System for cooling a heat exchanger on board an aircraft

A system for cooling a heat exchanger on board an aircraft comprising:

• an engine bleed air line including a first end and a second end, the first end of the engine bleed air line being connected by a plurality of engine bleed air line branches to an engine of the aircraft at a plurality of positions such that engine bleed air is supplied to the engine bleed air line, the engine of the aircraft generating propulsion force to move the aircraft, wherein the heat exchanger is attached to the engine bleed air line between the first end and the second end of the engine bleed air line, and the engine bleed air line is adapted to supply a first portion of the engine bleed air to the heat exchanger;
• a process air line including a first end and a second end, the first end of the process air line branching off from the engine bleed air line upstream of the heat exchanger such that a second portion of the engine bleed air supplied to the engine bleed air line is supplied to the process air line, and the second end of the process air line being attached to an input side of a turbine such that the second portion of the engine bleed air is supplied to the turbine;
• and
• a cooling air line including a first end and a second end, the first end of the cooling air line being attached to an output side of the turbine such that a flow of cooling air produced by an expansion of the second portion of the engine bleed air supplied to the turbine is supplied to the cooling air line, and the second end of the cooling air line being attached to the heat exchanger, wherein the heat exchanger is adapted to transfer energy between the flow of cooling air and the first portion of the engine bleed air supplied to the heat exchanger, thereby cooling the first portion of the engine bleed air, wherein the heat exchanger to be cooled is also positioned in a cooling duct connected to a source of ambient air so as to allow the heat exchanger to be flown through by a first flow of ambient air, to thereby transfer energy between the first flow of ambient air and the first portion of the engine bleed air, thereby cooling the first portion of the engine bleed air, wherein the cooling duct is separate from the engine, the cooling duct being positioned between the first end and the second end of the engine bleed air line, and the engine bleed air line passing through the heat exchanger and the cooling duct, such that the first portion of the engine bleed air is adapted to flow through the heat exchanger and the cooling duct within the engine bleed air line.