Air conditioner

Abstract

Disclosed in the present application is an air conditioner. A maximum operating frequency is preset for the air conditioner; the air conditioner performs a commissioning operation upon the initial startup after the installation of the air conditioner is completed; piping parameters of the air conditioner are determined during the commissioning operation; the actual maximum operating frequency of a compressor that is required for reaching the rated capacity of the air conditioner is determined on the basis of the piping parameters and the preset maximum operating frequency; the actual maximum operating frequency is written into a memory, and the actual maximum operating frequency is used as the upper limit operating frequency of the compressor; and the actual maximum operating frequency of the compressor is a frequency, which is suitable for the actual piping parameters of the air conditioner after installation and at which the rated capacity of the air conditioner can be achieved.

Description

air conditioner

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application No. 2024115626350 entitled "Air Conditioner", filed on November 4, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of electrical equipment technology, and in particular to an air conditioner. Background Technology

[0004] The horsepower of an air conditioner is determined at the factory, which means the maximum operating frequency of the compressor is fixed, and the compressor can only operate below the maximum operating frequency. The maximum frequency of the compressor is designed with the piping length at the standard length.

[0005] However, due to different installation scenarios, the length and height differences of air conditioner piping vary considerably. This is especially true in multi-split air conditioning heat pump units, where the large capacity of the outdoor unit often results in excessively long piping between the indoor and outdoor units. Further complicating matters, in high-rise buildings or shopping malls, the outdoor and indoor units, as well as the indoor units themselves, and the outdoor units themselves, are not on the same plane, resulting in significant height differences. Therefore, the actual piping configuration of air conditioners differs from the standard piping data used in the design. Summary of the Invention

[0006] This application proposes an air conditioner that solves the technical problem that existing air conditioners suffer from capacity reduction due to different pressure losses caused by the installation environment, resulting in the air conditioner's capacity not reaching its nominal horsepower when operating at maximum frequency.

[0007] An air conditioner, comprising:

[0008] compressor;

[0009] The memory stores the preset maximum operating frequency of the compressor corresponding to the air conditioner's horsepower. This preset maximum operating frequency serves as the compressor's upper limit frequency.

[0010] The controller is configured to control the air conditioner to perform a trial run when it is first run after installation, determine the air conditioner's piping parameters, determine the actual maximum operating frequency of the compressor to reach the air conditioner's horsepower based on the piping parameters and the preset maximum operating frequency, write the actual maximum operating frequency into the memory, and use the actual maximum operating frequency as the compressor's upper limit operating frequency.

[0011] In the above technical solution, the air conditioner undergoes a trial run upon its first operation after installation. During the trial run, the air conditioner's piping parameters are determined. Based on the piping parameters and the preset maximum operating frequency, the actual maximum operating frequency of the compressor to achieve the air conditioner's horsepower is determined. The actual maximum operating frequency is written into the memory and used as the compressor's upper limit operating frequency. The compressor's actual maximum frequency is the frequency that can achieve the nominal air conditioner horsepower when adapted to the piping parameters after the actual installation of the air conditioner. This avoids the problem of pressure loss caused by factors such as piping length and height difference, which leads to a decrease in the air conditioner's capacity and the inability to achieve the nominal horsepower within the preset maximum operating frequency range.

[0012] Other features and advantages of this application will become clearer after reading the detailed embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 is a diagram of the refrigerant circulation system of an air conditioner in a cooling mode according to some embodiments;

[0015] Figure 2 is a diagram of the refrigerant circulation system in the heating mode of an air conditioner according to some embodiments;

[0016] Figure 3 is a structural block diagram of an air conditioner according to some embodiments;

[0017] Figure 4 is a flowchart of determining the actual maximum operating frequency of the compressor according to some embodiments;

[0018] Figure 5 is a flowchart of determining the compressor start-up frequency according to some embodiments;

[0019] Figure 6 is a flowchart of determining the starting opening degree of the expansion valve according to some embodiments;

[0020] Figure 7 is a flowchart of determining air conditioning piping parameters during trial operation in cooling mode according to some embodiments;

[0021] Figure 8 is a flowchart of determining air conditioning piping parameters during trial operation in heating mode according to some embodiments;

[0022] Figure 9 is a control flowchart of an air conditioner according to some embodiments;

[0023] Figure 10 is a control flowchart of an air conditioner according to some other embodiments. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0026] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal conduction of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes or the use of other materials.

[0030] The horsepower of an air conditioner is determined at the factory, which means the maximum operating frequency of the compressor is also determined. The compressor can only operate below this maximum operating frequency. The maximum operating frequency of the compressor is designed with the piping length at the standard length.

[0031] However, the piping length varies significantly depending on the installation scenario. This is especially true in multi-split air conditioning heat pump units, where the large capacity of the outdoor unit often leads to excessively long piping between the indoor and outdoor units. Adding to the complexity, in high-rise buildings or shopping malls, there are often height differences between the outdoor and indoor units, between indoor units, and between outdoor units, meaning they are not on the same plane. Excessive piping length and height differences can cause significant refrigerant pressure loss, resulting in lower refrigerant pressure and density at the compressor's suction port. This leads to a decrease in refrigerant mass flow rate and cooling (heating) capacity at the same operating frequency, causing a performance degradation in the unit. Consequently, the performance at maximum frequency may not reach the air conditioner's rated horsepower.

[0032] Based on this, this application provides an air conditioner that avoids the performance degradation of the air conditioner caused by pressure loss due to factors such as pipe length and height difference, which in turn leads to the inability to reach the nominal horsepower within the preset maximum operating frequency range.

[0033] Air conditioners use a compressor, condenser, throttling device, and evaporator to perform a cooling or heating cycle, thereby cooling or heating an indoor space.

[0034] The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation.

[0035] Low-temperature, low-pressure refrigerant enters the compressor, which compresses it into a high-temperature, high-pressure refrigerant gas and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser.

[0036] The condenser condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment through the condensation process.

