Cooler suction flow rate limitation controlled by input power or motor current

Abstract

A cooler (22) includes an evaporator (46), a compressor (48) including a prime mover (84), a first pressure sensor (86) for detecting a first pressure in the evaporator (46), a second pressure sensor (88) for detecting a second pressure in a condenser (50), and a controller (100). The controller (100) determines a predicted energy level of the compressor (48) based on the first pressure and the second pressure, the predicted energy level being associated with a droplet flow entering the compressor (48), and compares the predicted energy level with an operating energy level, and modifies at least one of the input power and input current of the prime mover (84) based on the comparison satisfying modification conditions.

Description

[0001] This application is a divisional application of Chinese invention patent application filed on May 30, 2018, with international application number PCT / CN2018 / 089063, national application number 201880093961.8, and entitled "Cooler suction flow restriction controlled by input power or motor current". Background Technology

[0002] Refrigerants can transfer heat between fluids and can be used in a variety of applications, such as heating, ventilation, and air conditioning (HVAC) systems, heat pumps, or organic Rankine cycle (ORC) power generation. Refrigerants can be transported within refrigerant piping systems, which include pipes, fittings, valves, etc. These systems transport refrigerants between various containers and equipment within the HVAC system, such as compressors, turbines, pumps, evaporators, and condensers. Refrigerants can undergo one or more phase changes within the refrigerant piping system, allowing both liquid and vapor refrigerants to exist within the HVAC system. Summary of the Invention

[0003] One embodiment of this disclosure is a cooler. The cooler includes an evaporator that receives a first refrigerant stream, transfers heat to the first refrigerant stream, and outputs a second refrigerant stream. The cooler includes a compressor that receives the second refrigerant stream via a pipe between the evaporator and the compressor. The compressor includes a prime mover that performs work on the second refrigerant stream based on at least one of an input power to the prime mover and an input current to the prime mover. The cooler includes a first pressure sensor that detects a first pressure of refrigerant in the evaporator. The cooler includes a second pressure sensor that detects a second pressure of refrigerant in the condenser of the cooler. The cooler includes a controller that determines a predicted operating level of the compressor based on the first and second pressures, the predicted level being associated with a droplet flow in the second refrigerant stream received by the compressor. The controller compares the predicted level with the operating level of the compressor and modifies at least one of the input power and input current to the prime mover based on the comparison satisfying modification conditions.

[0004] Another embodiment of this disclosure is a method for limiting the suction flow rate of a cooler. The method includes receiving a first pressure from an evaporator pressure sensor connected to an evaporator by a controller. The method includes receiving a second pressure from a condenser pressure sensor connected to a condenser by the controller. The method includes determining a predicted operating level of the compressor by the controller based on the first and second pressures, the predicted level being associated with droplet flow from the evaporator to the condenser. The method includes comparing the predicted level with the operating level of the compressor by the controller. The method includes modifying at least one of the input power and input current to the prime mover of the compressor based on the comparison satisfying modification conditions.

[0005] Another embodiment of this disclosure is a cooler controller. The cooler controller includes one or more processors and a memory device storing computer-readable instructions, which, when executed by the one or more processors, cause the one or more processors to: receive a first pressure at a state detector from an evaporator pressure sensor connected to an evaporator; receive a second pressure at the state detector from a condenser pressure sensor connected to a condenser; determine a predicted energy level for compressor operation by an energy predictor based on the first pressure and the second pressure, the predicted energy level being associated with droplet flow from the evaporator to the condenser; compare the predicted energy level with an operating energy level by a compressor controller; and modify at least one of the input power and input current of the prime mover of the compressor based on the comparison satisfying modification conditions.

[0006] Those skilled in the art will recognize that the invention described herein is illustrative only and is not intended to be limiting in any way. Other aspects, inventive features, and advantages of the apparatus and / or process described herein, as defined only by the claims, will become clear from the detailed description set forth herein and taken in conjunction with the accompanying drawings. Attached Figure Description

[0007] Figure 1 This is a perspective view of a building served by a heating, ventilation, and air conditioning (HVAC) system, according to an exemplary embodiment.

[0008] Figure 2 This demonstrates in more detail the exemplary embodiments. Figure 1 A block diagram of a portion of an HVAC system shows a refrigeration circuit configured to circulate refrigerant between the evaporator and the condenser.

[0009] Figure 3 This is according to an exemplary embodiment. Figure 2 A block diagram of the controller for the refrigeration circuit.

