Reversible waste heat recovery system and method

Patent metadata

Field	Value
Publication number	US-9702289-B2
Application number	US-201414526216-A
Country	US
Kind code	B2
Filing date	Oct 28, 2014
Priority date	Jul 16, 2012
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A waste heat recovery (WHR) system operates in a reverse mode, permitting using the WHR system to transfer heat to the exhaust gas of an internal combustion engine. In another configuration, a WHR system may operate in two modes. The first mode removes heat from exhaust gas of an engine to perform useful work. The second mode transfers heat to the exhaust gas. The benefit of this flexible system is that a WHR system is adaptable to rapidly heat exhaust gas at startup and during other conditions where the temperature of the exhaust gas is less than a predetermined operating range. Because of the ability to rapidly warm engine exhaust gas, an exhaust gas receiving system, such as an EGR or an aftertreatment system, may function to reduce the emissions of the engine more quickly. Because this system is reversible, it retains the capability of a conventional WHR system.

First claim

What is claimed is:

1. A method of heating and cooling exhaust gas flowing through an exhaust gas circuit of an internal combustion engine, the method comprising:
measuring an exhaust gas temperature;
operating a waste heat recovery (WHR) system in a heating mode if the exhaust gas temperature is less than a predetermined temperature range, the heating mode comprising flowing a working fluid from a condenser/evaporator downstream to a turbine/compressor, through a heat exchanger, and then through an expansion valve to a switching valve; and
operating the WHR system in a cooling mode to maintain the exhaust gas temperature within the predetermined operating range, the cooling mode comprising flowing the working fluid flows from the condenser/evaporator through the switching valve to a feed pump and then downstream to the heat exchanger.

2. The method of claim 1 , wherein a particulate filter positioned along the exhaust gas circuit is configured to undergo regeneration when the exhaust gas temperature is within the predetermined temperature range.

3. The method of claim 1 , wherein a selective catalytic reduction catalyst positioned along the exhaust gas circuit is configured to reduce emissions in the exhaust gas when the exhaust gas temperature is within the predetermined temperature range.

4. The method of claim 1 , wherein an oxidation catalyst positioned along the exhaust gas circuit is configured to reduce emissions in the exhaust gas when the exhaust gas temperature is within the predetermined temperature range.

5. A method of heating and cooling an exhaust gas flowing through an exhaust gas circuit of an internal combustion engine, the method comprising:
providing a waste heat recovery (WHR) system, including a working fluid circuit, through a heat exchanger positioned along the exhaust gas circuit, the WHR system comprising a condenser/evaporator positioned along the working fluid circuit, a switching valve positioned along the working fluid circuit between the heat exchanger and the condenser/evaporator, a parallel circuit portion positioned along the working fluid circuit between the switching valve and the heat exchanger, the parallel circuit portion including a first branch and a second branch positioned in parallel to the first branch, a feed pump positioned along the first branch, and an expansion valve positioned along the second branch, and a turbine/compressor positioned along the working fluid circuit between the condenser/evaporator and the heat exchanger;
operating the WHR system in a first mode of operation so as to provide heated working fluid to the heat exchanger, the operating of the WHR system in the first mode of operation including:
configuring the switching valve to block fluid flow through the first branch and to permit fluid flow through the second branch, and
pumping the working fluid through the working fluid circuit in a first direction; and

operating the WHR system in a second mode of operation so as to provide cooled working fluid to the heat exchanger, the operating of the WHR system in the second mode of operation including:
configuring the switching valve to permit fluid flow through the first branch and to block fluid flow through the second branch, and
pumping the working fluid through the working fluid circuit in a second direction opposite the first direction.

6. The method of claim 5 , wherein a motor-generator is drivingly connected to the turbine/compressor, the motor-generator configured to pump the working fluid through the working fluid circuit in the first mode of operation, and wherein the feed pump is configured to pump the working fluid through the working fluid circuit in the second mode of operation.

7. The method of claim 6 , wherein the motor-generator is further configured to convert energy from the working fluid to useful energy in the second mode of operation.

8. The method of claim 5 , further comprising receiving a temperature signal from a temperature sensor located along the exhaust gas circuit, the temperature signal indicative of a temperature of the exhaust gas, wherein the operating of the WHR system in one of the first and second modes of operation is based on the temperature signal.

9. The method of claim 8 , wherein a control module is configured to:
receive the temperature signal, and
send a control signal to the switching valve to operate the WHR system in one of the first and second modes of operation based on the temperature signal.

10. The method of claim 8 , wherein the operating of the WHR system in the first mode of operation is based on the temperature signal indicating that the temperature of the exhaust gas is below a predetermined operating temperature range.

11. The method of claim 8 , wherein the operating of the WHR system in the second mode of operation is based on the temperature signal indicating that the temperature of the exhaust gas is above a predetermined operating temperature range.

12. The method of claim 5 , wherein the operating of the WHR system in the first mode of operation further includes operating a heater positioned along the working fluid circuit between the switching valve and the turbine/compressor.

13. The method of claim 5 , wherein the operating of the WHR system in the first mode of operation further includes controlling a position of the expansion valve to control an amount of expansion provided by the expansion valve.

14. The method of claim 5 , wherein the operating of the WHR system in the second mode of operation further includes controlling at least one of torque and speed of the motor-generator to control an amount of compression of the working fluid.

15. The method of claim 5 , wherein a particulate filter positioned along the exhaust gas circuit is configured to undergo regeneration when the exhaust gas temperature is within the predetermined temperature range.

16. The method of claim 5 , wherein a selective catalytic reduction catalyst positioned along the exhaust gas circuit is configured to reduce emissions in the exhaust gas when the exhaust gas temperature is within the predetermined temperature range.

17. The method of claim 5 , wherein an oxidation catalyst positioned along the exhaust gas circuit is configured to reduce emissions in the exhaust gas when the exhaust gas temperature is within the predetermined temperature range.

18. An internal combustion engine, comprising:
an exhaust gas circuit;
a heat exchanger positioned along the exhaust gas circuit;
an exhaust gas receiving portion positioned along the exhaust gas circuit downstream of the heat exchanger; and
a waste heat recovery (WHR) system including a working fluid circuit extending through the heat exchanger, a condenser/evaporator positioned along the working fluid circuit, a switching valve positioned along the working fluid circuit between the heat exchanger and the condenser/evaporator, a parallel circuit portion positioned along the working fluid circuit between the switching valve and the heat exchanger, the parallel circuit portion including a first branch and a second branch positioned in parallel to the first branch, a feed pump positioned along the first branch, and an expansion valve positioned along the second branch, and a turbine/compressor positioned along the working fluid circuit between the condenser/evaporator and the heat exchanger.

19. The internal combustion engine of claim 18 , wherein the WHR system is operable in a first mode wherein the working fluid flows from the condenser/evaporator through the switching valve to

Assignees

• Cummins Ip Inc

Inventors

• Dane Marten H

Classifications

• Y02T10/16

  Cross-Sectional Technologies · mapped topic

• F01N3/2006 Primary

  Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating (by electrically controlling the supply of combustible mixture or its constituents only F02D41/0235) · CPC title

• F01N9/00

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• F02G5/02

  Profiting from waste heat of exhaust gases · CPC title

• F01K23/10

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