Air bottoming cycle air cycle system source

1. A turbine engine assembly comprising:

a core engine including a core flow path where a core airflow is compressed in a main compressor section, communicated to a combustor section, mixed with fuel and ignited to generate an exhaust gas flow that is expanded through a turbine section, wherein the turbine section is coupled to drive the main compressor section through an engine drive shaft;

a tap at a location upstream of the combustor section where a bleed airflow is drawn; an auxiliary compressor section where the bleed airflow is pressurized; an exhaust heat exchanger where a portion of the bleed airflow is heated by the exhaust gas flow;

a power turbine coupled to drive the auxiliary compressor section and driven by heated bleed airflow from the exhaust heat exchanger; and an accessory system receiving pressurized airflow from the auxiliary compressor section

wherein the auxiliary compressor section includes a first compressor and a second compressor that are both coupled to the power turbine, a first compressed airflow from the first compressor is communicated to the second compressor and a second compressed airflow from the first compressor is communicated to the exhaust heat exchanger, and a compressed airflow from the second compressor is communicated to the accessory system.

2. The turbine engine assembly as recited in claim 1 , including a bleed air heat exchanger where the compressed airflow from the second compressor is cooled before being communicated to the accessory system.

3. The turbine engine assembly as recited in claim 2 , wherein the first compressed airflow is placed in thermal communication with the compressed airflow from the second compressor in the bleed air heat exchanger.

4. The turbine engine assembly as recited in claim 1 , wherein the tap is disposed forward of the main compressor section.

5. The turbine engine assembly as recited in claim 1 , wherein the main compressor section includes a low pressure compressor section and a high pressure compressor section and the tap draws the bleed airflow after the low pressure compressor section and before the high pressure compressor section.

6. The turbine engine assembly as recited in claim 1 , including a first control valve controlling the bleed airflow from the tap to the auxiliary compressor section.

7. The turbine engine assembly as recited in claim 1 , wherein the accessory system comprises an aircraft environmental control system.

8. A waste heat recovery system for a turbine engine including a compressor section, a combustor and a turbine section, the waste heat recovery system comprising:

a tap at a location upstream of the combustor where a bleed airflow is drawn;

an auxiliary compressor section where the bleed airflow is compressed;

an exhaust heat exchanger where a portion of the bleed airflow is heated by an exhaust gas flow from a turbine section of the turbine engine;

a power turbine coupled to drive the auxiliary compressor section and driven by the portion of the bleed airflow heated in the exhaust heat exchanger; and

an accessory system receiving pressurized airflow from the auxiliary compressor section

wherein the auxiliary compressor section includes a first compressor and a second compressor that are both coupled to the power turbine, a first compressed airflow from the first compressor is communicated to the second compressor and a second compressed airflow from the first compressor is communicated to the exhaust heat exchanger wherein the second compressed airflow is the portion of the bleed airflow that is heated and a compressed airflow from the second compressor is communicated to the accessory system.

9. The waste heat recovery system as recited in claim 8 , including a bleed air heat exchanger where the compressed bleed airflow is cooled before being communicated to the accessory system.

10. The waste heat recovery system as recited in claim 8 , wherein the tap is disposed forward of the main compressor section.

11. The waste heat recovery system as recited in claim 8 , wherein the main compressor section includes a low pressure compressor section and a high pressure compressor section and the tap draws the bleed airflow after the low pressure compressor section and before the high pressure compressor section.

12. A method of operating a turbine engine assembly, including a main compressor section, a combustor and a turbine section, comprising:

tapping a bleed airflow from a location upstream of at least a portion of the main compressor section of the turbine engine;

compressing the bleed airflow in a first compressor;

supplying a first portion of the bleed airflow from the first compressor to a second compressor;

supplying a second portion of the bleed airflow from the first compressor to an exhaust heat exchanger that receives thermal energy from an exhaust gas flow of a turbine in the turbine section;

heating the second portion of the bleed airflow in the exhaust heat exchanger using the thermal energy from the exhaust gas flow;

driving the first compressor and the second compressor with a power turbine by expanding the first portion of the bleed airflow heated in the waste heat exchanger through the power turbine; and

supplying the second portion of bleed airflow compressed in the second compressor to an air cycle system.

13. The method as recited in claim 12 , further comprising cooling the second portion of the bleed airflow compressed in the second compressor in a bleed air heat exchanger before supplying the second portion of the bleed airflow to the air cycle system.