A control method and system for preventing ice blockage of a heat pump unit base pan drain

Abstract

The present application relates to air conditioning refrigeration technology field, especially to a kind of control method and system for preventing ice block of heat pump unit chassis drain outlet, the system includes air side heat exchanger, V-type water collecting tank, water side heat exchanger, stainless steel water pipe, circulating water pump, temperature sensor and controller;Wherein, stainless steel water pipe is built into V-type water collecting tank and is arranged along groove type, and close to the upstream flow path of drain hole and the adjacent area of hole edge. The method determines the ice block risk index of drain outlet by collecting outdoor ambient temperature, defrosting state, drain duration and the temperature of adjacent area of drain hole, and controls the operation of circulating water pump according to the ice block risk index, so that the circulating medium implements directional heat transfer to the adjacent area of drain hole through stainless steel water pipe, and delays heat preservation after defrosting, to inhibit the formation of ice bridge and ice plug, improve the drain reliability and continuous operation ability of heat pump unit in low temperature environment.

Description

Technical Field

[0001] This invention relates to the field of air conditioning and refrigeration technology, and in particular to a control method and system for preventing ice blockage at the drain outlet of a heat pump unit chassis. Background Technology

[0002] Heat pump units, especially air-source heat pump units, operate in winter with their outdoor heat exchangers constantly exposed to low temperatures, high humidity, and alternating periods of frost and defrost. Water vapor in the outdoor air condenses and freezes on the surface of the air-side heat exchanger. When the unit enters defrost mode, the defrost water formed by melting frost, along with condensate generated during operation, drips to the bottom of the unit and is then discharged through the chassis's water collection structure and drain outlet. Because the chassis drain outlet and its adjacent area are typically affected by multiple adverse factors simultaneously, including cold air scouring, heat dissipation from the metal chassis, localized water accumulation, and refreezing after defrosting, the drain outlet location often becomes the first sensitive area to develop ice bridges and blockages. Once the drain outlet becomes blocked with ice, subsequent defrost water cannot be discharged in time. The accumulated water repeatedly freezes and gradually expands within the chassis, causing not only chassis icing and drainage structure deformation but also potential problems such as fan ice sweeping, secondary frost formation at the bottom of the heat exchanger, increased noise, and unit shutdown for protection purposes. This ultimately affects the unit's operational reliability and service life in low-temperature environments. The aforementioned problems are particularly prominent in cold regions, areas with large diurnal temperature differences, and long-term heating operation scenarios. Therefore, structural design and control strategies for preventing ice blockage at the chassis drain outlet have always been an important research direction in the field of heat pump units.

[0003] To address the problem of icing in drainage systems, existing technologies have proposed several solutions. One approach is to directly utilize the heat from the heat pump system's own thermal cycle to heat the area near the drainage channel or outlet. For example, document CN112240652A discloses a drainage pipe and a heat pump system. The drainage pipe has isolated drainage and heating channels, with the heating channels connected to the heat pump system's circulation piping. This allows the heat from the heat pump system's thermal cycle to heat the drainage channels. The document also explicitly states that the heating channels are arranged to heat the area near the drain pan outlet, preventing icing and blockage of the drainage pipe and outlet. This solution demonstrates that actively heating the drainage area using existing heat sources within the unit can, to some extent, avoid the energy consumption and safety issues associated with relying solely on electric heating, and provides a good anti-freezing effect.

[0004] Another approach is to connect the drainage components to the unit's water system, utilizing the existing circulating water or pressure difference within the unit to create flow, thereby increasing the local temperature of the drainage components and providing antifreeze protection. Document CN204226955U discloses an antifreeze device for the drainage pipe of an air-cooled chiller / hot water unit. This device connects the drainage pipe to the entire water system via a water pump drainage fitting, a sleeve drainage fitting, and connecting pipes. The pressure difference created by the water pump inlet and outlet pipes drives the circulating water in the drainage pipe, thereby increasing the water temperature and preventing the circulating water from freezing and the drainage pipe from cracking. This solution demonstrates that utilizing the existing water system for drainage pipe antifreeze in HVAC equipment is a feasible approach, improving drainage reliability under low-temperature conditions without significantly increasing the need for additional heating elements.

[0005] Another earlier existing technology involves installing dedicated anti-icing piping along the drainage channel, causing high-temperature refrigerant or other heat medium to bypass the drainage area, thereby reducing the possibility of freezing in the drainage channel and drain holes. Document CN1719143A discloses an anti-icing device for outdoor air conditioning units, which features a downwardly recessed drainage channel along the side of the heat exchanger on the chassis, with several drain holes in the channel; simultaneously, a plate-shaped channel is installed on the chassis along the drainage channel, allowing a portion of the high-temperature refrigerant flowing into the outdoor heat exchanger to flow along this channel, thus heating the drainage channel, preventing icing, and ensuring smooth drainage. Correspondingly, authorized document CN100516696C further discloses a scheme that installs anti-icing piping along the side of the drainage channel and controls the flow rate of high-temperature refrigerant by switching valves. These documents demonstrate that arranging heat medium piping along the drainage channel and implementing heat tracing in the drainage area is one of the typical technical approaches in this field for solving the problem of outdoor unit drainage icing.

[0006] While the aforementioned existing technologies have achieved some success in preventing the freezing of drainage structures, they still have several shortcomings in addressing the technical problem this invention aims to solve. Firstly, solutions such as CN112240652A focus on heating the drainage pipe or drainage channel itself, with the heat application primarily directed towards the drainage path itself. They lack targeted heat distribution and thermal field control for the critical area in the heat pump unit chassis where ice bridges first form—namely, the edge of the drainage hole where the chassis's water flow ultimately converges and its upstream short-distance confluence area. In other words, although existing technologies recognize the need for heating near the drainage outlet, their structural approach primarily focuses on preventing blockage of the entire drainage pipe, which is insufficient to address the ice blockage problem caused by the coupling between localized water stagnation within the chassis, ice formation at the hole edge, and refreezing sensitive areas.

[0007] Secondly, solutions such as those disclosed in CN204226955U, which utilize water pressure differentials to drive the flow of circulating water within the drain pipe, primarily address the issue of stagnant water freezing and bursting at low temperatures in the drain pipe. These solutions are more suited to scenarios involving water system evacuation or drain pipe protection. However, they lack the capability to provide continuous, directional, and adjustable heating to specific areas around the chassis drain outlet when dealing with the rapid discharge of large amounts of instantaneous defrost water and condensate generated during the heating-defrosting cycle of an air-source heat pump, as well as the repeated icing caused by alternating hot and cold temperatures around the drain hole. Therefore, when icing is mainly concentrated near the chassis drain hole rather than inside the long drain pipe, the applicability of these solutions remains limited.

[0008] Secondly, schemes like CN1719143A and CN100516696C, which arrange refrigerant anti-icing piping along the drain channel, can utilize high-temperature refrigerant to heat the drain channel. However, since the heat source is directly taken from the refrigerant circuit, it usually requires additional diversion, bypass, or valve-controlled design of the main refrigeration circuit. The system configuration is relatively complex, and it places higher demands on the overall refrigerant distribution, load matching, and operational safety. For heat pump units using water-side heat exchangers and with existing water circulation conditions, continuing to use the refrigerant circuitous heat tracing approach may lead to complex structural modifications, inconvenient installation and maintenance, and insufficient control precision. In addition, this type of scheme emphasizes heat tracing along the drain channel, but does not adequately consider issues such as the chassis confluence geometry, the local heat coverage area of ​​the drain hole, and the suppression of refreezing after defrosting.

