Jawaharlal Nehru Technological University, Hyderabad B.Tech IV ELECTRICAL AND HYBRID VEHICLES Previous Question Paper (February/March - 2022 - R18)

Conventional vehicles powered by internal combustion engines (ICE) contribute significantly to global warming primarily through the emission of greenhouse gases (GHGs). The combustion of fossil fuels like gasoline and diesel releases carbon dioxide (CO2), which is the most prevalent GHG. These gases accumulate in the atmosphere, creating a greenhouse effect by trapping solar heat that would otherwise escape into space.

Key mechanisms include:

• Carbon Dioxide Emissions: The chemical reaction of hydrocarbon fuel with oxygen produces CO2 as a byproduct, which persists in the atmosphere for centuries.
• Incomplete Combustion: Vehicles often emit methane and nitrous oxide, which have a significantly higher global warming potential than CO2.
• Secondary Pollutants: Nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight to form ground-level ozone, a potent greenhouse gas.
• Black Carbon: Particulate matter (soot) emitted from diesel engines absorbs sunlight and reduces the albedo effect when deposited on snow and ice, further accelerating global temperature rise.

The dynamic equation of vehicle motion describes the balance of forces acting on a vehicle as it moves. To maintain or change motion, the tractive force provided by the powertrain must overcome various resistive forces.

The fundamental equation is expressed as:

Where the forces are defined as:

• Tractive Force (F_t): The force generated by the motor or engine at the wheels to propel the vehicle.
• Aerodynamic Drag (F_a): The resistance due to air, calculated as
  0.5 * ρ * A * C_d * v^2
  , where ρ is air density, A is frontal area, C_d is drag coefficient, and v is velocity.
• Rolling Resistance (F_r): The resistance between tires and the road, calculated as
  m * g * C_r * cos(θ)
  , where m is mass, g is gravity, and C_r is the rolling resistance coefficient.
• Gradient Force (F_g): The force due to gravity when climbing a slope, calculated as
  m * g * sin(θ)
  , where θ is the road angle.
• Inertial Force (F_i): The force required to accelerate the vehicle mass, calculated as
  m * a
  , where a is acceleration.