Bottoming cycle for waste heat recovery and engine cooling

A waste heat recovery system for a gas turbine engine, the waste heat recovery system comprising:

• a first tap drawing bleed airflow from a core flow path up stream of a combustor section of the gas turbine engine;
• a bleed air heat exchanger placing the bleed airflow in thermal communication with an auxiliary flow for heating the bleed airflow, wherein the auxiliary flow comprises a flow at an elevated temperature that is greater than the bleed airflow and is communicated to an environmental control system after the bleed air heat exchanger;
• and
• an exhaust heat exchanger configured to transfer thermal energy from the exhaust gas flow into the bleed airflow;
• and
• a power turbine including an inlet receiving a heated bleed airflow, wherein the power turbine is configured to generate a mechanical power output;
• a first control device configured to control flow of the bleed airflow from the first tap to the bleed air heat exchanger;
• and
• a controller programmed to control operation of the first control device in response to a control input.

A method of operating a gas turbine engine assembly comprising:

• generating an exhaust gas flow by igniting a fuel mixed with a core airflow in a core engine, wherein the core engine includes a compressor section coupled to a turbine section through an engine shaft;
• communicating a portion of the core airflow as a bleed airflow through a tap located upstream of a combustor section;
• heating the bleed airflow with an auxiliary flow for an auxiliary system within a bleed air heat exchanger, wherein the auxiliary flow comprises a flow at an elevated temperature that is greater than the bleed airflow and is communicated to an environmental control system after the bleed air heat exchanger;
• heating bleed airflow in an exhaust heat exchanger in thermal communication with the combusted gas flow;
• and
• generating shaft power by expanding at least a portion of heated bleed airflow through a power turbine;
• coupling the engine shaft to the power turbine and applying a drive input to the engine shaft with the power turbine.