[0010] Figure 4 This is a flowchart of a method for limiting the suction flow of a cooler by controlling input power or motor current according to an exemplary embodiment. Detailed Implementation

[0011] This disclosure generally relates to the field of refrigeration systems. More specifically, this disclosure relates to cooler suction flow rate limitation controlled by input power or motor current. A refrigeration system may include a cooler, which may include an evaporator, a condenser, a compressor, and pipes connecting these and various other components. The evaporator evaporates refrigerant to provide net cooling of the process fluid (e.g., water) flowing through the pipes. It may be desirable for the evaporator to produce dry saturated vapor from the refrigerant, and it may be desirable for the compressor to receive the dry saturated vapor based on the suction generated by the compressor. However, in some cases, the refrigerant output from the evaporator comprises droplets that are drawn up along with a high-speed vapor flow based on the suction from the compressor. Furthermore, considerations of size, weight, power, and cost may necessitate a reduction in the size of the evaporator to meet the minimum design capacity requirements of the refrigeration system. However, because the boost pressure or differential pressure on the compressor is reduced due to the cooler operating conditions, the compressor may provide a higher capacity and suction flow rate, which can increase the gas velocity in the evaporator and carry droplets into the compressor. These effects may reduce the efficiency of the cooler and may damage the mechanical components of the compressor.

[0012] This solution addresses these considerations by implementing cooler suction flow limitation through input power or motor current control to effectively manage compressor operation and reduce or eliminate droplet flow from the evaporator to the compressor. For example, the system and method according to this solution can predict the power or current level corresponding to the evaporator's design speed limit (under which droplet flow to the compressor can be anticipated) and use a controller to limit further increases in power or current to prevent droplet flow to the compressor (e.g., liquid flow carrying). In some embodiments, a cooler includes an evaporator that receives a first refrigerant flow, transfers heat to the first refrigerant flow, and outputs a second refrigerant flow. The cooler includes a compressor that receives the second refrigerant flow via a pipe between the evaporator and the compressor. The compressor includes a prime mover that performs work on the second refrigerant flow based on at least one of an input power to the prime mover and an input current to the prime mover. The cooler includes a first pressure sensor that detects a first pressure of the refrigerant in the evaporator. The cooler includes a second pressure sensor that detects a second pressure of the refrigerant in the cooler's condenser. The cooler includes a controller that determines a predicted operating level for the compressor based on the first and second pressures, compares the predicted level with an operating level associated with droplet flow in the second refrigerant stream received by the compressor, and modifies at least one of the input power and input current to the prime mover based on the comparison satisfying modification conditions. Thus, if the predicted level is too high (e.g., greater than the operating level), the controller can appropriately limit the power or current to the prime mover to reduce or eliminate the risk of droplet flow entering the compressor, a risk that might otherwise occur if the evaporator's design speed limits are exceeded.

[0013] HVAC system

[0014] Figure 1A perspective view of building 10 is depicted. Building 10 is served by a heating, ventilation, and air conditioning (HVAC) system 20. HVAC system 20 may include a cooler 22, a boiler 24, a roof cooling unit 26, and multiple air handling units (AHUs) 36. HVAC system 20 uses a fluid circulation system to provide heating and / or cooling to building 10. The circulating fluid may be cooled in the cooler 22 or heated in the boiler 24, depending on whether cooling or heating is required. Boiler 24 may add heat to the circulating fluid by burning a flammable material (e.g., natural gas). Cooler 22 may allow the circulating fluid to exchange heat with another fluid (e.g., refrigerant) in a heat exchanger (e.g., an evaporator). The refrigerant removes heat from the circulating fluid during the evaporation process, thereby cooling the circulating fluid.

[0015] Circulating fluid from cooler 22 or boiler 24 can be delivered to AHU 36 via conduit 32. AHU 36 allows the circulating fluid to exchange heat with the airflow passing through it. For example, the airflow can pass through conduits through which circulating fluid flows in fan coil units or other air conditioning terminal units. AHU 36 can transfer heat between the airflow and the circulating fluid, thereby heating or cooling the airflow. Heated or cooled air can be delivered to building 10 via an air distribution system including air supply duct 38 and can be returned to AHU 36 via air return duct 40. HVAC system 20 may include independent AHU 36 on each floor of building 10. In other embodiments, a single AHU (e.g., a rooftop AHU) can supply air to multiple floors or areas. Circulating fluid from AHU 36 can be returned to cooler 22 or boiler 24 via conduit 34.

[0016] The refrigerant in cooler 22 can evaporate after absorbing heat from the circulating fluid. Vaporized refrigerant can be supplied to a compressor within cooler 22, in which the temperature and pressure of the refrigerant are increased (e.g., using a rotary impeller, screw compressor, scroll compressor, reciprocating compressor, centrifugal compressor, etc.). The compressed refrigerant can be discharged into a condenser within cooler 22. In some embodiments, water (or another fluid) flows through tubes in the condenser of cooler 22 to absorb heat from the refrigerant vapor, thereby causing the refrigerant to condense. The water flowing through the tubes in the condenser can be pumped from cooler 22 to cooling unit 26 via line 28. Cooling unit 26 can remove heat from the water using fan-driven cooling or fan-driven evaporation. Cooling water from cooling unit 26 can be delivered back to cooler 22 via line 30, and the cycle repeats.

