Heat exchanger, air conditioner and control method thereof

Abstract

The application provides a heat exchanger, an air conditioner and a control method thereof. The heat exchanger comprises a front section and a rear section. The front section is located upstream of the rear section along the flow direction of the refrigerant. The pipe diameter of the front section is smaller than that of the rear section, and / or the number of branch pipes of the front section is smaller than that of the rear section. The pipe diameter and / or the number of branch pipes of the front section and / or the pipe diameter and / or the number of branch pipes of the rear section can be adjusted according to the superheat degree of the heat exchanger. According to the application, the pipe diameter and flow path can be optimized, the heat exchange efficiency of the evaporator is improved, the material cost of the evaporator is saved while the heat exchange capacity of the evaporator is ensured, the actual superheat degree can be controlled near the target superheat degree, the sufficient heat exchange of the heat exchanger is ensured, the resistance loss is reduced, the heat exchange efficiency of the heat exchanger is improved, and the energy efficiency of the air conditioning system is improved.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, specifically to a heat exchanger, an air conditioner, and a control method thereof. Background Technology

[0002] Household air conditioners are now widely used, but their manufacturing and use result in significant energy consumption, and the production of heat exchangers requires a large amount of steel. Finned tube heat exchangers are a crucial component of refrigeration and air conditioning systems, and their operating condition directly affects the quality of the system.

[0003] In order to balance the cooling and heating performance of air conditioners, the industry usually designs the evaporator system based on meeting the performance requirements of heating conditions. This often results in the evaporator being relatively large, which can easily lead to severe overheating at the heat exchanger outlet. This not only affects the heat exchange capacity of the evaporator but also increases the cost of the evaporator.

[0004] Considering the refrigerant's state characteristics within the evaporator, the refrigerant enters the evaporator as a low-temperature, low-pressure gas-liquid two-phase mixture. Initially, its dryness is low; as the evaporation process progresses, the gas phase component increases while the liquid phase component decreases, resulting in increasing dryness until it is completely vaporized and enters the superheating section for superheating. Current technologies typically divide the refrigerant into several branches upon entry into the evaporator. However, due to the low dryness and specific volume of the refrigerant at the inlet, multiple branches lead to reduced flow velocity and heat transfer coefficient within the pipes, thus affecting the refrigerant's heat exchange performance.

[0005] Because existing evaporators suffer from low heat exchange efficiency and heat waste due to unreasonable pipe diameter and flow path design, this invention researches and designs a heat exchanger, an air conditioner, and a control method thereof. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the evaporator in the prior art, which are low heat exchange efficiency and easy heat waste due to unreasonable pipe diameter and flow path design. Thus, a heat exchanger, an air conditioner and its control method are provided.

[0007] To address the above problems, the present invention provides a heat exchanger comprising:

[0008] The front section and the rear section are located upstream of the rear section along the refrigerant flow direction, and the pipe diameter of the front section is smaller than that of the rear section, and / or the number of branches in the front section is smaller than the number of branches in the rear section; the number of branches in the front section can be adjusted according to the superheat of the heat exchanger, and / or the number of branches in the rear section can be adjusted according to the superheat of the heat exchanger.

[0009] In some implementations...

[0010] If the actual superheat is less than the target superheat, the number of branches in the front section can be adjusted to decrease, and / or the number of branches in the rear section can be adjusted to increase.

[0011] If the actual superheat is greater than the target superheat, the number of branches in the front section can be adjusted to increase, and / or the number of branches in the rear section can be adjusted to decrease.

[0012] The present invention also provides an air conditioner, which includes the aforementioned heat exchanger, and further includes a compressor, an indoor fan, an outdoor fan, and a throttling device.

[0013] The present invention also provides a control method for an air conditioner as described above, comprising:

[0014] The testing procedure involves detecting the current actual superheat ΔT1 of the air conditioner.

[0015] The judgment step is to compare the actual superheat ΔT1 with the target superheat ΔT;

[0016] The control steps are as follows: when ΔT1≤ΔT, control to reduce the number of branches in the front section and / or control to increase the number of branches in the rear section;

[0017] When ΔT1 > ΔT, control to increase the number of branches in the front section and / or control to decrease the number of branches in the rear section.

[0018] In some implementations...

[0019] Before controlling and adjusting the number of branches in the front section and / or the rear section, the control steps also include controlling and adjusting the frequency of the compressor, and / or controlling the speed of the fan, and / or controlling the opening size P of the throttling device.

