Patent Application
20130285822
The present disclosure relates to climate control systems for providing conditioned air to a space, and more specifically to refrigerant charge level of a cooling system for a space.
This section provides background information related to the present disclosure which is not necessarily prior art.
Refrigeration systems generally require a significant amount of energy to operate, and represent a significant portion of energy costs. As a result, it is in the consumers' best interest to closely monitor the performance of their air conditioner or heat pump systems to maximize their efficiency, thereby reducing operational costs. For example, the refrigerant charge level in the air conditioner or heat pump may become low due to losses during operation, which hinders the efficiency and ability of the system to provide adequate cooling. However, monitoring system performance typically involves tedious and time-consuming tasks utilizing temperature measuring equipment that may require expertise to accurately analyze refrigerant temperature data and relate that data to system performance and efficiency.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
Various embodiments of a system are provided for monitoring a refrigerant charge level in an air conditioner or heat pump. An exemplary embodiment of a system includes first and second sensors. The first sensor is operable to provide an output indicative of a sensed refrigerant liquid temperature of a liquid refrigerant line that is within or extending from an outlet of a condenser coil of an air conditioner or heat pump unit. The second sensor is operable to provide an output indicative of a sensed refrigerant liquid pressure in the liquid refrigerant line. A controller is configured to determine at least one target pressure value from the output indicative of the sensed refrigerant liquid temperature of the liquid refrigerant line. The controller is configured to determine if the level of refrigerant charge is at, above, or below an acceptable level based on a comparison of the output indicative of sensed refrigerant liquid pressure to the at least one target pressure value.
According to other aspects of the present disclosure, there are exemplary embodiments of methods for monitoring refrigerant charge level in an air conditioner or heat pump unit. In an exemplary embodiment, there is a method for monitoring refrigerant charge. This method includes sensing and providing a first output indicative of a sensed refrigerant liquid temperature of a liquid refrigerant line that is within or extending from an outlet of a condenser coil of an air conditioner or heat pump unit. This method also includes sensing and providing a second output indicative of a sensed refrigerant liquid pressure in the liquid refrigerant line. The method further includes determining at least one target pressure value from the output indicative of the sensed refrigerant liquid temperature of the liquid refrigerant line, and determining if the level of refrigerant charge is at, above, or below an acceptable level based on a comparison of the output indicative of sensed refrigerant liquid pressure to the at least one target pressure value.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
According to one aspect of the present disclosure, various embodiments of a system are provided for monitoring a refrigerant charge level in an air conditioner or heat pump. An exemplary embodiment of a system includes first and second sensors. The first sensor is operable to provide an output indicative of a sensed refrigerant liquid temperature of a liquid refrigerant line that is within or extending from an outlet of a condenser coil of an air conditioner or heat pump unit. The second sensor is operable to provide an output indicative of a sensed refrigerant liquid pressure in the liquid refrigerant line. A controller is configured to determine at least one target pressure value from the output indicative of the sensed refrigerant liquid temperature of the liquid refrigerant line. The controller is configured to determine if the level of refrigerant charge is at, above, or below an acceptable level based on a comparison of the output indicative of sensed refrigerant liquid pressure to the at least one target pressure value. The system may also include a display that displays an indication of whether the level of refrigerant charge is at, above, or below an acceptable level.
According to other aspects of the present disclosure, there are exemplary embodiments of methods for monitoring refrigerant charge level in an air conditioner or heat pump unit. In an exemplary embodiment, there is a method for monitoring refrigerant charge. This method includes sensing and providing a first output indicative of a sensed refrigerant liquid temperature of a liquid refrigerant line that is within or extending from an outlet of a condenser coil of an air conditioner or heat pump unit. This method also includes sensing and providing a second output indicative of a sensed refrigerant liquid pressure in the liquid refrigerant line. The method further includes determining at least one target pressure value from the output indicative of the sensed refrigerant liquid temperature of the liquid refrigerant line, and determining if the level of refrigerant charge is at, above, or below an acceptable level based on a comparison of the output indicative of sensed refrigerant liquid pressure to the at least one target pressure value. The method may also include displaying an indication of whether the level of refrigerant charge is at, above, or below an acceptable level, as explained herein.
Referring to
According to one aspect of the present disclosure, a system for monitoring refrigerant charge level is provided. The system includes a first sensor 102 that provides an output indicative of a sensed refrigerant liquid temperature of a liquid refrigerant line 26 that is within or extending from an outlet of a condenser coil 24 of the air conditioner or heat pump 20. At exit of the condenser, the refrigerant will be liquid after having been condensed from vapor at the inlet. Accordingly, the first sensor 102 is operable for sensing refrigerant liquid temperature of the liquid line 26 at the exit or outlet of the condenser coil 24. As the refrigerant is liquid not vapor at the exit or outlet of the condenser, the first sensor 102 is thus not sensing refrigerant vapor temperature.