[0017] Figure 2The diagram illustrates a portion of an HVAC system 20 according to an exemplary embodiment. A cooler 22 may include a refrigeration circuit 42 and a controller 100. The refrigeration circuit 42 may include an evaporator 46, a compressor 48, a condenser 50, and an expansion valve 52. The compressor 48 may be configured to circulate refrigerant through the refrigeration circuit 42. The compressor 48 may be operated by the controller 100. The compressor 48 may compress the refrigerant to a high pressure, high temperature state and discharge the compressed refrigerant into a compressor discharge line 54 that connects the outlet of the compressor 48 to the inlet of the condenser 50. For example, the compressor 48 may be or may include a screw compressor, a semi-hermetic screw compressor, or a hermetic or open screw compressor. The compressor 48 may also be or may include a scroll compressor, a reciprocating compressor, a centrifugal compressor, or another type of compressor.

[0018] Condenser 50 may receive compressed refrigerant from compressor discharge line 54. Condenser 50 may also receive a separate heat exchange fluid (e.g., water, a water-glycol mixture, another refrigerant, etc.) from cooling circuit 56. Condenser 50 may be configured to transfer heat from the compressed refrigerant to the heat exchange fluid, thereby causing the compressed refrigerant to condense from a gaseous refrigerant state into a liquid or mixed fluid state. Cooling circuit 56 may include a heat recovery circuit configured to use the heat absorbed from the refrigerant for heating applications. Cooling circuit 56 may include a pump 58 for circulating the heat exchange fluid between condenser 50 and cooling unit 26. Cooling unit 26 may include a cooling coil 60 configured to facilitate heat transfer between the heat exchange fluid and another fluid (e.g., air) flowing through cooling unit 26. Cooling unit 26 may include a cooling tower. The heat exchange fluid may dissipate heat in cooling unit 26 and return to condenser 50 via line 30.

[0019] The refrigeration circuit 42 may include a line 62 connecting the outlet of the condenser 50 to the inlet of the expansion device 52. The expansion device 52 expands the refrigerant in the refrigeration circuit 42 to a low-temperature and low-pressure state. The expansion device 52 may be a fixed-position device or a variable-position device (e.g., a valve). The expansion device 52 may be manually or automatically actuated (e.g., via a controller 100 via a valve actuator) to adjust the expansion of the refrigerant passing through it. The expansion device 52 may discharge the expanded refrigerant into a line 64 connecting the outlet of the expansion device 52 to the inlet of the evaporator 46.

[0020] Evaporator 46 may receive expanded refrigerant from line 64. Evaporator 46 may also receive a separate cooling fluid (e.g., water, a water-glycol mixture, another refrigerant, etc.) from cooling fluid circuit 66. Evaporator 46 may be configured to transfer heat from the cooling fluid to the expanded refrigerant in refrigeration circuit 42, thereby cooling the cooling fluid and evaporating the refrigerant. Cooling fluid circuit 66 may include a pump 68 that circulates the cooling fluid between evaporator 46 and AHU 36. AHU 36 may include a cooling coil 70 configured to facilitate heat transfer between the cooling fluid and another fluid (e.g., air) flowing through AHU 36. The cooling fluid may absorb heat in AHU 36 and return to evaporator 46 via line 34. Evaporator 46 may output heated refrigerant to compressor suction line 72, which connects the outlet of evaporator 46 to the inlet of compressor 48.

[0021] The cooling fluid circuit 66 may include a cooling fluid temperature sensor 74 positioned along the conduit 32. The cooling fluid temperature sensor 74 may be configured to detect the temperature T of the cooling fluid flowing within the conduit 32 between the evaporator 46 and the AHU 36. cf (e.g., temperature of the refrigerant leaving the cooling liquid). The refrigeration circuit 42 may include a suction temperature sensor 76 positioned along the compressor suction line 72. The suction temperature sensor 76 may be configured to detect the temperature T of the refrigerant flowing within the compressor suction line 72 between the evaporator 46 and the compressor 48. suc (That is, the temperature of the refrigerant entering the compressor 48). The refrigeration circuit 42 may include a suction pressure sensor 78 positioned along the compressor suction line 72. The suction pressure sensor 78 may be configured to detect the pressure P of the refrigerant flowing within the compressor suction line 72 between the evaporator 46 and the compressor 48. suc (That is, the pressure of the refrigerant entering the compressor 48). The refrigeration circuit 42 may include a discharge temperature sensor 80 positioned along the compressor discharge line 54. The discharge temperature sensor 80 may be configured to detect the temperature T of the refrigerant flowing within the compressor discharge line 54 between the compressor 48 and the condenser 50. dis (That is, the temperature of the refrigerant leaving compressor 48). Refrigeration circuit 42 may include a discharge pressure sensor 82 positioned along compressor discharge line 54. Discharge pressure sensor 82 may be configured to detect the pressure P of the refrigerant flowing within compressor discharge line 54 between compressor 48 and condenser 50. dis (That is, the pressure of the refrigerant leaving compressor 48).