[0020] In some implementations...

[0021] The control steps are as follows: when ΔT1 < ΔT, control to increase the compressor frequency, and / or control to increase the speed R1 of the internal fan, control to increase the speed R2 of the external fan, and / or control to decrease the opening degree P of the throttling device; when ΔT1 > ΔT, control to decrease the compressor frequency, and / or control to decrease the speed R1 of the internal fan, control to decrease the speed R2 of the external fan, and / or control to increase the opening degree P of the throttling device; when ΔT1 = ΔT, maintain the current state.

[0022] In some implementations...

[0023] In the control step, the target superheat ΔT is calculated as follows: ΔT = a i F +bi R 外 + c i R 内 + d i P +e i That is, by controlling the compressor frequency F and the internal fan speed R. 内 External fan speed R 外 The target superheat ΔT under this operating condition is calculated based on the opening degree P of the throttling device.

[0024] In some implementations...

[0025] F represents the compressor frequency adjustment amplitude, with a value range of 0Hz to 5Hz;

[0026] R 外 The adjustment range for the outdoor fan speed is 0 rpm to 100 rpm;

[0027] R 内 The indoor fan speed adjustment range is 0 rpm to 50 rpm;

[0028] P 外 The adjustment range for the opening of the electronic expansion valve is 0p to 50p.

[0029] The target superheat ΔT ranges from 1℃ to 3℃.

[0030] In some implementations...

[0031] a i b i c i d i e i The fitting coefficients are obtained from fitting during the flow path design process of different models;

[0032] i represents different coefficients for different temperature ranges, with values ​​ranging from 1 to 3.

[0033] In some implementations...

[0034] Based on the difference △t between the indoor ambient temperature and the air conditioner setting temperature in The size of a determines the size of a i b i c i d i and e i The value of ,

[0035] When △t in When ∈ (-6℃, t1), i=1, ΔT= a1F +b1R 外 + c1R 内 + d1 P +e1;

[0036] When △t in When ∈[t1, t2], i=2, ΔT= a2F +b2R 外 + c2R 内 + d2 P +e2;

[0037] When △t in When ∈ (t2, 6℃), i=3, ΔT= a3F +b3R 外 + c3R 内 + d3 P +e3,

[0038] Where t1 is taken as -2℃ to 0℃; t2 is taken as 0℃ to 2℃.

[0039] The heat exchanger, air conditioner, and control method provided by this invention have the following beneficial effects:

[0040] This invention configures the heat exchanger along the refrigerant flow direction as including a front section and a rear section, where the pipe diameter of the front section is smaller than that of the rear section, and / or the number of branches in the front section is less than that in the rear section. This allows for a "small pipe diameter / few branches" design in the front section of the evaporator flow path, increasing the flow velocity to improve heat exchange efficiency. As the evaporation process progresses, the gas phase composition gradually increases, and the refrigerant dryness and specific volume gradually increase. Therefore, this invention employs a "large pipe diameter / multiple branches" design in the rear section of the evaporator flow path, reducing the refrigerant flow velocity to decrease flow resistance losses. This optimizes the design of the pipe diameter and flow path, improving evaporation efficiency. The invention improves the heat exchange efficiency of the evaporator, reduces heat waste, and saves on evaporator material costs while ensuring the evaporator's heat exchange capacity. Furthermore, by adjusting the number of branches in the front section according to the superheat of the heat exchanger, and / or adjusting the number of branches in the rear section according to the superheat of the heat exchanger, the invention can control the actual superheat near the target superheat, ensuring sufficient heat exchange, reducing resistance loss, minimizing energy waste, improving the heat exchange efficiency of the heat exchanger, and enhancing the energy efficiency of the air conditioning system. Attached Figure Description

[0041] Figure 1 This is a cross-sectional structural diagram of the heat exchanger of the present invention (variable tube diameter).

[0042] Figure 2 This is a cross-sectional structural diagram of a second embodiment of the heat exchanger of the present invention (variable tube diameter).

[0043] Figure 3 This is a cross-sectional structural diagram (variable number of branches) of the heat exchanger of the present invention in a third embodiment.

[0044] Figure 4 This is a cross-sectional structural diagram (variable number of branches) of the heat exchanger of the present invention in the fourth embodiment.

