A cooling control mode method for a cold water tank

Abstract

The application relates to a cooling control mode method for a cold water tank and relates to the technical field of cold water tank cooling control. In a high-temperature range, a compressor runs at full power in cooperation with a fan rotating at the highest speed in the forward direction to rapidly reduce temperature at the maximum refrigeration capacity and relieve high-load pressure. When entering a medium-temperature range, the frequency of the compressor is linearly increased according to a water temperature difference, and the fan is finely classified and controlled according to the temperature difference, including adjusting the forward rotation speed, keeping high-speed forward rotation or switching to low-speed reverse rotation, so that the dynamic balance between refrigeration and heat dissipation is realized, and the energy efficiency is significantly improved. When the water temperature drops to a low-temperature range, the compressor stops running, and the fan only intermittently works at a low speed, which not only maintains uniform water temperature, but also avoids additional energy consumption and condensation problems. When water is replenished, corresponding cooling operations are synchronously performed, and through an adaptive zoning strategy, differentiated optimal instructions are provided for the heat load demand of different water temperature stages, so that the energy efficiency is optimized and the operation stability is improved while ensuring rapid temperature reduction and uniform water temperature.

Description

Technical Field

[0001] This application relates to the field of cold water tank cooling control technology, and specifically to a cooling control mode method for cold water tanks. Background Technology

[0002] As a key piece of equipment providing stable low-temperature circulating cooling water for production equipment or the environment, the energy efficiency, cooling rate, and operational stability of the cold water tank's control system directly affect production energy consumption, equipment cooling effect, and system reliability. In existing technologies, cold water tanks generally employ a start-stop control strategy based on a fixed temperature threshold. Specifically, when the water temperature sensor detects that the water temperature is higher than a preset upper limit, the control system starts the compressor and cooling fan for full-power cooling; when the water temperature drops to a preset lower limit, the compressor and fan are shut down, stopping cooling. This control logic has two main shortcomings, which directly lead to poor overall system performance: Because only fixed start and stop points are set, the compressor operates at rated power after startup and stops completely once the water temperature reaches the lower limit. This results in the compressor operating in high-energy-consumption mode when most of the water temperature is in the intermediate range (neither the high temperature urgently needed for strong cooling nor the low temperature that needs to be maintained), failing to smoothly adjust power according to real-time, subtle water temperature differences, leading to significant energy waste. Furthermore, frequent full-power start and stop operations can easily cause large, periodic fluctuations in water temperature, which is detrimental to providing a constant low-temperature environment for the cooled equipment.

[0003] In traditional solutions, cooling fans are typically used only as auxiliary equipment to the compressor, performing simple synchronous start-stop functions, with their capabilities not being fully developed and utilized. This results in the inability to actively enhance condenser heat dissipation by increasing fan speed when the compressor is operating under high load (high temperature range), thus limiting the system's peak cooling capacity and potentially leading to high-pressure protection or compressor overload due to insufficient heat dissipation. On the other hand, after the compressor stops (low temperature range), the fan also stops, and the water temperature in the tank may stratify due to insufficient natural convection. Furthermore, the air above the low-temperature water surface is prone to condensation, posing a risk to equipment safety and cleanliness. Summary of the Invention

[0004] This application provides a cooling control mode method for a chilled water tank, which deeply couples the variable frequency regulation of the compressor with the multi-state control of the cooling fan through a multi-mode, adaptive zoning control strategy. It provides differentiated optimal control commands for the different heat loads and heat dissipation requirements faced by the chilled water tank at different water temperature stages, thereby optimizing the overall energy efficiency and comprehensively improving the operational stability of the system while ensuring rapid cooling and uniform water temperature.

[0005] To achieve the above object, the present application provides the following technical solutions: The present application provides a cooling control mode method for a cold water tank. The cold water tank includes a housing, a water tank disposed inside the housing, an evaporation coil located inside the water tank, a refrigeration unit composed of a compressor, a condenser, and a throttling element, a temperature sensor for detecting the water temperature inside the water tank, and a cooling fan located above the water tank. The method includes the following steps: S1: Continuously collect the real-time water temperature T inside the water tank through the temperature sensor; S2: Compare the real-time water temperature T with a preset high temperature threshold T1 and a medium temperature threshold T2, where T1 > T2; S3: According to the temperature range where the real-time water temperature T is located, control the refrigeration unit and the cooling fan to execute different cooling control modes: When T ≥ T1, execute the first cooling mode, control the compressor to continuously operate at the rated power, and control the cooling fan to rotate forward at the first preset speed until the real-time water temperature T drops to T2; When T2 ≤ T < T1, execute the second cooling mode, control the compressor to operate at the operating frequency f calculated according to the formula f = f0 + k (T - T2), where f0 is the base frequency and k is the proportionality coefficient. At the same time, control the operating state of the cooling fan according to the real-time temperature difference ΔT = T - T2; When T < T2, execute the third cooling mode, control the compressor to stop operating, and control the cooling fan to operate according to the second preset program.

