摘要 |
A method of operating an internal combustion engine 100 comprising a cylinder 3 and a piston (25, fig.2), the method including directly injecting into the cylinder 3, as a flow of liquid, a fuel which has been condensed into its liquid phase via a refrigeration process, such that the fuel vaporises into its gaseous phase during a compression stroke of the piston and before combustion such that a rise in temperature caused by the compression stroke is limited by the absorption of heat by the fuel, and further comprising controlling the rate of the flow such that the absorption of heat by the fuel is commensurate with the instantaneous temperature difference between the fuel and surrounding air in the cylinder. The method allows the use of higher compression ratios than is possible with conventional Otto cycle engines without suffering from engine knock or preignition. |