[0037] The throttling device expands the high-temperature, high-pressure liquid refrigerant that condenses in the condenser into a low-pressure liquid refrigerant. In some embodiments, the throttling device is an electronic expansion valve.

[0038] The evaporator evaporates the refrigerant that expands in the throttling device and returns the refrigerant gas, which is in a low-temperature, low-pressure state, to the compressor. The evaporator achieves a cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled.

[0039] Throughout the cycle, the air conditioner can regulate the temperature of the indoor space.

[0040] The outdoor unit of an air conditioner refers to the part of the refrigeration cycle that includes the compressor and the outdoor heat exchanger, while the indoor unit includes the indoor heat exchanger. A throttling device can be provided in either the indoor or outdoor unit.

[0041] The indoor and outdoor heat exchangers function as either condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioner functions as a heater in heating mode; when the indoor heat exchanger is used as an evaporator, the air conditioner functions as a cooler in cooling mode.

[0042] Air conditioners include a refrigerant circulation system.

[0043] The refrigerant circulation system includes compressor 1.

[0044] In some embodiments, the air conditioner also includes a memory 10, which stores a preset maximum operating frequency of the compressor corresponding to the air conditioner's horsepower. The preset maximum operating frequency of the compressor serves as the upper limit frequency of the compressor, and the compressor operates within a frequency range lower than the preset maximum operating frequency. The preset maximum operating frequency of the compressor corresponds to the horsepower of the air conditioner under normal installation conditions (i.e., pressure loss caused by piping length, height difference, etc., is within the normal range).

[0045] In some embodiments, the air conditioner also includes a controller 20, which is configured to control the air conditioner to perform a trial run upon its first operation after installation, determine the air conditioner's piping parameters, determine the actual maximum operating frequency of the compressor to achieve the required air conditioning horsepower based on the piping parameters and a preset maximum operating frequency, and write the actual maximum operating frequency into the memory 10. The actual maximum operating frequency of the compressor is used as the compressor's upper limit frequency. The compressor operates within a frequency range lower than the actual maximum frequency, and all air conditioner operating parameters involving the upper limit frequency are controlled based on the actual maximum operating frequency.

[0046] Piping parameters are values ​​used to characterize the actual condition of the air conditioner's piping. These parameters are related to factors such as the length and height difference of the piping, and can be calculated from the air conditioner's operating parameters.

[0047] After installation, the air conditioner undergoes a trial run during its first operation. During this trial run, the actual piping parameters of the air conditioner are determined. Based on the actual piping parameters and the preset maximum operating frequency, the actual maximum operating frequency of the compressor to achieve the air conditioner's horsepower is determined. This actual maximum operating frequency is written into the memory and used as the upper limit operating frequency of the compressor. The compressor's actual maximum frequency is the frequency that can achieve the nominal air conditioner horsepower when adapted to the actual piping parameters after the air conditioner is installed. Running at this actual maximum frequency can achieve the nominal air conditioner horsepower, avoiding the problem of pressure loss caused by factors such as piping length and height difference, which leads to a decrease in the air conditioner's capacity and the inability to achieve the nominal horsepower within the preset maximum operating frequency range.

[0048] In some embodiments of this application, the air conditioner can be a multi-split air conditioner. The following description uses a multi-split air conditioner as an example. It should be understood that using a multi-split air conditioner as an example is only for the convenience of introducing the technical solution of this application, and is not intended to be limiting.

[0049] In the embodiments shown in Figures 1, 2, and 3, the air conditioner is a multi-split air conditioner, which includes an outdoor unit 101, a first indoor unit 201, and a second indoor unit 202.

[0050] The outdoor unit 101 includes a compressor 1, a low-pass valve 4, an outdoor heat exchanger 5, an outdoor electronic expansion valve 6, and a gas-liquid separator 3.

[0051] An exhaust pressure detection device 11 is provided at the exhaust end of compressor 1, which is configured to detect the exhaust pressure Pd.

[0052] A suction pressure detection device 12 is provided at the suction end of compressor 1, which is configured to detect suction pressure Ps.

[0053] The first indoor unit 201 includes a first indoor electronic expansion valve 8a and a first indoor heat exchanger 9a.

[0054] The second indoor unit 202 includes a second indoor electronic expansion valve 8b and a first indoor heat exchanger 9b.

[0055] The indoor unit is equipped with an indoor unit coil temperature detection device 30, which is configured to detect the indoor unit coil temperature.

[0056] For example, the first indoor unit 201 is provided with a first indoor unit coil temperature detection device 30a, which is configured to detect the first indoor unit coil temperature Tr1.

[0057] The second indoor unit 202 is equipped with a second indoor unit coil temperature detection device 30b, which is configured to detect the second indoor unit coil temperature Tr2.

[0058] The indoor unit is equipped with an indoor unit liquid pipe temperature detection device 40, which is configured to detect the temperature of the indoor unit liquid pipe.

[0059] For example, the first indoor unit 201 is provided with a first indoor unit liquid pipe temperature detection device 40a, which is configured to detect the first indoor unit liquid pipe temperature Trl1.

[0060] The second indoor unit 202 is equipped with a second indoor unit liquid pipe temperature detection device 40b, which is configured to detect the second indoor unit liquid pipe temperature Trl2.

[0061] In some embodiments, the memory 10 stores a first correspondence between a plurality of piping parameters or piping parameter ranges and their corresponding maximum frequency correction values.

[0062] The controller 20 is configured to determine the corresponding maximum frequency correction value based on the first correspondence and the piping parameters, and to correct the preset maximum operating frequency based on the maximum frequency correction value to obtain the actual maximum operating frequency.

[0063] By pre-determining the maximum frequency correction value corresponding to the piping parameters and correcting the preset maximum operating frequency based on the maximum frequency correction value, the actual maximum operating frequency can be quickly determined, making the determination of the actual maximum operating frequency more standardized, regulated, and accurate.