[0009] In summary, while existing technologies have proposed various solutions, such as using heat pump heat cycles to heat drainage sections, connecting drainage components to the unit's water circuit for freeze prevention, and installing heat medium piping along drainage channels for ice prevention, they still generally suffer from the following shortcomings: First, the heating of the most sensitive freezing point—the drainage outlet of the heat pump unit chassis—is not targeted enough, and the heat is often dispersed throughout the entire drainage pipe or drainage channel, failing to construct a shorter heat transfer path around the upstream confluence path of the drainage hole and the area adjacent to the hole edge; second, there is a lack of an arrangement method that matches the geometric characteristics of the chassis water collection structure, making it difficult to balance rapid confluence and localized freeze prevention; third, existing solutions focus more on structural freeze prevention, lacking sufficient adjustability of heating intensity under different low-temperature conditions, making it difficult to simultaneously achieve both ice prevention and operating energy consumption. Based on this, it is still necessary to propose a new technical solution to prevent ice blockage at the drain outlet of the heat pump unit chassis. This solution should be able to combine the characteristics of the chassis water collection structure to apply heat more specifically to the drain hole and its adjacent area, and utilize the existing water-side heat exchange circuit of the unit to achieve safer, more stable and adjustable heating, thereby further improving the reliability and continuous operation capability of the heat pump unit chassis drainage in low-temperature environments. Summary of the Invention

[0010] The technical objective of this invention is to address the problem that existing heat pump units are prone to ice blockage at the chassis drain outlet under low temperature, high humidity, and defrosting drainage conditions, which leads to water accumulation, freezing, poor drainage, and reduced operational reliability. This invention provides a control method and system to prevent ice blockage at the chassis drain outlet of heat pump units. This allows for more targeted heating and control of the area near the drain hole in conjunction with the chassis water collection structure, thereby reducing the risk of ice blockage at the drain outlet and improving the unit's drainage reliability and continuous operation capability in low-temperature environments.

[0011] Firstly, in order to achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0012] A control method for preventing ice blockage at the drain outlet of a heat pump unit chassis is applied to a heat pump unit including an air-side heat exchanger, a V-shaped water collection trough, a water-side heat exchanger, stainless steel water pipes, a circulating water pump, an outdoor temperature sensor, and a controller. The V-shaped water collection trough is located below the air-side heat exchanger, and a drain hole is provided at the lowest point of the trough bottom. The stainless steel water pipes are placed within the V-shaped water collection trough in an area overlapping with it and are arranged along the trough's shape. At least one section of the stainless steel water pipes is positioned close to the upstream confluence path and the area adjacent to the drain hole's edge. The stainless steel water pipes are connected to the water circuit of the water-side heat exchanger to form a circulating branch. The method includes the following steps:

[0013] S1: Collect outdoor ambient temperature Defrosting status indicator quantity Drainage duration and the temperature in the area near the drain hole ;

[0014] S2: The controller determines the outdoor ambient temperature based on the outdoor ambient temperature. Defrosting status indicator quantity Drainage duration and the temperature in the area near the drain hole Determine the risk index of ice blockage at the drain outlet And the risk index of ice blockage at the drain outlet. Compared with the first risk threshold Second risk threshold and the third risk threshold Comparison is used to determine the risk level corresponding to the current working condition; among which, ;

[0015] S3: When the controller determines the risk index of ice blockage at the drain outlet. Reaching the first risk threshold When the above conditions are met, start the circulating water pump; when the risk index of ice blockage at the drain outlet is reached... Each in , and During the interval, control the circulating water pump to operate at the first speed. Second rotation speed and the third rotation speed Operation allows the circulating medium to circulate between the water-side heat exchanger and the stainless steel water pipes; among which, ;

[0016] S4: Directional heat transfer is implemented through the stainless steel water pipe to the upstream confluence path of the drain hole and the area adjacent to the hole edge, so as to maintain the temperature of the area adjacent to the drain hole above the preset antifreeze temperature during defrosting and drainage and during the sensitive period of local refreezing after defrosting. ;

[0017] S5: When the defrost status indicator is... After switching from defrosting mode to non-defrosting mode, the controller keeps the circulating water pump running for a delayed heat preservation period. And in the drain outlet ice blockage risk index continuous The second time below the risk clearance threshold And it meets the gear shift backlash requirement. Output a pump stop signal under the specified conditions.

[0018] Preferably, the drain outlet ice blockage risk index mentioned in step S2 The outdoor ambient temperature Defrosting status indicator quantity Drainage duration and the temperature in the area near the drain hole The weighting function; preferably, the drainage outlet ice blockage risk index Determine using the following formula:

[0019] ;

[0020] in, , , , These represent the weight coefficients of each influencing factor; This represents the risk mapping amount corresponding to the outdoor ambient temperature. This represents the risk mapping value corresponding to the defrosting state; This represents the risk mapping amount corresponding to the duration of drainage; This represents the risk mapping amount corresponding to the temperature in the area adjacent to the drain hole.

[0021] Preferably, in step S3, when the risk index of ice blockage at the drain outlet is... First time reaching the first risk threshold At the above time, the controller first controls the circulating water pump to the first speed. Preheating operation is performed, and then the risk index of ice blockage at the drain outlet is used as a reference. Switching to the second speed Or the third rotation speed .

[0022] Preferably, in step S4, the stainless steel water pipe is set close to the bottom of the V-shaped water collection tank and spans the upstream confluence path of the drain hole and the area adjacent to the edge of the hole, so that the heat is preferentially applied to the area where ice bridges are easily formed.

[0023] Preferably, the circulating medium in step S4 is water or water-based antifreeze; wherein, the water-based antifreeze refers to a heat exchange medium with water as the continuous phase and containing antifreeze components.

[0024] Preferably, the gear shift backlash mentioned in step S5 This is used to limit the frequent switching of the circulating water pump between adjacent speeds when there are fluctuations in outdoor ambient temperature or temperature fluctuations in the area near the drain hole.

[0025] Preferably, the V-shaped water collection tank includes a first inclined guide surface and a second inclined guide surface arranged opposite to each other. The first inclined guide surface and the second inclined guide surface converge on the drain hole to form the lowest point of the tank bottom, so that the condensate and defrost water generated by the air-side heat exchanger are discharged into the drain hole in a concentrated manner.

[0026] Preferably, the drain hole is located in the middle region of the V-shaped water collection trough along the length of the trough, and the edge of the drain hole is located in the adjacent area of ​​the stainless steel water pipe.

[0027] Preferably, the stainless steel water pipe is fixed in the V-shaped water collection tank by positioning clips and / or pipe clamp brackets; wherein, the positioning clips are used to laterally limit the stainless steel water pipe, and the pipe clamp brackets are used to hug and support the stainless steel water pipe.

[0028] Preferably, the circulating water pump is located near the return water side of the stainless steel water pipe to reduce the backflow resistance in the circulating branch and improve the local flow stability of the heat medium.

[0029] Secondly, the present invention also provides a control system for preventing ice blockage at the drain outlet of the heat pump unit chassis, including an air-side heat exchanger, a V-shaped water collection tank, a water-side heat exchanger, a stainless steel water pipe, a circulating water pump, an outdoor temperature sensor, and a controller.

[0030] The V-shaped water collection trough is located below the air-side heat exchanger, and a drain hole is provided at the lowest point of the bottom of the V-shaped water collection trough.

[0031] The stainless steel water pipe is placed in the V-shaped water collection trough in the area overlapping with the V-shaped water collection trough and arranged along the trough shape of the V-shaped water collection trough, and at least one section of the stainless steel water pipe is set close to the upstream confluence path of the drain hole and the area adjacent to the edge of the hole.

[0032] The stainless steel water pipe is connected to the water circuit of the water-side heat exchanger to form a circulation branch.

