Question

compression ratio is 8.8:1, not sure what the question is asking

Step 3: Fuel Delivery at Max Power: At maximum output, calculate what the fuel-per-cycle quantity would be by using a 15:1 air-fuel ratio (Otto) or 22:1 (Diesel), based on the maximum mass contained in your combustion chamber. Note that the mass of air can be found using the ideal gas law and your initial conditions (ambient for an NA engine, for example). For force-fed

Answer 1

Given that,

air fuel ratio is 15:1 for otto cycle and 22:1 for diesel cycle

For NA (naturally aspirating) engine, initial ambient conditions would be : P₁ = 101 kPa , T₁ = 25^o C = 298 K

If the cubic capacity (cc) of the engine, and no. of cylinders (K) are given, the displacement volume (or) swept volume V_s can be found out by :

  V_s= (cubic capacity) / K

If the compression ratio (r_k) is given (here it is 8.8) , total cylinder volume V₁  (before compression starts) can be found out by :

r_{k =} V₁ / (V₁-V_s)

Since ideal gas law can be used to find the mass of air, using initial conditions,

M_1a = P₁ V₁ / R T₁   (where R is the specific gas constant for air = 287.058, J⋅kg⁻¹⋅K⁻¹)

using this, and air fuel ratio (A/F) =15:1 for otto cycle and 22:1 for diesel cycle,

  A/F = M_1a / M_f   (M_f is the mass of fuel per cycle)

Mass of fuel used per cycle can be found out.

The actual calculations can be done by using the values of cubic capacity and no. of cylinders in the engine.