AUTOCASCADE SYSTEM WITH SUPERHEAT CONTROL BASED ON WORKING FLUID CONCENTRATION LEVELS

Abstract

An autocascade heat transfer fluid circuit includes an evaporator, a sub-cooler, a heat exchanger, a compressor, a condenser, a working fluid concentration sensor, a pressure sensor, a temperature sensor, and a unit controller. The unit controller converts properties of respective components of a working fluid flowing through the heat transfer fluid circuit; receive a temperature and pressure of the working fluid; convert the received properties, temperature, and pressure of the working fluid into concentration percentages for the respective components of the working fluid; determine a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and control an expander to regulate a flow of the working fluid into an evaporator based on the determined suction super heat of the working fluid.

Claims

1. A controller method of operating an autocascade heat transfer fluid circuit, comprising: receiving properties of respective components of a working fluid flowing through an autocascade heat transfer fluid circuit; receiving a temperature and pressure of the working fluid; converting the received properties, temperature, and pressure of the working fluid into concentration percentages for the respective components of the working fluid; determining a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and controlling an expander to regulate a flow of the working fluid into an evaporator.

2. The controller method of claim 1, wherein the properties of the respective components of the working fluid are determined by a fluid property sensor.

3. The controller method of claim 1, wherein the properties of the respective components of the working fluid include speed of sound.

4. The controller method of claim 1, wherein the properties of the respective components of the working fluid include density.

5. The controller method of claim 1, wherein the converting includes mapping the percentages for the respective components of the working fluid against the received temperature and pressure of the working fluid.

6. The controller method of claim 1, wherein the controlling includes: opening the expander to increase a volume of working fluid in the evaporator when the determined suction super heat of the working fluid exceeds a threshold value; or closing the expander to decrease a volume of a working fluid in the evaporator when the determined suction super heat of the working fluid is below the threshold value.

7. A controller method of operating an autocascade heat transfer fluid circuit, comprising: receiving properties of respective components of a working fluid flowing through an autocascade heat transfer fluid circuit; receiving a temperature and pressure of the working fluid; converting the received properties, temperature, and pressure of the working fluid into concentration percentages for the respective components of the working fluid; determining a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and controlling an expander to regulate a charge of a liquid component of the working fluid within a phase separator.

8. The controller method of claim 7, wherein the properties of the respective components of the working fluid are determined by a fluid property sensor.

9. The controller method of claim 7, wherein the properties of the respective components of the working fluid include speed of sound.

10. The controller method of claim 7, wherein the properties of the respective components of the working fluid include density.

11. The controller method of claim 7, wherein the converting includes mapping the percentages for the respective components of the working fluid against the received temperature and pressure of the working fluid.

12. The controller method of claim 7, wherein the controlling includes controlling the expander to retain a higher level of a component of the working fluid having a higher concentration of the respective component having a higher temperature and lower pressure relative to other components of the working fluid.

13. A heat transfer fluid circuit, comprising: an evaporator; a sub-cooler; a heat exchanger; a compressor; a condenser; a working fluid concentration sensor; a pressure sensor; a temperature sensor; and a unit controller configured to: receive properties of respective components of a working fluid flowing through the heat transfer fluid circuit; receive a temperature and pressure of the working fluid; convert the received properties, temperature, and pressure of the working fluid into concentration percentages for the respective components of the working fluid; determine a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and control an expander to regulate a flow of the working fluid into the evaporator based on the determined suction super heat of the working fluid.

14. The heat transfer fluid circuit of claim 13, wherein the properties of the respective components of the working fluid are determined by a fluid property sensor.

15. The heat transfer fluid circuit of claim 13, wherein the properties of the respective components of the working fluid include speed of sound.

16. The heat transfer fluid circuit of claim 13, wherein the properties of the respective components of the working fluid include density.

17. The heat transfer fluid circuit of claim 13, wherein the converting includes mapping the percentages for the respective components of the working fluid against the received temperature and pressure of the working fluid.

18. The heat transfer fluid circuit of claim 13, wherein the controlling includes: opening the expander to reduce a volume of the working fluid in the evaporator when the determined suction super heat of the working fluid exceeds a threshold value; or closing the expander to increase the volume of the working fluid in the evaporator when the determined suction super heat of the working fluid is below the threshold value.

Description

DRAWINGS

[0012] FIG. 1 shows a schematic of an autocascade system according to at least some of the non-limiting example embodiments described and recited herein.

[0013] FIG. 2 shows a processing flow executed during operation of autocascade system 100, in accordance with at least some embodiments described and recited herein.

[0014] FIG. 3 shows an illustrative computing embodiment, in which any of the controlling functionalities may be implemented, in accordance with at least some embodiments described and recited herein.

DETAILED DESCRIPTION

[0015] This disclosure is directed to heat pump systems, including but not limited to autocascade heat transfer fluid circuit systems, for which liquid-vapor separation properties are utilized to adjust system performance for respective operation conditions.

[0016] In the following detailed description, reference is made to the accompanying drawings, which form a part of the description. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Furthermore, unless otherwise noted, the description of each successive drawing may reference features from one or more of the previous drawings to provide clearer context and a substantive explanation of the current example embodiment. Still, the example embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described and recited herein, as well as illustrated in the drawings, may be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

[0017] Additionally, portions of the present disclosure may be described herein in terms of functional block components and various/or processing operations. It should be appreciated that such functional blocks may be realized by any number of hardware and/or software components configured to perform the specified functions.

[0018] Further still, in the present description and recitation, the following terms may be used, in addition to their accepted meaning, as follows.

[0019] A vapor or gaseous phase of a working fluid, as referenced herein, refers to the working fluid, i.e., refrigerant, in a predominantly gaseous form, with the understanding that some liquid may persist therein due to, e.g., incomplete separation or subsequent partial condensation, etc. The liquid may be present in the predominantly vapor or gaseous phase as, e.g., entrained droplets.

[0020] A liquid phase of the working fluid, i.e., refrigerant, as referenced herein, refers to the working fluid in a predominantly liquid form, with the understanding that some gas or vapor may persist therein due to, e.g., incomplete separation, subsequent evaporation, incomplete condensation, etc.

[0021] Directly upstream or directly downstream, as referenced herein, pertains to fluid lines provided to convey a working fluid between such directly related elements. As referenced herein, upstream and downstream are defined with respect to the direction of flow of the working fluid or a component thereof through the fluid circuit.

[0022] FIG. 1 shows a schematic of autocascade system 100 according to at least some of the non-limiting example embodiments described and recited herein. As depicted, autocascade system 100 includes, at least, compressor 102, condenser 104, phase separator 106, cascade heat exchanger 108, sub-cooler 110, first expander 112, evaporator 114, second expander 116, lubricant separator 118, concentration sensor 120, temperature sensor 122, pressure sensor 124, and controller 126 that is configured to communicate with and/or control other components of autocascade system 100. Although illustrated as discrete components, various components may be divided into additional components, combined into fewer components, or eliminated altogether while being contemplated within the scope of the disclosed subject matter.

[0023] In accordance with the non-limiting example embodiments described and recited herein, the concentration levels of components of the working fluid, i.e., refrigerant, may be determined to serve as a basis for regulating an expander 112, e.g., expansion valve, to control a flow of working fluid from a sub-cooler into an evaporator. That is, if a measured conductive suction superheat is below a threshold level, as determined by operation of compressor 102, which is indicative of too much working fluid being present in the evaporator due to, e.g., overcharging, the expander may be closed to restrict the flow of working fluid to the evaporator. Operation of compressor 102 may establish a threshold level for conductive suction superheat to ensure adequate oil quality in the working fluid. Thus, as a non-limiting example, the threshold conductive suction superheat may be 9 F.; though 5 F. may be a more reliable threshold to take into account compressor 102 being either oil-based or oil-free.

[0024] In accordance with at least some non-limiting example embodiments described and recited herein, controller 126 may be configured to determine optimal suction superheat, based on, e.g., a predetermined mapping, of inlet and/or outlet water temperatures and ambient temperatures.

[0025] Controller 126 may determine an optimum control value for suction superheat that delivers a higher coefficient of performance (COP). Operation may require higher or lower superheat so long as it exceeds the thresholds described above to optimize system performance.

[0026] In addition, another expander 116, e.g., expansion valve, may be controlled based on the determined concentration levels of components of the working fluid to, e.g., regulate a flow of working fluid at the liquid outlet of the phase separator to thereby regulate the concentration of the working fluid that flows through the compressor.

[0027] Expander 116 is provided to optimize refrigerant concentration. For example, expander 116 may be closed to increase concentration of a higher pressure working fluid, e.g., refrigerant, to provide lower water temperatures and/or colder ambient temperatures. Alternatively, expander 116 may be opened to reduce the concentration of the higher pressure working fluid to provide higher water temperatures and/or higher ambient temperatures.

[0028] Controller 126 is further configured to record water temperatures and air temperatures in correspondence to refrigerant concentrations, as operation of system 100 is implemented. Thus, controller 126 is configured to ultimately pair detected water temperatures and air temperatures to an optimal working fluid concentration to produce a highest COP therefore by, e.g., generating a desired concentration of the working fluid. Alternatively, or in addition, controller 126 may pair detected condenser sink temperature and evaporator source temperature, which may be applied to any of water, air, other fluids, etc., in any combination thereof, etc., of water-water, air-water, water-air, air-air heat pumps.

[0029] Autocascade system 100 is configured to circulate a working fluid, i.e., refrigerant, that includes at least two components. The components of the working fluid may include any suitable component such as working fluid compositions, etc., of which non-limiting examples may include R1234ze(E) and carbon dioxide, or the like.

[0030] A working fluid may separate, or be separated, into liquid and vapor phases downstream of compressor 102. Further, the components of the working fluid may have different boiling points from one another. Thus, autocascade system 100 may be configured to allow the liquid and vapor phases to exchange heat with one another as features of the autocascade operation.

[0031] Further still, separated flows of a working fluid may be recombined, with the complete blend exchanging heat with the vapor phase at cascade heat exchanger 108. In accordance with at least some non-limiting example embodiments, autocascade system 100 may include additional phase separators 106 to thereby further concentrate low boiling point fluids in the working fluid supplied to evaporator 114. However, for descriptive purposes only, the embodiments described and recited herein will reference a single phase separator 106.

[0032] Compressor 102 is configured to compress working fluid of autocascade system 100 received at suction 128. Non-limiting examples of compressor 102 may be a screw compressor, a scroll compressor, a centrifugal compressor, etc.

[0033] Condenser 104 is configured to receive compressed working fluid from compressor 102 and to reject heat from the compressed working fluid, e.g., to an ambient environment in a cooling application, to a hot water supply loop, to a heating coil for heating air, or to another suitable medium.

[0034] Phase separator 106 is configured to receive partially condensed working fluid, from which heat has been rejected, from condenser 104, to separate the condensed working fluid into distinct liquid and vapor portions of the working fluid. That is, the working fluid is partially condensed, and low-pressure components are typically found to have higher concentrations in the liquid phase. The remaining vapor components of the working fluid are found to be of higher-pressure. Phase separator 106 separates the phases to exploit the pressure-temperature properties of the vapor to thereby raise evaporator pressure over system 100.

[0035] Liquid level sensor 130, which is optional, included in or attached to phase separator 106, is configured to measure an amount of each resulting liquid contained in phase separator 106. In accordance with at least some non-limiting example embodiments, liquid level sensor 130 may be configured to implement some of the functionalities of concentration sensor 120.

[0036] As shown in the non-limiting example embodiment of FIG. 1, a first component of the working fluid C1 may pass from phase separator 106 to cascade heat exchanger 108.

[0037] Cascade heat exchanger 108 is configured to facilitate heat exchange between first component C1, e.g., carbon dioxide, from phase separator 106 and a second component C2, e.g., R1234ze(E), flowing from one or both of sub-cooler 110 and second expander 116. Working fluid exiting from cascade heat exchanger 108 passes to suction 128 of compressor 102. In at least one non-limiting example embodiment, the exchange of heat at cascade heat exchanger 108 cools the first component from the phase separator 106. It is to be understood that a working fluid may contain two or more components (C1, C2, etc.). In an example embodiment, C1 (a low boiling point component) can be a component that is more volatile than C2 or has a boiling temperature lower or significantly lower than C2. C2 (a high boiling point component) can be a component that is less volatile than C1 or has a boiling temperature higher than or significantly higher C1. In an example embodiment, the boiling temperature of C1 can be e.g., at or around 78 C., and the boiling temperature of C2 can be e.g., at or around 18 C. That is, at or above a predetermined temperature (or at or beyond a predetermined temperature range), C1 can be more likely to be vaporized than C2. Below a predetermined temperature (or below a predetermined temperature range), C2 can be more likely to be liquidized than C1.

[0038] Sub-cooler 110 is configured to facilitate the exchange of heat between the first component exiting from cascade heat exchanger 108 and the first component exiting evaporator 114. Sub-cooler 110 further cools the first component prior to passing to first expander 112.

[0039] First expander 112 is configured to expand the received first component of the working fluid. Non-limiting examples of expander 112 may include, but not be limited to, any suitable expansion valve, e.g., electronic expansion valve (EXV); nozzle; orifice; combinations thereof; etc. That is, expander 112 may be closed to restrict the flow of working fluid to evaporator 114 if a measured conductive superheat is below a threshold level. Accordingly, expander 112 may be communicatively connected to controller 126 or, when a controlling processor is embedded therein, to concentration sensor 120, so that the opening and closing of the expander may be automatically regulated by, e.g., unit controller 126.

[0040] Evaporator 114 is configured to receive the first component of the working fluid from sub-cooler 110, via first expander 112, and expose the first component to heat, i.e., the first component absorbs heat at evaporator 114, to cool the working fluid.

[0041] At sub-cooler 110, the first component of the working fluid passes through to cool the first component on an opposite side of the sub-cooler 110, upstream of first expander 112. The first component that has passed through the sub-cooler 110, after exiting evaporator 114, joins a flow of the second component of the working fluid from second expander 116 to, in turn, flow through cascade heat exchanger 108 to suction 128 of compressor 102.

[0042] Second expander 116 is configured to receive the second component of the working fluid from phase separator 106 and to expand the second component of the working fluid. Non-limiting examples of second expander 116 may include, but not be limited to, any suitable expansion valve, e.g., electronic expansion valve (EXV); nozzle; orifice; combinations thereof; etc. Accordingly, expander 116 may be communicatively connected to controller 126 or, when a controlling processor is embedded therein, to concentration sensor 120, so that the opening and closing of the expander may be automatically regulated.

[0043] After exiting second expander 116, the second component of the working fluid may join the flow of the first component that exits sub-cooler 110 and then flows through cascade heat exchanger 108 to suction 128 of compressor 102.

[0044] Lubricant separator 118, which is optionally included in autocascade system 100, is configured to remove at least portions of lubricant from the working fluid passing there-through from compressor 102, of which lubricant separator 118 is downstream. The lubricant removed from the working fluid may be any compressor lubricant that has dissolved in or entrained in the working fluid.

[0045] Concentration sensor 120 is configured to determine a concentration of the two or more components of the working fluid, i.e., refrigerant. Non-limiting examples of concentration sensor 120 may include an ultrasonic sensor, any suitable chemical concentration sensor, analyzer, etc., that is capable of determining a concentration of a component of the working fluid. Other types of sensors may be utilized as concentration sensor including, but not limited to a non-dispersive infrared (NDIR) sensor.

[0046] As an ultrasonic sensor, concentration sensor 120 may emit high-frequency, e.g., 23 kHz to 40 kHz, sound waves through a working fluid passing therethrough. As a pulse of a soundwave is reflected back to an emitting portion of the ultrasonic sensor, a length of time between emission of the sound wave pulse and reception of the reflected pulse, is utilized to determine the concentration of components of the working fluid based on the speed of sound through the working fluid and/or density of the respective components.

[0047] As a non-limiting example, concentration sensor 120 may emits pulse at 200 kHz through the suction vapor to be received by same controller 126. Controller 126 reports the time it takes for the pulse to traverse the known distance between emitter and receiver, and thus the time and distance to generate the speed of sound may be calculated.

[0048] Controller 126 may be configured, in part, to generate a dataset of pressure, temperature, and speed of sound in relation to concentration and then apply a function fit to embed in the controls, thus establish a strong correlation in speed of sound as concentration of the working fluid changes. It is to be understood that speed of sound is a non-limiting example property that may be utilized by controller 126 to determine concentration of components of a working fluid.

[0049] Concentration sensor 120 may be provided along a flow path for the working fluid, at or near suction 128 of compressor 102. Thus, in accordance with at least some non-limiting example embodiments, concentration sensor 120 may be provided directly upstream of suction 128 of compressor 102 or between an outlet of cascade heat exchanger 108 and suction 128 of compressor 102.

[0050] In accordance with at least some non-limiting example embodiments, concentration sensor 120 is configured and/or dedicated to detect a different component of the working fluid of autocascade system 100 and to transmit the determined or detected concentration value to controller 126. That is, in some non-limiting example embodiments, the detected concentrations of the respective components of the working fluid are transmitted via a wired or wireless connection from concentration sensor 120 to controller 126.

[0051] However, at least one non-limiting example embodiment of system 100, concentration sensor 120, e.g., an ultrasonic sensor, has a controller integrated therein to: receive properties of respective components of a working fluid flowing through the heat transfer fluid circuit, receive or detect a temperature and pressure of the working fluid from the respective sensors, convert the received properties and the received or detected temperature and pressure of the working fluid into concentration percentages for the respective components of the working fluid, determine a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid. In at least one example embodiment, the determined suction super heat is utilized to control, e.g., expander 112 to regulate a flow of the working fluid from a sub-cooler into an evaporator based on the determined suction super heat of the working fluid. In the alterative, or in addition, the determined suction super heat is utilized to control, e.g., expander and 116 to regulate a charge of a liquid working fluid within a phase separator.

[0052] Temperature sensor 122 is configured to measure a temperature of the working fluid and may be disposed at or near one or more of concentration sensors 120 to measure a temperature of a respective component of the working fluid and to transmit the concentration value to controller 126, via a wired or wireless connection. In the alterative, or in addition, the measured temperature may be transmitted to concentration sensor 120 when a controller is integrated within the concentration sensor.

[0053] Furthermore, in accordance with at least some non-limiting alternative example embodiments, temperature sensor 122 may be provided at or near suction 128 of the compressor 102, directly upstream of suction 128 of compressor 102, between an outlet of cascade heat exchanger 108 and suction 128 of compressor 102 and/or at any other suitable location for determining a superheat value suitable for control of the autocascade system 100, e.g., a discharge of compressor 102.

[0054] Pressure sensor 124 is configured to measure a pressure of the working fluid at or near the one or more concentration sensors 120 and to report the measured pressure to controller 126, via a wired or wireless connection. In the alterative, or in addition, the measured pressure may be transmitted to concentration sensor 120 when a controller is integrated within the concentration sensor.

[0055] In accordance with at least some non-limiting example embodiments, pressure sensor 124 may be provided at or near suction 128 of compressor 102, directly upstream of suction 128 of compressor 102, between an outlet of cascade heat exchanger 108 and suction 128 of compressor 102, and/or at any other suitable location for determining a superheat value suitable for control of the autocascade system 100, e.g., a discharge of compressor 102.

[0056] Controller 126 is communicatively coupled to concentration sensor 120, temperature sensor 122, and pressure sensor 124. Accordingly, controller 126 may be configured to, at least, receive the detected properties, i.e., speed of sound and/or density, or determined concentrations of the components of the working fluid, i.e., refrigerant, from one or more concentration sensors 120, the detected and/or measured temperature of a working fluid from temperature sensor 122, and the detected and/or measured pressure of the working fluid from pressure sensor 124. Controller 126 may thus be configured to determine a current composition of the working fluid based on detected properties, e.g., speed of sound and/or density, received from the one or more concentration sensor 120.

[0057] Controller 126 may be communicatively coupled to the one or more sensors by any suitable wired or wireless communications. Similarly, controller 126 may be communicatively coupled to expanders 112 and 116 to control the opening and closing thereof to thereby regulate a passage of fluid therethrough.

[0058] Controller 126 may further be programmed, designed, and/or otherwise configured to control one or more components of the autocascade system 100, including but not limited to first expander 112 and/or second expander 116, based on at least the detected properties of the working fluid or determined concentrations of components of the working fluid received from controller 126. In addition, or in the alternative, controller 126 may be programmed, designed, and/or otherwise configured to control one or more components of the autocascade system 100, including but not limited to first expander 112 and/or second expander 116, based on a mapping of the detected properties or determined concentrations of components of the working fluid received from concentration sensor 120 against the temperature value of the working fluid received from temperature sensor 122 and/or the pressure of the working fluid received from pressure sensor 124.

[0059] Accordingly, controller 126 may be programmed, designed, and/or otherwise configured to convert the received properties, temperature, and pressure of the working fluid into concentration percentages for the respective components of the working fluid, determine a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid, and control expander 112 to regulate a flow of the working fluid from sub-cooler 110 into evaporator 114 based on the determined suction super heat of the working fluid.

[0060] In addition, or alternatively, controller 126 may be programmed, designed, and/or otherwise configured to convert the received properties, temperature, and pressure of the working fluid into concentration percentages for the respective components of the working fluid, determine a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid, and control expander 116 to regulate a charge of a liquid component of within phase separator 106.

[0061] FIG. 2 shows a non-limiting example processing flow executed during operation of autocascade system 100 to utilize the concentration of working fluid components to tune system performance. As depicted, processing flow 200 includes sub-processes executed by various components of controller 126 or, alternatively or in addition, a controller embedded within concentration sensor 120. However, processing flow 200 is not so limited, as obvious modifications may be made by re-ordering two or more of the sub-processes, eliminating or adding operations, etc.

[0062] At 205, controller 126 may receive from concentration sensor 120, properties of respective components of a working fluid flowing through an autocascade heat transfer fluid circuit. As described above, but listed here as non-limiting examples, the properties may include density and/or speed of sound through the working fluid.

[0063] In at least one alternative embodiment, in which concentration sensor 120 has a controller or controlling mechanism embedded therein, concentration sensor 120 may locally detect and determine the properties of the working fluid.

[0064] At 210, controller 126 may receive, from temperature sensor 122 and pressure sensor 124 respectively, a current temperature and pressure of the working fluid as the working fluid exits cascade heat exchanger 108.

[0065] In the alternative embodiment in which concentration sensor 120 has an embedded controller or controlling mechanism, concentration sensor 120 receives the current temperature and pressure from the respective sensors.

[0066] At 215, controller 126 may convert the received properties, temperature, and pressure of the working fluid into concentration percentages for the respective components of the working fluid. That is, based on a predetermined mapping of working fluid properties, to temperature and/or pressure, controller 126 is able to determine a percentage of respective components of the working fluid that has passed through cascade heat exchanger 108.

[0067] In the alternative embodiment in which concentration sensor 120 has an embedded controller or controlling mechanism, the determination of the respective percentages of the components of the working fluid is determined locally at concentration sensor 120.

[0068] At 220, controller 126 may determine a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid. For example, for a working fluid with a known concentration, the detected or measured pressure may be utilized to calculate the saturation temperature, i.e., dew point, of the fluid. A detected or measured difference between the temperature and dew point is the superheat. In accordance with an example embodiment, the dew point calculation has a concentration as an input as well, along with the pressure.

[0069] In the alternative embodiment in which concentration sensor 120 has an embedded controller or controlling mechanism, the calculation of the suction super heat is performed locally at concentration sensor 120.

[0070] At 225, based on the determined suction super heat, controller 126 may transmit instructions to automatically controller expanders 112 and/or 116, respectively and/or individually.

[0071] In the alternative embodiment in which concentration sensor 120 has an embedded controller or controlling mechanism, the transmission of instructions to control expanders 112 and 116, respectively, may originate from concentration sensor 120.

[0072] The instructions to control expander 112 are to regulate a flow of the working fluid from sub-cooler 110 into evaporator 114 based on the determined suction super heat of the working fluid. That is, expander 112 is controlled to be closed if a measured conductive suction superheat is below a threshold level, as determined by compressor 102, which is indicative of too much working fluid being present in the evaporator due to, e.g., overcharging, or be controlled to be opened to increase a volume of a working fluid in the evaporator when the determined suction super heat of the working fluid is below the threshold value.

[0073] The instructions to control expander 116 are to regulate a charge of the liquid components of the working fluid exiting phase separator 106. That is, expander 116 is controlled to optimize refrigerant concentration by, e.g., being closed to to increase concentration of a higher pressure working fluid to provide lower water temperatures and colder ambient temperatures or being opened to reduce the concentration of the higher pressure working fluid to provide higher water temperatures and higher ambient temperatures. Controller 126 is configured to pair detected water temperatures and air temperatures to an optimal working fluid concentration to produce a highest COP therefore.

[0074] Processing flow is periodically or even continually executed during operation of system 100.

[0075] FIG. 3 shows an illustrative computing embodiment, in which the processes for controlling tuning performance of an autocascade heat transfer fluid circuit may be executed.

[0076] In accordance with at least some non-limiting example embodiments, controller 300 may be implemented as a processor or processing device having a network element and/or any other device corresponding thereto, particularly as applicable to the applications and/or programs described above corresponding to system 100.

[0077] In a very basic configuration, processing device 300, e.g., 126 of FIG. 1, may typically include, at least, one or more processors 302, memory 304, one or more input components 306, and one or more output components 308.

[0078] Processor 302 may refer to, e.g., a microprocessor, a microcontroller, a digital signal processor, or any combination thereof.

[0079] Memory 304 may refer to, e.g., a volatile memory, non-volatile memory, or any combination thereof. Memory 304 may store, program data to perform the mapping of detected properties or determined concentrations of components of the working fluid received from concentration sensor 120 against the temperature value of the working fluid received from temperature sensor 122 and/or the pressure of the working fluid received from pressure sensor 124 to thereby determine or determine the suction super heat of the working fluid, which is the basis for controlling expanders 112 and 116, respectively.

[0080] Memory 304 may store executable instructions to implement any of the functions or operations described above and, therefore, memory 304 may be regarded as a computer-readable medium.

[0081] Input component 306 may refer to a built-in component or module to receive input from any and all of concentration sensor 120, temperature sensor 122, and pressure sensor 124.

[0082] Output component 308 may refer to a built-in component or module to output controlling instructions to, respectively, expanders 112 and 116.

[0083] From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

ASPECTS

[0084] Aspect 1. A controller method of operating an autocascade heat transfer fluid circuit, comprising: [0085] receiving properties of respective components of a working fluid flowing through an autocascade heat transfer fluid circuit; [0086] receiving a temperature and pressure of the working fluid; [0087] converting the received properties, temperature, and pressure of the working fluid into concentration percentages for the respective components of the working fluid; [0088] determining a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and [0089] controlling an expander to regulate a flow of the working fluid into an evaporator.

[0090] Aspect 2. The controller method of Aspect 1, wherein the properties of the respective components of the working fluid are determined by a fluid property sensor.

[0091] Aspect 3. The controller method of either Aspect 1 or Aspect 2, wherein the properties of the respective components of the working fluid include speed of sound.

[0092] Aspect 4. The controller method of any of Aspects 1-3, wherein the properties of the respective components of the working fluid include density.

[0093] Aspect 5. The controller method of any of Aspects 1-4, wherein the converting includes mapping the percentages for the respective components of the working fluid against the received temperature and pressure of the working fluid.

[0094] Aspect 6. The controller method of any of Aspects 1-5, wherein the controlling includes: opening the expander to increase a volume of working fluid in the evaporator when the determined suction super heat of the working fluid exceeds a threshold value; or closing the expander to decrease a volume of working fluid in the evaporator when the determined suction super heat of the working fluid is below the threshold value.

[0095] Aspect 7. A controller method of operating an autocascade heat transfer fluid circuit, comprising: [0096] receiving properties of respective components of a working fluid flowing through an autocascade heat transfer fluid circuit; [0097] receiving a temperature and pressure of the working fluid; [0098] converting the received properties, temperature, and pressure of the working fluid into concentration percentages for the respective components of the working fluid; [0099] determining a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and [0100] controlling an expander to regulate a charge of a liquid component of the working fluid within a phase separator.

[0101] Aspect 8. The controller method of Aspect 7, wherein the properties of the respective components of the working fluid are determined by a fluid property sensor.

[0102] Aspect 9. The controller method of either Aspect 7 or Aspect 8, wherein the properties of the respective components of the working fluid include speed of sound.

[0103] Aspect 10. The controller method of any of Aspects 7-9, wherein the properties of the respective components of the working fluid include density.

[0104] Aspect 11. The controller method of any of Aspects 7-10, wherein the converting includes mapping the percentages for the respective components of the working fluid against the received temperature and pressure of the working fluid.

[0105] Aspect 12. The controller method of any of Aspects 7-11, wherein the controlling includes controlling the expander to retain a higher level of a component of the working fluid having a higher concentration of a component having a higher temperature and lower pressure relative to other components of the working fluid.

[0106] Aspect 13. A heat transfer fluid circuit, comprising: [0107] an evaporator; [0108] a sub-cooler; [0109] a heat exchanger; [0110] a compressor; [0111] a condenser; [0112] a working fluid concentration sensor; [0113] a pressure sensor; [0114] a temperature sensor; and [0115] a unit controller configured to: [0116] receive properties of respective components of a working fluid flowing through the heat transfer fluid circuit; [0117] receive a temperature and pressure of the working fluid; [0118] convert the received properties, temperature, and pressure of the working fluid into concentration percentages for the respective components of the working fluid; [0119] determine a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and [0120] control an expander to regulate a flow of the working fluid into an evaporator based on the determined suction super heat of the working fluid.

[0121] Aspect 14. The heat transfer fluid circuit of Aspect 13, wherein the properties of the respective components of the working fluid are determined by a fluid property sensor.

[0122] Aspect 15. The heat transfer fluid circuit of Aspect 13 or Aspect 14, wherein the properties of the respective components of the working fluid include speed of sound.

[0123] Aspect 16. The heat transfer fluid circuit of any of Aspects 13-15, wherein the properties of the respective components of the working fluid include density.

[0124] Aspect 17. The heat transfer fluid circuit of any of Aspects 13-16, wherein the converting includes mapping the percentages for the respective components of the working fluid against the received temperature and pressure of the working fluid.

[0125] Aspect 18. The heat transfer fluid circuit of any of Aspects 13-17, wherein the controlling includes: [0126] opening the expander to increase a volume of working fluid in the evaporator when the determined suction super heat of the working fluid exceeds a threshold value; or [0127] closing the expander to decrease a volume of working fluid in the evaporator when the determined suction super heat of the working fluid is below the threshold value.

[0128] Aspect 19. A controller method of operating an autocascade heat transfer fluid circuit, comprising: [0129] converting properties of respective components of a working fluid flowing through an autocascade heat transfer fluid circuit into concentration percentages for the respective components of the working fluid; [0130] determining a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and [0131] controlling an expander to regulate a flow of the working fluid into an evaporator based on the determined suction super heat of the working fluid.

[0132] Aspect 20. The method of Aspect 19, wherein at least the converting and the determining are executed by a controller integrated into an ultrasonic sensor.

[0133] Aspect 21. The controller method of Aspect 20, [0134] wherein the ultrasonic sensor further detects a temperature and pressure of the components of the working fluid, and [0135] wherein the converting includes mapping the percentages for the respective components of the working fluid against the detected temperature and pressure.

[0136] Aspect 22. The controller method of any of Aspects 19-21, wherein the properties of the respective components of the working fluid include speed of sound.

[0137] Aspect 23. The controller method of any of Aspects 19-22, wherein the properties of the respective components of the working fluid include density.

[0138] Aspect 24. The controller method of any of Aspects 19-23, wherein the controlling includes: [0139] opening the expander to increase a volume of working fluid in the evaporator when the determined suction super heat of the working fluid exceeds a threshold value; or [0140] closing the expander to decrease a volume of a working fluid in the evaporator when the determined suction super heat of the working fluid is below the threshold value.

[0141] Aspect 25. A controller method of operating an autocascade heat transfer fluid circuit, comprising: [0142] converting properties of respective components of a working fluid flowing through an autocascade heat transfer fluid circuit into concentration percentages for the respective components of the working fluid; [0143] determining a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and [0144] controlling an expander to regulate a charge of a liquid component of the working fluid within a phase separator.

[0145] Aspect 26. The controller method of Aspect 25, wherein at least the converting and the determining are executed by a controller integrated into an ultrasonic sensor.

[0146] Aspect 27. The controller method of Aspect 26, [0147] wherein the ultrasonic sensor further detects a temperature and pressure of the components of the working fluid, and [0148] wherein the converting includes mapping the percentages for the respective components of the working fluid against the detected temperature and pressure.

[0149] Aspect 28. The controller method of any of Aspects 25-27, wherein the properties of the respective components of the working fluid include speed of sound.

[0150] Aspect 29. The controller method of any of Aspects 25-28, wherein the properties of the respective components of the working fluid include density.

[0151] Aspect 30. The controller method of any of Aspects 25-29, wherein the controlling includes controlling the expander to retain a higher level of a component of the working fluid having a higher concentration of a component having a higher temperature and lower pressure relative to other components of the working fluid.

[0152] Aspect 31. A heat transfer fluid circuit, comprising: [0153] an evaporator; [0154] a sub-cooler; [0155] a heat exchanger; [0156] a compressor; [0157] a condenser; [0158] an ultrasonic sensor configured to: [0159] receive properties of respective components of a working fluid flowing through the heat transfer fluid circuit; [0160] detect a temperature and pressure of the working fluid; [0161] convert the received properties and the detected temperature and pressure of the working fluid into concentration percentages for the respective components of the working fluid; [0162] determine a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and [0163] control an expander to regulate a flow of the working fluid into an evaporator based on the determined suction super heat of the working fluid.

[0164] Aspect 32. The heat transfer fluid circuit of Aspect 31, wherein the properties of the respective components of the working fluid include speed of sound.

[0165] Aspect 33. The heat transfer fluid circuit of Aspect 31 or Aspect 32, wherein the properties of the respective components of the working fluid include density.

[0166] Aspect 34. The heat transfer fluid circuit of any of any of Aspects 31-33, wherein the converting includes mapping the percentages for the respective components of the working fluid against the detected temperature and pressure of the working fluid.

[0167] Aspect 35. The heat transfer fluid circuit of any of Aspects 31-34, wherein the ultrasonic sensor is to control the expander by: [0168] opening the expander to increase a volume of working fluid in the evaporator when the determined suction super heat of the working fluid exceeds a threshold value; or [0169] closing the expander to decrease a volume of a working fluid in the evaporator when the determined suction super heat of the working fluid is below the threshold value.

[0170] Aspect 36. A heat transfer fluid circuit, comprising: [0171] an evaporator; [0172] a sub-cooler; [0173] a heat exchanger; [0174] a compressor; [0175] a condenser; [0176] an ultrasonic sensor configured to: [0177] receive properties of respective components of a working fluid flowing through the heat transfer fluid circuit; [0178] detect a temperature and pressure of the working fluid; [0179] convert the received properties and the detected temperature and pressure of the working fluid into concentration percentages for the respective components of the working fluid; [0180] determine a suction super heat of the working fluid based on the concentration percentages for the respective components of the working fluid; and [0181] control an expander to regulate a charge of a liquid component of within a phase separator.

[0182] Aspect 37. The heat transfer fluid circuit of Aspect 36, wherein the properties of the respective components of the working fluid include speed of sound.

[0183] Aspect 38. The heat transfer fluid circuit of Aspect 36 or Aspect 37, wherein the properties of the respective components of the working fluid include density.

[0184] Aspect 39. The heat transfer fluid circuit of any of any of Aspects 36-38, wherein the converting includes mapping the percentages for the respective components of the working fluid against the detected temperature and pressure of the working fluid.

[0185] Aspect 40. The heat transfer fluid circuit of any of Aspects 36-39, wherein the controlling includes controlling the expander to retain a higher level of a component of the working fluid having a higher concentration of a component having a higher temperature and lower pressure relative to other components of the working fluid.

[0186] The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.