[0064] In some embodiments, the piping parameter for cooling mode is A, and the maximum frequency correction value is ΔFA.

[0065] The correspondence between piping parameter A in cooling mode and the maximum frequency correction value ΔFA is as follows:

[0066] The value of A1 in the first interval is less than the value of A2 in the second interval, the value of A2 in the second interval is less than the value of A3 in the third interval, and the value of A3 in the third interval is less than the value of A4 in the fourth interval.

[0067] 1<ΔFA1<ΔFA2<ΔFA3<ΔFA4.

[0068] For example, the correspondence between the piping parameter A in cooling mode and the maximum frequency correction value ΔFA can be:

[0069] In some embodiments, the actual maximum operating frequency Fmax is equal to the product of the preset maximum operating frequency Fmax0 and the maximum frequency correction value ΔFA.

[0070] In some embodiments, the heating mode piping parameter is B, and the maximum frequency correction value is ΔFB.

[0071] The relationship between the heating mode piping parameter B and the maximum frequency correction value ΔFB is as follows:

[0072] The B1 value in the first interval is less than the B2 value in the second interval, the B2 value in the second interval is less than the B3 value in the third interval, and the B3 value in the third interval is less than the B4 value in the fourth interval.

[0073] 1<ΔFB1<ΔFB2<ΔFB3<ΔFB4.

[0074] In some embodiments, the actual maximum operating frequency Fmax is equal to the product of the preset maximum operating frequency Fmax0 and the maximum frequency correction value ΔFB.

[0075] The preset maximum operating frequency Fmax0 ensures that the unit can operate at its rated capacity under standard piping parameters, i.e., it can reach the nominal horsepower.

[0076] In some embodiments, the memory 10 stores a second correspondence between the actual maximum operating frequency and the piping parameters and the preset maximum operating frequency, wherein the second correspondence is a predetermined functional relationship.

[0077] In some embodiments, the actual maximum operating frequency = m * preset maximum operating frequency + piping parameters. m is obtained in advance through experiments based on a function curve fitting.

[0078] The controller 20 is configured to obtain the actual maximum operating frequency based on the piping parameters and the second correspondence.

[0079] By pre-determining the second correspondence between the actual maximum operating frequency and the piping parameters, and the actual maximum operating frequency, the actual maximum operating frequency can be obtained based on the piping parameters and the second correspondence. This allows for a rapid determination of the actual maximum operating frequency, making the determination of the actual maximum operating frequency more standardized, regulated, and accurate.

[0080] Referring to Figure 4, in some embodiments, the method for determining the actual maximum frequency of the compressor includes the following steps.

[0081] S41, Begin.

[0082] S42. Read the compressor's preset maximum operating frequency.

[0083] For example, controller 20 reads the preset maximum operating frequency of the compressor from memory 10.

[0084] S43. Determine the piping parameters under the trial operation mode during the trial operation.

[0085] S44. Determine the actual maximum operating frequency of the compressor based on the piping parameters and preset maximum operating frequency under the trial operation mode.

[0086] The method for determining the actual maximum operating frequency of the compressor based on the piping parameters and preset maximum operating frequency under trial operation mode can refer to the aforementioned embodiments and will not be repeated here.

[0087] S45. Write the actual maximum operating frequency into the memory, and use the actual maximum operating frequency as the upper limit operating frequency of the compressor.

[0088] The compressor must not exceed its actual maximum operating frequency during operation, and other control parameters of the air conditioner that involve the compressor's upper limit operating frequency shall be controlled based on the actual maximum operating frequency.

[0089] By increasing the upper limit of the operating frequency, the unit's capabilities under long piping connection schemes can be fully utilized.

[0090] In long-pipeline interconnection schemes, air conditioners are prone to other reliability issues besides insufficient capacity. For example, excessive refrigerant can lead to refrigerant return problems during startup, and it can also result in insufficient responsiveness. Therefore, the control parameters of the air conditioner during startup can be adjusted according to the piping parameters.

[0091] In some embodiments, the compressor start-up frequency is adjusted according to piping parameters.

[0092] The memory 10 stores the preset start frequency of the compressor;

[0093] The controller 20 is configured to determine the actual starting frequency of the compressor based on the piping parameters and the preset starting frequency, and control the compressor to start at the actual starting frequency.

[0094] Adjusting the actual starting frequency of the compressor according to the piping parameters can improve the reliability and responsiveness of the air conditioner.

[0095] In some embodiments, the memory 10 stores a third correspondence between several piping parameters or piping parameter ranges and corresponding start-up frequency correction values.

[0096] The controller 20 is configured to determine the start-up frequency correction value based on the third correspondence relationship and the piping parameters, and then correct the preset start-up frequency based on the start-up frequency correction value to obtain the actual start-up frequency.

[0097] By pre-determining the start-up frequency correction value corresponding to the piping parameters and correcting the preset start-up frequency based on the start-up frequency correction value, the actual start-up frequency can be quickly determined, making the determination of the actual start-up frequency more standardized, regulated, and accurate.

[0098] In some embodiments, the piping parameter for cooling mode is A, and the start-up frequency correction value is ΔHstartA.

[0099] The correspondence between the piping parameter A in cooling mode and the start-up frequency correction value ΔHstartA is as follows:

[0100] The value of A1 in the first interval is less than the value of A2 in the second interval, the value of A2 in the second interval is less than the value of A3 in the third interval, and the value of A3 in the third interval is less than the value of A4 in the fourth interval.

[0101] 1>ΔHstartA1>ΔHstartA2>ΔHstartA3>ΔHstartA4.

[0102] In some embodiments, the actual startup frequency Hstart is equal to the product of the preset startup frequency Hstart0 and the startup frequency correction value ΔHstartA.

[0103] For example, the correspondence between the piping parameters in cooling mode and the start-up frequency correction value is as follows:

[0104] In some embodiments, the heating mode piping parameter is B, and the start-up frequency correction value is ΔHstartB.

