Heat of Combustion Calculator
A sealed bomb measures internal energy and recovers the water's latent heat — an engine does neither.
The formula
q = C * dT ; heat of combustion = -q / moles burned
The calorimeter is the thermometer
A bomb calorimeter measures heat by measuring its own temperature rise. Its heat capacity is established beforehand by burning a reference substance of known energy — benzoic acid, almost always — so every subsequent measurement is really a comparison against that standard.
Constant volume, not constant pressure
A bomb is sealed, so what it measures is the change in internal energy, not the enthalpy. The two differ by the work of any volume change, which matters when the number of gas molecules changes during the reaction. For most fuels the correction is under one per cent, which is why it is often passed over in silence.
Higher and lower heating values
A calorimeter condenses the water it produces and recovers the latent heat, giving the higher heating value. An engine or a boiler sends the water out as vapour and never sees that heat, so the lower heating value is what matters in practice. For methane the gap is about eleven per cent, which is large enough that quoting a fuel's energy without saying which one is meaningless.
Where these models stop
Michaelis-Menten assumes a single substrate and a steady state; Langmuir assumes one layer on identical sites with no interaction between them; Stokes-Einstein assumes a hard sphere much larger than the solvent molecules around it. Each is an idealisation that happens to describe real systems well over a useful range, and each fails predictably outside it. Knowing which assumption a number rests on is usually more valuable than the number.