Method and system of controlling a thermodynamic system in a vehicle

Patent metadata

Field	Value
Publication number	US-9784141-B2
Application number	US-201514596528-A
Country	US
Kind code	B2
Filing date	Jan 14, 2015
Priority date	Jan 14, 2015
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

A vehicle has a vehicle system with a waste heat fluid. An expander, a condenser, a pump, and an evaporator are provided in sequential fluid communication in a thermodynamic cycle containing a working fluid. The evaporator is configured to transfer heat from the waste heat fluid to the working fluid. At least one valve adjacent to the pump is controlled to control fluid flow through at least one chamber to maintain a pressure of the fluid at a pump inlet at a threshold pressure above a saturated vapor pressure associated with a temperature at a condenser outlet when ambient temperature varies.

First claim

What is claimed is:

1. A vehicle comprising:
a vehicle system having a waste heat fluid;
an expander, a condenser, a pump, and an evaporator in sequential fluid communication in a thermodynamic cycle containing a working fluid, the evaporator configured to transfer heat from the waste heat fluid to the working fluid;
a plurality of chambers arranged in parallel fluid connection and positioned between the condenser and the pump;
at least one valve in fluid communication with the plurality of chambers and configured to selectively control flow of the working fluid between the plurality of chambers; and
a controller configured to control the at least one valve to vary a volume of the thermodynamic cycle such that a pressure of the working fluid at an inlet to the pump is at a threshold pressure, the threshold pressure being a saturated vapor pressure of the working fluid plus a pressure offset, wherein the saturated vapor pressure is a function of a temperature of the working fluid at an outlet of the condenser, the temperature and the saturated vapor pressure varying with ambient temperature.

2. The vehicle of claim 1 wherein a first chamber of the plurality of chambers has a first volume, and a second chamber of the plurality of chambers has a second volume greater than the first volume.

3. The vehicle of claim 2 further comprising a pressure sensor in fluid communication with the inlet to the pump;
wherein the controller is further configured to receive a signal from the pressure sensor indicative of the pressure of the working fluid at the inlet to the pump, and control the at least one valve to provide flow of the working fluid through the first chamber when the pressure is less than the threshold pressure to decrease the volume of the thermodynamic cycle and provide an increase in pressure at the inlet to the pump.

4. The vehicle of claim 2 further comprising a pressure sensor in fluid communication with the inlet to the pump;
wherein the controller is further configured to receive a signal from the pressure sensor indicative of the pressure of the working fluid at the inlet to the pump, and control the at least one valve to provide flow of the working fluid through the second chamber when the pressure is greater than the threshold pressure to increase the volume of the thermodynamic cycle and provide a decrease in pressure at the inlet to the pump.

5. The vehicle of claim 2 wherein a third chamber of the plurality of chambers has a third volume greater than the second volume; and
wherein the at least one valve comprises a valve associated with each chamber of the plurality of chambers.

6. A method comprising:
controlling a pump, an evaporator, an expander, and a condenser in a closed loop in a vehicle for energy recovery using a mixed phase working fluid;
controlling a first valve to a first chamber adjacent to the pump to maintain a pressure of the mixed phase working fluid at a pump inlet at a threshold pressure above a saturated vapor pressure associated with a temperature at a condenser outlet when ambient temperature varies, the first chamber positioned between the first valve and the pump inlet; and
controlling a second valve to maintain the pressure of the mixed phase working fluid at the pump inlet at the threshold pressure when ambient temperature varies, the second valve adjacent to the pump and controlling flow through a second chamber positioned between the second valve and the pump inlet, the second chamber in parallel fluid connection with the first chamber, the second chamber having a greater volume than the first chamber; and
the steps of controlling the first and second valves maintains the pressure of the mixed phase working fluid at the pump inlet by varying a volume of the closed loop.

7. The method of claim 6 wherein the threshold pressure is maintained at a pressure offset above the saturated vapor pressure.

8. The method of claim 6 wherein the temperature of the condenser outlet is at an offset above ambient temperature; and
wherein the saturated vapor pressure increases with a temperature increase of the mixed phase working fluid at the condenser outlet.

9. The method of claim 6 further comprising transferring heat to the mixed phase working fluid in the evaporator from a waste heat fluid in the vehicle thereby providing a vapor phase of the fluid;
rotating the expander using the vapor phase of the mixed phase working fluid to generate power;
transferring heat from the mixed phase working fluid in the condenser to ambient air thereby providing a liquid phase of the mixed phase working fluid; and
pumping the liquid phase of the mixed phase working fluid using the pump.

10. The method of claim 6 further comprising:
receiving a signal from a pressure sensor in fluid communication with the pump inlet that the pressure is less than the threshold pressure; and
opening the first valve and closing the second valve to decrease the volume of the closed loop thereby increasing pressure at the pump inlet.

11. The method of claim 6 further comprising:
receiving a signal from a pressure sensor in fluid communication with the pump inlet that the pressure is greater than the threshold pressure; and
closing the first valve and opening the second valve to increase volume of the closed loop thereby lowering pressure at the pump inlet.

12. The method of claim 6 further comprising:
receiving a signal from a pressure sensor in fluid communication with the pump inlet that the pressure is greater than the threshold pressure; and
controlling the first and second valves to selectively control flow of the mixed phase working fluid to at least one of first and second chambers to increase a volume of the closed loop thereby decreasing pressure at the pump inlet, each chamber receiving the mixed phase working fluid from the condenser outlet and providing the mixed phase working fluid to the pump inlet.

13. A method comprising:
controlling upstream and downstream valve assemblies of first and second fluidly parallel chambers to selectively control flow therethrough thereby varying a volume of a closed loop having a pump, an evaporator, an expander, and a condenser sequentially connected thereto for vehicle waste heat energy recovery using a mixed phase working fluid to maintain pump inlet pressure above a saturated vapor pressure associated with a condenser outlet temperature as ambient temperature varies.

14. The method of claim 13 wherein, in response to a decreasing pump inlet pressure, the upstream and downstream valve assemblies are controlled to provide flow through only the first chamber to decrease the volume of the closed loop.

15. The method of claim 14 wherein, in response to an increasing pump inlet pressure, the upstream and downstream valve assemblies are controlled to provide flow through both the first and second chambers to increase the volume of the closed loop.

16. The method of claim 14 wherein a volume of the first chamber is less than a volume of the second chamber; and
wherein, in response to an increasing pump inlet pressure, the upstream and downstream valve assemblies are controlled to provide flow through only the second chamber to increase the volume of the closed loop.

Assignees

• Ford Global Tech Llc

Inventors

• Zhou Shiguang

Classifications

• B60R16/08

  fluid · CPC title

• F01K23/065

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

• F01K25/00

  Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for · CPC title

• F01N5/02

  the devices using heat · CPC title

• Y10S903/904

  Component specially adapted for hev · CPC title