[0105] The relationship between the heating mode piping parameter B and the start-up frequency correction value ΔHstartB is as follows:

[0106] The B1 value in the first interval is less than the B2 value in the second interval, the B2 value in the second interval is less than the B3 value in the third interval, and the B3 value in the third interval is less than the B4 value in the fourth interval.

[0107] 1>ΔHstartB1>ΔHstartB2>ΔHstartB3>ΔHstartB4.

[0108] In some embodiments, the actual startup frequency Hstart is equal to the product of the preset startup frequency Hstart0 and the startup frequency correction value ΔHstartB.

[0109] The preset start-up frequency Hstart0 is the unit's preset start-up frequency, which can meet the reliability and adaptability requirements of standard piping connection schemes.

[0110] By reducing the start-up frequency, the start-up reliability of long-piped units can be ensured.

[0111] In some embodiments, the memory 10 stores a fourth correspondence between the actual start-up frequency and the piping parameters and the preset start-up frequency, wherein the fourth correspondence is a predetermined functional relationship.

[0112] In some embodiments, the actual starting frequency = n * preset starting frequency + piping parameters. n is obtained through prior experiments based on a function curve fitting.

[0113] The controller 20 is configured to obtain the actual starting frequency based on the piping parameters and the fourth correspondence.

[0114] By pre-determining the fourth correspondence between the actual starting frequency and the piping parameters and the preset starting frequency, and obtaining the actual starting frequency based on the piping parameters and the fourth correspondence, the actual starting frequency can be determined quickly, making the determination of the actual starting frequency more standardized, regulated and accurate.

[0115] Referring to Figure 5, in some embodiments, the method for determining the compressor start frequency includes the following steps.

[0116] S51, Begin.

[0117] S52, Read the compressor's preset start frequency.

[0118] For example, the controller 20 reads the preset start frequency of the compressor from the memory 10.

[0119] S53. Determine the piping parameters under the trial operation mode during the trial operation.

[0120] S54. Determine the actual starting frequency of the compressor based on the piping parameters and preset starting frequency under the trial operation mode.

[0121] The method for determining the actual starting frequency of the compressor based on the piping parameters and preset starting frequency under trial operation mode can refer to the aforementioned embodiments.

[0122] S55. Write the actual starting frequency into the memory and control the compressor to start at the actual starting frequency.

[0123] In some embodiments, the opening degree of the expansion valve is adjusted according to the piping parameters.

[0124] The memory 10 stores the preset start-up opening of the expansion valve.

[0125] The controller 20 is configured to determine the actual starting opening of the expansion valve based on the piping parameters and the preset starting opening, and control the expansion valve to start according to the actual starting opening.

[0126] Adjusting the actual starting opening of the expansion valve according to the piping parameters can improve the reliability and responsiveness of the air conditioner.

[0127] In some embodiments, the memory 10 stores a fifth correspondence between a plurality of piping parameters or piping parameter ranges and corresponding opening correction values;

[0128] The controller 20 is configured to determine the opening correction value based on the fifth correspondence relationship and the piping parameters, and then correct the preset starting opening of the expansion valve according to the opening correction value to obtain the actual starting opening.

[0129] By pre-determining the opening correction value corresponding to the piping parameters and correcting the preset starting opening based on the opening correction value, the actual starting opening of the expansion valve can be quickly determined, making the determination of the actual starting opening more standardized, regulated, and accurate.

[0130] In some embodiments, the piping parameter for cooling mode is A, and the start-up opening correction value is ΔEVstartA.

[0131] The correspondence between the piping parameter A in cooling mode and the start-up opening correction value ΔEVstartA is as follows:

[0132] The value of A1 in the first interval is less than the value of A2 in the second interval, the value of A2 in the second interval is less than the value of A3 in the third interval, and the value of A3 in the third interval is less than the value of A4 in the fourth interval.

[0133] 1>ΔEVstartA1>ΔEVstartA2>ΔEVstartA3>ΔEVstartA4.

[0134] In some embodiments, the actual start-up opening EVstart is equal to the product of the preset start-up opening EVstart0 and the start-up frequency correction value ΔEVstartA.

[0135] For example, the correspondence between piping parameters and the start-up opening correction value ΔEVstart is as follows:

[0136] In some embodiments, the piping parameter determined by the heating mode is B, and the start-up opening correction value is ΔEVstartB.

[0137] The relationship between the piping parameter B in heating mode and the start-up opening correction value ΔEVstartB is as follows:

[0138] The B1 value in the first interval is less than the B2 value in the second interval, the B2 value in the second interval is less than the B3 value in the third interval, and the B3 value in the third interval is less than the B4 value in the fourth interval.

[0139] 1>ΔEVstartB1>ΔEVstartB2>ΔEVstartB3>ΔEVstartB4.

[0140] In some embodiments, the actual start-up opening EVstart is equal to the product of the preset start-up opening EVstart0 and the start-up opening correction value ΔEVstartB.

[0141] The preset start-up opening EVstart0 is the unit's preset start-up opening, which can meet the reliability and adaptability requirements of standard piping connection schemes.

[0142] By reducing the opening degree of the expansion valve, the start-up reliability of long-pipe units can be ensured.

[0143] In some embodiments, the memory 10 stores a sixth correspondence between the actual start-up opening degree and the piping parameters and the preset start-up opening degree, wherein the sixth correspondence is a predetermined functional relationship.

[0144] In some embodiments, the actual start-up opening degree = k * preset start-up opening degree + piping parameters. k is obtained in advance through experiments based on function curve fitting.

[0145] The controller 20 is configured to obtain the actual start-up opening degree based on the piping parameters and the sixth correspondence.

[0146] By pre-determining the correspondence between the actual start-up opening and the piping parameters and preset start-up opening, and obtaining the actual start-up opening based on the piping parameters and the correspondence, the actual start-up opening can be determined quickly, making the determination of the actual start-up opening more standardized, regulated and accurate.

