Conditioning fuel system for an auxiliary power unit of an aircraft

A conditioning system for an aircraft comprising an Auxiliary Power Unit, wherein the Auxiliary Power Unit comprises:

• a fuel inlet configured to supply a pressurized gas fuel to a fuel conduit,
• an engine comprising an inlet connected to the fuel conduit,
• an outlet connected to an APU outlet, the APU outlet being configured to exhaust gases out of the engine,
• a plurality of injectors, and
• a plurality of combustion chambers,
• the fuel conduit connecting the fuel inlet to the engine,
• wherein the conditioning system comprises:
• a fuel tank comprising an outlet connected to the fuel inlet of the Auxiliary Power Unit, the fuel tank being configured to maintain the pressurized gas fuel pressurized at pressure Pf,
• a pressure regulator located downstream of the fuel tank, the pressure regulator being configured to regulate the pressure of the pressurized gas fuel injected to the fuel inlet of the Auxiliary Power Unit,
• a first temperature sensor located downstream of the pressure regulator and a second temperature sensor located upstream of the engine,
• a first pressure sensor located inside the fuel tank, a second pressure sensor located downstream of the pressure regulator and a third pressure sensor located at the inlet of the engine, and
• a controller connected to the first, second and third pressure sensors, and to the first and second temperature sensors, the controller being configured to receive temperature and pressure values from the first, second and third pressure sensors and from the first and second temperature sensors and to actuate on at least one of the pressure regulator or the injection position of the pressurized gas fuel inside the plurality of combustion chambers of the engine,
• the controller further comprising a fuel controller and an engine controller, wherein the first temperature sensor and the first and second pressure sensors are connected to the fuel controller, wherein the second temperature sensor and the third pressure sensor are connected to the engine controller, and
• the conditioning system being configured to:
• actuate the pressure regulator and inject the pressurized gas fuel at a fix position into the plurality of combustion chambers of the engine via the controller when a pressure P3 of the third pressure sensor is higher or equal to a pressure pre-established reference value Pref, or
• actuate the pressure regulator and inject the pressurized gas fuel at a lower position into the plurality of combustion chambers of the engine via the controller when the pressure P3 of the third pressure sensor is lower than Pref.