[0033] The circulating water pump is installed on the circulating branch and is used to drive the flow of the circulating medium.

[0034] The outdoor temperature sensor is used to collect outdoor ambient temperature.

[0035] The controller is electrically connected to the outdoor temperature sensor and the circulating water pump, and is configured to execute the control method.

[0036] Preferably, the controller is also electrically connected to a temperature sensor in the vicinity of the drain hole to obtain the temperature of the vicinity of the drain hole. .

[0037] Preferably, the controller is configured to activate the preheating control of the circulating water pump before the unit enters the defrosting state or at the initial stage of entering the defrosting state, so as to reduce the probability of ice bridges forming in the initial stage of defrosting drainage.

[0038] Thirdly, the present invention also provides a computer-readable storage medium having a computer program or instructions stored thereon, which, when executed by a processor, implement the steps of the method.

[0039] Fourthly, the present invention also provides a computer program product, including a computer program or instructions that, when executed by a processor, implement the steps of the method.

[0040] This invention focuses the anti-icing control on the upstream confluence path of the heat pump unit's chassis drain outlet and the easily frozen area near the outlet edge. Combined with the directional confluence of the V-shaped water collection trough, the short-distance heat transfer of the stainless steel water pipes, and graded circulation control based on ice blockage risk, this ensures that defrost water and condensate receive continuous targeted heat compensation as they drain towards the drain outlet, effectively suppressing the formation of ice bridges and ice blockages at the drain outlet. Simultaneously, this invention utilizes the unit's existing water-side heat exchange circuit as a heat source, eliminating the need for additional high-power electric heating components or complex refrigerant bypass structures. This reduces additional energy consumption and system modification complexity while ensuring antifreeze performance. Furthermore, by implementing phased and leveled control for different low-temperature operating conditions, the defrosting process, and the sensitive period of refreezing after defrosting, it reduces problems such as repeated freezing of water on the chassis, fan ice sweeping, secondary frosting at the bottom of the heat exchanger, increased noise, and protection shutdowns. This significantly improves the drainage reliability, operational stability, continuous heating capacity, and overall service life of the heat pump unit in low-temperature and high-humidity environments. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the system structure for preventing ice blockage at the drain outlet of the heat pump unit chassis according to the present invention.

[0042] Figure 2 for Figure 1 A magnified view of the area near the central drainage hole.

[0043] Figure 3 The graph shows the change in flow rate of the drain hole over time for different machines.

[0044] Figure 4 Comparison chart of ice accumulation quality on the chassis of different machines.

[0045] Figure 5 This is a graph showing the temperature change over time in the area near the drain hole. (Detailed implementation method)

[0046] The technical solution of the present invention will be further described clearly and completely below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. Based on the content disclosed in this invention, equivalent substitutions, conventional modifications, or local optimizations made by those skilled in the art without departing from the concept of the present invention should all fall within the scope of protection of the present invention.

[0047] In this specification, terms such as "upper," "lower," "inner," "outer," "left," "right," "front," "back," "upstream," "downstream," and "adjacent" are used primarily to describe the relative positional relationships shown in the accompanying drawings. They are used only for the purpose of illustrating the invention and simplifying the description, and are not intended to limit the absolute installation direction, spatial orientation, or geometric dimensions of the invention.

[0048] I. Terminology Explanation

[0049] To facilitate understanding of this invention, the main terms used herein will be briefly explained first:

[0050] Air-side heat exchanger: refers to the heat exchange component in a heat pump unit that exchanges heat with outdoor air. It is prone to frost formation under heating conditions and produces defrost water during the defrosting process.

[0051] Water-side heat exchanger: refers to the heat exchange component in a heat pump unit that exchanges heat with the circulating medium in the water circuit, and is used to provide a heat source for the anti-ice blockage circulation branch in this invention.

[0052] V-shaped water collection trough: refers to a water receiving structure located below the air-side heat exchanger, with two oppositely arranged inclined guide surfaces that converge at the lowest point of the trough bottom.

[0053] Drainage hole: refers to the opening structure set at the lowest point of the V-shaped water collection tank for draining condensate and defrost water.

[0054] The area adjacent to the drainage hole: refers to the easily frozen area centered on the edge of the drainage hole, including its upstream short-distance confluence path, the perimeter of the hole edge, and the local refreezing sensitive area.

[0055] Upstream confluence path: refers to the last confluence path that condensate or defrost water travels before flowing from the V-shaped water collection tank to the drain hole.

[0056] Ice blockage risk index: refers to a comprehensive risk measure used to characterize the possibility of ice bridges or ice blockages occurring in the area near the drainage hole.

[0057] Directional heat transfer: refers to a localized heating method in which heat is not evenly distributed throughout the chassis, but rather preferentially acts on the upstream confluence path of the drain hole and the area adjacent to the hole edge.

[0058] Extended insulation time: refers to the period of time during which the circulating water pump continues to run after defrosting to prevent the refreezing of residual water and water film.

[0059] Gear shift hysteresis: refers to the allowable temperature difference set to prevent the circulating water pump from frequently switching between adjacent gears.

[0060] II. System Structure

[0061] like Figure 1 and Figure 2 As shown, the control system for preventing ice blockage at the drain outlet of a heat pump unit chassis according to the present invention includes an air-side heat exchanger 6, a V-shaped water collection tank 4, a water-side heat exchanger 1, a stainless steel water pipe 2, a circulating water pump 3, an outdoor temperature sensor, and a controller.

[0062] The air-side heat exchanger 6 is located in the outdoor heat exchange area of ​​the heat pump unit. During heating, it comes into contact with cold air, and its surface is prone to condensation and frost formation. When the unit enters defrosting mode, the frost melts to form defrost water, which drips along with other condensed liquids into the V-shaped water collection tank 4 below the air-side heat exchanger 6. The V-shaped water collection tank 4 is preferably a long strip-shaped confluence structure extending along the lower edge of the heat exchanger. It includes a first inclined guide surface and a second inclined guide surface arranged opposite each other. The two guide surfaces converge from both sides of the tank towards the middle or a designated bottom area, forming the lowest point of the tank bottom at the convergence point, where a drain hole 5 is provided. Through this structure, dripping water from different positions of the air-side heat exchanger 6 can quickly concentrate towards the drain hole 5 under the action of gravity, reducing the probability of water remaining in the middle or edge of the chassis for a long time.

[0063] This invention does not employ a method of simply setting up an independent electric heating element near the drain hole, nor does it employ a method of heating the entire drain pipe. Instead, it uses a stainless steel water pipe 2 that matches the V-shaped water collection trough 4 as a local heating actuator. The stainless steel water pipe 2 is placed inside the V-shaped water collection trough 4 in the area overlapping with it, and is arranged along its trough shape. Preferably, at least one section of the stainless steel water pipe 2 is set close to the upstream confluence path and the area adjacent to the drain hole 5. This section of the stainless steel water pipe 2 can extend along the bottom of the V-shaped water collection trough 4, or it can form a partially bent, partially parallel, or partially enclosed heat-covering section near the drain hole 5, so as to concentrate the heat as much as possible on the critical area where freezing first occurs. Because the stainless steel water pipe 2 itself has good corrosion resistance, structural strength, and thermal conductivity stability, it can adapt to the long-term hot and cold cycles, vibration and shock, and drainage flushing conditions of the heat pump unit in the outdoor environment.