[0022] Refrigeration circuit 42 may include detecting the pressure P of the refrigerant flowing within evaporator 46. evapThe evaporator pressure sensor 86 and the pressure P of the refrigerant flowing within the condenser 50 are also included. cond The condenser pressure sensor 88. Sensors 86 and 88 may be similar to sensors 78 and 82; sensors 78 and 82 may respectively perform the functions of sensors 86 and 88 related to measuring the pressures associated with the evaporator 46 and compressor 48, as further described herein. Sensors 86 and 88 may be located at different points in or near the evaporator 46 and condenser 50 to detect the corresponding pressure P. evap and P cond .

[0023] Compressor 48 includes prime mover 84 (e.g., a motor). Prime mover 84 can be a constant-speed drive or a variable-speed drive. Controller 100 can control the operation of prime mover 84, for example, by transmitting control signals to prime mover 84 to control the speed, flow rate, or other operating parameters of compressor 48. Controller 100 can control the operation of prime mover 84 based on at least one of power or current corresponding to the operation of compressor 48. Depending on the operating conditions in refrigeration circuit 42, refrigerant droplets may flow from evaporator 46 to compressor 48. Controller 100 can control the operation of prime mover 84 to reduce or eliminate droplet flow from evaporator 46 to compressor 48.

[0024] Chiller suction flow limit with input power or motor current control

[0025] Figure 3A block diagram of a refrigeration system 150 including a controller 100 according to an exemplary embodiment is depicted. The controller 100 can control the operation of a compressor 48, for example, by controlling the operation of the compressor 48 based on at least one of input power or motor current control. Power and current (e.g., input power, input current, motor power, motor current) can include power or current to the refrigeration system 150 (e.g., a cooler), power or current to the motor controller of the refrigeration system 150, power or current to the drive unit (e.g., a variable speed drive) of the compressor 48, power or current to the motor of the compressor 48, or other power or current used to move the compressor 48. The controller 100 can use power and current limiting to protect the compressor 48 (e.g., a prime mover 84) or to limit building energy use, and such limiting can be very stable in terms of control method (e.g., the controller 100 does not need to rely on detected droplets as input to the feedback control loop, and therefore can prevent droplet carrying before it occurs). For example, controller 100 can control the operating power of variable speed drive prime mover 84, or it can control the operating current of constant speed drive prime mover 84. Controller 100 can determine a predicted operating level of compressor 48 (at which the suction flow from evaporator 46 to compressor 48 can be expected to cause droplets to flow into compressor 48), compare the predicted level with the actual operating level of compressor 48, and determine, based on the comparison, a limit on the capacity of compressor 48 to protect compressor 48 from the effects of droplet flow.

[0026] The controller 100 may include a communication interface 102 and processing circuitry 104. The communication interface 102 may include a wired or wireless interface (e.g., a socket, antenna, transmitter, receiver, transceiver, wire terminal, etc.) for data communication with various systems, devices, or networks. For example, the communication interface 102 may include an Ethernet card and / or port for sending and receiving data via an Ethernet-based communication network. In some embodiments, the communication interface 102 includes a wireless transceiver (e.g., a WiFi transceiver, Bluetooth transceiver, NFC transceiver, ZigBee, etc.) for communication via a wireless communication network. The communication interface 102 may be configured to communicate via a local area network (e.g., a building LAN, etc.) and / or a wide area network (e.g., the Internet, cellular networks, radio communication networks, etc.) and may use various communication protocols (e.g., BACnet, TCP / IP, point-to-point, etc.).

[0027] Communication interface 102 facilitates the reception of input from various sensors. These sensors may include, for example, a cooling fluid temperature sensor 74 configured to detect the temperature of the cooling fluid at the outlet of evaporator 46, a suction pressure sensor 78 configured to detect the refrigerant pressure in the compressor suction line 72, a discharge pressure sensor 82 configured to detect the refrigerant pressure in the compressor discharge line 54, and / or other sensors of the cooler 22 and / or HVAC system 20 (e.g., suction temperature sensor 76, discharge temperature sensor 80, cooling fluid temperature sensor 74, etc.). Communication interface 102 can receive input from sensors directly, via a local area network, and / or via a remote communication network. Communication interface 102 enables communication between controller 100 and compressor 48.

[0028] Processing circuitry 104 may include processor 106 and memory 108. Processor 106 may be a general-purpose or special-purpose processor, an application-specific integrated circuit (ASIC), one or more field-programmable gate arrays (FPGAs), a set of processing units, or other suitable processing units. Processor 106 may be configured to execute computer code or instructions stored in memory 108 (e.g., fuzzy logic, etc.) or received from other computer-readable media (e.g., CD-ROM, network storage device, remote server, etc.) to perform one or more processes described herein.

[0029] Memory 108 may include one or more data storage devices (e.g., memory cells, memory devices, computer-readable storage media, etc.) configured to store data, computer code, executable instructions, or other forms of computer-readable information. Memory 108 may include random access memory (RAM), read-only memory (ROM), hard disk drive storage devices, temporary storage devices, non-volatile memory, flash memory, optical memory, or any other suitable memory for storing software objects and / or computer instructions. Memory 108 may include database components, object code components, scripting components, or any other type of information structure for supporting the various activities and information structures described herein. Memory 108 may be communicatively connected to processor 106 via processing circuitry 104 and may include computer code for performing (e.g., by processor 106) one or more processes described herein.