[0045] Figure 5 This is a cross-sectional structural diagram (variable number of branches) of the fifth embodiment of the heat exchanger of the present invention.

[0046] Figure 6 This is a cross-sectional structural diagram (variable number of branches) of the sixth embodiment of the heat exchanger of the present invention.

[0047] The reference numerals in the attached figures are as follows:

[0048] 1. First part; 2. Second part. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0051] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0052] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0053] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0054] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0055] like Figure 1-6 As shown, the present invention provides a heat exchanger comprising:

[0056] The front section 1 and the rear section 2 are located upstream of the rear section 2 along the refrigerant flow direction. The pipe diameter of the front section 1 is smaller than that of the rear section 2, and / or the number of branches in the front section 1 is smaller than the number of branches in the rear section 2. The number of branches in the front section 1 can be adjusted according to the superheat of the heat exchanger, and / or the number of branches in the rear section 2 can be adjusted according to the superheat of the heat exchanger.

[0057] This invention configures the heat exchanger along the refrigerant flow direction as including a front section and a rear section, where the pipe diameter of the front section is smaller than that of the rear section, and / or the number of branches in the front section is less than that in the rear section. This allows for a "small pipe diameter / few branches" design in the front section of the evaporator flow path, increasing the flow velocity to improve heat exchange efficiency. As the evaporation process progresses, the gas phase composition gradually increases, and the refrigerant dryness and specific volume gradually increase. Therefore, this invention employs a "large pipe diameter / multiple branches" design in the rear section of the evaporator flow path, reducing the refrigerant flow velocity to decrease flow resistance losses. This optimizes the design of the pipe diameter and flow path, improving evaporation efficiency. The invention improves the heat exchange efficiency of the evaporator, reduces heat waste, and saves on evaporator material costs while ensuring the evaporator's heat exchange capacity. Furthermore, by adjusting the number of branches in the front section according to the superheat of the heat exchanger, and / or adjusting the number of branches in the rear section according to the superheat of the heat exchanger, the invention can control the actual superheat near the target superheat, ensuring sufficient heat exchange, reducing resistance loss, minimizing energy waste, improving the heat exchange efficiency of the heat exchanger, and enhancing the energy efficiency of the air conditioning system.

[0058] In some implementations...

[0059] If the actual superheat is less than the target superheat, the number of branches in the front section 1 can be adjusted to decrease, and / or the number of branches in the rear section 2 can be adjusted to increase.

[0060] If the actual superheat is greater than the target superheat, the number of branches in the front section 1 can be adjusted to increase, and / or the number of branches in the rear section 2 can be adjusted to decrease.

[0061] The present invention further improves upon the following: when the actual superheat is less than the target superheat, the number of branches in the front section 1 can be adjusted to decrease, and / or the number of branches in the rear section 2 can be adjusted to increase. This increases the number of multi-branch pipes in the rear section of the evaporator, facilitating a reduction in refrigerant flow rate for sufficient heat exchange and keeping the superheat near the target superheat. Conversely, when the actual superheat is greater than the target superheat, the number of branches in the front section 1 can be adjusted to increase, and / or the number of branches in the rear section 2 can be adjusted to decrease. This increases the number of fewer branches in the front section of the evaporator, facilitating a higher refrigerant flow rate for enhanced heat exchange and keeping the superheat near the target superheat. This ensures sufficient heat exchange in the heat exchanger, reduces resistance loss, minimizes energy waste, improves the heat exchanger's efficiency, and enhances the energy efficiency of the air conditioning system.

[0062] This invention combines the state characteristics of refrigerant with its flow and heat exchange characteristics in the evaporator for air conditioner system flow path design. Based on the V-type indoor heat exchanger, the flow path design is carried out to explore the relationship between refrigerant flow characteristics and system flow path design, and proposes a variable flow rate air conditioner and its design method.

[0063] This invention proposes a variable flow rate air conditioner and its control method. Based on the changes in refrigerant state and heat exchange resistance characteristics in the indoor heat exchanger, a flow path design with variable pipe diameter (small diameter → large diameter) and variable branches (few branches → many branches) is selected. Since the refrigerant enters the evaporator as a low-temperature, low-pressure gas-liquid two-phase mixture with low dryness and specific volume, a "small diameter, few branches" design is chosen in the front section of the evaporator flow path to increase the flow rate and improve heat exchange efficiency. As the evaporation process progresses, the gas phase composition gradually increases, and the refrigerant dryness and specific volume gradually increase. Therefore, a "large diameter, many branches" design is chosen in the rear section of the evaporator flow path to reduce the refrigerant flow rate and decrease flow resistance losses. This approach ensures the evaporator's heat exchange capacity is maximized while also saving on evaporator material costs.