[0147] Referring to Figure 6, in some embodiments, the method for determining the starting opening degree of the expansion valve includes the following steps.

[0148] S61, Begin.

[0149] S62. Read the preset start-up opening degree of the expansion valve.

[0150] For example, the controller 20 reads the preset start-up opening of the expansion valve from the memory 10.

[0151] S63. Determine the piping parameters under the trial operation mode during the trial operation.

[0152] S64. Determine the actual starting opening of the expansion valve based on the piping parameters and preset starting opening under the trial operation mode.

[0153] The method for determining the actual starting opening of the expansion valve based on the piping parameters and preset starting opening under the trial operation mode can refer to the aforementioned embodiments.

[0154] S65. Write the actual starting opening degree into the memory, and control the expansion valve to open based on the actual starting opening degree.

[0155] In some embodiments, when a multi-split air conditioner includes an indoor electronic expansion valve and an outdoor electronic expansion valve, the actual starting opening of the indoor electronic expansion valve can be determined based on the piping parameters of the cooling mode and the preset starting opening, and the actual starting opening of the outdoor electronic expansion valve can be determined based on the piping parameters of the heating mode and the preset starting opening.

[0156] In other embodiments, when the multi-split air conditioner includes an indoor electronic expansion valve and an outdoor electronic expansion valve, the opening of the indoor electronic expansion valve and the outdoor electronic expansion valve can be controlled simultaneously based on the actual starting opening degree determined by the piping parameters of the cooling mode or the piping parameters of the heating mode. The relationship between the starting opening degrees of the indoor electronic expansion valve and the outdoor electronic expansion valve can be determined according to the actual situation.

[0157] In some embodiments, the controller 20 is configured to control the air conditioner to run for at least a set time during the trial run, during which all indoor units operate simultaneously and at the compressor’s preset maximum operating frequency.

[0158] By setting up a trial operation process and applying the same control to all indoor units during the trial operation, the determination of piping parameters can be made under the same conditions, thereby improving the accuracy of the determination of piping parameters.

[0159] In some embodiments, the set time is 20 minutes, meaning the trial run must be at least 20 minutes. If it is less than 20 minutes, the system cannot switch to normal operation or be shut down. If other operation signals are received before the set time has elapsed during the trial run, an alarm will be issued, indicating that the system is in trial operation and cannot perform other operations. Other operation signals will be executed after the trial run has ended.

[0160] The control methods during the trial operation are consistent with the normal maximum capacity operation mode.

[0161] In some embodiments, the controller 20 is configured to acquire operating parameters after a period of time following the start of trial operation, and determine the piping parameters of the air conditioner based on the operating parameters.

[0162] After the trial run has stabilized, the operating parameters are then tested. The piping parameters of the air conditioner are determined based on the operating parameters obtained during the stable operation, which can further improve the accuracy of the piping parameter determination.

[0163] In some embodiments, operating parameters are monitored for a portion of the time after the trial run. That is, during the trial run, after a first period of time following the start of the trial run, operating parameters are monitored for a preset time period, also known as the monitoring time. For example, if the trial run is 20 minutes, operating parameters are monitored during the 15th-20th minute of the trial run, and the average value of the relevant operating parameters within the monitoring time is calculated. The operating parameters used to calculate the piping parameters are the average values ​​of the corresponding operating parameters within the monitoring time.

[0164] In some embodiments, the air conditioner includes a cooling test run, which means that the test run process is in cooling mode.

[0165] The following describes the method for calculating piping parameter A under refrigeration commissioning conditions.

[0166] The controller 20 detects the temperature of the liquid pipe of each indoor unit through the indoor unit liquid pipe temperature detection device, and detects the suction pressure Ps through the suction pressure detection device 102.

[0167] Then controller 20 calculates the average liquid pipe temperature Trl_average for all indoor units.

[0168] For example, referring to the embodiments shown in Figures 1 and 2, the controller 20 detects the liquid pipe temperature Trl1 of the first indoor unit through the first indoor unit liquid pipe temperature detection device 40a, and detects Trl2 through the second indoor unit liquid pipe temperature detection device 40b. Then, it calculates the average liquid pipe temperature of the first indoor unit 201 and the second indoor unit 202 according to the following formula: Trl_average=0.5×(Trl1+Trl2).

[0169] The controller 20 determines the evaporation pressure Pcs (i.e., the saturation temperature corresponding to Trl_average) corresponding to the indoor unit's average liquid pipe temperature Trl_average and the suction pressure Ps, based on a preset correspondence between the liquid pipe temperature and the evaporation pressure. Thus, the pressure loss per unit length of piping can be obtained from the indoor unit's average liquid pipe temperature Trl_average and the suction pressure Ps; that is, the pressure loss per unit length of piping is equal to Pcs minus Ps.

[0170] The controller 20 calculates the turbulent pressure drop according to the following formula: ΔP=ε×L / D×v2×ρ

[0171] Wherein, ε is the resistance coefficient, which is mainly related to the surface roughness coefficient of the piping, and is generally taken as 0.012 to 0.03; L is the characteristic length, which is the equivalent piping length between the indoor unit and the compressor suction side, and is taken as 1 when calculating the pressure loss value per unit piping length; D is the characteristic diameter, which is determined by the specifications of the connection piping interface of the outdoor unit, and is generally between 0.015 and 0.04; v is the refrigerant flow velocity in the piping, which is related to the compressor frequency, and v can be calculated according to the following formula: v=H×C / (π×D2 / 4), where C is the compressor displacement, π is pi, H is the preset maximum operating frequency of the compressor, and D is the characteristic diameter; ρ is the refrigerant density on the suction side of the compressor, and the ρ value (saturated gaseous refrigerant density) corresponding to Pcs (or Ps, or the intermediate value of Pcs and Ps) can be determined according to the correspondence between the evaporation pressure and the refrigerant density on the suction side of the compressor.