The system further includes a second sensor 104 that provides an output indicative of a sensed refrigerant liquid pressure in the liquid refrigerant line 26 that is within or extending from the outlet of condenser coil 24. Again, the refrigerant will be liquid at the exit of the condenser after having been condensed from vapor at the inlet. Accordingly, the second sensor 104 is operable for sensing refrigerant liquid pressure of the liquid line 26 at the exit or outlet of the condenser coil 24. As the refrigerant is liquid not vapor at the exit or outlet of the condenser, the second sensor 104 is thus not sensing refrigerant vapor pressure.
The first and second sensors 102, 104 are operable for sensing temperature and pressure, respectively, of the liquid line 26 at the exit of the condenser. By way of background, a liquid line may be generally considered to be the line connected to an outlet of a condenser to a pressure reduction device, e.g., a throttle or orifice at the entry to an evaporator.
With continued reference to
The controller 100 includes or is in communication with a display 106 that displays an indication of whether the level of refrigerant charge is at, above, or below an acceptable level. The system may be in the form of a monitoring control having a controller 100 in communication with the first sensor 102, second sensor 104, and display 106. The system may alternatively, for example, have a controller 100 associated with a defrost control. The controller 100 may also be incorporated into a unitary control that is configured to connect a power source to activate at least a compressor 22 of an air conditioner or heat pump 20, as explained herein.
Referring to
The unitary control 124 includes a controller 100, which may be a 28 pin PIC16F microprocessor manufactured by Microchip, for example, which includes a plurality of Analog to Digital data inputs for receiving information from various inputs, such as the first sensor 102 and second sensor 104 for respectively sensing temperature and pressure for a liquid refrigerant line within or extending from a condenser coil 24 as shown in
In the above embodiment, the controller 100 in
In an air conditioner or heat pump 20, the level of resulting high side pressure of the refrigerant is dependent on operation of the compressor 22 and other factors, which may include ambient temperature, compressor suction pressure and refrigerant level. Accordingly, the refrigerant exiting the compressor 22 may be at a given pressure level when it enters the condenser coil 24, where the refrigerant cools to a saturation temperature at which the refrigerant transitions from a vapor state to a liquid state. Thus, refrigerant leaving the outlet of the condenser coil 24 is in a liquid state.
Based on a known temperature-pressure curve relationship of saturation temperature—saturation pressure for given refrigerants, it is possible to convert the sensed temperature of refrigerant in a saturated liquid state to a corresponding saturation pressure, and to convert pressure of refrigerant in a saturated state to a saturation temperature. The sensed pressure of refrigerant in a saturated liquid state corresponds to a given saturation temperature, which differs from the sensed temperature of liquid refrigerant by a “sub-cool” amount that represents the extent that refrigerant is cooled below saturation temperature.
The “sub-cooled” liquid refrigerant at the condenser coil outlet has a sensed temperature that is below the refrigerant's saturation temperature:
T
SENSED
=T
SATURATION
−T
SUBCOOL),(TSUBCOOL=TSATURATION−TSENSED)
Likewise, the “sub-cooled” liquid refrigerant should be at a pressure that is below the saturation pressure. Accordingly, a target pressure may be determined by a conversion (using temperature-pressure relationship), of the sensed temperature of the liquid refrigerant line 26 plus a “sub-cool” amount, into a corresponding pressure value, as shown below:
T
SENSED
+T
SUBCOOL
=T
SAT; convert to pressure=PTARGET (Equ. 1)
A plurality of target pressure values representing various ranges (e.g., above, below or within an acceptable refrigerant level) are determined by:
T
SAT TARGET A
=T
SENSED
+T
A, which converted to pressure→PA
T
SAT TARGET B
=T
SENSED
+T
B, which converted to pressure→PB
T
SAT TARGET C
=T
SENSED
+T
C, which converted to pressure→PC
T
SAT TARGET D
=T
SENSED
+T
D, which converted to pressure→PD
T
SAT TARGET E
=T
SENSED
+T
E, which converted to pressure→PE
where TC is a median value=TSUBCOOL (see TSUBCOOL equation).
where TA, TB, TC, TD, and TE above (as are A, B, C, D, and E in
The stored values TA, TB, TC, TD, and TE may differ from system to system, and may also differ according to ambient air temperature. By way of example, typical values may range from 5° F. to 15° F. (e.g., 5° F., 8° F., 10° F., 12° F., and 15° F., etc.). As shown in
Thus, the controller 100 may be configured to determine at least one target pressure value by converting a sum of the sensed temperature of the liquid refrigerant line 26 and a sub-cool temperature value into a corresponding pressure value based on a temperature-pressure relationship for the refrigerant. Alternatively, the target pressure value may also be determined by converting the temperature of the liquid refrigerant line 26 to a corresponding pressure value (based on temperature-pressure relationship) and further adding a pressure offset corresponding to a proper amount of subcool, as shown below:
P
SATURATION
=P
T CONVERTED
+P
SUBCOOL (Equ. 2)
where PT CONVERTED=TSENSED converted to pressure
A plurality of target pressure values representing various ranges (above, below or within an acceptable refrigerant level) may be determined by:
T
SENSED CONVERTED TO PRESSURE
→P
T CONVERTED
+P
A
=P
SAT TARGET A
T
SENSED CONVERTED TO PRESSURE
→P
T CONVERTED
+P
B
=P
SAT TARGET B
T
SENSED CONVERTED TO PRESSURE
→P
T CONVERTED
+P
C
=P
SAT TARGET C
T
SENSED CONVERTED TO PRESSURE
→P
T CONVERTED
+P
D
=P
SAT TARGET D
T
SENSED CONVERTED TO PRESSURE
→P
T CONVERTED
+P
E
=P
SAT TARGET E
where PC represents an offset corresponding to a proper amount of subcool.
