Waste heat recovery for power generation and engine warm up

Patent metadata

Field	Value
Publication number	US-10094246-B2
Application number	US-201615340815-A
Country	US
Kind code	B2
Filing date	Nov 1, 2016
Priority date	Nov 1, 2016
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

Methods and systems are provided for heating an engine and generating energy from a common waste heat recovery system. In one example, a method comprises, responsive to a first condition, expanding a working fluid of a waste heat recovery system via an expander to generate electricity, and responsive to a second condition, compressing the working fluid of the waste heat recovery system via the expander to transfer heat to an engine.

First claim

The invention claimed is:

1. A method comprising:
responsive to a first condition, expanding a working fluid of a waste heat recovery system via an expander to generate electricity, and blocking flow of the working fluid through one or more heat exchangers in thermal communication with an engine; and
responsive to a second condition, compressing the working fluid of the waste heat recovery system via the expander to transfer heat to the engine via the one or more heat exchangers.

2. The method of claim 1 , wherein expanding the working fluid of the waste heat recovery system to generate electricity comprises rotating the expander of the waste heat recovery system in a first direction and generating electricity via a generator coupled to the expander.

3. The method of claim 2 , wherein compressing the working fluid of the waste heat recovery system comprises rotating the expander in a second direction by a motor to compress the working fluid.

4. The method of claim 1 , wherein expanding the working fluid of the waste heat recovery system to generate electricity comprises:
flowing the working fluid through the expander of the waste heat recovery system in a first direction, including flowing the working fluid from an evaporator in thermal communication with an engine exhaust system to an inlet of the expander, through the expander, and out an outlet of the expander, and translating the expansion into electricity via a generator coupled to the expander.

5. The method of claim 4 , wherein compressing the working fluid of the waste heat recovery system comprises:
flowing the working fluid through the expander in a second direction, including flowing the working fluid from the evaporator to the outlet of the expander, through the expander, and out the inlet of the expander, and
transferring heat from the compressed working fluid to the engine by flowing the compressed working fluid from the inlet of the expander to the one or more heat exchangers in thermal communication with the engine.

6. The method of claim 5 , wherein the first condition comprises an engine coolant temperature above a first threshold temperature and the second condition comprises the engine coolant temperature below the first threshold temperature.

7. The method of claim 6 , further comprising, responsive to the engine coolant temperature above a second threshold temperature, higher than the first threshold temperature, flowing the working fluid through the one or more heat exchangers.

8. The method of claim 5 , wherein operating the expander of the waste heat recovery system in the first direction further comprises flowing the working fluid from the outlet of the expander to a condenser, from the condenser to a pump, and from the pump to the evaporator.

9. The method of claim 8 , wherein operating the expander of the waste heat recovery system in the second direction further comprises flowing the working fluid from the inlet of the expander to the one or more heat exchangers, and flowing the working fluid from the one or more heat exchangers to the evaporator, bypassing the condenser and the pump.

10. An exhaust heat recovery system, comprising:
one or more engine system heat exchangers;
an evaporator configured to transfer heat from an engine exhaust system to a working fluid;
a pump configured to selectively supply the working fluid to the one or more engine system heat exchangers and the evaporator;
an expander/compressor downstream of the evaporator;
a condenser downstream of the expander/compressor and upstream of the pump; and
a controller configured to:
during a first mode, harvest heat from the engine exhaust system via the evaporator and convert the heat into electricity via the expander/compressor by operating the expander/compressor as an expander driving a motor/generator, and flowing expanded working fluid through the condenser; and
during a second mode, harvest heat from the engine exhaust system via the evaporator and heat one or more engine components by operating the expander/compressor as a compressor driven by the motor/generator, the working fluid compressed by the compressor supplied to the one or more engine system heat exchangers and bypassing the condenser.

11. The system of claim 10 , further comprising:
an expander inlet line fluidically coupling an outlet of the evaporator to an expander inlet of the expander/compressor;
an expander outlet line fluidically coupling an expander outlet of the expander/compressor to an inlet of the condenser;
a compressor inlet line fluidically coupling the outlet of the evaporator to a compressor inlet of the expander/compressor; and
a compressor outlet line fluidically coupling a compressor outlet of the expander/compressor to a conduit upstream of the one or more engine system heat exchangers.

12. The system of claim 11 , wherein during the first mode, working fluid is configured to flow from the evaporator to the expander/compressor via the expander inlet line and from the expander/compressor to the condenser via the expander outlet line, and during the second mode, working fluid is configured to flow from the evaporator to the expander/compressor via the compressor inlet line and from the expander/compressor to the one or more engine system heat exchangers via the compressor outlet line.

13. The system of claim 11 , further comprising:
a first valve positioned between the pump and the evaporator;
a second valve positioned between the evaporator and the expander/compressor; and
a third valve positioned between the expander and the condenser, and wherein the controller is configured to,
during the first mode, open the first valve and adjust a position of the second valve to a first position of the second valve, and therein establish fluidic communication between the pump and an inlet of the evaporator and between the outlet of the evaporator and the expander inlet of the expander/compressor via the expander inlet line, and adjust a position of the third valve to a first position of the third valve, and
during the second mode, adjust the position of the second valve to a second position of the second valve and adjust a position of the third valve to a second position of the third valve, and therein establish fluidic communication between the outlet of the evaporator and the compressor inlet of the expander/compressor via the compressor inlet line, and close the first valve to block fluidic communication between the pump and the evaporator.

14. The system of claim 13 , wherein the one or more engine system heat exchangers comprise a first heat exchanger in thermal communication with engine coolant and a second heat exchanger in thermal communication with engine oil, and where the system further comprises:
a fifth valve upstream of the first heat exchanger; and
a fourth valve upstream of the second heat exchanger; and wherein the controller is configured to, during the first mode, close the fifth valve and close the fourth valve, and during the second mode, open the fifth valve and open the fourth valve.

15. The system of claim 10 , further comprising an engine including a plurality of cylinders configured to supply exhaust gas to the engine exhaust system and a transmission configured to drive one or more wheels, the transmission coupled to one or more of the engine and an electric machine, wherein the first mode comprises engine coolant temperature above a first threshold temperature, wherein the second mode comprises engine coolant temperature below the first threshold temperature, and wherein the controller is configured to, responsive to engine coolant temperature

Assignees

• Ford Global Tech Llc

Inventors

• Zhou Shiguang

Classifications

• F01K23/10

  with exhaust fluid of one cycle heating the fluid in another cycle (F01K17/025 takes precedence) · CPC title

• F01N5/02

  the devices using heat · CPC title

• F02G5/02

  Profiting from waste heat of exhaust gases · CPC title

• F01K23/065 Primary

  the combustion taking place in an internal combustion piston engine, e.g. a diesel engine · CPC title

• F01K15/02

  for driving vehicles, e.g. locomotives · CPC title