166 results about "Evaporation temperature" patented technology

The invention provides an evaporative cooling type water cooling system and a control method thereof.The evaporative cooling type water cooling system comprises a compressor, a freezing pipeline and an evaporator, a freezing water pump is arranged on the freezing pipeline, and the control method of the evaporative cooling type water cooling system comprises the steps that the frequency of the compressor is adjusted, the water outlet temperature of the freezing pipeline is within a first preset range, and the frequency when the compressor is stable at the moment is obtained; an adjustment coefficient X is obtained according to the ratio of the frequency F1 when the compressor is stable to the maximum set frequency F1max of the compressor; determining the initial adjustment frequency of the chilled water pump through the adjustment coefficient X; and adjusting the frequency of the chilled water pump on the basis of the operation of the initial adjustment frequency of the chilled water pump to enable the evaporation temperature of the evaporator to be within a second preset range. By means of the technical scheme, the problem that in the prior art, an evaporative cooling type water cooling system is high in energy consumption can be solved.

The invention provides a condenser type refrigeration cycle intelligent adaptation control method and system, and relates to the technical field of refrigeration. The method comprises the steps that environment state parameters are obtained, the environment frost point temperature is calculated, and an altitude correction factor representing the air side heat exchange capacity is calculated; executing boundary contraction transformation on a preset compressor operation envelope based on the altitude correction factor, and determining an allowable condensing pressure upper limit; an evaporator temperature response sequence is monitored, the time domain integral cumulant of the temperature response sequence relative to the environment frost point temperature is calculated, and the allowable evaporation temperature lower limit is dynamically increased based on the cumulant; constructing a target operation domain according to the allowable condensation pressure upper limit and the allowable evaporation temperature lower limit; and determining a current operation working point, and adjusting the control variable to enable the operation working point to fall into the target operation domain. The safety of the condensation side and the frost prevention stability of the evaporation side can be considered under the high-altitude and complex environment working conditions, and the continuous operation reliability of refrigeration circulation is improved.

The refrigerating system comprises a compressor, an evaporative condenser, a gas-liquid separator, a heat regenerator, an evaporator, a heat recoverer, an energy storage device, a terrace heat exchanger, an oil separator, an oil cooler, a water pump, a temperature control valve, an electronic expansion valve, a three-way valve, a control device, a temperature sensor and a pressure sensor. The control device collects signals of compressor outlet and inlet pressure sensors and temperature sensors, evaporator outlet pressure sensors and temperature sensors, an oil return temperature sensor and a floor heat exchanger temperature sensor. Condensing pressure is adjusted by controlling starting and stopping of a condenser side fan and a water pump, and the opening degree of the three-way valve is controlled to enable the oil return temperature to be within a safe range. The evaporation temperature is maintained by adjusting the opening degree of an evaporator inlet electronic expansion valve. By monitoring the terrace temperature in the refrigeration house, the electromagnetic valve is controlled to adjust the refrigerant flow in the terrace heat exchanger to maintain the outlet temperature, and the energy storage device is intermittently put into the refrigeration house to improve the system energy efficiency.

This invention provides a method and device for preventing condensation in a wall-mounted inverter air conditioner. The control method includes the following steps: when the air conditioner enters the cooling anti-direct-blow mode, time-sharing frequency limiting control and airflow compensation control are executed simultaneously. The time-sharing frequency limiting control, within the time window before condensation forms, controls the compressor to operate at the highest frequency limit corresponding to the currently set fan speed of the indoor fan to cool and dehumidify; then, frequency reduction is used to further reduce condensation formation. The airflow compensation control uses the airflow at the default position of the air guide vane during normal cooling as a reference, and compensates for the airflow loss caused by changes in the position of the air guide vane by increasing the indoor fan speed, thereby increasing the evaporation temperature and outlet air temperature. This invention solves the problem that existing technologies, when dealing with condensation generated in the anti-direct-blow mode of wall-mounted air conditioners with large vanes, cannot simultaneously consider user experience, cooling effect, and hardware cost.