[0064] The water-side heat exchanger 1 is provided with a water-side heat exchanger outlet 11 and a water-side heat exchanger return outlet 12. A stainless steel water pipe 2 is connected to the water-side heat exchanger 1 via a pipeline, thus forming a circulation branch. A circulating water pump 3 is preferably located near the return side of the stainless steel water pipe 2, or in a location with low resistance and easy maintenance within the circulation branch, used to drive the circulating medium to circulate between the water-side heat exchanger 1 and the stainless steel water pipe 2. The circulating medium can be water or a water-based antifreeze, such as an aqueous solution of ethylene glycol, an aqueous solution of propylene glycol, or other heat exchange media suitable for heat pump water circuit systems. This invention utilizes the heat conditions of the existing water-side heat exchange system of the heat pump unit to provide continuous or graded heat compensation to the area near the drain hole 5, thereby avoiding complex modifications to the main refrigerant circuit and avoiding the increased energy consumption and electrical safety risks associated with relying solely on high-power electric heating.

[0065] An outdoor temperature sensor is used to collect outdoor ambient temperature signals. A local temperature sensor can also be installed near the drain hole to detect the temperature in the vicinity of the drain hole. The controller is electrically connected to the outdoor temperature sensor, the local temperature sensor, and the circulating water pump 3. When necessary, it can also receive defrost status signals from the unit, compressor operating status signals, four-way valve reversing status signals, or operating condition indicator signals from within the control board. Based on the acquired multi-source operating information, the controller calculates the drain outlet ice blockage risk index and controls the circulating water pump 3 to operate at different speeds according to the risk level, or maintains delayed insulation after defrosting, thus forming a complete control chain of risk assessment—tiered heating—risk clearance and pump shutdown.

[0066] To ensure that the stainless steel water pipe 2 maintains a stable position relative to the area adjacent to the drain hole 5 during long-term operation, the stainless steel water pipe 2 is fixed within the V-shaped water collection tank 4 by at least one fastener. The fastener can be a positioning clip 7 and / or a pipe clamp bracket 8. The positioning clip 7 provides lateral restraint in the transverse section or local transition section of the water pipe, preventing lateral displacement under water flow impact and unit vibration. The pipe clamp bracket 8 uses its body and openable clamping part to encircle and support the stainless steel water pipe 2, preventing warping, sagging, or detachment from the tank bottom. Through this fixing structure, the heat output position of the stainless steel water pipe 2 can remain stable over a long period, ensuring a continuous and effective heat coverage area near the drain hole 5.

[0067] III. Specific Technical Route for Implementing the Method of the Invention

[0068] The technical approach of this invention is not simply to turn on the circulating water pump when the temperature is low, but rather to couple and control three key aspects: the upstream confluence path of the drain hole, the area near the drain hole edge, and the sensitive period of refreezing after defrosting. In summary, the technical approach can be described as follows: First, a V-shaped water collection trough is used to achieve directional confluence of condensate and defrost water; second, stainless steel water pipes arranged close to the upstream confluence path and the area near the drain hole edge form a locally enhanced heat field; then, the controller determines the ice blockage risk index of the drain outlet based on information such as outdoor ambient temperature, defrosting status, drainage duration, and local temperature; subsequently, the circulating water pump is controlled to operate at the corresponding speed according to the ice blockage risk level, allowing the circulating medium to carry heat from the water-side heat exchanger through the stainless steel water pipes, providing tiered heating to the critical areas most prone to ice bridge formation; finally, after defrosting, delayed insulation is maintained until the risk index is eliminated to prevent residual water or thin water film from refreezing in a short period.

[0069] From an innovative mechanism perspective, this invention does not provide uniform heating to the entire chassis. Instead, through a collaborative design of convergence geometry, localized heat coverage, and risk control, it prioritizes heat and control resources to the locations that truly determine whether ice blockage will occur. This technical approach can effectively improve the drainage reliability and continuous operation capability of the heat pump unit chassis drain outlet in low-temperature and high-humidity environments without significantly increasing system complexity.

[0070] The specific implementation of the method of the present invention will be described in detail below with reference to steps S1 to S5.

[0071] IV. Step S1: Multi-source state variable acquisition

[0072] Step S1 is: Collect outdoor ambient temperature. Defrosting status indicator quantity Drainage duration and the temperature in the area near the drain hole .in, Indicates the outdoor ambient temperature; A status indicator showing whether the unit is in the defrosting process; This indicates the cumulative duration of a single defrosting and drainage process from the start of drainage. This indicates the temperature of the area near the drain hole.

[0073] 1. Outdoor ambient temperature Acquisition

[0074] Outdoor ambient temperature The temperature is collected by an outdoor temperature sensor. This sensor is preferably installed inside the unit casing, in a location open to the outside but avoiding direct water exposure, high-temperature components, and strong radiation sources. For example, it can be installed in a ventilation area of ​​the outdoor unit casing or in an area with natural air circulation around the unit. To reduce the impact of direct fan airflow, solar radiation, and casing heat on the measurement results, the outdoor temperature sensor can be equipped with a shielding structure or installed inside a ventilation opening. The controller can sample the outdoor ambient temperature according to a preset sampling period, such as every 1 second, 2 seconds, 5 seconds, or 10 seconds, and perform mean filtering, median filtering, or first-order low-pass filtering on several consecutive sample values ​​to improve the stability of the temperature input signal.

[0075] Outdoor ambient temperature This is a crucial input parameter used in this invention to determine the tendency of the basic environment to freeze. Generally, under similar conditions of relative humidity, wind speed, and defrosting / drainage, The lower the temperature, the more easily ice bridges, ice blockages, or frozen edge layers form in the area adjacent to the drain hole. Therefore, this invention will... As one of the basic inputs for assessing ice blockage risk.

[0076] 2. Defrosting status indicator quantity Acquisition

[0077] Defrosting status indicator quantity This is used to indicate whether the heat pump unit is currently in the defrost process. There are several ways to obtain this information. In one implementation, the controller directly reads the defrost status bit output by the unit's main control board. When the unit enters defrost operation, Take the first state value; when the unit exits defrosting operation, Take the second state value. In another implementation, the controller can comprehensively determine whether it is in the defrosting state by considering the four-way valve reversing signal, the compressor operating status, the fan stop / start logic, the coil temperature change characteristics, and the defrosting time timing logic.

[0078] Set defrost status indicator quantity The reason is that the main trigger for ice blockage at drain outlets is not just low temperature, but the combination of low temperature and defrost drainage. In other words, even if the ambient temperature is low, ice blockage may not occur immediately when there is no significant drainage flow; however, during the specific time window at the beginning or end of defrost, a large amount of defrost water is discharged in a concentrated manner and the local temperature fluctuates rapidly, making it most likely for localized ice to form at the edge of the drain outlet. Therefore, Incorporating control logic can significantly improve the accuracy of assessing the actual risks of ice blockage.

[0079] 3. Drainage duration Acquisition

[0080] Drainage duration This represents the cumulative duration from the start of a defrost drainage cycle to the current moment. Its start time can be defined as the defrost status indicator. The moment of entering defrost mode can also be defined as the moment a drainage start signal is detected or a significant change in liquid flow / temperature occurs in the vicinity of the drain hole. The controller activates the timing module after detecting the start time, and accumulates the time in real time. .

[0081] Introducing drainage duration The reason is that ice blockage does not occur instantaneously, but typically involves a process of localized water accumulation—low-temperature cooling—formation of crystal nuclei at the orifice edge—ice bridge expansion—reduction of effective flow area—and subsequent obstruction of drainage. The longer the drainage duration, the more pronounced the ice accumulation effect at the orifice edge and along its upstream confluence path under low-temperature conditions; especially in the short period after defrosting, residual water films and droplets are more prone to refreezing. Therefore, It can characterize the degree of risk accumulation and is an important parameter for the sequential anti-blocking control in this invention.