[0030] The memory 108 may include various modules for performing the processes described herein. More specifically, the memory 108 includes a state detector 110, an energy predictor 112, and a compressor controller 114. Although in Figure 3Various modules with specific functions are shown, but controller 100 and memory 108 may include any number of modules for performing the functions described herein. For example, the activities of multiple modules may be combined into a single module, and additional modules with additional functions may be included. Controller 100 may further control other processes beyond the scope of this disclosure, including but not limited to controlling the operation of various components of the refrigeration system 150 based on desired or anticipated load conditions.

[0031] The status detector 110 can receive status data from various sensors in the refrigeration system 150. For example, the status detector 110 can receive pressure data from the evaporator pressure sensor 86 and the condenser pressure sensor 88. The status detector 110 can also receive temperature data from temperature sensors.

[0032] The energy predictor 112 can receive state data from the state detector 110 and determine the predicted energy level of the compressor 48's operation based on the received state data. The predicted energy level can correspond to at least one of the following: compressor speed, compressor capacity, water flow rate, water temperature, suction volume flow rate, compressor performance, motor performance, and starter performance.

[0033] The energy predictor 112 can determine the predicted energy level based on a first pressure received by the state detector 110 from the evaporator pressure sensor 86 and a second pressure received by the state detector 110 from the condenser pressure sensor 88. The energy predictor 112 can execute an energy prediction function to calculate the predicted energy level.

[0034] The energy prediction function may include an energy predictor 112 that can be applied to a first pressure and a second pressure to calculate one or more calculated parameters for predicting energy levels. One or more calculated parameters may be determined based on experimental and / or simulation tests of the operation of the refrigeration system 150. For example, one or more calculated parameters may be determined by identifying energy levels associated with various values ​​of evaporator and condenser pressures; and by fitting curves, functions, or other representations to energy levels based on the values ​​of evaporator and condenser pressures. Energy levels may be identified by operating the refrigeration system 150 (or its drivetrain) under various operating conditions. Energy levels may be identified by operating the refrigeration system 150 under partial load conditions, which can provide a more accurate representation of the refrigeration system behavior when using one or more calculated parameters to predict energy levels. It should be understood that the calculated parameters determined for the first refrigeration system 150 can be applied to various other refrigeration systems 150. One or more calculation parameters for a specific refrigeration system can be determined by using inputs such as capacity, water flow rate, and water temperature, and feedback values ​​such as evaporator pressure, condenser pressure, suction volumetric flow rate, and input current (or input power); and by performing an iterative process due to the correlation between evaporator pressure (or saturation temperature), suction volumetric flow rate limits, capacity, and desired volumetric flow rate. In determining calculation parameters based on the drive system of refrigeration system 150 (e.g., to extrapolate the determined calculation parameters to other units with similar drive systems), performance parameters (e.g., compressor performance, motor performance, starter performance) can be determined based on boundary condition variables of compressor 48 (e.g., suction pressure, volumetric flow rate (or dimensionless flow rate, θ), and discharge pressure (or dimensionless head, ω)) to determine the corresponding input current (or input power). Thus, if the values ​​of the boundary condition variables (e.g., volumetric flow rate or θ) are chosen to be at appropriate limits, the drive system calculation can directly provide the data needed to determine the calculation parameters. It should be understood that the calculation parameters can be determined using processing circuit 104 or a processing circuit of a device located away from the refrigeration system 150 (or away from the drive system), the processing circuit operating to identify the relationship between evaporator pressure, condenser pressure, and droplet flow.

[0035] The energy predictor 112 can select a specific energy prediction function to be executed based on the operating characteristics of the compressor 48, which can be stored in the energy predictor 112. The operating characteristics can indicate whether the prime mover 84 of the compressor 48 operates in a variable speed mode or a constant speed mode. If the operating characteristics indicate that the prime mover 84 operates in a variable speed mode, then the energy predictor 112 can select the energy prediction function according to Equation 1:

[0036]

[0037] If the operating characteristics indicate that the prime mover 84 operates in a constant speed mode, then the energy predictor 112 can select the energy prediction function according to Equation 2:

[0038]

[0039] In this way, the energy predictor 112 can use calculated parameters as well as the first pressure and the second pressure (e.g., p) evap =

[0040] First pressure, p cond =Second pressure) to perform an appropriate energy prediction function to calculate the predicted energy level. It should be understood that the values ​​of the calculation parameters can be determined by appropriately fitting the curve of the form shown in Equation 1 or Equation 2 to the identified values ​​of the energy level as a function of evaporator pressure and condenser pressure. An iterative optimization process can be used to determine the values ​​of the calculation parameters. The functions shown in Equations 1 and 2 can be linearized (e.g., by taking the logarithm of both sides of the corresponding equations, such as the natural logarithm) to reduce the computational requirements for determining the calculation parameters by being able to use linear fitting methods (e.g., linear least squares).

