Fuel Science4 min read
The Wood Considered Unfit as Fuel Is Green, Unseasoned Wood
Freshly cut wood can be half water. That moisture halves the usable heat, produces heavy smoke and deposits creosote in your chimney.
Fuel Science
Calorific value, ignition temperature, combustion products and what actually makes one fuel better than another.
This section covers the properties that decide how a fuel behaves: calorific value, ignition temperature, flash point, combustion products and the measures engineers use to compare engines. They are usually taught as a list to memorise, which is a shame, because each one explains something you can see in an ordinary kitchen.
Calorific value is the conversion between a price and a result — it is what lets you answer whether a gas cylinder is expensive for the amount of cooking it does. Ignition temperature explains why a match lights paper instantly and does nothing to a log. Flash point explains why kerosene can sit in an open wick appliance in a living room and petrol absolutely cannot. And the difference between complete and incomplete combustion — blue flame against yellow — is the difference between heat and carbon monoxide.
Where a figure appears in these guides, its source is listed at the foot of the page, because numbers in this field get copied between textbooks for decades without anyone rechecking them.
What goes wrong most often
- Comparing fuels by price rather than by calorific value.
- Confusing flash point with ignition temperature — they answer different questions.
- Treating a yellow flame as normal rather than as a warning.
- Assuming moisture in wood only makes it harder to light, rather than halving its usable energy.
- Quoting a figure without the conditions attached to it.
10 guides in Fuel Science
Fuel Science4 min read
Cetane Number: What a Higher Cetane Fuel Actually Does
Higher cetane means a shorter ignition delay: smoother diesel combustion, easier cold starts, less knock. And how it differs from octane.
Fuel Science4 min read
The SI Unit of Specific Fuel Consumption
Specific fuel consumption is fuel mass per unit of energy produced. Its SI unit is kg/J; engineers quote g/kWh, and jet engines kg/(N·h).
Fuel Science4 min read
A Liquid Fuel Used in Homes Is Kerosene
Kerosene is the liquid fuel used in homes, in wick stoves, lamps and heaters. Here is why it suits domestic use where petrol never could.
Fuel Science4 min read
Why Carbon and Its Compounds Are Used as Fuels
Carbon compounds burn in air releasing large amounts of heat, store easily and are abundant — which is why nearly every practical fuel is one.
Fuel Science4 min read
Incomplete Combustion of Fuel Leads to the Formation of Carbon Monoxide and Soot
Burning fuel in too little oxygen makes carbon monoxide, soot and unburnt hydrocarbons — with far less heat and a hazard you cannot smell.
Fuel Science4 min read
Ignition Temperature: Why a Fuel Must Be Heated Before It Burns
A fuel must reach its ignition temperature before it burns. What that means, why it varies so widely, and why not every combustible is a fuel.
Fuel Science4 min read
Which Fuel Has the Highest Calorific Value? Hydrogen, and Why
Hydrogen, at about 150,000 kJ/kg — roughly three times petrol. The full ranking, and why hydrogen still is not in general use.
Fuel Science4 min read
Characteristics of a Good Fuel: What Makes an Ideal Fuel
High calorific value, moderate ignition temperature, low ash and smoke, controlled burning, safe storage — and why no fuel scores full marks.
Fuel Science4 min read
Calorific Value of a Fuel: Definition, Units and How to Calculate It
Calorific value is the heat from burning one kilogram of fuel completely. Expressed in kJ/kg, and here is how it is measured and compared.