[0006] Further, in the second cooling mode, controlling the operating state of the cooling fan according to the real-time temperature difference ΔT specifically includes: when ΔT ≥ Ta, control the cooling fan to rotate forward and the speed is positively correlated with ΔT; when Tb ≤ ΔT < Ta, control the cooling fan to rotate forward and operate at a fixed speed R1; when ΔT < Tb, control the cooling fan to rotate backward and operate at a fixed speed R2; where Ta and Tb are preset temperature difference thresholds, and Ta > Tb > 0, R1 > R2.

[0007] Further, in the second cooling mode, when ΔT ≥ Ta, the speed V of the cooling fan is positively correlated with both the real-time temperature difference ΔT and the compressor operating frequency f, and specifically satisfies the relationship: V = α ΔT + β f, where α and β are preset weight coefficients.

[0008] Further, the value of Ta is in the range of 2-4℃, and the value of Tb is in the range of 0.5-1.5℃; the fixed speed R1 is 80%-100% of the rated speed of the cooling fan, and the fixed speed R2 is 30%-50% of the rated speed of the cooling fan.

[0009] Furthermore, the cold water tank also includes a liquid level sensor for detecting the water level in the tank. In step S3, before executing any cooling mode, the real-time water level H is obtained through the liquid level sensor; it is determined whether the real-time water level H is lower than the minimum warning water level H1; if so, the water inlet valve is opened to replenish water, and the cooling control mode corresponding to step S3 is executed immediately according to the current real-time water temperature T, until the water level reaches the rated water level H2 and the water temperature stabilizes.

[0010] Furthermore, in the water level cooling linkage step, while replenishing water and executing the cooling control mode, the real-time water level H and real-time water temperature T are continuously acquired at a preset period t3. When it is determined that the real-time water level H≥H2 and the rate of change of the real-time water temperature T is less than the set threshold for N consecutive periods, it is determined that the water temperature has reached stability and the normal cooling control process is restored.

[0011] Furthermore, in the first cooling mode, the cooling fan is controlled to rotate forward at a first preset speed, and the cooling fan is controlled to continuously rotate forward at 100% of its rated speed.

[0012] Furthermore, in the third cooling mode, the second preset program is to control the cooling fan to operate intermittently, wherein the running time t1 is 2-5 minutes, the stopping time t2 is 5-10 minutes, and the running speed is 20%-40% of the rated speed.

[0013] Furthermore, the value range of T1 is 10-12℃, the value range of T2 is 5-7℃, and T1-T2≥3℃; the value range of the fundamental frequency f0 is 1.5-2 times the minimum allowable frequency of the compressor, and the value range of the proportional coefficient k is (2-5) Hz / ℃.

[0014] Furthermore, in the second cooling mode, when the compressor is controlled to run at a frequency f, the frequency f is limited between the lowest allowed frequency f_min and the rated frequency f_max of the compressor.

[0015] This application provides a cooling control mode method for a cold water tank. The method continuously collects the real-time water temperature in the tank using a temperature sensor. Based on the comparison between the water temperature and preset high-temperature thresholds T1 and medium-temperature thresholds T2, the control process is divided into three temperature ranges with clear boundaries and different control logics. When the water temperature is in the high-temperature range, the control scheme causes the compressor to run continuously at its rated power, while the cooling fan rotates at its highest speed to quickly reduce the water temperature with maximum cooling capacity. When the water temperature enters the medium-temperature range, the compressor is frequency-controlled, with its operating frequency linearly increasing based on the difference between the real-time water temperature and the medium-temperature threshold. Simultaneously, the cooling fan's operating state is finely graded and controlled according to the real-time temperature difference, including increasing the forward rotation speed as the temperature difference increases, maintaining a fixed high forward rotation speed, or switching to a low-speed reverse rotation. When the water temperature drops to the low-temperature range, the control scheme stops the compressor and controls the cooling fan to run intermittently at a low speed. Furthermore, the scheme integrates water level-cooling linkage control, automatically starting water replenishment when the water level is detected to be too low, and simultaneously executing cooling control corresponding to the current water temperature until both the water level and temperature reach a stable state.

