System and method for split-cycle engine waste heat recovery

Abstract

A waste heat recovery system for a split-cycle engine includes a heat exchange unit. An air compressor device is in communication with the heat exchange unit. A waste heat input receives waste heat from the engine and is in fluid communication with the heat exchange unit. An ambient air intake connected to the air compressor device draws air into the air compressor device. A compressed air outlet member on the air compressor device in fluid communication with a compression cylinder of the split-cycle engine delivers compressed air from the air compressor device to the engine. Engine waste heat is communicated to the heat exchange unit and energy from the waste heat is used to drive the air compressor device, causing the air compressor device to draw in ambient air through the ambient air intake, compress the ambient air, and deliver compressed air to the engine through the compressed air outlet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic view generally illustrating a waste heat recovery system for a split-cycle engine;

FIG. 2 is a schematic view of the waste heat recovery system of FIG. 1 illustrating an air compression subsystem and engine waste heat subsystem in detail;

FIG. 3 is a schematic view of a split-cycle engine utilizing the waste heat recovery system; and

FIG. 4 is an alternative schematic view of a split-cycle engine utilizing the waste heat recovery system.

Claims

1. A waste heat recovery system for a split-cycle engine including a compression cylinder, a power cylinder, and a gas passage interconnecting the compression cylinder and the power cylinder, the waste heat recovery system comprising: a heat exchange unit;an air compressor device in fluid communication with the heat exchange unit;a waste heat input for receiving waste heat from the engine in fluid communication with the heat exchange unit;an ambient air intake connected to the air compressor device for drawing air into the air compressor device; anda compressed air outlet member on the air compressor device in fluid communication with the compression cylinder of the split-cycle engine for delivering compressed air from the air compressor device to the engine;wherein engine waste heat is communicated to the heat exchange unit and energy from the waste heat is used to drive the air compressor device.

2. The waste heat recovery system of claim 1, wherein an engine coolant subsystem is in communication with the heat exchange unit, and engine coolant is circulated from the engine through the heat exchange unit.

3. The waste heat recovery system of claim 1, wherein an engine exhaust subsystem is in communication with the heat exchange unit to pass engine exhaust gas through the heat exchange unit.

4. The waste heat recovery system of claim 1, including a circulation line for circulating heat exchange medium between the heat exchange unit and the air compressor device.

5. The waste heat recovery system of claim 4, wherein the heat exchange medium is one of a refrigerant and water.

6. The waste heat recovery system of claim 4, including a condenser operatively connected to the circulation line.

7. The waste heat recovery system of claim 4, including a pump operatively connected to the circulation line for pumping the heat exchange medium through the circulation line.

8. The waste heat recovery system of claim 1, wherein the split-cycle engine includes an air storage tank, and the compressed air is stored in the air storage tank.

9. The waste heat recovery system of claim 8, including a first valve for controlling flow into the storage tank, a second valve for controlling flow out of the storage tank, and a third valve for controlling flow across the gas passage, wherein the compressed air simultaneously charges the storage tank and drives the power cylinder when the first and second valves controlling flow into and out of the storage tank are open and the third valve controlling flow across the gas passage is closed.

10. A waste heat recovery system for a split-cycle engine including a compression cylinder and a power cylinder, the waste heat recovery system comprising: a heat exchange unit for transferring thermal energy from engine waste heat to a heat exchange medium, the heat exchange unit having a waste heat side and a heat exchange medium side;the heat exchange unit waste heat side including a waste heat input for receiving waste heat from the engine;the heat exchange unit heat exchange medium side including a heat exchange medium inlet for receiving heat exchange medium;a waste heat outlet connected to the waste heat side of the heat exchange unit;a heat exchange medium outlet connected to the heat exchange medium side of the heat exchange unit; andan air compressor device including: a heat exchange medium inlet in communication with the heat exchange medium outlet of the heat exchange unit;a heat exchange medium outlet operatively connected in a loop fashion to the heat exchange medium inlet of the heat exchange unit;an ambient air intake for drawing in ambient air into the air compressor device;a compressed air outlet connected to an air intake of the compression cylinder of the split-cycle engine for delivering compressed air to the engine;wherein energy extracted from the heat exchange medium drives the air compressor device.

11. A method of recovering waste heat from a split-cycle engine including a compression cylinder and a power cylinder, the method comprising: providing an air compression system including an air compressor device;delivering waste heat from the engine to the air compression system;utilizing energy from the waste heat to power the air compressor device; anddelivering waste-heat generated compressed air from the air compressor device to the compression cylinder of the split-cycle engine.

12. The method of claim 11, including the step of: providing a heat exchange unit to utilize the waste heat to change a heat exchange medium from a liquid phase to a gas phase.

13. The method of claim 12, wherein the step of delivering waste heat from the engine to the air compression system includes: circulating engine coolant through the engine and the heat exchange unit.

14. The method of claim 12, wherein the step of delivering waste heat from the engine to the air compression system includes: passing engine exhaust gases from the engine through the heat exchange unit.

15. The method of claim 14, including the step of: venting the exhaust gases to the atmosphere through an engine exhaust system after the exhaust gases are passed through the heat exchange unit.

16. The method of claim 12, including the step of: circulating the heat exchange medium through the heat exchange unit and the air compressor device.

17. The method of claim 16, wherein the step of circulating the heat exchange medium includes: pumping the heat exchange medium.

18. The method of claim 16, including the step of: providing a condenser downstream of the air compressor device to change the heat exchange medium from the gas phase to the liquid phase.

19. The method of claim 18, including the step of: venting excess heat from the condenser is to the atmosphere.

20. The method of claim 11, including the step of: drawing ambient air into the air compressor device through an ambient air intake.

21. The method of claim 11, including the step of: delivering waste-heat generated compressed air to the engine through a compressed air outlet operatively connected to an engine air intake.

22. The method of claim 11, including the step of: storing waste-heat generated compressed air from the compression cylinder in an air storage tank of the split-cycle engine.

23. The method of claim 11, including the steps of: charging a storage tank of the split-cycle engine with waste-heat generated compressed air from the compression cylinder; andsimultaneously driving the power cylinder with waste-heat generated compressed air from the air storage tank.