[0082] 4. Temperature in the area near the drain hole Acquisition

[0083] Temperature in the area near the drain hole Temperature data can be collected by a localized temperature sensor located near the edge of the drain hole, in the area adjacent to the bottom of the V-shaped water collection trough, or between the stainless steel water pipe and the drain hole. The localized temperature sensor preferably uses waterproof, condensation-proof, and low-temperature-resistant elements, such as thermistors, digital temperature chips, or surface-mount temperature probes. To avoid the sensor itself affecting the localized drainage flow, it can be embedded inside the bottom material of the V-shaped water collection trough, on the outer sidewall of the drain hole, or in a location adjacent to the water pipe but not directly obstructing the water flow.

[0084] Temperature in the area near the drain hole This is one of the parameters in this invention that most directly reflects whether a local area is in a critical state of freezing. Compared with simply using the outdoor ambient temperature, This directly reflects the local thermal field, the working status of the antifreeze circulation branch, and the temperature changes caused by liquid flushing. Through simultaneous data acquisition... and This invention can distinguish between two different operating conditions: one where the environment is cold but the local heat coverage is sufficient, and the other where the environment is not extremely cold but the local heat is insufficient and there is a tendency for ice bridging. This improves the targeting and accuracy of the control.

[0085] In summary, step S1 is not simply data sampling, but rather the foundation for constructing a multi-source input for subsequent risk assessment. It comprehensively incorporates the external environment, unit operating conditions, risk accumulation time, and local actual thermal state, laying the groundwork for a judgment that more closely approximates the actual icing process.

[0086] V. Step S2: Determination of Ice Blockage Risk Index and Classification

[0087] Step S2 is: The controller determines the outdoor ambient temperature... Defrosting status indicator quantity Drainage duration and the temperature in the area near the drain hole Determine the risk index of ice blockage at the drain outlet And the risk index of ice blockage at the drain outlet. Compared with the first risk threshold Second risk threshold and the third risk threshold Comparison is used to determine the risk level corresponding to the current working condition.

[0088] in, This indicates the risk of ice blockage in the area adjacent to the drain hole; , , These represent risk thresholds from low to high, and satisfy the following conditions: .

[0089] Step S2 is one of the steps that makes the greatest contribution to the inventiveness of this invention. Its core significance lies in the fact that this invention no longer directly equates low ambient temperature with inevitable ice blockage at the drain outlet. Instead, it comprehensively evaluates the multiple factors that actually determine the formation of ice blockage and then drives subsequent heating control accordingly. This avoids unnecessary long-term operation of the circulating water pump when the risk is low, reducing energy consumption, and can promptly increase the heating intensity when the risk truly rises, improving the anti-icing effect.

[0090] In a preferred embodiment, the risk index of ice blockage at the drain outlet is... It is determined by the following relationship:

[0091] ;

[0092] in, , , , These represent the weight coefficients of each influencing factor; This represents the risk mapping amount corresponding to the outdoor ambient temperature. This represents the risk mapping value corresponding to the defrosting state; This represents the risk mapping amount corresponding to the duration of drainage; This represents the risk mapping amount corresponding to the temperature in the area adjacent to the drain hole.

[0093] The above formula is not limited to a specific precise mathematical form; its essence lies in mapping different input quantities to a unified risk dimension and then performing a weighted summation. Technical personnel in the relevant field can set the mapping functions and weights based on actual conditions such as the unit model, regional climate, chassis geometry, and drainage outlet size. For example:

[0094] for It can be set to random. A piecewise or linear function that decreases and monotonically increases;

[0095] for A higher risk mapping value can be assigned to the defrosting state, and a lower risk mapping value can be assigned to the non-defrosting state.

[0096] for This can map a longer drainage duration to a higher cumulative risk;

[0097] for This can map the risk as the local temperature approaches or falls below the freezing critical range.

[0098] In actual control, The calculation does not require absolute mathematical precision, but rather aims to develop a stable, interpretable, and calibrable risk ranking capability. This is achieved through comparison with three risk thresholds. , , By comparison, the controller can classify the current operating condition into low risk, medium risk, and high risk, or further subdivide it into early warning level, enhanced level, and strong antifreeze level.

[0099] Preferably, when the controller switches risk levels, it can also employ a continuous confirmation mechanism, which requires confirmation within a certain number of consecutive sampling periods. The risk level is only switched when all values ​​are within the target range. This avoids misjudgments caused by short-term measurement fluctuations, instantaneous wind from the fan, or drainage pulsations. If necessary, different thresholds can be set or hysteresis can be introduced when the risk level is upgraded or downgraded to further enhance system stability.

[0100] The innovative value of this step lies in the fact that it truly couples the structural heating system with the operating condition drive control, so that the synergistic effect of stainless steel water pipes, V-shaped water collection tanks and circulating water pumps is based on dynamic risk assessment, rather than relying on a crude start-up logic based on a single low temperature threshold.

[0101] VI. Step S3: Staged Pump Control and Preheating Operation

[0102] Step S3 is: when the controller determines the risk index of ice blockage at the drain outlet. Reaching the first risk threshold When the above conditions are met, start the circulating water pump; when the risk index of ice blockage at the drain outlet is reached... Each in , and During the interval, control the circulating water pump to operate at the first speed. Second rotation speed and the third rotation speed The operation allows the circulating medium to circulate between the water-side heat exchanger and the stainless steel water pipes. Among these... , , These represent the operating speeds of the three circulating water pumps, from low to high, and satisfy the following conditions: .

[0103] The main function of step S3 is to convert the risk level obtained in step S2 into a specific, actionable heat supply intensity. Compared with the simple binary control in the prior art that turns on when the temperature is low and off when the temperature recovers, this invention achieves graded regulation of the heat transfer medium flow through graded control of the circulating water pump, thereby ensuring that the heat output from the stainless steel water pipe matches the actual risk of ice blockage.

[0104] In one embodiment, the circulating water pump 3 can be a three-speed constant-speed pump, which has a first speed, a second speed, and a third speed in its hardware; in another embodiment, the circulating water pump 3 can also be a variable frequency pump, with the controller implementing graded speed control through PWM, analog signals, or bus commands. Regardless of the method used, as long as different flow outputs corresponding to different risk levels can be achieved, the requirements of this invention can be met.

[0105] when When in the low-risk range, the controller sets the circulating water pump to its first speed. During operation, the circulating medium flow rate is low, primarily used for preheating and maintaining the area near the drain hole above the dangerous temperature range. When the risk level rises to the medium-risk range, the controller increases the circulating water pump to the second speed. This is to increase heat input and compensate for the increased risks caused by increased defrosting drainage, increased local water accumulation, or further drop in ambient temperature. When the risk level rises to the high-risk range, the controller further increases the circulating water pump speed to the third speed. This allows more heat medium to pass through the stainless steel water pipe quickly, forming a stronger local heat coverage capacity, so as to ensure that there is no substantial blockage at the edge of the drain hole and the upstream confluence path.

[0106] In a preferred embodiment, the present invention can also set a preheating operation sub-strategy before the circulating water pump officially enters high-speed operation. For example, when the controller detects that the unit is about to enter defrost mode, or has just entered defrost mode and drainage has not yet clearly started, it first operates at the first speed. Start the circulating water pump to preheat the area near the drain hole. The technical significance of this is that many ice bridges do not begin to appear only after sufficient drainage has formed, but rather begin to crystallize and adhere when the initial small amount of liquid flows through the low-temperature hole edge. If a local thermal field can be established before or in the early stages of initial drainage, the probability of ice nucleation formation can be significantly reduced, thus inhibiting the subsequent expansion of ice blockage from the source.