[0064] The following technical problems were solved:

[0065] 1. Solve the problem of low heat exchange efficiency and heat waste caused by unreasonable evaporator tube diameter and flow path design in existing technologies.

[0066] 2. It reduces the cost of the refrigeration system to a certain extent.

[0067] The present invention also provides an air conditioner, which includes the aforementioned heat exchanger, and further includes a compressor, an indoor fan, an outdoor fan, and a throttling device.

[0068] The present invention also provides a control method for an air conditioner as described above, comprising:

[0069] The testing procedure involves detecting the current actual superheat ΔT1 of the air conditioner.

[0070] The judgment step is to compare the actual superheat ΔT1 with the target superheat ΔT;

[0071] The control steps are as follows: when ΔT1≤ΔT, control to reduce the number of branches in the front segment 1 and / or control to increase the number of branches in the rear segment 2;

[0072] When ΔT1 > ΔT, the number of branches in the front segment 1 is increased, and the number of branches in the rear segment 2 is decreased.

[0073] This invention increases the number of branches in the downstream section of the evaporator by adjusting the number of branches in the front section 1 to decrease and / or the number of branches in the downstream section 2 to increase the actual superheat when it is less than the target superheat. This facilitates reducing the refrigerant flow rate for sufficient heat exchange and keeps the superheat near the target superheat. Conversely, when the actual superheat is greater than the target superheat, the invention increases the number of branches in the front section 1 and / or decreases the number of branches in the downstream section 2. This increases the number of branches in the front section of the evaporator, facilitating increased refrigerant flow rate for enhanced heat exchange and keeping the superheat near the target superheat. This ensures sufficient heat exchange in the heat exchanger, reduces resistance loss, minimizes energy waste, improves the heat exchanger's efficiency, and ultimately enhances the energy efficiency of the air conditioning system.

[0074] In some implementations...

[0075] Before controlling and adjusting the number of branches of the front section 1 and / or the rear section 2, the control steps also control and adjust the frequency of the compressor, and / or control the speed of the fan, and / or control the opening size P of the throttling device.

[0076] This invention, by controlling the frequency of the compressor, the speed of the fan, and the opening degree P of the throttling device before controlling the number of branches of the front section 1 and / or the rear section 2, can first control the actual superheat to reach near the target superheat for coarse adjustment. Then, by further adjusting the number of branches of the front section 1 and / or the rear section 2, fine adjustment of the superheat can be achieved, further improving the heat exchanger's heat exchange performance, further reducing resistance loss, reducing energy waste, improving the heat exchanger's heat exchange efficiency, and improving the energy efficiency of the air conditioning system.

[0077] In some implementations...

[0078] The control steps are as follows: when ΔT1 < ΔT, control to increase the compressor frequency, and / or control to increase the speed R1 of the internal fan, control to increase the speed R2 of the external fan, and / or control to decrease the opening degree P of the throttling device; when ΔT1 > ΔT, control to decrease the compressor frequency, and / or control to decrease the speed R1 of the internal fan, control to decrease the speed R2 of the external fan, and / or control to increase the opening degree P of the throttling device; when ΔT1 = ΔT, maintain the current state.

[0079] This invention is based on superheat control logic in a variable flow rate flow path design:

[0080] Detect the current actual superheat ΔT1 and compare it with the target superheat ΔT:

[0081] 1) When ΔT1≤ΔT, it indicates that the refrigerant heat exchange in the evaporator is insufficient. The first step is to adjust the load parameters. This can be done by increasing the compressor frequency F (which increases the speed of work and improves the efficiency of the system, making the evaporator heat exchange more complete), or increasing the speed of the indoor and outdoor fans R1 and R2, or reducing the opening of the electronic expansion valve P, so that the refrigerant can exchange heat fully. If this still cannot improve the situation, consider increasing the number of large-diameter pipes and multiple branches in the downstream section of the evaporator to reduce the refrigerant flow rate and make it exchange heat fully.

[0082] 2) When ΔT1=ΔT, it indicates that the current flow path design and its load parameter design are relatively reasonable.