[0016] The effect of this technical solution is that, in the high-temperature range, the combination of full-power compressor operation and powerful fan cooling maximizes the system's cooling speed, effectively alleviating system pressure under high load. In the medium-temperature range, through the linkage adjustment of compressor operating frequency and water temperature, and the precise matching of cooling fan speed and direction with temperature difference, a dynamic balance between cooling output and heat dissipation demand is achieved, significantly improving operating efficiency in this temperature range. In the low-temperature range, by stopping compressor cooling and activating low-speed intermittent fan operation, the uniformity of water temperature in the tank is maintained, while unnecessary energy consumption and potential condensation problems are avoided. Water level linkage control ensures the continuity and coordination of cooling function during water replenishment, guaranteeing the consistency and stability of system operation. Attached Figure Description

[0017] Figure 1 A flowchart of a cooling control mode method for a cold water tank provided in this application. Detailed Implementation

[0018] The present application will now be described in further detail with reference to embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the scope of the application.

[0019] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] Please see Figure 1 The image shows a cooling control method for a cold water tank provided in an embodiment of this application. This embodiment offers a cooling control method for a cold water tank, aiming to solve the technical problems of low energy efficiency, slow water temperature drop, poor water temperature uniformity within the tank, and insufficient system stability caused by traditional cold water tank control schemes that rely on fixed temperature point start / stop of the compressor and simple start / stop or single-direction operation of the cooling fan. This embodiment combines compressor variable frequency technology with multi-state collaborative control of the cooling fan through a refined zone control strategy, executing differentiated control logic for different water temperature ranges. This allows for meeting rapid cooling requirements while optimizing system energy efficiency and maintaining stable water temperature at low temperatures.

[0021] This embodiment applies to a chilled water tank system comprising a housing, a water tank housed within the housing, an evaporator coil located within the water tank, a refrigeration unit consisting of a compressor, a condenser, and a throttling element, a temperature sensor for detecting the water temperature inside the water tank, and a cooling fan located above the water tank. The temperature sensor continuously acquires the real-time water temperature T inside the water tank. This sensor is typically a PT100 or PT1000 platinum resistance temperature sensor, and its measurement signal is sent to the central processing unit of the controller via an analog-to-digital converter. The real-time water temperature T is the fundamental input variable for all subsequent control decisions. The controller has a built-in or external storage unit pre-stored with a high-temperature threshold T1 and a medium-temperature threshold T2, satisfying the relationship T1 > T2.

[0022] These thresholds are set based on the specific application and energy efficiency requirements of the chilled water tank. For example, in industrial equipment or laboratory scenarios requiring low-temperature cooling water, T1 can be set to 10℃ and T2 to 6℃, ensuring that the temperature difference between T1 and T2 is not less than 3℃, thus forming a clear and reasonable control range separation. By continuously collecting water temperature and comparing it with preset thresholds, an accurate basis for judgment is provided for subsequently implementing differentiated cooling control modes, avoiding the problem of frequent compressor start-stop caused by single-point threshold control.

[0023] The controller compares the real-time water temperature T with preset high-temperature threshold T1 and medium-temperature threshold T2, and divides the water temperature into three distinct ranges based on the comparison results. When the real-time water temperature T is greater than or equal to T1, the water temperature is determined to be in the high-temperature range; when the real-time water temperature T is less than T1 but greater than or equal to T2, the water temperature is determined to be in the medium-temperature range; and when the real-time water temperature T is less than T2, the water temperature is determined to be in the low-temperature range. This zoning method is based on the operating characteristics and energy efficiency characteristics of the refrigeration system.

[0024] In the high-temperature range, the primary goal of the system is to rapidly reduce the water temperature, with less consideration for energy efficiency; in the medium-temperature range, the system may operate for a longer time, and it is necessary to prioritize operating energy efficiency while ensuring the cooling capacity; in the low-temperature range, the main goal is to maintain the water temperature stability and prevent overcooling. By dividing into three ranges and corresponding different control logics, the control strategy can adapt to different stages of the water temperature change and achieve an accurate match between the control objective and the current system state.

