What are primary and secondary fuels? To which class of fuel do the following belong: coke, wood, petroleum, LPG?
Primary fuels - Fuels that directly produce heat on ignition are called primary fuels. They are
raw fuels.
Examples are wood, coal, petroleum, natural gas, animal dung, etc.
Secondary fuels - Fuels that are processed and prepared from primary fuelsare called
secondary type of fuels.
Examples are charcoal, coke, petrol, diesel, kerosene.