Take a look at the Clarke XR80 space heater. For their physical size and heat output diesel and paraffin space heaters are often used in warehouses and workshop to provide high heat outputs in cold areas. This model offers a maximum heat output of 20.5kw, and can run for a period of 9 hours of one full tank of fuel.
Please note that these diesel/paraffin space heaters require adequate ventilation when in use.