[0172] In some embodiments, the refrigerant density ρ on the compressor's suction side can also be determined by the suction pressure Ps and suction temperature Ts on the compressor's suction side. For example, ρ corresponding to Ps and Ts can be determined based on a preset relationship between suction pressure, suction temperature, and refrigerant density on the compressor's suction side, resulting in higher accuracy. The suction temperature Ts on the compressor's suction side can be detected by a compressor suction temperature detection device 50 located on the suction side of compressor 1.

[0173] Controller 20 calculates the piping parameter A for cooling mode according to any of the following formulas: A = (Pcs - Ps) / ΔP;

[0174] Alternatively, A = (Pcs - Ps) × Pcs / (a ​​× H2 × ρ);

[0175] Alternatively, A = (Pcs - Ps) × Pcs / (a ​​× H2);

[0176] Alternatively, A = (Pcs - Ps) × Ps / (a ​​× H2);

[0177] Alternatively, A = (Pcs - Ps) × (Pcs + Ps) / (a ​​× H2).

[0178] In the above formulas, Pcs is the evaporation pressure, Ps is the suction pressure, ΔP is the turbulent pressure drop, H is the compressor's preset maximum operating frequency, ρ is the refrigerant density on the compressor's suction side, and a is a constant, which can be determined through experimental testing or set through theoretical analysis. In some embodiments, the indoor unit's liquid pipe temperature and suction pressure are both average suction pressures over the detection period.

[0179] Referring to Figure 7, in some embodiments, the method for determining the piping parameters of the air conditioner during trial operation in cooling mode includes the following steps.

[0180] S71, Begin.

[0181] S72. Determine if the timer has reached the first time. If yes, proceed to step S73; otherwise, continue with step S72.

[0182] In some embodiments, the timing start time is the start time of the operation mode. The length of the first time is less than the total duration of the trial operation. That is, step S73 is executed after the first time has elapsed since the start of the trial operation.

[0183] The purpose of step S72 is to obtain the operating parameters of the air conditioner after the trial run has entered a stable state, so that the obtained parameter values ​​are more accurate.

[0184] S73, detects the temperature of the liquid pipe and the suction pressure of the indoor unit.

[0185] In some embodiments, the air conditioner has multiple indoor units, and the controller 20 detects the liquid pipe temperature of each indoor unit through a liquid pipe temperature detection device of each indoor unit, and detects the suction pressure through a suction pressure detection device 20 located at the suction end of the compressor 1.

[0186] For example, according to the embodiments shown in Figures 1 and 2, the first indoor unit liquid pipe temperature Trl1 is detected by the first indoor unit liquid pipe temperature detection device 40a, and the second indoor unit liquid pipe temperature Trl2 is detected by the second indoor unit liquid pipe temperature detection device 40b.

[0187] S74. Determine whether the timer has reached the trial run set time. If yes, proceed to step S75; otherwise, proceed to step S73.

[0188] S75. Calculate the average liquid pipe temperature, average suction pressure, and average evaporation pressure of the indoor unit.

[0189] In step S73, between the first time and the set time for trial operation, the liquid pipe temperature, suction pressure and evaporation pressure of each indoor unit are measured multiple times, so in step S75, the average value of these parameters is calculated.

[0190] S76. Calculate piping parameter A using the refrigeration piping parameter calculation formula based on the indoor unit's average liquid pipe temperature, average suction pressure, and average evaporation pressure.

[0191] The formulas for calculating piping parameters are the same as those in the previous embodiments and will not be repeated here.

[0192] In some embodiments, the air conditioner includes a heating test run, which refers to a test run in heating mode.

[0193] The following describes the method for calculating piping parameter B under heating test operation mode.

[0194] The controller 20 detects the coil temperature of each indoor unit using the indoor unit coil temperature detection device, and then calculates the average coil temperature of all indoor units. The controller 20 also detects the suction pressure Ps using the suction pressure detection device 102 and the exhaust pressure Pd using the exhaust pressure detection device 101.

[0195] For example, in the examples of Figures 1 and 2, the controller 20 detects the first indoor unit coil temperature Tr1 through the first indoor unit coil temperature detection device 30a and the second indoor unit coil temperature Tr2 through the second indoor unit coil temperature detection device 30b, and then calculates the average coil temperature of all indoor units according to the following formula: Tr_average=0.5×(Tr1+Tr2).

[0196] The controller 20 also determines the condensing pressure Pc corresponding to Tr_average (i.e., the saturation temperature corresponding to Tr_average) based on the preset relationship between coil temperature and condensing pressure, and calculates the turbulent pressure drop according to the following formula: ΔP=ε×L / D×v2×ρd

[0197] Where ε is the resistance coefficient, mainly related to the surface roughness coefficient of the piping, generally taken as 0.012 to 0.03; L is the characteristic length, taken as 1 when calculating the unit pressure loss value; D is the characteristic diameter, determined by the specifications of the outdoor unit's connecting piping interface, generally between 0.015 and 0.04; v is the refrigerant flow velocity in the piping, related to the compressor frequency, and v can be calculated using the following formula: v=H×C×ρ / (ρd×π×D2 / 4), where C is the compressor displacement, π is pi; H The maximum operating frequency of the compressor is preset; D is the characteristic diameter; ρd is the refrigerant density on the exhaust side, which can be determined based on the preset relationship between the refrigerant density on the exhaust side and the exhaust pressure Pd. The corresponding ρd (i.e., the saturated gaseous refrigerant density corresponding to Pd) can be determined based on the preset relationship between Pcs and ρ, according to Pcs (or Ps, or the intermediate value of Pcs and Ps).

[0198] In some embodiments, density can also be determined by pressure and temperature simultaneously, resulting in higher accuracy.

[0199] Controller 20 calculates the heating mode piping parameter B according to any of the following formulas: B=(Pd-Pc) / ΔP;

[0200] Alternatively, B = (Pd - Pc) / (b * H2 * ρ2 / ρd);

[0201] Alternatively, B = (Pd - Pc) * Ps² / (H² * Pd);

[0202] Alternatively, B = (Pd - Pc) * Ps² / (H² * Pc);

[0203] Alternatively, B = (Pd - Pc) * Ps² / (H² * (Pc + Pd)).

