Motor vehicle engines in present use almost without exception operate on petroleum or gasoline which is made from petroleum.
There are two main objections to these engines. One is that the fuel they use is non-recyclable and at the present rate of consumption, the world's petroleum reserves may soon be gone. A second objection is that the products of fuel combustion when exhausted to the atmosphere are a major cause of air pollution.
It is among the objects of this invention to provide a system of operating an engine which utilizes a relatively non-polluting, recyclable fuel. The fuel is selected from the group consisting of magnesium, aluminum, magnesium plus aluminum, magnesium-aluminum alloy, magnesium hydride, aluminum hydride and magnesium aluminum hydride. A fuel could, for example, be made up of a compressed or sintered mass of particles of some or all of the materials comprising the above group. The solid products of combustion would be aluminum oxide (Al.sub.2 O.sub.3), magnesium oxide (MgO), magnesium hydroxide (Mg(OH).sub.2) and aluminum hydroxide (Al(OH).sub.3). These oxides and hydroxides can be collected and reduced to magnesium and aluminum and reformed for reuse as a fuel or for other end uses such, for example, as the manufacture of containers or cans for food and other products. The fuel is relatively non-polluting since after the oxides and hydroxides are collected there is substantially nothing but air to be exhausted to the atmosphere.
Other objects include utilizing the products of combustion to preheat the air used to burn the fuel; providing a separator to collect the solid portion of the products of combustion for recycling; making use of the separator as the combustion chamber for the fuel; and using a heat transfer means such as a sodium or other heat pipe in such a manner as to heat the working fluid of the engine by the fuel indirectly through the heat pipe. Of course, the working fluid can also be heated directly without using a heat transfer means.