REFRIGERANT LEAK-DETECTION SYSTEMS

A refrigerant leak-detection system is provided to monitor a level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment enclosing a refrigeration unit. The system comprises a sensor positioned in the ventilated environment to measure a level of refrigerant/refrigerant by-products in the ambient air, and a detection controller to receive signals associated with the level of refrigerant/refrigerant by-products in the ambient air and to perform an action as a function of the signals. The detection controller stops a ventilation unit for given periods of time to allow the sensor to measure the level of refrigerant/refrigerant by-products in the ambient air during the given periods of time. A method for monitoring the level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment enclosing a refrigeration unit is also provided.

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Description
CROSS-REFERENCE TO RELATED APPLICATION

This patent application claims priority on U.S. Provisional Patent Application No. 60/982,572, filed on Oct. 25, 2007.

FIELD OF THE APPLICATION

The present application relates to refrigeration systems, and more particularly to leak detection for refrigeration systems.

BACKGROUND ART

The declining condition of the environment is a growing concern. Global warming has had severe repercussions on the climate of numerous countries. One of the factors responsible for global warming is greenhouse-effect gases.

One source of greenhouse-effect gases is the refrigerant used in the food industry. Accordingly, refrigerants have evolved to be less harmful to the environment. However, the refrigerants used today still produce greenhouse-effect gases if exposed to ambient temperatures. It is therefore desirable to produce refrigeration systems that are as leakproof as possible. On the other hand, it is also desirable to provide safety systems to measure refrigerant leaks to quickly reduce the exposure of refrigerants to ambient conditions.

SUMMARY OF THE APPLICATION

It is therefore an aim of the present application to provide a novel refrigerant leak-detection system and method.

Therefore, in accordance with the present application, there is provided a refrigerant leak-detection system of the type used to monitor a level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment enclosing a refrigeration unit, comprising: a sensor positioned in the ventilated environment, the sensor being provided to measure a level of refrigerant/refrigerant by-products in the ambient air; and a detection controller for receiving signals associated with the level of refrigerant/refrigerant by-products in the ambient air, and for performing an action as a function of the signals, the detection controller stopping a ventilation unit for given periods of time to allow the sensor to measure the level of refrigerant/refrigerant by-products in the ambient air during the given periods of time.

Further in accordance with the present application, there is provided a method for monitoring a level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment enclosing a refrigeration unit, comprising: stopping a ventilation unit from circulating air in/out of the closed/semi-closed ventilated environment at given periods of time; measuring the level of refrigerant/refrigerant by-products in the ambient air during the given periods of time; and actuating an alarm if the level of refrigerant/refrigerant by-products is away from a threshold value.

Still further in accordance with the present application, there is provided a method for monitoring a level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment enclosing a refrigeration unit, comprising: temporarily stopping a ventilation unit from circulating air in/out of the closed/semi-closed ventilated environment at given periods of time; measuring the level of refrigerant/refrigerant by-products in the ambient air during the given periods of time; and stopping the refrigeration unit at least partially if the level of refrigerant/refrigerant by-products is above a threshold value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a refrigerant leak-detection system in accordance with a preferred embodiment of the present application; and

FIG. 2 is a flow chart illustrating a method for monitoring a level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment.

 DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, a refrigerant leak-detection system in accordance with a preferred embodiment is generally shown at 10. The detection system 10 operates in association with a refrigeration unit in a closed/semi-closed environment, such as a mechanical room.

In the embodiment of FIG. 1, the refrigeration unit A is confined to a mechanical room B. The refrigeration unit A is typically a mechanical apparatus or apparatuses in which a refrigerant circulates. For instance, the refrigeration unit A is a refrigeration pack having a plurality of compressors, as well as appropriate valves, piping network and/or headers, an oil-separation system (for compressors using oil), satellite compressors, amongst other items. As illustrated in FIG. 1, pipes are connected to the refrigeration unit A for the inflow and outflow of refrigerant to/from the mechanical room B. The mechanical room B typically hosts mechanical equipment, such as the refrigeration unit A, as a function of the nature of the building featuring the mechanical room B.

Mechanical rooms are often provided with ventilation units. In the embodiment of FIG. 1, a ventilation unit C is provided to exhaust ambient air from the mechanical room B. Optionally, the ventilation unit C also lets air into the mechanical room B, for instance to control temperature in the room B, or to ensure the quality of the air in the room.

In a preferred embodiment, the detection system 10 has a leak-detection controller 11 connected to a leak sensor 12 and to an alarm 13.