[0107] Furthermore, to prevent the circulating water pump from frequently shifting up and down near the critical point of the risk level, the present invention preferably incorporates a shift hysteresis. The controller uses a higher decision threshold when upshifting and a lower decision threshold when downshifting, or requires local temperature, outdoor temperature, and risk index to remain stable for several consecutive sampling periods before switching. This extends the effective operating time of each gear, reduces frequent pump operation, and improves the overall system lifespan and control stability.

[0108] Through step S3, this invention truly achieves dynamic coupling of risk, flow rate, and heat. In other words, the circulating water pump is no longer just a fixed-flow actuator, but becomes a core actuator that actively adjusts the heating intensity according to the development trend of ice blockage. This hierarchical control capability is also one of the important features that distinguishes this invention from traditional fixed heat tracing or simple low-temperature start-stop solutions.

[0109] VII. Step S4: Directional heat transfer and localized thermal coverage

[0110] Step S4 involves: implementing directional heat transfer through the stainless steel water pipe to the upstream confluence path of the drain hole and the area adjacent to the hole edge, so as to maintain the temperature of the area adjacent to the drain hole above the preset antifreeze temperature during defrosting and drainage and during the sensitive period of local refreezing after defrosting. .in, This indicates the minimum antifreeze control temperature used to inhibit the formation of ice bridges or ice plugs.

[0111] Step S4 is the step in which the present invention differs most significantly from traditional overall antifreeze solutions for drainage channels at the structural-mechanism level, and it is also one of the steps that makes the greatest contribution to the inventiveness. The core technology of this step is not the broad concept of supplying heat to the chassis, but rather the specific spatial arrangement of the stainless steel water pipes 2, which allows heat to be preferentially transferred to the vicinity of the drainage hole edge and its upstream short-distance confluence area where ice bridges are most likely to form, thereby establishing a locally enhanced thermal field and inhibiting the initial formation of ice bridges and the expansion of ice blockages.

[0112] 1. Selection of directional heat transfer objects

[0113] This invention specifically defines the directional heat transfer target as the upstream confluence path of the drain hole and the area adjacent to the hole edge, rather than simply heating the entire drain pipe, the entire chassis, or the entire drip tray uniformly. This is because ice blockage at the drain outlet of the heat pump unit chassis does not always occur first on the drain path far from the hole, but often first occurs in the following areas:

[0114] First, there's the drainage hole's edge itself. The material at the hole edge experiences rapid localized heat dissipation and significant boundary cooling, and the water flow cross-section changes noticeably near the hole opening, easily forming a thin water film or water droplets clinging to the edge, thus providing conditions for ice bridge formation.

[0115] Second, the final confluence path upstream of the orifice. The water flow velocity and liquid layer thickness in this area are greatly affected by the geometry of the V-shaped collection trough. If the temperature is low and the heat is insufficient, localized freezing and accumulation can easily form at the bottom of the trough or in front of the orifice.

[0116] Thirdly, the area where residual water film remains during the refreezing sensitive period after defrosting. At this time, although the main drainage volume has been significantly reduced, the local residual water is more likely to freeze into a thin ice film due to the rapid drop in temperature, gradually reducing the effective drainage cross-section.

[0117] Based on the above-mentioned ice blockage formation mechanism, this invention focuses heat coverage on these key areas, thus achieving a higher anti-blockage effect with less heat.

[0118] 2. Arrangement of stainless steel water pipes

[0119] like Figure 2 As shown, the stainless steel water pipe 2 is preferably installed close to the bottom of the V-shaped water collection tank 4. "Close to" means that the distance between the stainless steel water pipe 2 and the bottom of the tank is sufficient to form a short heat transfer path, while not hindering the smooth flow of condensate and defrost water. Those skilled in the art can determine the appropriate distance between the two based on the depth and width of the V-shaped water collection tank 4, the outer diameter of the water pipe, the maximum drainage capacity, and the installation process.

[0120] In one embodiment, the stainless steel water pipe 2 extends longitudinally along the bottom of the V-shaped water collection trough 4, and forms a local reinforcement section near the drain hole 5, so that the reinforcement section simultaneously covers the upstream confluence path of the drain hole 5 and the area near the hole edge. In another embodiment, the stainless steel water pipe 2 may form a local bend or fold near the drain hole 5 to increase the heat density per unit length at that location. In yet another embodiment, a local section of the stainless steel water pipe 2 may be distributed along both sides of the drain hole to form a lateral heat coverage, suppressing asymmetrical icing on both sides of the hole edge.

[0121] Regardless of the specific form adopted, the essential requirement of this invention is that at least one section of the stainless steel water pipe 2 is located near the most sensitive freezing formation area of ​​the drain hole 5, so that when the circulating medium flows through this section, heat can be quickly transferred through the stainless steel pipe wall and adjacent structures to the water flow contact area and the hole edge boundary area.

[0122] 3. Heat transfer mechanism

[0123] When the circulating medium flows through the stainless steel water pipe 2 under the drive of the circulating water pump 3, the heat it carries is first conducted to the pipe wall, and then transferred from the pipe wall to the bottom material of the adjacent V-shaped water collection tank 4, the local air film, and the liquid flowing over it. Since the stainless steel water pipe 2 is arranged upstream of the drainage hole and near the edge of the hole, this heat transfer process can directly increase the local structural temperature and liquid temperature, reducing the probability of the liquid freezing before reaching the drainage hole.

[0124] When the local liquid is still in a flow state, heat increases its temperature on the one hand, and raises the boundary temperature of the pore edge region on the other, reducing the possibility of ice crystal formation and adhesion. When defrosting is nearing completion, the liquid flow rate decreases, or even only a water film remains, the local structure can still continuously receive heat input during the delayed heat preservation stage, thereby inhibiting water film freezing and ice layer expansion. It can be seen that the directional heat transfer of the present invention is not a one-time or transient process, but rather covers the entire process of local thermal management from drainage formation to the main drainage period, the end of drainage, and the refreezing sensitive period.

[0125] 4. Preset antifreeze temperature The determination

[0126] Preset antifreeze temperature This is the lowest antifreeze control temperature used to suppress the formation of ice bridges or ice plugs. It's not necessary to mechanically use 0°C; instead, the setting can be based on chassis material, flow rate, liquid composition, local climate, and system margin. Those skilled in the art can... The temperature value is set slightly higher than the local freezing critical temperature, and different antifreeze control ranges can also be set according to different unit models.

[0127] During controller operation, and The relationship between these factors directly reflects the local heating effect. When Below or close to When this occurs, it means that the local heat coverage is insufficient, and it is necessary to maintain or increase the circulating water pump speed; when Continuously stable above Furthermore, when other risk inputs decrease, it can provide a basis for subsequent downshifting or pump shutdown.

[0128] In summary, step S4 constructs a locally enhanced thermal field in the critical area of ​​the drain hole that is most prone to freezing by using a specially arranged stainless steel water pipe and circulating heat medium, thereby actively suppressing the source of ice bridge formation. This is a significant improvement of the present invention compared to existing structural antifreeze solutions.

[0129] 8. Step S5: Delayed heat preservation after defrosting and pump shutdown after risk assessment

[0130] Step S5 is: when the defrost status indicator is reached... After switching from defrosting mode to non-defrosting mode, the controller keeps the circulating water pump running for a delayed heat preservation period. And in the drainage outlet ice blockage risk index continuous The second time below the risk clearance threshold And it meets the gear shift backlash requirement. Output a pump stop signal under the specified conditions.

[0131] in, Indicates the duration of extended heat preservation after defrosting; Indicates the number of consecutive confirmations; Indicates the risk resolution threshold; This indicates the temperature hysteresis used to suppress frequent switching of circulating water pumps.