[0025] When it is determined that the real-time water temperature T≥T1, the controller executes the first cooling mode. In this mode, the controller sends an instruction to the compressor drive circuit to control the compressor to continuously operate at the rated power. Operating at the rated power means that the compressor operates at its rated frequency and voltage marked on the nameplate. For example, for a compressor with a rated frequency of 50Hz, it is controlled to operate at full load at 50Hz. At the same time, the controller sends an instruction to the motor driver of the cooling fan to control the cooling fan to rotate forward at the first preset speed. The first preset speed is usually set to the rated speed of the cooling fan, that is, the highest speed of the fan motor under the rated voltage. For example, the fan is controlled to continuously rotate forward at 100% of the rated speed.

[0026] The full-power operation of the compressor provides the maximum refrigeration capacity, and the full-speed forward rotation of the cooling fan accelerates the air flow in the condenser and evaporator coil areas, strengthening the heat dissipation effect. This mode aims to rapidly reduce the water temperature from the high-temperature state by enabling the refrigeration unit and the cooling fan to work together with the maximum capacity, directly targeting the application scenarios with high high-temperature loads and the need for rapid cooling, and solving the problems of slow cooling speed and long continuous high-load operation time of the traditional solution in the high-temperature section due to the possible intermittent operation of the compressor or insufficient fan speed. The control process continues until the real-time water temperature T collected by the temperature sensor drops below T1 and further drops to T2, then this mode is exited.

[0027] When it is determined that the real-time water temperature T satisfies T2≤T<T1, the controller executes the second cooling mode. This mode is the core of this control method and aims to achieve the optimal energy efficiency operation. In this mode, the operating frequency f of the compressor is no longer fixed, but is dynamically adjusted according to the difference between the real-time water temperature T and the medium-temperature threshold T2. The controller calculates the target operating frequency according to the formula f=f0 + k (T - T2).

[0028] Here, f0 is the base frequency, which is the minimum effective operating frequency that the compressor needs to maintain when the real-time water temperature T equals T2. Its value ranges from 1.5 to 2 times the compressor's minimum allowable frequency. For example, if the compressor's minimum allowable frequency is 20Hz, then f0 can be set to 30Hz to 40Hz. k is a proportionality coefficient, representing the sensitivity of the frequency to temperature changes. Its value ranges from 2 to 5Hz / ℃. For example, setting k=3Hz / ℃ means that for every 1℃ increase in water temperature above T2, the compressor frequency increases by 3Hz. Through this calculation formula, the compressor's cooling capacity can be proportionally matched to the current heat load (reflected in the temperature difference T-T2).

[0029] The frequency f calculated by the controller is limited between the compressor's minimum allowable frequency f_min and the rated frequency f_max. For example, if f_min = 20Hz and f_max = 50Hz, the compressor will operate at 20Hz if the calculated value is lower than 20Hz, and at 50Hz if it is higher than 50Hz, ensuring that the compressor operates within a safe operating range. This variable frequency control method allows the compressor to smoothly adjust its output in the medium-temperature range, reducing the number of start-stop cycles and inrush currents, significantly reducing the average operating power consumption under this condition, and directly solving the problem of low energy efficiency in the medium-temperature range of traditional solutions.

[0030] In the second cooling mode, the cooling fan's operating state is not set independently, but is closely coupled with the compressor's operation and the real-time temperature difference ΔT = T - T2 for fine-tuning. The controller further subdivides fan control into three sub-states based on the calculated real-time temperature difference ΔT. When ΔT ≥ Ta, it indicates that the current water temperature is still significantly higher than the target intermediate temperature threshold T2, indicating a large heat load.

[0031] At this time, the controller controls the cooling fan to run in the forward direction, and its speed V is not only positively correlated with ΔT, but also positively correlated with the current operating frequency f of the compressor, specifically satisfying the relationship: V=α ΔT+β f. Where α and β are preset weighting coefficients used to balance the influence of temperature difference and compressor frequency on fan speed. For example, α can be set to 50 rpm / ℃ and β to 10 rpm / Hz.

[0032] In the second cooling mode, the cooling fan's operation is controlled in a more refined multi-state manner based on the real-time temperature difference ΔT, which is the difference between the real-time water temperature T and the intermediate temperature threshold T2. Specifically, the system presets two temperature difference thresholds, Ta and Tb, where Ta is greater than Tb and greater than zero. When the real-time temperature difference ΔT is greater than or equal to Ta, it indicates that the water temperature is still significantly higher than the target temperature. At this time, the cooling fan is controlled to run in forward rotation, and its speed V is positively correlated with both the real-time temperature difference ΔT and the compressor operating frequency f, specifically satisfying the relationship V = α. ΔT + β f, where α and β are preset weight coefficients.

