The Helium Turbine Engine is an external combustion engine. In this image the burner is designed for burning liquid or gas fuels.
The engine works by heating a propellant made from Helium and two other propellant gases. The propellant gas circulates from the hot side to the 'cold' side, in the process turning a turbine which is attached to permanent magnets. The permanent magnets induce current in an inductor coil. The propellant cycle is a closed cycle.
In this particular design for the Helium Turbine Engine, the inlet takes in already warm air, and passes it over the exhaust manifold, heating it and compressing it even more.
A fuel injection systems introduces fuel into the system, causing it to combust completely (methane, ethanol, hydrogen), leaving very clean exhaust gases.
The burner in this engine comprises of four chambers. This is to allow the minimum required fuel to obtain the desired output. The chamber the furthest from the turbine is the 1st chamber, where fuel is introduced to obtain low output, the chambers progressively getting closer to the turbine are to facilitate higher output respectively. The exhaust outlet is close to the turbine to allow the maximum heat transfer from the exhaust gases through the heat pipes in to the propellant heating system. This allows for maximum efficiency, thereby reducing fuel consumption per watt of electrical power.