[0132] The setting of step S5 is an important aspect that further distinguishes this invention from the general method of stopping heating immediately after defrosting. In actual operation, many ice blockages do not form during the stage of maximum drainage of the main defrosting process, but rather after defrosting ends. This is because residual water film, water dripping from the orifice edges, and a small amount of accumulated water lose their heat source and cool down rapidly, resulting in localized refreezing. This refreezing phenomenon is often insidious. If the control system stops the pump immediately after defrosting, a thin layer of ice blockage can easily regenerate within tens of seconds to several minutes.

[0133] Therefore, the present invention indicates the defrosting status quantity. After switching from defrosting mode to non-defrosting mode, the circulating water pump is not stopped immediately, but the extended heat preservation time is maintained. During this period, stainless steel water pipe 2 continues to supply heat to the upstream confluence path of the drain hole and the area adjacent to the hole edge, allowing sufficient time for the residual liquid to drain or evaporate, reducing the probability of refreezing. (Extended insulation duration) It can be set according to factors such as unit specifications, drainage capacity, chassis structure, and regional temperature conditions, or it can be set to a fixed value or an adaptive value that changes with the risk level.

[0134] Meanwhile, to prevent the circulating water pump from stopping prematurely due to instantaneous measurement fluctuations, this invention requires an ice blockage risk index at the drain outlet. continuous The second time below the risk clearance threshold Only then is it permissible to stop the pump. Among these, This indicates the number of consecutive confirmations, which can be 2, 3, or more. Its essence is to ensure that the risk reduction is continuous rather than accidental. Risk resolution threshold. It is preferable to use a value lower than the threshold related to upshifting or pump start-up, thereby creating a risk exit retracement and avoiding repeated start-stop cycles near the threshold.

[0135] In addition, gear shift backlash The introduction of this feature can also be used for final confirmation before stopping the pump. For example, when the outdoor ambient temperature... or local temperature When the temperature rises to near the pump stop boundary, the controller does not immediately stop the pump. Instead, it requires the temperature change to meet the hysteresis condition to ensure that the false safe state is not caused by a brief disturbance.

[0136] Through step S5, this invention extends the control logic from providing heating when a risk occurs to maintaining thermal protection until the risk is completely eliminated. This effectively covers the often-overlooked but highly impactful operational phase of refreezing after defrosting, which significantly affects ice blockage at drain outlets. This step is crucial for improving overall system stability and preventing repeated ice blockages.

[0137] IX. Application Example: Laboratory Prototype Verification for Preventing Ice Blockage at the Chassis Drainage Outlet of a Heat Pump Unit

[0138] 1. Experimental Objective

[0139] To verify the effectiveness of the control method and system proposed in this invention for preventing ice blockage at the chassis drain outlet of a heat pump unit in suppressing ice blockage in the drain hole, reducing ice accumulation on the chassis, and improving the stability of continuous operation of the unit under low temperature and high humidity heating / defrosting conditions, a laboratory prototype platform was built to conduct comparative tests on the prototype of this invention and the comparative prototype.

[0140] 2. Experimental prototype and grouping

[0141] Three sets of outdoor air source heat pump prototypes with the same rated heat capacity, the same size of the air-side heat exchanger, and the same chassis dimensions were selected as the experimental subjects.

[0142] Example A: Using the scheme of the present invention, a V-shaped water collection tank 4 is set below the air-side heat exchanger 6, and a drain hole 5 is set at the lowest point of the tank bottom; a stainless steel water pipe 2 is built into the V-shaped water collection tank 4 and arranged along the tank shape, wherein the local reinforced section is close to the upstream confluence path and the area adjacent to the drain hole 5; the stainless steel water pipe 2 is connected to the water-side heat exchanger 1 to form a circulation branch, a circulation water pump 3 is set, and the controller performs risk classification control according to the outdoor temperature, defrosting status, drainage duration and the temperature of the area adjacent to the drain hole.

[0143] Comparative prototype B: Only a V-shaped water collection tank 4 and a drain hole 5 are installed, without stainless steel water pipe 2, circulating water pump 3 and related control logic.

[0144] Comparative prototype C: It is equipped with a V-shaped water collection tank 4 and a drain hole 5, and a circulating water pump and stainless steel water pipes that operate at a constant low speed. However, it does not adopt the risk assessment, graded speed regulation and post-defrost heat preservation control of the present invention. The pump is only started when the outdoor temperature is below 0°C and stopped when the outdoor temperature is above 0°C.

[0145] 3. Experimental Environment and Operating Conditions

[0146] The experiment was conducted in a controlled enthalpy difference laboratory. The outdoor ambient temperature was set to [temperature value missing]. The relative humidity was 85%, and the unit operated continuously in heating mode, periodically entering automatic defrosting mode. Each prototype was tested continuously for 8 hours, and the defrosting drainage, drainage hole icing, chassis ice accumulation, fan ice removal, and shutdown protection were recorded.

[0147] To further verify the technical effectiveness of this invention under more stringent conditions, an extreme operating condition was added: the outdoor ambient temperature was... The relative humidity was 90%, and the test was conducted continuously for 6 hours.

[0148] 4. Test Items

[0149] The test items include: (1) the time for the first ice bridge to form in the drain hole; (2) the time for the drain hole to become completely blocked; (3) the drainage volume per unit time; (4) the mass of ice accumulation on the chassis; (5) the number of times refreezing occurs within 10 minutes after defrosting; (6) the number of times the fan sweeps ice; (7) the number of times the machine shuts down for protection; and (8) the average temperature in the area adjacent to the drain hole. (9) Additional cycle energy consumption.

[0150] Among them, the time of the first ice bridge formation at the drain hole refers to the time from the start of the test to the observation of a continuous ice bridge structure spanning across the edge of the drain hole; the time of complete blockage of the drain hole refers to the time when the effective flow area of ​​the drain outlet is less than 20% of the initial area; and the mass of ice accumulation on the chassis refers to the mass of the residual ice layer in the chassis after the test is completed and the machine is disassembled and weighed.

[0151] 5. Data and Results Analysis

[0152] Table 1. Conventional Low Temperature Operating Conditions ( Test results (85%RH)

[0153]

[0154] Note: As shown in Table 1, under normal low temperature and high humidity conditions, comparative sample B developed ice bridges in the drain holes after 52 minutes and became significantly blocked after 96 minutes. This indicates that when only a standard water collection and drainage structure is used, the edge of the drain holes and its upstream confluence path are highly susceptible to ice formation. Although comparative sample C delayed ice bridge formation and complete blockage by using low-level constant heating, it still experienced refreezing and localized drainage obstruction after prolonged operation. This suggests that simple start-stop or constant low-intensity heating is insufficient to meet the dynamic antifreeze requirements during and after defrosting.

[0155] In contrast, prototype A of the embodiment did not exhibit ice bridging or complete blockage of the drain holes during the entire 8-hour test, with a cumulative drainage volume of 14.8L and an ice accumulation mass of only 0.42kg on the chassis, significantly outperforming the two comparative prototypes. This is because the present invention uses risk assessment to drive tiered heating, enabling the stainless steel water pipe 2 to provide directional thermal compensation to the upstream confluence path and adjacent area of ​​the drain hole 5 during both the main defrosting and drainage phase and the sensitive refreezing phase after defrosting. This significantly inhibits the initiation and expansion of ice bridges.

[0156] Table 2 Extreme Low Temperature Conditions ( Test results (90%RH)

[0157]

[0158] The results show that, under more severe extreme low-temperature conditions, although a thin layer of ice appeared on the drain hole of prototype A at 217 minutes, it did not form a continuous, substantial ice bridge, nor did it become completely blocked. In contrast, prototype B became completely blocked at 57 minutes, and prototype C showed significant blockage at 176 minutes. This demonstrates that the present invention can significantly improve the anti-icing capability of the drain hole even under extreme conditions.