[0033] This enables the fan speed to simultaneously respond to the water temperature deviation and the real-time load of the refrigeration system, achieving a dynamic matching of the heat dissipation capacity and the refrigeration demand, and further optimizing the collaborative energy efficiency. When the real-time temperature difference ΔT is between Tb and Ta, it indicates that the water temperature is already close to the target range. The cooling fan is controlled to rotate forward at a relatively high fixed speed R1 to provide stable auxiliary heat dissipation.

[0034] When the real-time temperature difference ΔT is less than Tb, it indicates that the water temperature is already very close to or slightly lower than the target temperature T2. At this time, the cooling fan is controlled to rotate in reverse at a relatively low fixed speed R2. The reverse rotation of the fan can guide the air flow to flow in different paths, which helps to disturb the upper layer of air in the water tank, promote the uniform distribution of the water temperature, prevent local temperature from being too low or condensation from occurring, and at the same time, the low-speed operation reduces the energy consumption.

[0035] When the water temperature is high (ΔT is large) and the compressor operates at a high frequency (f is large), the fan will rotate forward at a high speed to provide sufficient heat dissipation air volume to match the high-load heat dissipation demand of the system. When the temperature difference Tb ≤ ΔT < Ta, it indicates that the water temperature is close to but not yet fully in the stable range. At this time, the controller controls the cooling fan to rotate forward at a fixed speed R1. The fixed speed R1 is usually set to 80% to 100% of the rated speed of the cooling fan, for example, 90% of the rated speed is taken.

[0036] In this state, the fan provides a stable and strong heat dissipation air flow, supporting the system to smoothly transition to a lower temperature state. When ΔT < Tb, it indicates that the water temperature is already very close to T2 and the heat load is very small. At this time, the controller controls the cooling fan to rotate in reverse at another fixed speed R2. The fixed speed R2 is usually significantly lower than R1, for example, it is set to 30% to 50% of the rated speed of the cooling fan. The reverse rotation of the fan changes the air flow direction, which helps to stir the upper air in the water tank, promote the uniform temperature in the tank, and can prevent the evaporation coil surface from prematurely condensing in a low-temperature and high-humidity environment.

[0037] The values of the temperature difference thresholds Ta and Tb can be set according to the system characteristics. For example, the value range of Ta is 2 - 4°C (such as 3°C), and the value range of Tb is 0.5 - 1.5°C (such as 1°C). This multi-state control of the cooling fan finely adjusts the rotation direction and speed according to the real-time heat load (ΔT), and cooperates with the variable-frequency control of the compressor to jointly achieve the dynamic optimal balance among the refrigeration capacity, heat dissipation demand and energy consumption in the medium-temperature range, solving the problems of insufficient heat dissipation or energy consumption waste caused by the simple start and stop of the fan in the traditional scheme.

[0038] When it is determined that the real-time water temperature T < T2, the controller executes the third cooling mode. At this time, the main cooling demand has been met, and the core goal is to maintain a low temperature state and ensure uniform water temperature. In this mode, the controller controls the compressor to stop running, completely eliminating the power consumption of this main energy-consuming component.

[0039] At the same time, the cooling fan is controlled to operate according to the second preset program. The second preset program is usually designed as an intermittent operation mode, that is, the fan does not run continuously, but works in a cycle of "run - stop". For example, the cooling fan is controlled to rotate forward at a low speed (such as 20% - 40% of the rated speed) for a period of time t1 (such as 3 minutes), and then stops running for a period of time t2 (such as 8 minutes), and so on. The weak air flow generated by the low-speed operation is sufficient to promote the remaining temperature stratification in the water tank to be uniform, preventing local temperature from being too low or too high.

[0040] The intermittent operation further reduces the energy consumption of the fan itself and avoids the risk of unnecessary heat input or condensation caused by continuous gentle breeze. While maintaining the water temperature uniformity and preventing condensation, this mode realizes the lowest energy consumption operation of the system in the heat preservation stage, solving the problems of the traditional solution that may completely shut down all equipment in the low temperature section, resulting in a rapid temperature rise, or continuously running the fan, leading to unnecessary energy consumption and condensation risk.