[0083] 3) When ΔT1 > ΔT, it indicates that the refrigerant in the evaporator is severely overheated. The first priority is to adjust the load parameters. This can be done by reducing the compressor frequency F, or reducing the speed of the indoor and outdoor fans R1 and R2, or increasing the opening of the electronic expansion valve to increase the refrigerant flow and avoid overheating losses. If this still cannot be improved, consider increasing the number of small-diameter pipes with fewer branches in the front section of the evaporator to facilitate increased refrigerant flow rate and enhanced heat exchange.

[0084] In some implementations...

[0085] In the control step, the target superheat ΔT is calculated as follows: ΔT = a i F +b i R 外 + c i R 内 + d i P +e i That is, by controlling the compressor frequency F and the internal fan speed R. 内 External fan speed R 外 The target superheat ΔT under this operating condition is calculated based on the opening degree P of the throttling device.

[0086] The present invention can accurately calculate the target superheat using the above formula, which is related to the compressor frequency, the speed of the internal and external fans and the opening degree of the throttling device, thus achieving accurate calculation of the target superheat.

[0087] In some implementations...

[0088] F represents the compressor frequency adjustment amplitude, with a value range of 0Hz to 5Hz;

[0089] R 外 The adjustment range for the outdoor fan speed is 0 rpm to 100 rpm;

[0090] R 内 The indoor fan speed adjustment range is 0 rpm to 50 rpm;

[0091] P 外 The adjustment range for the opening of the electronic expansion valve is 0p to 50p.

[0092] The target superheat ΔT ranges from 1℃ to 3℃.

[0093] In some implementations...

[0094] a i b i c i d i e i The fitting coefficients are obtained from fitting during the flow path design process of different models;

[0095] i represents different coefficients for different temperature ranges, with values ​​ranging from 1 to 3.

[0096] In some implementations...

[0097] Based on the difference △t between the indoor ambient temperature and the air conditioner setting temperature in The size of a determines the size of a i b i c i d i and e i The value of ,

[0098] When △t in When ∈ (-6℃, t1), i=1, ΔT= a1F +b1R 外 + c1R 内 + d1 P +e1;

[0099] When △t in When ∈[t1, t2], i=2, ΔT= a2F +b2R 外 + c2R 内 + d2 P +e2;

[0100] When △t in When ∈ (t2, 6℃), i=3, ΔT= a3F +b3R 外 + c3R 内 + d3 P +e3,

[0101] Where t1 is taken as -2℃ to 0℃; t2 is taken as 0℃ to 2℃.

[0102] The target superheat ΔT of this invention can be expressed as:

[0103] ΔT = a i F +b i R 外 + c i R内 + d i P +e i ;

[0104] This invention is based on the difference Δt between the indoor ambient temperature and the air conditioner's set temperature. in The magnitude of the target superheat, and the corresponding formula for calculating the target superheat, are shown in the table below:

[0105] Table 1

[0106] （-6，t1） <![CDATA[a1F +b1R 外 + c1R 内 + d1P +e1]]> [t1, t2] <![CDATA[a2F +b2R 外 + c2R 内 + d2P +e2]]> （t2，6） <![CDATA[a3F +b3R 外 + c3R 内 + d3P +e3]]>

[0107] in,

[0108] t1 is used with △t in When comparing sizes, the temperature range is generally -2℃ to 0℃.

[0109] t2 is used with △t in When comparing sizes, the temperature range is generally 0℃ to 2℃.

[0110] The target superheat ΔT during the experimental test has a range of 1℃ to 3℃ (because the target superheat ΔT has a range, the coefficients a1, a2, etc. are not limited to a range).

[0111] F represents the compressor frequency adjustment amplitude, with a value range of 0Hz to 5Hz;

[0112] R represents the adjustment range of the outdoor fan speed, ranging from 0 rpm to 100 rpm;

[0113] R represents the indoor fan speed adjustment range, which is 0 rpm to 50 rpm.

[0114] P represents the adjustment range of the electronic expansion valve opening, ranging from 0p to 50p.

[0115] ai, bi, ci, di, and ei are fitting coefficients obtained from fitting during the flow path design process of different models.

[0116] i represents different coefficients for different temperature ranges, with values ​​ranging from 1 to 3.