The invention discloses a subcooler and a deep subcooler for a refrigerating system and a control method of the subcooler and the deep subcooler, and belongs to the technical field of refrigeration. The deep subcooler comprises a subcooling heat exchange unit, an independent cold source loop and a pressure control valve; the supercooling heat exchange unit is connected between the high-pressure liquid reservoir and the throttling device in series, and the primary liquid refrigerant is deeply cooled to be equal to or close to the target value of the evaporation temperature through low-temperature cooling capacity provided by a low-pressure evaporation system or an independent cold source loop. The independent cold source is driven by a compressor with the minimum refrigerating capacity in the system, and an air return pipeline of the independent cold source is bridged with air return pipelines of other compressors of the system through an outlet pressure balance valve, so that the surplus refrigerating capacity is fully utilized. The evaporation pressure of a cold source loop is changed by monitoring the supercooled liquid temperature and feeding back and adjusting the opening degree of a pressure control valve, precise closed-loop control over the supercooled temperature is achieved, throttling flash gas can be remarkably reduced or even eliminated, the effective refrigerating capacity of unit refrigerant and the heat exchange efficiency of an evaporator are improved, and the system energy efficiency is greatly improved.

The small-temperature-difference double-evaporation-temperature single-stage refrigerating system comprises a compressor, a condenser, a low-temperature loop and a high-temperature loop, the compressor is used for compressing low-temperature refrigerant gas into high-temperature refrigerant gas, and the condenser is used for cooling the high-temperature refrigerant gas into high-pressure liquid; the high-pressure liquid enters a low-temperature loop and a high-temperature loop, a low-temperature evaporator is arranged in the low-temperature loop, a high-temperature evaporator is arranged in the high-temperature loop, the low-temperature evaporator is arranged outside a refrigeration house, the high-temperature evaporator is arranged in the refrigeration house, and air is fed into the refrigeration house after being cooled by the low-temperature evaporator. And the high-temperature evaporator is in direct contact with food.

The application provides a compressor performance test system and a test method thereof, wherein the compressor performance test system comprises a to-be-tested compressor, at least two condensers, at least two calorimeters and a control unit, a temperature sensor, a pressure sensor and an electronic expansion valve are arranged between the inlet of the calorimeter and the outlet of the condenser, and the outlet of the calorimeter and the liquid reservoir are spaced apart to arrange the pressure sensor and the temperature sensor. In the compressor performance test system and the test method thereof provided in the application, two or more sets of calorimeter systems are used to simultaneously obtain refrigerating capacity of two or more evaporation sides and heating capacity of two or more condensation sides, so as to meet the performance test requirements of the compressor with multiple evaporation temperatures and multiple condensation temperatures.

The invention relates to a refrigerating system control method and device, computer equipment and a computer readable storage medium, and the method comprises the steps that in the operation stage of a refrigerating system, the target frequency of an inverter compressor is obtained according to the required refrigerating capacity of a secondary refrigerant side and the target condensation temperature and target evaporation temperature of a refrigerant side; controlling the inverter compressor to output by taking the target frequency as the current frequency, and running for a first preset duration; and when the current frequency is within the upper and lower limit range of the target frequency, the current frequency of the inverter compressor is adjusted based on the relation between the actual liquid supply temperature flowing to the evaporator from the refrigerant side and the target liquid supply temperature. The actual liquid supply temperature is close to the target liquid supply temperature so as to guarantee the temperature control effect, meanwhile, the inverter compressor can operate at the frequency matched with the temperature control working condition, the inverter compressor is prevented from operating at the high frequency all the time, power consumption of a refrigerating system and a heating system is reduced, meanwhile, temperature control through excessive dependence on the heating system can be avoided, and the energy consumption of the refrigerating system and the heating system is reduced. And the temperature control effect is ensured.

The invention relates to a refrigerant circulation system control method, a refrigerant circulation control device, a refrigerant circulation system and a storage medium, and the refrigerant circulation system control method comprises the steps that under the cold storage and refrigeration mode of the refrigerant circulation system, the actual evaporation temperature of the refrigerant circulation system is obtained; according to the difference value between the actual evaporation temperature of the refrigerant circulation system and the target evaporation temperature of the system, the total output capacity of the refrigerant circulation system is adjusted; wherein the system target evaporation temperature is the target evaporation temperature of the refrigerant circulation system. The overall output capacity of the refrigerant circulation system is adjusted based on the difference value between the actual evaporation temperature and the target evaporation temperature of the refrigerant circulation system, efficient cold storage in the valley electricity period can be utilized to the maximum extent for use in the peak electricity period, it can be guaranteed that the refrigeration effect of an indoor unit assembly meets the comfort level of a user, the overall energy efficiency ratio of the system can be increased, and the energy efficiency of the system is improved. The energy-saving heat exchange device plays a role in saving energy.