[0041] To further improve the adaptability and reliability of the system, the cold water tank in this embodiment further includes a liquid level sensor for detecting the water level in the tank. Before executing any cooling mode in step S3, the controller preferentially executes the water level - cooling linkage step. The controller obtains the real-time water level H of the water tank through the liquid level sensor (such as a float type, capacitive or pressure type liquid level sensor).

[0042] Before executing any cooling mode, the system first obtains the real-time water level H through the liquid level sensor and determines whether it is lower than the lowest warning water level H1. If the water level is lower than H1, the water inlet valve is immediately controlled to open for water replenishment, and at the same time, according to the current real-time water temperature T, the corresponding cooling control mode described above is executed, ensuring that during the water replenishment process, the cooling system can work synchronously, avoiding water temperature fluctuations or temperature rises caused by water replenishment. While replenishing water and executing the cooling control, the system continuously monitors the real-time water level H and the real-time water temperature T at a preset period t3.

[0043] When it is judged that the real-time water level reaches or exceeds the rated water level H2, and the change rate of the real-time water temperature T is less than the set threshold for N consecutive cycles, the system determines that the water temperature has reached a stable state, and then exits the water level - cooling linkage step and resumes the normal cooling control process based on the water temperature range.

[0044] The controller determines whether the real-time water level H is lower than the preset minimum warning water level H1. The minimum warning water level H1 is usually set to ensure that the evaporator coil is completely submerged with a certain safety margin. If the real-time water level H is not lower than H1, it directly enters the cooling control mode corresponding to the current water temperature.

[0045] If the real-time water level H is lower than H1, the controller first opens the inlet valve to replenish water into the tank, preventing the evaporator coil from being exposed, the heat exchange efficiency from dropping sharply, or even the compressor from being damaged due to the low water level. Simultaneously with the water replenishment, the controller does not wait for the replenishment to complete but immediately executes the cooling control mode corresponding to step S3 in claim 1 based on the current real-time water temperature T. For example, if the water temperature T ≥ T1 during the water replenishment process, the first cooling mode (compressor at full speed, fan rotating at full forward speed) is immediately activated.

[0046] This linkage mechanism ensures that even in abnormal situations where the water level is insufficient, the cooling function can still be activated or maintained according to the actual water temperature requirements. It achieves parallel processing of water level protection and temperature control, solving the problem that traditional solutions may completely shut down due to water shortage protection and cannot cope with the urgent cooling needs at high temperatures.

[0047] In the water level cooling linkage step, after the inlet valve is opened, the controller continuously acquires the real-time water level H and real-time water temperature T at a preset short period t3 (e.g., 10 seconds). The controller continuously judges two conditions: first, whether the real-time water level H has reached or exceeded the rated working water level H2; second, whether the rate of change of the real-time water temperature T has tended to stabilize.

[0048] The criterion for water temperature stability can be set as follows: within N consecutive sampling periods (e.g., N=6, i.e., 1 minute consecutively), the absolute value of the rate of change of real-time water temperature T (the amount of temperature change per unit time) is less than a set small threshold (e.g., 0.1℃ / minute). The controller determines that the system has returned to a stable operating state only when both conditions are met simultaneously: "real-time water level H≥H2" and "the rate of change of water temperature is less than the set threshold for N consecutive periods".

[0049] Subsequently, the controller closes the inlet valve and exits the water level cooling linkage step. Subsequent temperature control will then fully follow the aforementioned normal cooling control process based on three temperature ranges, no longer subject to the forced intervention of the water level linkage. This step ensures that the system can quickly respond to temperature changes during water level recovery and smoothly transition to the conventional optimized control mode after both water level and temperature stabilize, improving the system's robustness under dynamic operating conditions.

[0050] In the first cooling mode, the cooling fan is controlled to rotate forward at a first preset speed, specifically by controlling the cooling fan to continuously rotate forward at 100% of its rated speed. This means that the fan motor drive circuit receives a control signal with the full duty cycle, causing the fan blades to rotate at maximum speed, generating the maximum airflow that the fan can provide.

[0051] The powerful airflow generated by the full-speed forward rotation blows directly onto the condenser and water tank casing, maximizing the intensity of forced convection heat dissipation and thus promptly removing the large amount of condensation heat generated by the compressor during full-load operation. This design addresses the urgent need for rapid heat dissipation in high-temperature ranges, maximizing heat dissipation capacity to assist the refrigeration system in quickly lowering the water temperature and helping to reduce condensing pressure. This alleviates the operating pressure on the compressor under high temperature and high load conditions, providing crucial support for quickly exiting the high-temperature range.