[0041] Compressor controller 114 can control the operation of compressor 48 (e.g., control the operation of prime mover 84). Compressor controller 114 can output a control signal corresponding to the desired input power or input current to compressor 48, including appropriately limiting the input power or input current. Compressor controller 114 can use the operating characteristics of compressor 48 to determine whether to generate a control signal to control the input power (e.g., if compressor 48 is operating in a variable speed mode) or the input current (e.g., if compressor 48 is operating in a constant speed mode). Compressor controller 114 can initially calculate the input power or input current based on input variables (e.g., desired water flow rate, water temperature, or other variables representing the performance of refrigeration system 150). Compressor controller 114 can limit the initially calculated input power or input current to reduce or eliminate droplet flow into compressor 48.

[0042] The compressor controller 114 compares a predicted energy level determined by the energy predictor 112 with an operating energy level. Given certain values ​​of evaporator and condenser pressures, the predicted energy level may correspond to an energy level at which droplet flow from evaporator 46 to compressor 48 can be expected. For example, the predicted energy level may correspond to an energy level exceeding the design speed limit of evaporator 46, or an energy level at which droplet flow has been determined through experimental and / or simulation testing. The operating energy level may be the current energy level of compressor 48; thus, the compressor controller 114 can use the comparison to determine whether compressor 48 is operating under conditions exceeding the predicted energy level (at which droplet flow from evaporator 46 to compressor 48 can be expected).

[0043] The compressor controller 114 can measure at least one of the actual input current and the actual input power. For example, the compressor controller 114 may include an input current sensor (e.g., a current transformer) to measure the actual input current. The compressor controller 114 may include an input power sensor, such as a voltage sensor that can be used to determine the actual input power (e.g., based on the actual input current and the actual input power). The compressor controller 114 can determine the operating level based on at least one of the actual input current and the actual input power.

[0044] The compressor controller 114 modifies at least one of the input power or input current of the compressor 48 based on a comparison that satisfies modification conditions. For example, if the predicted energy level is a value that should not be exceeded, the compressor controller 114 may limit at least one of the input power or input current in response to the operating energy level exceeding the predicted energy level (e.g., limiting at least one of the input power and input current if the operating energy level is greater than the predicted energy level). If the predicted energy level is set to a value that triggers a limit, the compressor controller 114 may limit at least one of the input power and input current in response to the operating energy level being equal to the predicted energy level (e.g., limiting at least one of the input power and input current if the predicted energy level is equal to the operating energy level). The compressor controller 114 may calculate the predicted energy level as at least one of the predicted input current and the predicted input power, such that the compressor controller 114 can perform the comparison by comparing at least one of the actual input current with the predicted input current and the actual input power with the predicted input power.

[0045] If the modification conditions are not met, for example, if the operating energy level is lower than the predicted energy level, then the compressor controller 114 can determine not to limit the input power or input current; for example, the compressor controller 114 can continue to monitor the first and second pressures; the compressor controller 114 can determine to increase at least one of the input power and input current (if a desired performance indicator, such as water flow rate or water temperature, indicates an increase in at least one of the input power and input current). Thus, if the measured value of the input power and / or input current is higher than the predicted value, the compressor controller 114 can reduce the operating capacity of the compressor 48; if the measured value of the input power and / or input current is lower than the predicted value, the operating capacity of the compressor 48 (and therefore the refrigeration system 150) is not limited by the suction flow rate, and the compressor controller 114 can control at least one of the input power and input current by performing various processes, such as by using a T-value based on the temperature of the cooling fluid leaving the evaporator 46, as detected by the cooling fluid temperature sensor 74. cf (For example, by using T) cf With T cfThe compressor controller 114 can perform capacity control of the compressor 48 based on one or more variations in the compressor speed using the following: a variable speed drive; a compressor suction flow damper or pre-rotating blade flow throttling; a compressor discharge variable geometry diffuser flow throttling; or a capacity control slide valve (e.g., if the compressor 48 includes a screw compressor).

[0046] The compressor controller 114 can limit at least one of the input power or input current by setting at least one of the input power or input current to a previous value. For example, the compressor controller 114 can maintain a database of power and current values. In response to determining to limit the input power or input current, the compressor controller 114 can retrieve previous values ​​of the input power or input current from history, such as previous values ​​at a point in time when the compressor controller 114 determines not to modify at least one of the input power or input current based on a corresponding previously predicted energy level.

[0047] The compressor controller 114 can maintain a database including evaporator pressure, condenser pressure, input power, input current, predicted energy level and various other operating parameters, as well as comparison indicators indicating that input power or input current will be limited.

[0048] The compressor controller 114 can output an alarm indicating that droplet flow may be occurring based on comparison. For example, the compressor controller 114 can send the alarm via the communication interface 102. The alarm may include information such as operating parameters maintained by the compressor controller 114 in a database. The alarm may include an indication of the value of a performance variable corresponding to the fulfillment of modification conditions, such as the water flow rate or water temperature that results in a predicted energy level associated with droplet flow.