The application discloses a refrigerating unit, an air conditioner and a valve control method, and relates to the technical field of refrigeration. The refrigerating unit comprises a compressor, a condenser, a supercooling assembly and an evaporator. In the technical scheme, the refrigerants in the two supercooling devices are alternately static, the refrigerant in one supercooling device is static and then gas-liquid separation is performed, the flash vapor after separation is compressed by the compressor, the liquid part flows into the evaporator to absorb heat and refrigerate, and the refrigerant in the other supercooling device is static. The refrigerant in the static state is cooled by changing the evaporation temperature of the heat exchanger, and then gas-liquid separation is performed. The refrigerant flowing into the evaporator is deeply cooled by alternating static cooling, the refrigerant in the evaporator is prevented from being cooled and heated at the same time, the refrigerating capacity of the heat exchanger is improved, and the system energy efficiency is improved.

The embodiment of the invention provides an air conditioner control method, system and equipment for electric parking and a medium, and belongs to the field of vehicle air conditioners. The method comprises the steps that the requirement for the refrigerating capacity of the air conditioner is judged, the rotating speed of the electric compressor is adjusted according to the difference value between the evaporation temperature and the target temperature, when the evaporation temperature is lower than the minimum value of the target temperature, the compressor enters a low-speed protection state, and when the evaporation temperature is continuously below the basic protection temperature in the low-speed protection state, the compressor is forcibly closed. According to the environment temperature data, the time when the air conditioning system quits the icing protection state is determined; and the evaporation temperature for quitting the low-speed protection state is determined according to the difference value between the indoor temperature and the panel set temperature. The refrigerating capacity demand and heat input of the vehicle are estimated through a temperature sensor related to an air conditioning system, the rotating speed and opening and closing of an electric compressor are controlled, and the temperature control precision of the electric parking air conditioner is improved; meanwhile, by reducing unnecessary repeated starting and stopping of an air conditioner compressor, comfort is improved, system reliability is improved, and the service life of parts is prolonged.

The utility model relates to an evaporation pressure stabilizer for an organic Rankine cycle system, which comprises an evaporation cavity and a waste gas cavity, the evaporation cavity and the waste gas cavity are vertically arranged in a separated manner, the evaporation cavity is connected with a steam outlet, a pressure stabilizing system is arranged between the evaporation cavity and the steam outlet, and the evaporation cavity is filled with an organic working medium; the heat pipes are uniformly distributed in the evaporation pressure stabilizer, and each heat pipe comprises a condensation section located in the evaporation cavity and an evaporation section located in the waste gas cavity; the evaporation cavity, the waste gas cavity and the pressure stabilizing system are integrated, the structure is compact, the evaporation cavity, the waste gas cavity and the pressure stabilizing system are integrated, the evaporation cavity, the waste gas cavity and the pressure stabilizing system can be installed as a whole, the waste gas inlet is used for connecting high-temperature waste heat steam exhaust and fully utilizing waste heat, the number of the heat pipes is large, the heat pipes are evenly arranged, and heat absorption and heat release are conducted at the same time; the heat exchange efficiency is high, and the evaporation temperature can be flexibly controlled.

The application relates to the air conditioning technical field, and particularly provides an air conditioning system and a control method thereof, and aims to solve the problem of how to ensure the heating effect of the air conditioner under the condition of air conditioner frequency reduction operation. For the purpose, the air conditioning system is provided with a phase change material, and a heat storage channel and a heat exchange channel which are not communicated with each other in a heat storage device, the heat storage channel and the heat exchange device form a heat storage loop, so that the first refrigerant in the heat exchange device can exchange heat with the first refrigerant in the heat storage channel, and then the heat generated by the driving mechanism can be stored in the phase change material. The two ends of the heat exchange channel are arranged on the inlet side of the evaporator, thereby forming a heat exchange branch, so that the second refrigerant enters the heat exchange branch before entering the evaporator, the second refrigerant in the heat exchange branch can absorb the heat released by the phase change material, the temperature of the second refrigerant is increased, thereby the evaporation temperature of the evaporator is increased, so that the air conditioner can still ensure the heating effect under the condition of frequency reduction operation.

