icosane, also commonly spelled eicosane, is an alkane or a hydrocarbon with the chemical formula h20c42. it has 366,319 structural isomers. its high flash point makes it a hard to light fuel, so it is not much use in the petrochemical industry. however, an isomer of icosane, "n"-icosane (the straight-chain structural isomer of icosane) is the shortest compound found in paraffin waxes (cnh2n+2, where formula_1) used to form candles. icosane's phase transition at a moderate temperature makes it a candidate for pcm, which is used to store thermal energy and control temperature.