[0049] Figure 4 A method 400 for operating a refrigeration system (e.g., a cooler) according to an exemplary embodiment is depicted. Method 400 can use... Figure 1 HVAC systems and / or Figures 2-3 The refrigeration system 150 is used to perform the operation.

[0050] At 405, the controller receives a first pressure from the evaporator pressure sensor. This first pressure may represent the pressure of the refrigerant flowing through the evaporator. The evaporator may receive the first refrigerant flow, transfer heat to the first refrigerant flow, and output a second refrigerant flow.

[0051] At 410, the controller receives a second pressure from the condenser pressure sensor. This second pressure can represent the pressure of the refrigerant flowing through the condenser.

[0052] At 415, the controller determines a predicted energy level for compressor operation. The compressor may receive a second refrigerant flow via a pipe between the evaporator and the compressor. The predicted energy level can be determined using an energy prediction function that takes a first pressure and a second pressure as inputs and evaluates the inputs using predetermined parameters. The compressor may include a prime mover that performs work on the second refrigerant flow based on at least one of an input power to the prime mover and an input current to the prime mover. The prime mover may include a variable speed drive that the controller drives using the input power. The prime mover may also include a constant speed drive that the controller drives using the input current.

[0053] At 420, the controller compares the predicted operating level of the compressor with the operating level. The predicted level can be associated with the droplet flow in the second refrigerant stream received by the compressor. The predicted level can correspond to the design speed limit of the evaporator. The compressor controller can determine the operating level using at least one of the actual input current and the actual input power.

[0054] At 425, the controller determines whether the comparison meets the modification conditions. The modification conditions can correspond to the operating energy level being greater than the predicted energy level, or the operating energy level being greater than or equal to the predicted energy level.

[0055] At 430, the controller limits at least one of the input power and input current to the prime mover based on a comparison that satisfies modification conditions. The controller can modify at least one of the input power and input current to limit it to a value that reduces or eliminates droplet flow from the evaporator to the compressor. The controller can output an alarm in response to modifying at least one of the input power and input current to the prime mover based on a comparison that satisfies modification conditions. If the comparison does not satisfy the modification conditions, for example, if the operating level is lower than the predicted level, the controller can continue to monitor the pressure received from the evaporator pressure sensor and the condenser pressure sensor. If the comparison does not satisfy the modification conditions, for example, if the operating level is lower than the predicted level, and if the desired performance of the cooler (e.g., desired water flow rate or water temperature) indicates a command to increase the input power or input current, the controller can appropriately continue to increase the input power or input current.

[0056] A reference to "or" can be interpreted as inclusive, such that any item described using "or" can refer to a single item, more than one item, or any of all of the items. A reference to at least one item in a consecutive list of items can be interpreted as inclusive "or" to refer to a single item, more than one item, or any of the items. For example, a reference to "at least one of 'A' and 'B'" can include only 'A', only 'B', or both 'A' and 'B'. Such references used in conjunction with "include" or other open-ended terms can include additional items.

[0057] The construction and arrangement of the systems and methods illustrated in the various exemplary embodiments are merely illustrative. Although only exemplary embodiments are described in detail in this disclosure, many modifications are possible (e.g., variations in the size, dimensions, structure, shape and scale of various elements, parameter values, installation arrangements, use of materials, color, orientation, etc.). For example, the positions of elements may be reversed or otherwise varied, and the nature, number, or position of discrete elements may be altered or changed. Therefore, such modifications are intended to be included within the scope of this disclosure. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. Other substitutions, modifications, alterations, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of this disclosure.

Claims

1. A controller for a heating, ventilation, and air conditioning (HVAC) system, comprising: One or more processors; as well as A memory device storing computer-readable instructions, which, when executed by the one or more processors, cause the one or more processors to: First data is received from a first sensor, wherein the first data indicates a first pressure within the evaporator of the HVAC system; Second data is received from a second sensor, wherein the second data indicates a second pressure within the condenser of the HVAC system; The predicted operating level of the compressor of the HVAC system is determined based on the first pressure and the second pressure, wherein the operation of the compressor at the predicted operating level is expected to cause droplet flow from the evaporator to the compressor; Determine the actual operating energy level of the compressor; and The operation of the compressor is adjusted based on a comparison between the predicted energy level and the actual operating energy level.

2. The controller as claimed in claim 1, wherein, The controller is configured to output a control signal to adjust the input power or input current supplied to the compressor in order to adjust the operation of the compressor.

3. The controller as claimed in claim 1, wherein, The controller is configured to execute an energy prediction function to determine the predicted energy level, the energy prediction function using the first pressure and the second pressure as inputs to the energy prediction function.

4. The controller as claimed in claim 3, wherein, The controller is configured to select a specific energy prediction function from a plurality of energy prediction functions as the energy prediction function.

5. The controller as claimed in claim 4, wherein, The controller is configured to select the specific energy prediction function based on the operating characteristics of the compressor.