[0117] Invention 1: Flow path design for a variable flow rate air conditioning system

[0118] This invention proposes a variable flow rate air conditioner and its control method. Taking the pressure-enthalpy diagram of R32 refrigerant as an example, the method is based on the changes in the refrigerant state during the evaporation process. That is, when the refrigerant enters the evaporator, it is a low-temperature and low-pressure gas-liquid two-phase mixture. When it first enters the evaporator, the dryness is relatively small. As the evaporation process proceeds, the gas phase component increases continuously, the liquid phase component decreases continuously, and the dryness increases until it is completely vaporized and enters the superheating section for superheating.

[0119] This invention employs a "small pipe diameter / few branches" design in the initial flow path of the evaporator when the refrigerant has low dryness and specific volume, increasing the flow velocity to improve heat exchange. As the evaporation process progresses, the gas phase composition gradually increases, leading to increased refrigerant dryness and specific volume. Therefore, in the later flow path of the evaporator, with higher dryness and specific volume, a "large pipe diameter / multiple branches" design is chosen to reduce refrigerant flow resistance and losses by decreasing the refrigerant flow velocity. This approach ensures optimal heat exchange capacity of the evaporator while also saving on material costs.

[0120] 2. Variable pipe diameter flow path design

[0121] This invention is based on the refrigerant state changes and heat exchange characteristics of air conditioner indoor heat exchangers. It adopts a variable pipe diameter design with a small to large flow path. In the early stage when the refrigerant just enters the evaporator, the refrigerant flow rate can be increased by setting a pipe with a smaller inner diameter while keeping the refrigerant mass flow rate constant, thereby enhancing the heat exchange effect. In the process of refrigerant evaporation, it gradually changes from a gas-liquid two-phase state to a gaseous state, and both dryness fraction and specific volume gradually increase. Therefore, in the later stage of the evaporator, a pipe with a larger inner diameter is set to reduce the refrigerant flow rate, thereby effectively reducing flow losses and improving heat exchange efficiency.

[0122] like Figure 1-2 When determining that the indoor heat exchanger is set up in sections, we will give priority to the variable pipe diameter design, mainly to facilitate uniform liquid distribution and avoid affecting the performance of the whole machine.

[0123] Taking the evaporator flow path design of a cabinet air conditioner as an example, such as Figure 1-2 The variable pipe diameter design shown in Figure 1 uses a V-shaped two-fold heat exchanger with a smaller pipe diameter at the front and a larger pipe diameter at the rear. The smaller pipe diameter at the front is Φ5, and the larger pipe diameter at the rear is Φ7. Currently, commonly used pipe diameters for heat exchangers are 5mm, 7mm, 9mm, or 9.52mm, etc. The variable pipe diameter design here only refers to the relative size of the inner pipe diameter.

[0124] In this context, the front section of the heat exchanger refers to the front section in the direction of refrigerant flow. For example, in the variable pipe diameter design 2, the front section of the evaporator refers to the outer side of the two heat exchangers, while the rear section of the evaporator refers to the inner side of the two heat exchangers.

[0125] In addition, the segmentation of heat exchangers is not limited to the V-shaped two-section design of cabinet air conditioners, but also includes the three-section design of wall-mounted air conditioners, the U-shaped segmentation design of cabinet air conditioners, and many other forms.

[0126] 3. Variable branch flow path design

[0127] This invention is based on the refrigerant state changes and heat transfer characteristics of air conditioner indoor heat exchangers. It employs a variable branching design with fewer to more flow paths. Since the refrigerant enters the evaporator as a low-pressure, low-temperature gas-liquid two-phase mixture, its dryness is initially low. As the evaporation process progresses, the gas phase component increases while the liquid phase component decreases, resulting in increasing dryness until complete vaporization before entering the superheating section. If the refrigerant were to branch into multiple paths upon entering the evaporator, the low dryness and specific volume at the inlet would reduce the flow velocity within the pipes, lowering the heat transfer coefficient and affecting the refrigerant's heat transfer effect. Therefore, having few or no branches at the evaporator inlet is beneficial for heat transfer. However, as the dryness gradually increases, the amount of gaseous refrigerant increases, its specific volume increases, and its flow velocity also accelerates. To reduce the refrigerant's flow resistance, multiple branches should be designed at this point to decrease the flow velocity.

[0128] When determining whether an indoor heat exchanger is an integral type (in the form of a segmented design), a variable branch design will be given priority. In addition to considering the impact of uniform liquid distribution, the heat exchange effect between flow paths of different pipe diameters also needs to be taken into account.

