System and method for dynamically determining refrigerant film thickness and dynamically controlling refrigerant film thickness at rolling-element bearing of an oil free chiller

Patent metadata

Field	Value
Publication number	US-11725859-B2
Application number	US-202117456749-A
Country	US
Kind code	B2
Filing date	Nov 29, 2021
Priority date	Dec 17, 2015
Publication date	Aug 15, 2023
Grant date	Aug 15, 2023

Abstract

Methods are directed towards dynamically determining refrigerant film thickness at the rolling-element bearing and for dynamically controlling refrigerant film thickness at the rolling-element bearing. Further, an oil free chiller system is configured for dynamically determining refrigerant film thickness at the rolling-element bearing of the oil free chiller system, wherein the oil free chiller system is also configured for dynamically controlling refrigerant film thickness at the rolling-element bearing of the oil free chiller system.

First claim

What is claimed is:

1. A chiller system, comprising:
a refrigeration circuit configured to circulate a refrigerant, including:
an oil-free compressor having a drive motor and a bearing, the bearing configured to receive a flow of the refrigerant;
a condenser;
an evaporator;
a liquid temperature affecting device configured to affect a temperature of the flow of the refrigerant, the liquid temperature affecting device configured to receive liquid refrigerant from between the condenser and the evaporator of the chiller system; and

a controller configured to:
determine a film thickness of refrigerant at the bearing; and
adjust an output temperature of the liquid temperature affecting device based on the film thickness.

2. The chiller system of claim 1 , wherein the liquid temperature affecting device is a heat exchanger.

3. The chiller system of claim 2 , wherein the heat exchanger is a brazed plate heat exchanger.

4. The chiller system of claim 2 , further comprising a modifier configured to adjust an inlet temperature at the heat exchanger for refrigerant exchanging heat with the flow of refrigerant.

5. The chiller system of claim 4 , wherein the controller is configured to adjust the output temperature of the flow of refrigerant by controlling the modifier.

6. The chiller system of claim 1 , further comprising a temperature sensor configured to measure the temperature of the flow of the refrigerant, wherein the controller is configured to determine the film thickness based at least in part on the temperature of the flow of the refrigerant.

7. The chiller system of claim 1 , further comprising a pressure sensor configured to measure a pressure of the refrigerant at the condenser, wherein the controller is further configured to determine film thickness further based on the pressure of the refrigerant at the condenser.

8. The chiller system of claim 1 , wherein the controller is configured to determine the film thickness based at least in part on a speed of rotation of the drive motor.

9. A controller for a chiller system, configured to:
receive refrigerant lubrication parameters including at least one of a temperature of refrigerant at a bearing in an oil-free chiller and a speed of rotation of a drive motor of the chiller system;
determine film thickness of the refrigerant at the bearing in the oil-free chiller based only on the temperature and the speed of rotation; and
direct adjustment of a temperature of a flow of the refrigerant from a liquid temperature affecting device to the bearing based on the determined film thickness, the liquid temperature affecting device configured to receive liquid refrigerant from the chiller system.

10. The controller of claim 9 , wherein the liquid temperature affecting device is a heat exchanger configured to affect the temperature of the flow of the refrigerant, and the controller is configured to direct adjustment of the temperature of the flow of the refrigerant by controlling the heat exchanger.

11. The controller of claim 9 , wherein the controller is configured to direct adjustment of the temperature of the flow of the refrigerant by altering operation of a modifier configured to adjust a temperature of a fluid exchanging heat with the flow of the refrigerant.

12. A method for controlling a chiller system, comprising:
obtaining refrigerant lubrication parameters including at least one of a temperature of refrigerant at a bearing in an oil-free chiller, a condenser pressure of the chiller system, or a speed of rotation of a drive motor of the chiller system;
determining, using a controller, film thickness of the refrigerant at the bearing in the oil-free chiller based on the refrigerant lubrication parameters; and
adjusting a temperature of a flow of the refrigerant from a liquid temperature affecting device to the bearing based on the determined film thickness, the liquid temperature affecting device configured to receive liquid refrigerant from between a condenser and an evaporator of the chiller system.

13. The method of claim 12 , wherein the liquid temperature affecting device is a heat exchanger configured to affect the temperature of the flow of the refrigerant, and adjusting the temperature of the flow includes controlling the heat exchanger.

14. The method of claim 13 , wherein the heat exchanger is a brazed plate heat exchanger.

15. The method of claim 13 , wherein the heat exchanger adjusts the temperature by receiving a relatively cool refrigerant from a point between a condenser and an evaporator of the chiller, and exchanging heat between the flow of refrigerant and the relatively cool refrigerant.

16. The method of claim 12 , wherein adjusting the temperature of the flow includes altering operation of a modifier configured to adjust a temperature of a fluid exchanging heat with the flow of the refrigerant.

17. The method of claim 12 , wherein adjusting the temperature of the flow of refrigerant to the bearing based on the determined film thickness includes reducing a temperature of the flow of refrigerant to the bearing when the determined film thickness is below a threshold film thickness.

18. The method of claim 17 , wherein the threshold film thickness is based on an operating mode of the chiller.

19. The method of claim 17 , wherein the threshold film thickness is a range of values.

20. The method of claim 17 , further comprising determining whether the threshold film thickness can or cannot be achieved, and shutting down the chiller when the threshold film thickness cannot be achieved.

Assignees

• Trane Int Inc

Inventors

• Johnson Jay H

Classifications

• F25B49/025 Primary

  Motor control arrangements · CPC title

• F04D27/001

  Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring · CPC title

• F04D29/059

  Roller bearings · CPC title

• F04D29/063

  specially adapted for elastic fluid pumps · CPC title

• F04D29/584

  cooling or heating the machine (F04D29/5846, F04D29/5853 take precedence) · CPC title