In the preferred embodiment, the leak-detection controller 11 is provided to control the actuation of the ventilation unit C in view of readings taken by the leak sensor 12. The leak-detection controller 11 stops actuation of the refrigeration unit A in case of emergency, and actuates the alarm 13.

The leak sensor 12 is provided to measure the level of refrigerant or refrigerant by-products in the ambient air of the mechanical room B (for instance in terms of ppm).

The alarm 13 is provided to signal a problem (e.g., refrigerant leak, inoperative leak sensor 12) as detected by the leak sensor 12.

The leak-detection controller 11 is a processing unit (e.g., a computer). The controller 11 is connected to the leak sensor 12 so as to receive reading signals therefrom. The reading signals are associated with a level of refrigerant or refrigerant by-products (hereinafter refrigerant) in the ambient air. The controller 11 is programmed with threshold values for the level of refrigerant in the ambient air, at which safety procedures are triggered, such as actuating the alarm 13, stopping the refrigeration unit A, amongst other examples.

The controller 11 is also connected to the ventilation unit C. More specifically, the constant air circulation in the mechanical room B results in an air change that maintains the level of refrigerant relatively low in the air. Accordingly, the controller 11 has an internal clock that is programmed so as to periodically stop the ventilation unit C for a given amount of time. The periodic stops of the ventilation unit C allow the refrigerant level to increase if there is a leak in the refrigeration unit A. Alternatively, the flow of air of the ventilation unit C may be reduced during these periods.

Accordingly, referring to FIG. 1, the detection system 10 has at least the leak sensor 12 positioned appropriately in the mechanical room B so as to measure the level of refrigerant in the air. The leak-detection controller 11 does not need to be positioned in the room B. Moreover, through appropriate networks, the leak-detection controller 11 can be positioned off-site. It is also considered to provide the leak-detection controller 11 with interfaces, such that the levels of refrigerant can be monitored off-site.

It is considered to operate the leak sensor 12 continuously, and not simply during the periodic stops of the ventilation unit C. Therefore, a leak resulting in a significant increase in the level of refrigerant in the ambient air is likely to be detected sooner.

The alarm 13 is preferably positioned outside the mechanical room B. In an embodiment, the alarm 13 is a visual indicator (e.g., flashing light), or an audio indicator. In another embodiment, in which the leak-detection controller 11 is connected to a control station, the alarm 13 is a signal of any form on a screen of the control station (e.g., pop-up window, warning email, etc.). The alarm is to prompt the operator of the refrigeration unit A to service the refrigeration unit A.

The leak-detection controller 11 is optionally connected to an operating system of the refrigeration unit A. Therefore, in the event that the reading signals obtained from the leak sensor 12 indicate high levels of refrigerant in the ambient air, the controller 11 may temporarily end operation of the refrigeration unit A to stop or reduce the increase in the ambient air of the level of refrigerant.

Now that the components of the refrigerant leak-detection system 10 have been described, an embodiment of a method 20 of operation is set forth, with reference to FIG. 2.

According to Step 21, the ventilation unit C is stopped for a given period of time. The leak-detection controller 10 periodically stops the ventilation unit C from operating. Accordingly, there is limited flow of air into/out of the mechanical room B for a given amount of time. For instance, in every 60 minutes, 5 minutes are dedicated to the periodic stop of the ventilation unit C.

According to Step 22, when the refrigeration unit A is operating but while the ventilation unit C is stopped, the leak sensor 12 measures the level of refrigerant or refrigerant by-products in the ambient air. However, the measures may be constant as well.

The leak-detection controller 11 receives the reading signals from the leak sensors 12 and compares the reading signals to threshold values to determine whether any safety procedure must be initiated. This monitoring is performed throughout the operation of the refrigeration unit A, and not only during the periodic stops of the ventilation unit C. According to Decision 23, it is determined whether the level of refrigerant or refrigerant by-products in the ambient air is outside a given threshold.

According to Step 24, if the level of refrigerant or refrigerant by-products in the ambient air is outside a given threshold, an action is performed by the leak-detection controller 11. Amongst the safety procedures, the controller 11 may trigger the alarm 13 to produce different types of warning signals as a function of the measured level of refrigerant in the ambient air. Optionally, the controller 11 may modify the rate at which measurements are taken by the leak sensor 12, or may increase the number of periodic stops or the duration of the stops. Alternatively, the controller 11 may stop the refrigeration unit A if the measured level of refrigerant in the ambient air is above a maximum threshold.