[0052] In the third cooling mode, the second preset program is implemented by controlling the cooling fan to operate intermittently. The controller has timing control logic, for example, controlling the cooling fan to rotate forward at a low speed (e.g., 30% of the rated speed) for a duration of t1, where t1 can range from 2 to 5 minutes, for example, set to 3 minutes; then controlling the fan to stop for a duration of t2, where t2 can range from 5 to 10 minutes, for example, set to 7 minutes; this cycle repeats. The operating speed is set in the low-speed range of 20%-40% of the rated speed, sufficient to generate slight airflow disturbance.

[0053] This intermittent low-speed operation mode, during the short cycles of fan operation, allows a weak airflow to break up the water temperature stratification formed by slow natural convection within the tank, promoting overall water temperature uniformity. During the long cycles when the fan is off, almost no additional energy is introduced, keeping the system in a near-adiabatic state. This program, while achieving the primary functions of maintaining uniform water temperature and preventing localized overcooling, significantly reduces energy consumption during the low-temperature maintenance phase and minimizes the risk of condensation caused by continuous airflow intruding humid air from outside the tank.

[0054] Regarding the specific values ​​of the control parameters, the high-temperature threshold T1 can be set according to the required cooling water temperature, with a range of, for example, 10-12℃; the medium-temperature threshold T2 serves as the upper limit of the energy efficiency priority control range, with a range of, for example, 5-7℃, and it is ensured that T1-T2≥3℃ to form a sufficiently wide medium-temperature control range. The base frequency f0 determines the minimum operating frequency of the compressor when it is near the shutdown point (T=T2), with a range of, for example, 1.5-2 times the compressor's minimum allowable frequency, to ensure that there is still a certain amount of cooling capacity and adjustment margin at this time.

[0055] The proportional gain k determines the compressor frequency's response to temperature changes, with a value ranging from 2-5 Hz / ℃, to achieve a linear match between cooling capacity and heat load. In the fan control sub-state thresholds of the second cooling mode, Ta determines the critical point at which the fan enters a high-load coordinated state, with a value ranging from 2-4℃, for example, 3℃; Tb determines the critical point at which the fan switches to reverse uniform mode, with a value ranging from 0.5-1.5℃, for example, 1℃. The fixed speed R1 is the fan's operating speed under medium load, ranging from 80%-100% of the rated speed, for example, 90%; the fixed speed R2 is the fan's operating speed in reverse uniform mode, ranging from 30%-50% of the rated speed, for example, 40%.

[0056] The cold water tank cooling control method provided in this embodiment addresses the technical pain points of existing technologies, such as low energy efficiency, slow cooling speed, poor water temperature uniformity, and insufficient system stability, which are caused by controlling the compressor with fixed start and stop temperatures and the cooling fan only performing simple start and stop operations. Based on the real-time water temperature relative to the high, medium, and low threshold ranges, it triggers three cooling modes with significant differences in control logic and the working state of the execution components. In particular, in the core medium-temperature operating range, it creatively and deeply couples the variable frequency regulation of the compressor with the multi-state regulation of the cooling fan.

[0057] The real-time water temperature T provided by the temperature sensor serves as the unified input and judgment benchmark for the entire control logic. Based on the range of T, the controller selects the first, second, or third cooling mode. In the first mode, the compressor operates at its rated speed in conjunction with the fan running at full speed to achieve maximum power cooling. In the second mode, the controller synchronously calculates the compressor's inverter command f = f0 + k. (T-T2) and fan control commands (based on ΔT to determine the state) cause the cooling output of the refrigeration unit and the airflow output of the heat dissipation unit to change in tandem with the heat load, achieving optimal dynamic energy efficiency. In the third mode, the compressor shuts down and the fan operates intermittently at low speed in coordination to achieve minimum energy consumption for heat preservation. The liquid level sensor signal serves as a feedforward condition, and its triggered water replenishment action is executed in parallel with the cooling mode corresponding to the current water temperature, ensuring the continuity and safety of system control under abnormal water shortage conditions.