6. The controller as claimed in claim 5, wherein, The operating characteristics indicate whether the compressor is configured to operate in variable speed mode or constant speed mode.

7. The controller as claimed in claim 1, wherein, The controller is configured to determine the actual operating level of the compressor based on a measured input current supplied to the compressor, a measured input power supplied to the compressor, or both.

8. The controller as claimed in claim 1, wherein, The controller is configured to limit the operation of the compressor in response to determining that the actual operating energy level exceeds the predicted energy level.

9. The controller as claimed in claim 8, wherein, To limit the operation of the compressor, the controller is configured to adjust the compressor speed, adjust the compressor's suction flow damper, adjust the compressor's pre-rotating blades, adjust the compressor's variable geometry diffuser, adjust the compressor's slide valve, or any combination thereof.

10. The controller as claimed in claim 1, wherein, The predicted energy level corresponds to the design speed limit of the evaporator.

11. A heating, ventilation, and air conditioning (HVAC) system, comprising: A controller configured to communicatively connect to multiple sensors of the HVAC system and the compressor of the HVAC system, wherein the controller is configured to: Data indicating a first pressure of the refrigerant within the evaporator of the HVAC system is received from the first sensor of the plurality of sensors; Data indicating a second pressure of the refrigerant within the condenser of the HVAC system is received from a second sensor of the plurality of sensors; The predicted operating level of the compressor of the HVAC system is determined based on the first pressure and the second pressure of the refrigerant, wherein the operation of the compressor at the predicted operating level is expected to cause droplet flow from the evaporator to the compressor. Determine the actual operating energy level of the compressor; and The operation of the compressor is limited based on the determination that the actual operating energy level exceeds the predicted energy level.

12. The heating, ventilation, and air conditioning (HVAC) system as claimed in claim 11, wherein, In order to limit the operation of the compressor, the controller is configured to limit the input power supplied to the compressor, limit the input current supplied to the compressor, or both.

13. The heating, ventilation, and air conditioning (HVAC) system as described in claim 12, wherein, The controller is configured to limit the input power supplied to the compressor based on determining that the compressor is configured to operate in variable speed mode.

14. The heating, ventilation, and air conditioning (HVAC) system as claimed in claim 12, wherein, The controller is configured to limit the input current supplied to the compressor based on determining that the compressor is configured to operate in a constant speed mode.

15. The heating, ventilation, and air conditioning (HVAC) system as claimed in claim 12, wherein, To limit the operation of the compressor, the controller is configured to adjust the compressor's suction flow damper, adjust the compressor's pre-rotating blades, adjust the compressor's variable geometry diffuser, adjust the compressor's slide valve, or any combination thereof.

16. The heating, ventilation, and air conditioning (HVAC) system as claimed in claim 11, wherein, The controller is configured to determine the actual operating level of the compressor based on a measured input current supplied to the compressor and detected by a third sensor of the plurality of sensors, a measured input power supplied to the compressor and detected by a fourth sensor of the plurality of sensors, or both.

17. A memory device for a heating, ventilation, and air conditioning (HVAC) system controller, wherein, The memory device includes computer-executable instructions stored thereon, and the computer-executable instructions, when executed by one or more processors, are configured to cause the one or more processors to: Receive first data indicating the first pressure inside the evaporator; Receive second data indicating the second pressure within the condenser; A predicted operating level for the compressor is determined based on the first pressure and the second pressure, wherein the operation of the compressor at the predicted operating level is expected to cause droplet flow from the evaporator to the compressor; Determine the actual operating energy level of the compressor; and The compressor operation is controlled based on a comparison between the predicted energy level and the actual operating energy level.

18. The memory device of claim 17, wherein, When executed by the one or more processors, the computer-executable instructions are configured to cause the one or more processors to execute an energy prediction function to determine the predicted energy level, the energy prediction function using the first pressure and the second pressure as inputs to the energy prediction function.

19. The memory device of claim 18, wherein, The computer-executable instructions, when executed by the one or more processors, are configured to cause the one or more processors to: Select a specific energy prediction function from among multiple energy prediction functions as the energy prediction function; as well as The specific energy prediction function is selected based on the operating characteristics of the compressor. The operating characteristics indicate whether the compressor is configured to operate in variable speed mode or constant speed mode.

20. The memory device of claim 17, wherein, When executed by the one or more processors, the computer-executable instructions are configured to cause the one or more processors to limit the input power supplied to the compressor in response to determining that the actual operating energy level exceeds the predicted energy level, to limit the input current supplied to the compressor in response to determining that the actual operating energy level exceeds the predicted energy level, or both.

21. A controller for a heating, ventilation, and air conditioning (HVAC) system, comprising any one of the technical features of claims 1-10 or any combination of the technical features.

22. A heating, ventilation and air conditioning (HVAC) system comprising any one of the technical features of claims 11-16 or any combination of the technical features.

23. A memory device for a heating, ventilation, air conditioning (HVAC) system controller, comprising any one of the technical features of claims 17-20 or any combination of the technical features.

Images