Based on the above, the controller can determine at least one target pressure value by converting sensed temperature into a corresponding pressure value and adding a pressure offset corresponding to a subcool amount. It should be noted that the saturation temperature can be calculated from sensed temperature and pressure of the liquid refrigerant line (for pressures above 150 PSIA) as follows:
T
SAT=−6.161×10−10*PS4+1.328×10−6*PS3−0.001*PS2−0.657*PS−28.92
The “subcool” can be calculated from sensed temperature and pressure of the liquid refrigerant line (for pressures below 150 PSIA) as follows:
T
SAT=−9.327×10−8*PS4+0.0001*PS3−0.012*PS2+1.775*PS·75.417
From the above equations for determining at least one target pressure value, the controller 100 may be configured to compare the output of second sensor 104 that is indicative of sensed refrigerant liquid pressure to the at least one target pressure value above to determine if the sensed refrigerant liquid pressure is below a minimum threshold indicative of a low refrigerant charge, and to cause a display to display an indication of low refrigerant charge. More preferably, the controller 100 is configured to convert the temperature of the liquid refrigerant line 26 to a corresponding pressure, and to determine at least two target pressure values from the sum of the corresponding pressure value and at least two pressure offset values. From the at least two target pressure values, the controller 100 is configured to determine if the output of second sensor 104 indicative of pressure is within or outside of an acceptable range defined by the at least two target pressure values, and to responsively display whether the refrigerant level is within or outside of an acceptable level, respectively.
Referring to
Referring to
In the embodiment shown in
According to another aspect of the present disclosure, various embodiments of a method for monitoring refrigerant charge are provided. The controller described in the various exemplary embodiments is preferably programmed to control operation as shown in
In one preferred embodiment of the above method, the step of determining at least one target pressure value comprises converting at least the sensed temperature of the liquid refrigerant line into a corresponding pressure value based on a temperature-pressure relationship for the refrigerant. More preferably, the step of determining at least one target pressure value comprises converting a sum of the sensed temperature of the liquid refrigerant line 26 (in
While the display described in above embodiment pertains to an isolated control for monitoring refrigerant level, or a unitary control 124, or a defrost control, other embodiments may incorporate the above described monitoring means. For example, in one alternate embodiment, the controller 100 described above may be configured for wireless communication with a thermostat (such as thermostat 30 shown in
Alternatively, the controller 100 may be incorporated into a thermostat (e.g., thermostat 30 shown in
Accordingly, aspects of the present disclosure generally relate to the ability to detect a low or high refrigerant level in a vapor compression air conditioning apparatus, such as a central home air conditioner. Aspects also generally relate to the ability to generate a display of the degree of sub-cooling, e.g., in degrees Fahrenheit. For example, disclosed here are exemplary embodiments of methods that include sensing the temperature of the liquid line, sensing the pressure of the liquid line, and using these sensed temperature and pressure values to determine the degree of sub-cooling and the status of the refrigerant level in the system. In exemplary embodiments, the method may also include adding the sensed temperature to a range of stored temperature values to generate a table of temperature values. Each generated sum for a temperature is converted to an equivalent saturation pressure, to generate a range or table of saturation pressures, derived from the list of temperatures. Then, each of these derived pressure values is compared to the value for the liquid line pressure. The logical comparison of these values to the directly sensed liquid line pressure determines the state of the refrigerant charge in the system. A signal may then be outputs to a display device. For example, a signal may be output to a display device having 5 LEDs such that one of the 5 LEDs is illuminated to indicate to a user the state of refrigerant charge in the system. In addition, this exemplary method also uses the temperature of the liquid line and a calculated saturation temperature from the sensed liquid line pressure to determine a value for the degree of sub-cooling in the system, and then outputs that value to a human readable display, such as a segmented LED.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
This application is a continuation-in-part of U.S. patent application Ser. No. 13/101,516 filed May 5, 2011, which will issue Jun. 18, 2013 as U.S. Pat. No. 8,466,798. The entire disclosure of the above application is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13101516 | May 2011 | US |
| Child | 13917781 | US |