[0159] Average temperature in the area near the drain hole As can be seen, prototype A in the embodiment consistently maintained a temperature above 0°C, while prototype C in the comparative example, although providing localized heating, still had an average temperature below 0°C, potentially leading to refreezing during low-flow periods after defrosting. It is evident that the present invention, through a combination of risk index, graded pump control, and delayed insulation, significantly outperforms a single constant low-speed operation mode in maintaining a localized thermal field.

[0160] 6. Sexual verification

[0161] Table 3. Impact of different control strategies on local thermal field and drainage reliability

[0162]

[0163] Table 3 further illustrates that this invention does not simply increase the overall chassis temperature, but effectively improves the local thermal state of the drainage hole edge and the upstream confluence area in front of the hole, keeping the most critical frozen area within a temperature range more conducive to drainage. Due to the targeted enhancement of the local thermal field, the drainage flow rate is significantly improved, and the refreezing probability is significantly reduced, mechanistically proving the effectiveness of the directional heat transfer + risk-driven control mechanism of this invention.

[0164] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A control method for preventing ice blockage at the drain outlet of a heat pump unit chassis, characterized in that, This method is applied to heat pump units including an air-side heat exchanger, a V-shaped water collection trough, a water-side heat exchanger, stainless steel water pipes, a circulating water pump, an outdoor temperature sensor, and a controller. The V-shaped water collection trough is located below the air-side heat exchanger, and a drain hole is provided at the lowest point of the trough's bottom. The stainless steel water pipes are placed within the V-shaped water collection trough in an area overlapping with it and are arranged along the trough's shape. At least one section of the stainless steel water pipe is positioned close to the upstream confluence path and the area adjacent to the drain hole's edge. The stainless steel water pipes are connected to the water circuit of the water-side heat exchanger to form a circulating branch. The method includes the following steps: S1: Collect outdoor ambient temperature Defrosting status indicator quantity Drainage duration and the temperature in the area near the drain hole ; S2: The controller determines the outdoor ambient temperature based on the outdoor ambient temperature. Defrosting status indicator quantity Drainage duration and the temperature in the area near the drain hole Determine the risk index of ice blockage at the drain outlet And the risk index of ice blockage at the drain outlet. Compared with the first risk threshold Second risk threshold and the third risk threshold Comparison is used to determine the risk level corresponding to the current working condition; among which, ; S3: When the controller determines the risk index of ice blockage at the drain outlet. Reaching the first risk threshold When the above conditions are met, start the circulating water pump; when the risk index of ice blockage at the drain outlet is reached... Each in , and During the interval, control the circulating water pump to operate at the first speed. Second rotation speed and the third rotation speed Operation allows the circulating medium to circulate between the water-side heat exchanger and the stainless steel water pipes; among which, ; S4: Directional heat transfer is implemented through the stainless steel water pipe to the upstream confluence path of the drain hole and the area adjacent to the hole edge, so as to maintain the temperature of the area adjacent to the drain hole above the preset antifreeze temperature during defrosting and drainage and during the sensitive period of local refreezing after defrosting. ; S5: When the defrost status indicator is... After switching from defrosting mode to non-defrosting mode, the controller keeps the circulating water pump running for a delayed heat preservation period. And in the drain outlet ice blockage risk index continuous The second time below the risk clearance threshold And it meets the gear shift backlash requirement. Output a pump stop signal under the specified conditions.

2. The control method according to claim 1, characterized in that, The risk index of ice blockage at the drain outlet mentioned in step S2 The outdoor ambient temperature Defrosting status indicator quantity Drainage duration and the temperature in the area near the drain hole The weighting function; preferably, the drainage outlet ice blockage risk index Determine using the following formula: ； in, , , , These represent the weight coefficients of each influencing factor; This represents the risk mapping amount corresponding to the outdoor ambient temperature. This represents the risk mapping value corresponding to the defrosting state; This represents the risk mapping amount corresponding to the duration of drainage; This represents the risk mapping amount corresponding to the temperature in the area adjacent to the drain hole.

3. The control method according to claim 1, characterized in that, In step S3, when the risk index of ice blockage at the drain outlet is... First time reaching the first risk threshold At the above time, the controller first controls the circulating water pump to the first speed. Preheating operation is performed, and then the risk index of ice blockage at the drain outlet is used as a reference. Switching to the second speed Or the third rotation speed .

4. The control method according to claim 1, characterized in that, In step S4, the stainless steel water pipe is set close to the bottom of the V-shaped water collection tank and spans the upstream confluence path of the drain hole and the area adjacent to the edge of the hole, so that heat is preferentially applied to the area where ice bridges are easily formed. Preferably, the circulating medium in step S4 is water or water-based antifreeze; wherein, the water-based antifreeze refers to a heat exchange medium with water as the continuous phase and containing antifreeze components.

5. The control method according to claim 1, characterized in that, The gear shift backlash mentioned in step S5 This is used to limit the frequent switching of the circulating water pump between adjacent speeds when there are fluctuations in outdoor ambient temperature or temperature fluctuations in the area near the drain hole.

6. The control method according to claim 1, characterized in that, The V-shaped water collection tank includes a first inclined guide surface and a second inclined guide surface arranged opposite to each other. The first inclined guide surface and the second inclined guide surface converge at the drain hole to form the lowest point of the tank bottom, so that the condensate and defrost water generated by the air-side heat exchanger are discharged into the drain hole in a concentrated manner. Preferably, the drain hole is located in the middle region of the V-shaped water collection trough along the length of the trough, and the edge of the drain hole is located in the adjacent area of ​​the stainless steel water pipe. Preferably, the stainless steel water pipe is fixed in the V-shaped water collection tank by positioning clips and / or pipe clamp brackets; wherein, the positioning clips are used to laterally limit the stainless steel water pipe, and the pipe clamp brackets are used to hug and support the stainless steel water pipe. Preferably, the circulating water pump is located near the return water side of the stainless steel water pipe to reduce the backflow resistance in the circulating branch and improve the local flow stability of the heat medium.

7. A control system for preventing ice blockage at the drain outlet of a heat pump unit chassis, characterized in that, The device includes an air-side heat exchanger, a V-shaped water collection trough, a water-side heat exchanger, stainless steel water pipes, a circulating water pump, an outdoor temperature sensor, and a controller. The V-shaped water collection trough is located below the air-side heat exchanger, and a drain hole is provided at the lowest point of the trough bottom. The stainless steel water pipes are placed within the V-shaped water collection trough in an area overlapping with it and are arranged along the trough shape. At least one section of the stainless steel water pipes is positioned close to the upstream confluence path and the area adjacent to the drain hole. The stainless steel water pipes are connected to the water circuit of the water-side heat exchanger to form a circulating branch. The circulating water pump is located on the circulating branch and is used to drive the flow of the circulating medium. The outdoor temperature sensor is used to collect the outdoor ambient temperature. The controller is electrically connected to the outdoor temperature sensor and the circulating water pump and is configured to execute the control method according to any one of claims 1 to 7.

8. The control system according to claim 7, characterized in that, The controller is also electrically connected to a temperature sensor in the vicinity of the drain hole to obtain the temperature of the vicinity of the drain hole. ; And / or, the controller is configured to: activate the preheating control of the circulating water pump before the unit enters the defrosting state or at the initial stage of entering the defrosting state, so as to reduce the probability of ice bridges forming in the initial stage of defrosting drainage.

9. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method according to any one of claims 1-6.

10. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method according to any one of claims 1-6.

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