[0129] Taking the U-shaped evaporator flow path design of a cabinet air conditioner as an example, such as Figure 3-6 As shown, flow paths 1, 2, 3, and 4 are all variable branch flow path designs with fewer to more branches. Flow path 1 places the fewer branch flow path at the lower end of the heat exchanger in the direction of gravity, while flow paths 2, 3, and 4 place the fewer branch flow path at the upper end of the heat exchanger in the direction of gravity. In addition, flow paths 1 and 2 are both variable branch flow path designs with 2 to 4 branches, while flow paths 3 and 4 are variable branch flow path designs with 3 to 4 branches and 2 to 6 branches, respectively.

[0130] The "few-to-many" variable branch flow design here refers only to the number of branches. It means that fewer branches are needed in the initial flow path in the direction of refrigerant flow into the evaporator, while more branches are needed in the later flow path in the same direction. The specific number of branches and the location of the fewer / more branches at the top / bottom of the heat exchanger need to be determined based on the actual heat exchanger size and overall system performance.

[0131] 4. The variable flow rate air conditioner flow path design optimization control logic of this invention

[0132] In order to balance the cooling and heating performance of air conditioners, the industry typically designs evaporator systems based solely on meeting the performance requirements of heating conditions. However, without considering the changes in refrigerant state and heat exchange characteristics, the evaporator size is often slightly too large, easily leading to severe overheating at the heat exchanger outlet. This not only affects the evaporator's heat exchange capacity but also increases its cost. This patent addresses this issue by using a variable pipe diameter and branching design based on the changes in the refrigerant's operating state within the evaporator, allowing the refrigerant flow rate to be adjusted according to these changes.

[0133] Based on the aforementioned variable flow rate flow path design method, the corresponding internal and external fan speeds, compressor frequency, and electronic expansion valve opening should also be adaptively adjusted. In actual evaporator piping experiments, the rationality of the current flow path design is judged by the relationship between the actual superheat ΔT1 and the target superheat ΔT.

[0134] (1) The target superheat ΔT can be expressed as:

[0135] ΔT = a i F +b i R 外 + c i R 内 + d i P +e i ;

[0136] Based on the difference Δt between the indoor ambient temperature and the air conditioner setting temperature during the experiment... in The magnitude of the target superheat is calculated using the formula shown in Table 1 above.

[0137] in,

[0138] t1 is used with △t in When comparing sizes, the temperature range is generally -2℃ to 0℃.

[0139] t2 is used with △t in When comparing sizes, the temperature range is generally 0℃ to 2℃.

[0140] The target superheat ΔT during the experimental test has a range of 1℃ to 3℃ (because the target superheat ΔT has a range, the coefficients a1, a2, etc. are not limited to a range).

[0141] F represents the compressor frequency adjustment amplitude, with a value range of 0Hz to 5Hz;

[0142] R represents the adjustment range of the outdoor fan speed, ranging from 0 rpm to 100 rpm;

[0143] R represents the indoor fan speed adjustment range, which is 0 rpm to 50 rpm.

[0144] P represents the adjustment range of the electronic expansion valve opening, ranging from 0p to 50p.

[0145] a i b i c i d i e i The fitting coefficients are obtained from fitting during the flow path design process of different models;

[0146] i represents different coefficients for different temperature ranges, with values ​​ranging from 1 to 3.

[0147] (2) Superheat control logic based on variable flow rate flow path design

[0148] Detect the current actual superheat ΔT1 and compare it with the target superheat ΔT:

[0149] 1) When ΔT1≤ΔT, it indicates that the refrigerant heat exchange in the evaporator is insufficient. The first step is to adjust the load parameters. This can be done by increasing the compressor frequency F (which increases the speed of work and improves the efficiency of the system, making the evaporator heat exchange more complete), or increasing the speed of the indoor and outdoor fans R1 and R2, or reducing the opening of the electronic expansion valve P, so that the refrigerant can exchange heat fully. If this still cannot improve the situation, consider increasing the number of large-diameter / multi-branch pipes in the downstream section of the evaporator to reduce the refrigerant flow rate and make it exchange heat fully.

[0150] 2) When ΔT1=ΔT, it indicates that the current flow path design and its load parameter design are relatively reasonable.