[0204] In the above formulas, Pd is the discharge pressure, Pc is the condensing pressure, Ps is the suction pressure, ΔP is the turbulent pressure drop, H is the preset maximum operating frequency of the compressor, ρd is the refrigerant density on the discharge side, ρ is the refrigerant density on the suction side, and b is a constant that can be obtained from experimental tests or set through theoretical analysis.

[0205] Referring to Figure 8, in some embodiments, the method for determining the piping parameters of the air conditioner during trial operation in heating mode includes the following steps.

[0206] S81, Begin.

[0207] S82. Determine if the timer has reached the first time. If yes, proceed to step S83; otherwise, continue with step S82.

[0208] For an explanation of the first step, please refer to step S72, which will not be repeated here.

[0209] S83, detects indoor unit coil temperature, suction pressure, and exhaust pressure.

[0210] In some embodiments, the air conditioner has multiple indoor units, and the controller 20 detects the liquid pipe temperature of each indoor unit through a liquid pipe temperature detection device of each indoor unit.

[0211] In step S73, between the first time and the set time for trial operation, the liquid pipe temperature, suction pressure, and evaporation pressure of each indoor unit are measured multiple times.

[0212] S84. Determine whether the timer has reached the trial run set time. If yes, proceed to step S85; otherwise, proceed to step S83.

[0213] S85: Calculate the indoor unit's average coil temperature, average suction pressure, average discharge pressure, and average condensing pressure.

[0214] S86. Calculate piping parameter B using the heating piping parameter calculation formula based on the indoor unit's average coil temperature, average suction pressure, average discharge pressure, and average condensing pressure.

[0215] The formulas for calculating piping parameters are the same as those in the previous embodiments and will not be repeated here.

[0216] The trial operation may be in cooling mode or heating mode. Therefore, the calculation methods for the air conditioner piping parameters should be determined separately for cooling mode and heating mode to ensure the accuracy of the piping parameter calculation.

[0217] In some embodiments, the controller 20 is configured to, upon receiving a heating mode control signal, control the air conditioner to perform a heating test run, obtain heating mode piping parameters, and determine the actual maximum frequency based on the heating piping parameters; and upon receiving a cooling mode control signal, control the air conditioner to perform a cooling test run, obtain cooling mode piping parameters, and determine the actual maximum frequency based on the cooling piping parameters.

[0218] In some embodiments, the air conditioner can automatically enter trial operation without the need for a trial operation control button. It only needs to start the air conditioner in cooling or heating mode to determine the piping parameters. After determining the actual maximum frequency based on the piping parameters, the trial operation ends and the air conditioner can directly enter the demand mode, avoiding cumbersome operation for the user.

[0219] Referring to Figure 9, in some embodiments, the control flow of the air conditioner includes the following steps:

[0220] S91, Begin.

[0221] S92. Determine if the air conditioner is running for the first time. If yes, proceed to step S93; otherwise, proceed to step S98.

[0222] S93. Determine whether the received signal is a cooling mode signal. If yes, proceed to step S94; otherwise, proceed to step S95.

[0223] S94. Enter the refrigeration test run. During the refrigeration test run, calculate the piping parameter A. Based on the piping parameter A, determine the actual maximum operating frequency of the compressor, the compressor starting frequency, and the expansion valve starting opening. Proceed to step S96.

[0224] S95. Enter the heating test run. During the heating test run, calculate the piping parameter B. Based on the piping parameter B, determine at least one of the following: the actual maximum operating frequency of the compressor, the compressor starting frequency, and the expansion valve starting opening. Proceed to step S96.

[0225] S96. Determine whether other control signals are received during the trial operation. If not, continue with steps S94 and S95. If yes, proceed to step S97.

[0226] S97. An alarm is triggered, indicating that the trial run is not complete. Proceed to steps S94 and S95.

[0227] S98, Enter normal control.

[0228] In some embodiments, the controller 20 is configured to control the air conditioner to undergo trial operation upon receiving a trial operation control signal.

[0229] In some embodiments, the air conditioner is provided with a test run control button. When the test run control button is triggered, the air conditioner is controlled to enter the test run process to improve the user's understanding of the air conditioner's functions.

[0230] Referring to Figure 10, in some embodiments, the control flow of the air conditioner includes the following steps.

[0231] S101, Begin.

[0232] S102, Receive trial operation control signal.

[0233] S103. Determine whether the received signal is a cooling mode signal. If yes, proceed to step S104; otherwise, proceed to step S105.

[0234] S104. Enter the refrigeration test run. During the refrigeration test run, calculate the piping parameter A. Based on the piping parameter A, determine at least one of the following: the actual maximum operating frequency of the compressor, the compressor starting frequency, and the expansion valve starting opening. Proceed to step S106.

[0235] S105. Enter the heating test run. During the heating test run, calculate the piping parameter B. Based on B, determine at least one of the following: the actual maximum operating frequency of the compressor, the compressor starting frequency, and the expansion valve starting opening. Proceed to step S106.

[0236] S106. During the trial operation, are other control signals received? If not, continue with steps S104 and S105. If yes, proceed to step S107.

[0237] S107. An alarm is triggered, indicating that the trial run is not complete. Proceed to steps S104 and S105.

[0238] The air conditioner determines the impact of resistance factors such as piping length on the unit based on operating parameters, increases the unit's maximum frequency, and optimizes other operating parameters to reduce capacity degradation and enhance comfort. Furthermore, the air conditioner solves the problem solely through control methods, without increasing costs.