According to Step 25, if the level of refrigerant or refrigerant by-products in the ambient air is within a given threshold, in an embodiment in which the ventilation unit C is controlled by the leak-detection controller 11, the ventilation unit C is turned back on. Moreover, after Step 24, the ventilation unit C is restarted according to Step 24 to exhaust the refrigerant/refrigerant by-products from the closed environment.

It is pointed out that the leak-detection controller 10 is not necessarily connected to the ventilation unit C. For instance, it is considered to program the ventilation unit C such that it stops automatically at predetermined periods. In such a case, the leak-detection controller 10 does not need to be connected to the ventilation unit C as it does not need to stop its operation.

Claims

1. A refrigerant leak-detection system of the type used to monitor a level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment enclosing a refrigeration unit, comprising:

a sensor positioned in the ventilated environment, the sensor being provided to measure a level of refrigerant/refrigerant by-products in the ambient air; and
a detection controller for receiving signals associated with the level of refrigerant/refrigerant by-products in the ambient air, and for performing an action as a function of the signals, the detection controller stopping a ventilation unit for given periods of time to allow the sensor to measure the level of refrigerant/refrigerant by-products in the ambient air during the given periods of time.

2. The refrigerant leak-detection system according to claim 1, wherein the detection controller is connected to the ventilation unit to control a ventilation of the ventilated environment.

3. The refrigerant leak-detection system according to claim 2, wherein the detection controller modifies a time delay between the given periods of time as a function of the signals received.

4. The refrigerant leak-detection system according to claim 1, wherein the action performed by the detection controller comprises actuating an alarm.

5. The refrigerant leak-detection system according to claim 4, wherein the alarm is a visual alarm on a monitor associated with the detection controller.

6. The refrigerant leak-detection system according to claim 5, wherein the visual alarm is an off-site visual alarm.

7. The refrigerant leak-detection system according to claim 1, wherein the detection controller is connected to the refrigeration unit and the action performed by the detection controller comprises stopping at least partially the refrigeration unit.

8. The refrigerant leak-detection system according to claim 1, wherein the sensor measures the level of refrigerant/refrigerant by-products only during the given periods of time.

9. The refrigerant leak-detection system according to claim 1, wherein the refrigeration unit is a refrigeration pack.

10. A method for monitoring a level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment enclosing a refrigeration unit, comprising:

stopping a ventilation unit from circulating air in/out of the closed/semi-closed ventilated environment at given periods of time;
measuring the level of refrigerant/refrigerant by-products in the ambient air during the given periods of time; and
actuating an alarm if the level of refrigerant/refrigerant by-products is away from a threshold value.

11. The method according to claim 10, wherein stopping the ventilation unit comprises varying the given period of time for stopping the ventilation unit as a function of the measured level of refrigerant/refrigerant by-products.

12. The method according to claim 10, wherein measuring the level of refrigerant/refrigerant by-products in the ambient air comprises measuring the level during the given periods of time and outside the given periods of time.

13. The method according to claim 10, wherein actuating an alarm comprises actuating a visual alarm on a controller monitor for an operator of the refrigeration unit.

14. A method for monitoring a level of refrigerant/refrigerant by-products in ambient air in a closed/semi-closed ventilated environment enclosing a refrigeration unit, comprising:

temporarily stopping a ventilation unit from circulating air in/out of the closed/semi-closed ventilated environment at given periods of time;
measuring the level of refrigerant/refrigerant by-products in the ambient air during the given periods of time; and
stopping the refrigeration unit at least partially if the level of refrigerant/refrigerant by-products is above a threshold value.

15. The method according to claim 14, wherein stopping the ventilation unit comprises varying the given period of time for stopping the ventilation unit as a function of the measured level of refrigerant/refrigerant by-products.

16. The method according to claim 14, wherein measuring the level of refrigerant/refrigerant by-products in the ambient air comprises measuring the level during the given periods of time and outside the given periods of time.

Patent History
Publication number: 20090107157
Type: Application
Filed: Oct 23, 2008
Publication Date: Apr 30, 2009
Inventor: Serge Dube (St-Zotique)
Application Number: 12/256,504
Classifications
Current U.S. Class: Withdrawing Or Adding Refrigerant From Or To Normally Closed System (62/149); Operatively Correlated With Automatic Control (62/126); Processes (62/56)
International Classification: F25B 45/00 (20060101); F25B 49/00 (20060101); F25D 3/00 (20060101);