[0151] 3) When ΔT1 > ΔT, it indicates that the refrigerant in the evaporator is severely overheated. The first priority is to adjust the load parameters. This can be done by reducing the compressor frequency F, or reducing the speed of the indoor and outdoor fans R1 and R2, or increasing the opening of the electronic expansion valve to increase the refrigerant flow and avoid overheating losses. If this still cannot be improved, consider increasing the number of small-diameter / few-branch pipes in the front section of the evaporator to facilitate increased refrigerant flow rate and enhanced heat exchange.

[0152] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A heat exchanger, characterized in that: include: The front section (1) and the rear section (2) are located upstream of the rear section (2) along the flow direction of the refrigerant, and the pipe diameter of the front section (1) is smaller than that of the rear section (2), and / or the number of branches of the front section (1) is smaller than that of the rear section (2); the number of branches of the front section (1) can be adjusted according to the superheat of the heat exchanger, and / or the number of branches of the rear section (2) can be adjusted according to the superheat of the heat exchanger.

2. The heat exchanger according to claim 1, characterized in that: If the actual superheat is less than the target superheat, the number of branches in the front section (1) can be adjusted to decrease, and / or the number of branches in the rear section (2) can be adjusted to increase. If the actual superheat is greater than the target superheat, the number of branches in the front section (1) can be adjusted to increase, and / or the number of branches in the rear section (2) can be adjusted to decrease.

3. An air conditioner, characterized in that: The heat exchanger according to any one of claims 1-2 further includes a compressor, an internal fan, an external fan, and a throttling device.

4. A control method for an air conditioner as described in claim 3, characterized in that: include: The testing procedure involves detecting the current actual superheat ΔT1 of the air conditioner. The judgment step is to compare the actual superheat ΔT1 with the target superheat ΔT; The control steps are as follows: when ΔT1≤ΔT, control to reduce the number of branches in the front section (1) and / or control to increase the number of branches in the rear section (2); When ΔT1 > ΔT, control to increase the number of branches in the front section (1) and / or control to decrease the number of branches in the rear section (2).

5. The control method according to claim 4, characterized in that: The control steps, before controlling and adjusting the number of branches of the front section (1) and / or the rear section (2), also control and adjust the frequency of the compressor, and / or control the speed of the fan, and / or control the opening size P of the throttling device.

6. The control method according to claim 5, characterized in that: The control steps are as follows: when ΔT1 < ΔT, control to increase the compressor frequency, and / or control to increase the speed of the internal fan R1, control to increase the speed of the external fan R2, and / or control to decrease the opening degree P of the throttling device; when ΔT1 > ΔT, control to decrease the compressor frequency, and / or control to decrease the speed of the internal fan R1, control to decrease the speed of the external fan R2, and / or control to increase the opening degree P of the throttling device; when ΔT1 = ΔT, maintain the current state.

7. The control method according to claim 5, characterized in that: In the control step, the target superheat ΔT is calculated as follows: ΔT = a i F +b i R 外 + c i R 内 + d i P +e i That is, by controlling the compressor frequency F and the internal fan speed R. 内 External fan speed R 外 The target superheat ΔT under this operating condition is calculated based on the opening degree P of the throttling device.

8. The control method according to claim 7, characterized in that: F represents the compressor frequency adjustment amplitude, with a value range of 0Hz to 5Hz; R 外 The adjustment range for the outdoor fan speed is 0 rpm to 100 rpm; R 内 The indoor fan speed adjustment range is 0 rpm to 50 rpm; P 外 The adjustment range for the opening of the electronic expansion valve is 0p to 50p. The target superheat ΔT ranges from 1℃ to 3℃.

9. The control method according to claim 7 or 8, characterized in that: a i b i c i d i e i The fitting coefficients are obtained from fitting during the flow path design process of different models; i represents different coefficients for different temperature ranges, with values ​​ranging from 1 to 3.

10. The control method according to claim 9, characterized in that: Based on the difference Δt between the indoor ambient temperature and the air conditioner's set temperature in The size of a determines the size of a i b i c i d i and e i The value of , When △t in When ∈ (-6℃, t1), i=1, ΔT= a1F +b1R 外 + c1R 内 + d1 P +e1; When △t in When ∈[t1, t2], i=2, ΔT= a2F +b2R 外 + c2R 内 + d2 P +e2; To △t in When ∈ (t2, 6℃), i=3, ΔT= a3F + b3R 外 + c3R 内 + d3 P +e3, Where t1 is taken as -2℃ to 0℃; t2 is taken as 0℃ to 2℃.

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