Claims

1. A cooling control mode method for a cold water tank, the cold water tank comprising a shell, a water tank disposed within the shell, an evaporator coil located within the water tank, a refrigeration unit consisting of a compressor, a condenser, and a throttling element, a temperature sensor for detecting the water temperature within the water tank, and a cooling fan located above the water tank, characterized in that, The method includes the following steps: S1: Continuously collect the real-time water temperature T in the water tank through the temperature sensor; S2: Compare the real-time water temperature T with a preset high-temperature threshold T1 and a medium-temperature threshold T2, where T1 > T2; S3: According to the temperature range where the real-time water temperature T is located, control the refrigeration unit and the cooling fan to execute different cooling control modes: When T ≥ T1, execute the first cooling mode, control the compressor to continuously operate at the rated power, and control the cooling fan to rotate forward at a first preset speed until the real-time water temperature T drops to T2; When T2 ≤ T < T1, the second cooling mode is executed, and the compressor is controlled to operate at an operating frequency f calculated according to the formula f = f0 + k (T - T2), where f0 is the base frequency and k is the proportionality coefficient. At the same time, the operating state of the cooling fan is controlled according to the real-time temperature difference ΔT = T - T2; When T < T2, execute the third cooling mode, control the compressor to stop operating, and control the cooling fan to operate according to a second preset program.

2. The cooling control mode method according to claim 1, characterized in that, In the second cooling mode, control the operating state of the cooling fan according to the real-time temperature difference ΔT. Specifically, it includes: when ΔT ≥ Ta, control the cooling fan to rotate forward and the speed is positively correlated with ΔT; when Tb ≤ ΔT < Ta, control the cooling fan to rotate forward and operate at a fixed speed R1; when ΔT < Tb, control the cooling fan to rotate backward and operate at a fixed speed R2; where Ta and Tb are preset temperature difference thresholds, and Ta > Tb > 0, R1 > R2.

3. The cooling control mode method according to claim 2, characterized in that, In the second cooling mode, when ΔT ≥ Ta, the speed V of the cooling fan is positively correlated with both the real-time temperature difference ΔT and the compressor operating frequency f, specifically satisfying the relationship: V = α ΔT+β f, where α and β are preset weighting coefficients.

4. The cooling control mode method according to claim 2, characterized in that, The value range of Ta is 2 - 4°C, and the value range of Tb is 0.5 - 1.5°C; the fixed speed R1 is 80% - 100% of the rated speed of the cooling fan, and the fixed speed R2 is 30% - 50% of the rated speed of the cooling fan.

5. The cooling control mode method according to claim 1, characterized in that, The cold water tank further includes a liquid level sensor for detecting the water level in the tank. In step S3, before executing any cooling mode, it further includes obtaining the real-time water level H through the liquid level sensor; judging whether the real-time water level H is lower than the lowest warning water level H1; if so, control the water inlet valve to open for water replenishment, and immediately execute the cooling control mode corresponding to step S3 according to the current real-time water temperature T until the water level reaches the rated water level H2 and the water temperature reaches stability.

6. The cooling control mode method according to claim 5, characterized in that, In the water level cooling linkage step, while replenishing water and executing the cooling control mode, continuously obtain the real-time water level H and the real-time water temperature T at a preset period t3, and when it is judged that the real-time water level H ≥ H2 and the change rate of the real-time water temperature T is less than the set threshold for N consecutive periods, determine that the water temperature has reached stability and resume the normal cooling control process.

7. The cooling control mode method according to claim 1, characterized in that, In the first cooling mode, control the cooling fan to rotate forward at a first preset speed, and control the cooling fan to continuously rotate forward at 100% of the rated speed.

8. The cooling control mode method according to claim 1, characterized in that, In the third cooling mode, the second preset program is: control the cooling fan to operate intermittently, where the operation duration t1 is 2 - 5 minutes, the stop duration t2 is 5 - 10 minutes, and the speed during operation is 20% - 40% of the rated speed.

9. The cooling control mode method according to claim 1, characterized in that, The value range of T1 is 10 - 12°C, the value range of T2 is 5 - 7°C, and T1 - T2 ≥ 3°C; the value range of the base frequency f0 is 1.5 - 2 times the lowest allowable frequency of the compressor, and the value range of the proportionality coefficient k is (2 - 5) Hz / °C.

10. The cooling control mode method according to claim 1, characterized in that, In the second cooling mode, when the compressor is controlled to run at a frequency f, the frequency f is limited between the compressor's minimum allowed frequency f_min and the rated frequency f_max.

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