[0239] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0240] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An air conditioner, comprising: compressor; The memory stores the preset maximum operating frequency of the compressor corresponding to the air conditioner's horsepower, and the preset maximum operating frequency of the compressor serves as the upper limit frequency of the compressor. as well as The controller is configured as follows: After the air conditioner is installed and is run for the first time, control the air conditioner to perform a trial run and determine the air conditioner's piping parameters; The actual maximum operating frequency of the compressor that reaches the air conditioner's horsepower is determined based on the piping parameters and the preset maximum operating frequency, and the actual maximum operating frequency is written into the memory. as well as The actual maximum operating frequency is used as the upper limit operating frequency of the compressor.

2. The air conditioner according to claim 1, wherein, The memory stores a first correspondence between several piping parameters or piping parameter ranges and the corresponding maximum frequency correction values. The controller is configured to determine the maximum frequency correction value based on the first correspondence relationship and the piping parameters, and then correct the preset maximum operating frequency based on the maximum frequency correction value to obtain the actual maximum operating frequency.

3. The air conditioner according to claim 2, wherein, The memory stores a second correspondence between the actual maximum operating frequency and the piping parameters and the preset maximum operating frequency; The controller is configured to obtain the actual maximum operating frequency based on the piping parameters and the second correspondence.

4. The air conditioner according to any one of claims 1-3, wherein, The memory stores the compressor's preset start frequency; The controller is configured to determine the actual starting frequency of the compressor based on the piping parameters and the preset starting frequency, and control the compressor to start at the actual starting frequency.

5. The air conditioner according to claim 4, wherein, The memory stores a third correspondence between several piping parameters or piping parameter ranges and corresponding start-up frequency correction values. The controller is configured to determine the start-up frequency correction value based on the third correspondence relationship and the piping parameters, and then correct the preset start-up frequency according to the start-up frequency correction value to obtain the actual start-up frequency.

6. The air conditioner according to claim 4, wherein, The memory stores a fourth correspondence between the actual start frequency and the piping parameters and the preset start frequency; The controller is configured to obtain the actual start-up frequency based on the piping parameters and the fourth correspondence.

7. The air conditioner according to any one of claims 1-6, wherein, The air conditioner includes: Expansion valve; The memory stores the preset start-up opening of the expansion valve; The controller is configured to determine the actual starting opening of the expansion valve based on the piping parameters and the preset starting opening, and control the expansion valve to start according to the actual starting opening.

8. The air conditioner according to claim 7, wherein, The memory stores a fifth correspondence between several piping parameters or piping parameter ranges and their corresponding opening correction values. The controller is configured to determine the opening correction value based on the fifth correspondence and the piping parameters, and then correct the preset start-up opening value to obtain the actual start-up opening value.

9. The air conditioner according to claim 7, wherein, The memory stores a sixth correspondence between the actual start-up opening degree and the piping parameters and the preset start-up opening degree; The controller is configured to obtain the actual start-up opening degree based on the piping parameters and the sixth correspondence.

10. The air conditioner according to any one of claims 1-9, wherein, The controller is configured to maintain a set time during the trial operation, during which all indoor units operate simultaneously and at the compressor's preset maximum operating frequency.

11. The air conditioner according to claim 10, wherein, The controller is configured to acquire operating parameters after a period of time following the start of trial operation to determine the piping parameters of the air conditioner.

12. The air conditioner according to any one of claims 1-11, wherein, The trial operation process of the air conditioner includes a cooling trial operation; The air conditioner also includes: The indoor unit liquid pipe temperature detection device is configured to detect the temperature of the indoor unit liquid pipe; A suction pressure detection device is installed at the suction end of the compressor and is configured to detect the suction pressure Ps. During the refrigeration trial run, the controller is configured to calculate the evaporation pressure Pcs based on the indoor unit liquid pipe temperature, and to calculate the refrigeration mode piping parameter A according to any of the following formulas: A = (Pcs - Ps) / ΔP; A=(Pcs-Ps)×Pcs / (a×H2×ρ); A = (Pcs - Ps) × Pcs / (a ​​× H2); A = (Pcs - Ps) × Ps / (a ​​× H2); A=(Pcs-Ps)×(Pcs+Ps) / (a×H2) Where Pcs is the evaporation pressure, Ps is the suction pressure, ΔP is the turbulent pressure drop, H is the preset maximum operating frequency of the compressor, ρ is the refrigerant density on the suction side of the compressor, and a is a constant.

13. The air conditioner according to any one of claims 1-12, wherein, The trial operation process of the air conditioner includes a heating trial operation, and the air conditioner also includes: The indoor unit coil temperature detection device is configured to detect the indoor unit coil temperature; A suction pressure detection device is disposed on the suction side of the compressor and configured to detect suction pressure Ps; An exhaust pressure detection device is disposed on the exhaust side of the compressor and configured to detect the exhaust pressure Pd; During the heating test run, the controller is configured to calculate the condensing pressure Pc based on the indoor unit coil temperature, and to calculate the heating mode piping parameter B according to any of the following formulas: B = (Pd - Pc) / ΔP; B = (Pd - Pc) / (b * H2 * ρ2 / ρd); B = (Pd - Pc) * Ps² / (H² * Pd); B = (Pd - Pc) * Ps² / (H² * Pc); B=(Pd-Pc)*Ps2 / (H2*(Pc+Pd)); Where Pd is the discharge pressure, Pc is the condensation pressure, Ps is the suction pressure, ΔP is the turbulent pressure drop, H is the preset maximum operating frequency of the compressor, ρd is the refrigerant density on the discharge side, ρ is the refrigerant density on the suction side, and b is a constant.

14. The air conditioner according to claim 12, wherein, The controller is configured as follows: When receiving the cooling mode control signal, the air conditioner is controlled to run a cooling test, and the cooling mode piping parameters are obtained. The actual maximum frequency is then determined based on the cooling mode piping parameters.

15. The air conditioner according to claim 13, wherein, The controller is configured as follows: When receiving the heating mode control signal, the system controls the air conditioner to run in heating mode, obtains the heating piping parameters, and determines the actual maximum frequency based on the heating piping parameters.

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