Fuels — typical calorific value of automotive diesel Select the closest standard lower heating value for diesel fuel used in compression-ignition engines.

Introduction / Context:The calorific value of diesel determines available energy per kilogram and influences specific fuel consumption and engine mapping. Diesel typically contains heavier hydrocarbons than petrol, giving a similar or slightly higher LHV depending on formulation.

Given Data / Assumptions:

• Values refer to LHV in MJ/kg for pump diesel.
• No biodiesel blending or seasonal extreme variations assumed.
• Standard ambient conditions.

Concept / Approach:Typical LHV for diesel fuel is near 42–43 MJ/kg. This reflects the average hydrogen-to-carbon ratio and distillation range. While HHV is higher, engine calculations for CI engines usually rely on LHV due to exhaust water remaining as vapor.

Step-by-Step Solution:

Verification / Alternative check:Thermochemical tables and engine texts list diesel LHV commonly around 42.5 MJ/kg; local fuel specs vary slightly.

Why Other Options Are Wrong:

• 36.5 or 38.5 MJ/kg: lower than typical for diesel; closer to some oxygenated fuels.
• 45.5 MJ/kg: on the high side for LHV; more akin to HHV claims or specific kerosene fractions.
• 40.0 MJ/kg: possible for certain blends, but not the canonical design figure.

Common Pitfalls:Confusing HHV and LHV; ignoring the effect of biodiesel (which slightly lowers LHV).

Final Answer: