Patent Publication Number: US-2022228783-A1

Title: Heat exchanger assembly with valve

Description:
RELEVANT APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 63/140,253, filed Jan. 21, 2021, the entire content of which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     Embodiments described herein relate to heat exchangers and, more specifically, evaporators with valve control. 
     Evaporators are commonly arranged within a refrigeration loop with an expansion valve upstream of the evaporator. The expansion valve configuration and operation affects the performance, efficiency, and capacity of the evaporator and the refrigeration system. Expansion valves can control the amount of liquid and vapor distributed to the evaporator. 
     SUMMARY 
     One embodiment provides a method for disrupting a flow of refrigerant through a heat exchanger. The method includes receiving, with a controller, a first signal from a first sensor, the first signal indicative of a pressure of the refrigerant flowing through the heat exchanger. The method includes setting, with the controller, an operating frequency of a valve based on the first signal. The valve regulates refrigerant flow through the heat exchanger. The operating frequency includes a rate at which the valve actuates between a first valve position that sets a first refrigerant flow rate through the heat exchanger and a second valve position that sets a second refrigerant flow rate through the heat exchanger. The method includes controlling, with the controller, operation of a solenoid to actuate the valve at the operating frequency. The refrigerant includes refrigerant in the liquid phase and refrigerant in the gaseous phase. Actuating the valve at the operating frequency disrupts the flow of the refrigerant through the heat exchanger such that when the valve is moved from the first valve position to the second valve position, the refrigerant in the liquid phase is more equally distributed through the heat exchanger. 
     Another embodiment provides a control system for disrupting a flow of refrigerant through a heat exchanger. The control system comprises a valve for regulating the flow of refrigerant through the heat exchanger, a solenoid coupled to the valve that actuates the valve, and a first sensor that provides signals indicative of a pressure of the flow of refrigerant within the heat exchanger. The control system also includes a controller coupled to the solenoid and the sensor, the controller including an electronic processor and a memory. The controller is configured to receive a first signal from the first sensor, set an operating frequency of the valve based on the first signal, and control operation of the solenoid to actuate the valve at the operating frequency. The operating frequency includes a rate at which the valve actuates between a first valve position that sets a first refrigerant flow through the heat exchanger and a second valve position that sets a second refrigerant flow rate through the heat exchanger. The flow of refrigerant includes refrigerant in the liquid phase and refrigerant in the gaseous phase. Actuating the valve at the operating frequency disrupts the flow of the refrigerant through the heat exchanger such that, when the valve is moved from the first valve position to the second valve position, the refrigerant in the liquid phase is more equally distributed through the heat exchanger. 
     Another embodiment provides a heat exchanger assembly comprising a heat exchanger core, a valve, a solenoid, a first sensor, and a controller. The heat exchanger core includes a refrigerant channel, an inlet manifold, and an outlet manifold. The valve is configured to regulate refrigerant flow into the heat exchanger core. The solenoid actuates the valve between a first valve position that sets a first refrigerant flow rate through the heat exchanger core and a second valve position that sets a second refrigerant flow rate through the heat exchanger core. The first sensor is configured to provide signals indicative of characteristics of the flow of refrigerant through the heat exchanger core. The controller includes an electronic processor and a memory. The controller is configured to receive a first signal from the first sensor, set an operating frequency of the valve based on the first signal, and control operation of the solenoid to actuate the valve at the set operating frequency. The operating frequency is the rate at which the valve actuates between the first valve position and the second valve position. 
     Other features, aspects, and benefits of various embodiments will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a general heat exchanger assembly with an expansion valve configuration according to one embodiment. 
         FIG. 2  is a schematic view of a distribution valve of a heat exchanger assembly according to one embodiment. 
         FIG. 3  is a schematic view of the distribution valve of  FIG. 2  according to one embodiment. 
         FIG. 4  is a schematic view of the distribution valve of  FIG. 2  according to another embodiment. 
         FIG. 5  is a schematic view of the distribution valve of  FIG. 2  according to another embodiment. 
         FIG. 6A  is a schematic view of the embodiment of  FIG. 5  according to one embodiment. 
         FIG. 6B  is a schematic view of the embodiment of  FIG. 5  according to one embodiment. 
         FIG. 6C  is a schematic view of the embodiment of  FIG. 5  according to one embodiment. 
         FIG. 7  is a block diagram of a control system of the heat exchanger assembly  FIG. 1  according to one embodiment. 
         FIG. 8  is a block diagram of a method performed by the control system of  FIG. 7  according to one embodiment. 
         FIGS. 9A  is side view of the expansion valve configuration of  FIG. 1  according to one embodiment. 
         FIG. 9B  is another side view of the expansion valve configuration of  FIG. 1  according to one embodiment. 
         FIG. 10  is a pressure-enthalpy graph for a valve actuation cycle according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     A heat exchanger assembly of  FIG. 1  includes a heat exchanger core  10  having plates  12  stacked to form alternating coolant channels  11  and refrigerant channels  13 . The coolant channels  11  and refrigerant channels  13  are in thermal contact with each other. The plates  12  extend from a bottom plate to a top plate  16 . The core  10  includes a coolant inlet and a coolant outlet. A connection block  20  extends from the top plate  16  of the core  10 , the connection block  20  being sealed to the core  10  by brazing, welding, or other joining methods. The connection block  20  includes an inlet  22  and an outlet. A connection block inlet channel  26  extends from the inlet  22  to an inlet manifold  15  of the core  10 . 
     A valve assembly  30  is provided on or in the connection block  20 . The valve assembly  30  includes a driving mechanism  70 , which may be a solenoid or motor, such as a stepper or servo motor. The driving mechanism  70  actuates a valve  72  to open and close the valve  72  to regulate a flow of refrigerant  90  into the core  10 . The valve assembly  30  has a valve assembly refrigerant channel  38  that is aligned with the connection block inlet channel  26  at least at one end of the valve assembly refrigerant channel  38  to provide refrigerant flow to the core  10 . 
     In some embodiments, the valve  72  is actuated in a pulsing manner to reset (e.g., disrupt) the flow of refrigerant and prevent an equilibrium state of the two phases (i.e., the gas and the liquid phase of the refrigerant  90 ) of the refrigeration within the heat exchanger assembly. This mitigates the dry out of the refrigerant flow channels  13  within the core  10 . During an equilibrium state refrigerant channels  13  with more liquid refrigerant would have less pressure drop and are a path of least resistance for more liquid refrigerant flow. This lessens the flow of liquid (i.e., increases the drying out) of other refrigerant channels  11 . Pulsing or cycling the valve  72  prevents this condition and provides more equal distribution of liquid refrigerant to all of the refrigerant flow channels  11 . Additionally, pulsing or cycling the valve  72  improves the performance of the evaporator by providing the more equal distribution of liquid refrigerant to all of the refrigerant flow channels  11 . 
       FIG. 2  provides another embodiment where a distribution valve assembly  40  is located downstream of the valve assembly  30 . The distribution valve assembly  40  includes a first valve  42  that moves independently of an included second valve  46 . The first valve  42  has a first valve arm  44  with an inner channel. A second valve arm  50  is situated within the inner channel of the first valve arm  44  and translates by the second valve  46 . Both the first valve  42  and the second valve  46  are driven by a second driving mechanism (not shown). Springs  18 ,  52  are included with the distribution valve assembly  40  to allow independent travel between the first valve  42  and the second valve  46 . The first and second valves can be seated against first and second valve seats  54 ,  56 .  FIG. 3  schematically shows the flow of refrigerant through the distribution valve assembly  40 . As shown in  FIG. 3 , the flow of refrigerant  90  enters the distribution valve assembly  40  at both ends. The first and second valves  42 ,  46  may be actuated such that the flow of refrigerant  90  is distributed to refrigerant channels  11  in a mostly liquid state, again being cycled to prevent an equilibrium of liquid and vaper within the heat exchanger. 
       FIG. 4  shows another embodiment of the heat exchanger assembly including an air to liquid heat exchanger core  110 . The core  110  includes an inlet manifold  112  and an outlet manifold  114 . Refrigerant flow tubes  116  extend between the inlet manifold  112  and the outlet manifold  114 . The valve assembly  30  of  FIG. 1 , as discussed above, is fluidly connected to the inlet manifold  112  and is located upstream of the inlet manifold  112 . In some embodiments, the distribution valve assembly  40  of the alternative embodiment of  FIGS. 2 and 3  is also be included within this core  110 . In embodiments where the distribution valve assembly  40  is included, refrigerant connections (not shown) are included between the valve assembly  30  and the opposites sides of the inlet manifold  112  to provide the flow of refrigerant  90  to the opposite sides of the inlet manifold  112 . The distribution valve assembly  40  is actuated as described above. The flow of refrigerant  90  moves from the inlet manifold  112  through the tubes  116  to the outlet manifold  114  to transfer heat between air and the flow of refrigerant  90  within the tubes  116 . The flow of refrigerant then exits the core  110  at an outlet port of the outlet manifold  114 . 
       FIGS. 5 and 6A-6C  depict another embodiment where the heat exchanger assembly includes a core  210  formed from a stack of plates  212 . The core  210  includes refrigerant inlet manifolds  218  and a refrigerant outlet manifold  220 . The core  210  also includes a coolant inlet manifold  214  and a coolant outlet manifold  216 . The plates  212  are stacked to provide refrigerant channels  230  that alternate with coolant channels  232  to transfer heat between adjacent refrigerant and coolant channels. This embodiment also includes the valve assembly  30  arranged upstream of the inlet manifolds  218 . The valve assembly  30  is controlled to cycle to reset the refrigerant preventing equilibrium of the liquid and vapor within the core. Thus, liquid flow is reset at the entrance of the inlet manifolds  218 . In some embodiments, the core  210  includes only a single inlet manifold  218 . Such embodiments may include the distribution valve assembly  40 , which is shown in  FIG. 5  and operates as described above. Refrigerant lines (not shown) are provided from the valve assembly  30  to opposite sides of the distribution valve assembly  40 , which is contained within a valve housing or channel. The distribution valve assembly  40  selectively directs the flow of refrigerant to one of the inlet manifold  218 . 
       FIG. 7  provides a control system  700  for the heat exchanger assembly of  FIG. 1 . The control system  700  includes a controller  705 , a compressor sensor  720 , a temperature sensor  725 , a pressure sensor  730 , and the driving mechanism  70 . In some embodiments, the control system  700  may include only a single one of the compressor sensor  720 , the temperature sensor  725 , the pressure sensor  730 , or otherwise any combination thereof. For example, in some preferred embodiments, the temperature sensor  725  and the pressure sensor  730  are included in the control system  700 . The controller  705  includes an electronic processor  710  (for example, a programmable microprocessor, a microcontroller, programmable logic controller, or other suitable device) and a memory  715 . 
     The memory  715  is a non-transitory computer readable medium that includes, for example, a program storage area and a data storage area. The program storage area and the data storage area can include combinations of different types of memory, for example read-only memory (“ROM”), random access memory (“RAM”) (for example, dynamic RAM [“DRAM”], synchronous DRAM [“SDRAM”], etc.), electrically erasable programmable read-only memory (“EEPROM”), flash memory, a hard disk, an SD card, or other suitable magnetic, optical, physical, or electronic memory devices. In one example, the electronic processor  710  is connected to the memory  715  and executes software instructions that are capable of being stored in a RAM of the memory  715  (for example, during execution), a ROM of the memory  715  (for example, on a generally permanent basis), or another non-transitory computer-readable medium. Software included in the implementation of the driving mechanism  70  can be stored in the memory  715 . The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The electronic processor  710  is configured to retrieve from the memory  715  and execute, among other things, instructions related to the control processes and methods described herein. 
     The compressor sensor  720  is configured to provide signals to the controller  705  indicative of the rotation speed (e.g., a rate per minute [RPM]) of a compressor (not shown) that drives refrigerant through the heat exchanger assembly of  FIG. 1 . The speed of the compressor impacts the overall pressure of the refrigerant in the heat exchanger assembly, which will impact the ratio of liquid versus gaseous refrigerant within the system. As a result, the compressor speed may indicate a total refrigerant capacity of the heat exchanger assembly even though the volume of the heat exchanger assembly remains fixed. 
     The temperature sensor  725  is configured to provide signals to the controller  705  indicative of a temperature of the refrigerant  90 . The temperature sensor  725  may detect the temperature of the refrigerant  90 , for example, at the inlet manifold  112 , the outlet manifold  114 , the refrigerant inlet manifolds  218 , the refrigerant outlet manifold  220 , or another location having a flow of the refrigerant  90 . The pressure sensor  730  is configured to provide signals to the controller  705  indicative of a pressure of the refrigerant  90 . The pressure sensor  730  may detect a pressure of the refrigerant  90 , for example, at the inlet manifold  112 , the outlet manifold  114 , the refrigerant inlet manifolds  218 , the refrigerant outlet manifold  220 , or another location. 
     As previously stated, the valve  72  may be actuated in a pulsing manner to reset (e.g., disrupt) the flow of refrigerant and prevent an equilibrium state of the two phases of the refrigerant within the heat exchanger assembly.  FIG. 8  provides a method  800  performed by the controller  705  for resetting the flow of refrigerant. At block  805 , the controller  705  receives temperature signals from the temperature sensor  725 . The controller  705  may determine a temperature of the refrigerant  90  based on the temperature signals. At block  810 , the controller  705  receives pressure signals from the pressure sensor  730 . The controller  705  may determine a pressure of the refrigerant  90  based on the pressure signals. At block  815 , the controller  705  receives speed signals from the compressor sensor  720 . The controller  705  may determine a speed of the compressor based on the speed signals. 
     At block  820 , the controller  705  sets an operating frequency based on at least one of the temperature signals, the pressure signals, and the speed signals. For example, the memory  715  may store a control curve used by the controller  705  to set the operating frequency. The temperature of the refrigerant  90 , the pressure of the refrigerant  90 , and the speed of the compressor may be used as inputs to the control curve. The operating frequency may be set to a value between approximately 0 Hz and 500 Hz. In some embodiments, the operating frequency is set to a value between approximately 80 Hz and 250 Hz. When the operating frequency is set to 0 Hz, the controller  705  may be configured to reset the valve  72  (and therefore flow of the refrigerant  90 ) after a predetermined time period has been satisfied. For example, the controller  705  resets the valve  72  every 5 minutes, every 10 minutes, or the like. 
     At block  825 , the controller  705  controls opening and closing of the valve  72  (i.e., actuation of the valve  72 ) according to the operating frequency. For example, the controller  705  may provide a pulse width modulation (PWM) signal having the set operating frequency to the driving mechanism  70  (e.g., the solenoid or motor). The valve  72  then opens and closes at a frequency equal to the operating frequency. In some embodiments, opening and closing the valve  72  includes moving the valve  72  from a minimum movement position (e.g., a first valve position) to a maximum movement position (e.g., a second valve position). For example, the valve  72  may move from a location that is 0% of possible actuation (which allows no refrigerant flow or minimum refrigerant flow to pass through the valve  72 ) to a location that is 100% of possible actuation (which allows maximum refrigerant flow through the valve  72 ). In other embodiments, opening and closing the valve  72  includes moving the valve  72  from a percentage of possible movement, such as from 20% of possible actuation to 99% of possible actuation. Flow rates through the valve  72  correlate to the percentage of possible movement of the valve. The correlation can be linear, exponential, or another correlation. A flow rate of the refrigerant  90  may be different at the first valve position than the second valve position. For example, when the first valve position is a closed position, the flow rate of the refrigerant  90  is significantly less than when compared to when the first valve position is a fully opened position. 
     At block  830 , the controller  705  continues to monitor and/or receive at least one new temperature, pressure, and new speed signals from the temperature sensor  725 , the pressure sensor  730 , and the compressor sensor  720 , respectively. At block  835 , the controller  705  adjusts the operating frequency based on the new temperature, pressure and speed signals. For example, the new temperature, pressure, and speed signals are compared to the control curve stored in the memory  715 . The controller  705  then returns to block  825  to control opening and closing of the valve  72  according to the adjusted operated frequency. In this manner, the controller  705  adjusts the operating frequency as conditions of the refrigerant  90  change throughout operation of the heat exchanger assembly. 
     In some embodiments, the controller  705  may only use a single one of the temperature signals, the pressure signals, or the speed signals to set the operating frequency of the valve  72 . For example, the control curve stored in the memory  715  may provide an operating frequency for a given temperature, a given pressure, or a given speed of the compressor. In other embodiments, the controller  705  may use any combination of two of the temperature, pressure, and speed signals to set the operating frequency of the valve  72 . In yet other embodiments, the controller  705  no sensor signal to set the operating frequency of the valve  72 , and instead sets and/or adjusts the operating frequency of the valve  72  based on a value stored in the memory  715 . 
     In some situations, control of the valve  72  to exactly 100% of it&#39;s actuation range (e.g., the closed position) may be difficult. Further slamming of the valve  72  to the closed position may be detrimental to the system. Additionally, some systems may not be capable of precise actuation of the valve  72  to a given position. Accordingly, in some embodiments, the valve  72  includes an internal passage  900 , shown in  FIGS. 9A and 9B .  FIG. 9A  illustrates the valve  72  in an open position. When the valve  72  is opened, the internal passage  900  is in a closed position.  FIG. 9B  illustrates the valve  72  in a closed position. When the valve  72  is closed, the internal passage  900  is in an open position, and allows a metered flow of refrigerant  90  to pass through the valve  72 . The metered flow is dependent on the size (e.g., diameter) of the internal passage  900 . The metered flow functions to avoid the “slamming” full closure of the valve  72 , and thus extends the life of the system. Further, in cases where precise actuation of the system is not possible, the valve  72  can still operate to actuate the valve between extreme valve positions, which does not require precise actuation. However, the internal passage  900  functions such that the flow of refrigerant is subjected to a valve position between 100% (the fully open position) and the metered flow (at the “closed” position). As a result, the valve  72  actuates between 100% flow and the metered flow without precise control of the valve  72 . 
       FIG. 10  provides a pressure-enthalpy (“P-h”) graph  1000  for a given temperature. The pressure-enthalpy graph  1000  illustrates how actuation of the valve  72  influences the cycle of pressure and enthalpy for the refrigerant  90 . The three indicated lines on the graph  1000  represent three different operating positions of the valve  72 . The “target condition” represents the fixed position that a non-oscillating valve would be in. The “Valve max” and “Valve min” lines represent the two positions an oscillating valve as described herein would cycle between. The “Valve max” line on the P-h graph yields a minimum pressure drop through the valve  72  and the “Valve min” line on the P-h graph yields a maximum pressure drop through the valve  72 . By oscillating, the valve  72  achieves the “target condition” even though the valve  72  is not held in a fixed position. 
     Thus, embodiments provide, among other things, a heat exchanger assembly with valve control. Various features, advantages, and embodiments are set forth in the following claims.