p> Signup and view all the answers

    What is the mechanical efficiency of an engine calculated from?

    <p>The ratio of brake power to indicated power</p> Signup and view all the answers

    What is a common range for mechanical efficiency in engines?

    <p>0.7 to 0.9</p> Signup and view all the answers

    What are typical values of bsfc for naturally aspirated automobile engines?

    <p>200 to 400 g/kWh</p> Signup and view all the answers

    What constrains the combustion efficiency in an engine during a cycle?

    <p>The brief time available for fuel and oxygen interaction</p> Signup and view all the answers

    In SI units, how is brake specific fuel consumption (bsfc) expressed?

    <p>kg/kWh</p> Signup and view all the answers

    What causes knock in compression ignition (CI) engines?

    <p>A long delay period</p> Signup and view all the answers

    How does Homogeneous Charge Compression Ignition (HCCI) differ from traditional spark ignition engines?

    <p>Utilizes compression to ignite the fuel-air mixture</p> Signup and view all the answers

    What is a characteristic feature of the combustion process in HCCI engines?

    <p>Simultaneous ignition at multiple sites</p> Signup and view all the answers

    Which of the following is an advantage of HCCI combustion?

    <p>Ability to operate at very high compression ratios</p> Signup and view all the answers

    What is the primary method of combustion initiation in HCCI engines?

    <p>Temperature increase during compression</p> Signup and view all the answers

    What is one of the disadvantages of HCCI combustion?

    <p>Difficulty in controlling auto-ignition</p> Signup and view all the answers

    What effect does using very lean mixtures in HCCI engines have on emissions?

    <p>Minimizes particulate emissions</p> Signup and view all the answers

    Which fuel types can HCCI engines operate on?

    <p>Gasoline, diesel fuel, and alternative fuels</p> Signup and view all the answers

    Study Notes

    Introduction to Heat Engines

    • A heat engine is any type of engine or machine that takes heat energy from the combustion of fuel and converts this energy into mechanical work.
    • Heat engines can be grouped into two main classes: external and internal combustion engines.

    External Combustion Engines

    • Combustion of fuel occurs outside the cylinder, such as in steam engines.
    • Heat from combustion generates steam which powers a piston or turbine.
    • Examples include steam turbines and gas turbines.
    • Often used for locomotives, ships, and generating electricity.
    • Advantages over internal combustion engines: cheaper fuels (including solids), high starting torque, self-starting with working fluid, flexible arrangement.

    Internal Combustion Engines

    • Combustion of fuel occurs inside the cylinder.
    • Fuel mixes with oxygen in the air inside the engine cylinder.
    • Engines using mixtures of combustible gases and air are called gas engines.
    • Engines using lighter liquid fuels (e.g., petrol) are called petrol engines.
    • Engines using heavier liquid fuels (e.g., oil) are called compression ignition engines or diesel engines.
    • Commonly used in road vehicles, aircraft, locomotives, and industrial applications.

    Advantages of Reciprocating Internal Combustion Engines

    • Higher overall efficiency
    • Greater mechanical simplicity
    • Easy starting from cold conditions
    • Lower weight to power ratio
    • Lower initial cost
    • Compact units, requiring less space

    Principles of Internal Combustion Engines

    • Conventional internal combustion engines have one or more cylinders in which combustion of the fuel takes place.
    • Main cylinder parts include: cylinder head, valve stem, clearance volume, cylinder, bottom dead center, spark plug, inlet valve, air, fuel injector, exhaust valve, connecting rod, crankshaft, crank case, sump.

    Engine Components

    • Cylinder: Cylindrical container for piston movement.
    • Cylinder Head: Top end of the cylinder, houses valves and spark plugs.
    • Inlet and Exhaust Valves: Control air and exhaust flow.
    • Piston: Transmits combustion force to connecting rod.
    • Connecting Rod: Connects piston to crankshaft.
    • Crank Shaft: Rotates to produce rotational energy.
    • Crankcase: Main engine body housing crankshaft, and bearings.
    • Flywheel: A large wheel mounted on the crankshaft to maintain constant speed.

    Cylinder Geometry

    • Cylinder Bore (D): Inner diameter of the cylinder.
    • Piston Area (A): Area of a circle with a diameter equal to the bore.
    • Stroke (L): Linear distance of piston travel.
    • Bore Stroke Ratio: Ratio of bore to stroke.
      • Square: Equal bore and stroke.
      • Over-square: Stroke shorter than bore.
      • Under-square: Stroke longer than bore.

    Engine Classifications

    • Based on ignition type (spark ignition or compression ignition).
    • Based on number of strokes per cycle (two-stroke or four-stroke).
    • Based on application (automotive, marine, etc.).

    Working Cycle

    • Four-stroke: intake, compression, power, exhaust.
    • Two-stroke: much simpler but less efficient than four-stroke.
    • Supercharging/Turbocharging: increase air density for higher power output.
      • Mechanical supercharger: Driven by engine crankshaft.
      • Turbocharger: Turbine driven by exhaust gases.

    Valve Location

    • Valve in block, L head: Older applications.
    • Valve in head, I head: Standard for modern automobiles.
    • One valve in head and one in block, F head: Less common.
    • Valves in block on opposite sides of cylinder, T head.

    Fuel Used

    • Gasoline (petrol)
    • Fuel oil (diesel fuel)
    • Natural gas
    • Liquid petroleum gas
    • Alcohols (e.g., methanol, ethanol)
    • Hydrogen

    Method of Mixture Preparation

    • Carburetor
    • Fuel injection into intake ports/manifold
    • Fuel injection into the engine cylinder

    Method of Ignition

    • Spark ignition: Spark plug initiates combustion.
    • Compression ignition: Fuel self-ignites due to high compression temperatures.

    Combustion Chamber Design

    • Shape of combustion chamber impacts knock and performance.
    • Used in connection with spark ignition engines.

    Method of Load Control

    • Throttling of fuel/air flow.
    • Control of fuel flow alone.

    Method of Cooling

    • Water cooled
    • Air cooled

    Engine Cycles

    • Otto Cycle: Four-stroke, spark ignition.
    • Diesel Cycle: Four-stroke, compression ignition.
    • Dual Cycle

    Engine Performance

    • Evaluating engine performance depends on measures.
    • Specific fuel consumption (brake and indicated)
    • Brake mean effective pressure
    • Specific power output, specific weight, exhaust smoke, other emissions.

    Additional Notes

    • Many different types of internal combustion engines exist with various characteristics and applications.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Description

    Test your knowledge on internal combustion engines with this quiz. It covers important concepts such as horsepower, brake power, and the functions of various engine strokes. Perfect for students studying mechanical engineering or automotive technology.

    More Like This

    Ciclo Otto o Cuatro Tiempos
    10 questions
    Ciclo Otto Teórico y Real
    117 questions
    TEMA 4 Ciclo Otto Teórico y Real FCS
    128 questions
    Use Quizgecko on...
    Browser
    Browser