The invention discloses a control method of a variable air volume ventilation air conditioner and an air conditioning system, and relates to the technical field of heating and ventilation control. According to the control method, the real-time evaporation temperature of the refrigerant is collected, the target evaporation temperature is updated, the total load, the real-time evaporation temperature and the target evaporation temperature are input into the load controller, the rotating speed error of the compressor is calculated, then the real-time current and the rotating speed error are input into the rotating speed controller, and the input current of the compressor is updated. In the control process of the variable air volume ventilation air conditioner, the feed-forward control part of the load controller is continuously updated. The feed-forward control part updated in real time comprises the magnetic resistance change of the compressor, the driving error is calculated when the compressor is dormant, the magnetic resistance coefficient of the rotating speed controller is updated, and the feed-forward control part is initialized according to the updated magnetic resistance coefficient, so that the control precision of the air conditioner compressor is improved.

The invention belongs to the technical field of heat pump drying, and particularly relates to a heat pump drying system and a control method.The heat pump drying system comprises a compressor, two evaporators, two condensers, two throttling devices and a drying air channel, and in the drying air channel, the double condensers are arranged on the downstream of the air flowing direction of the double evaporators; the double evaporators are arranged in the drying air channel in parallel to form stepped cooling and dehumidification, and the double condensers are arranged in the drying air channel in parallel to form stepped heating. According to the heat pump drying system, rapid temperature rising, deep dehumidification in the middle stage and stable temperature rising in the later stage are achieved in the early stage of drying, the dehumidification efficiency and the drying speed of the whole drying process are improved, particularly, the high dehumidification amount can still be kept in the later stage of drying, and the problems that a traditional heat pump drying system is single in evaporation temperature, insufficient in dehumidification capacity and low in drying efficiency are solved.

Provided is a thermal cycling system including: a working medium; a compressor; a condenser; a pressure reducing device; and an evaporator, in which the working medium includes HFO-1123, HFO-1234yf, and R290, in a case in which a content of the R290 is defined as A mass % and a content of the HFO-1123 is defined as B mass %, the A and the B satisfy Equation (1) and Equation (2) below, a total content of the HFO-1123, the HFO-1234yf, the R290 is 99.0 mass % or more with respect to a total amount of the working medium, the evaporator is controlled such that an evaporation temperature of the working medium is −45° C. or higher, Equation (1) is −1.6433×A+38.1000≤B≤0.0136×A2−0.8364×A+61.0167, and Equation (2) is 2.0≤A≤9.0.

The utility model relates to a kind of high-speed motor cooling device based on annular unpowered heat pipe, it includes compressor and the cooling mechanism being set in the exterior of compressor, the cooling mechanism includes with the exhaust pipe and reflux pipe being connected with the compressor shell, the connecting position of the exhaust pipe and reflux pipe with the compressor shell is respectively located the both sides of stator in axial direction, the compressor shell inner wall is provided with the venturi injection pipe being connected with the reflux pipe, the outer end of the exhaust pipe and reflux pipe is connected with condensing component.The high-speed motor cooling device, it is directly set on the compressor shell, the magnetic suspension motor and magnetic bearing cooling in the compressor shell interior, independent of heat pump refrigerant circulation, can realize motor internal evaporation temperature lower than the motor temperature control of high-temperature heat pump system evaporation temperature.On the basis of guaranteeing motor safety, motor coil and rotor temperature are greatly reduced, prolong motor life, improve motor efficiency.

The invention relates to the technical field of refrigeration houses, in particular to a control method of a refrigerating system and the refrigerating system, and aims to solve the problem that the dehumidification capacity is insufficient due to the fact that the evaporation temperature is limited. Therefore, the precooler is provided with a first refrigerant channel and a second refrigerant channel which can exchange heat with each other, and the compressor, the condenser, the first refrigerant channel, the first throttling component and the evaporator are sequentially connected to form a first refrigerant circulation loop. The compressor, the first electromagnetic valve, the heat exchanger, the second throttling component and the second refrigerant channel are sequentially connected to form a second refrigerant circulation loop, the refrigeration system has a refrigeration mode and a dehumidification mode, and when the dehumidification mode is operated, the control method comprises the steps that the first refrigerant circulation loop is operated; and the first electromagnetic valve is intermittently opened, so that the second refrigerant circulation loop is intermittently operated. Therefore, when the dehumidification mode is operated, the precooler can improve the supercooling degree of the refrigerant in the first refrigerant circulation loop, so that the refrigerating capacity of the evaporator is enhanced, and the dehumidification effect is improved.

The invention discloses a control method and device of an air source heat pump unit, a storage medium and electronic equipment, and relates to the technical field of heat pumps, and the method comprises the steps that when the water inlet and outlet temperature difference, the outdoor environment temperature or the evaporation temperature meet the preset first condition, the temperature change value of the water inlet temperature is calculated; according to the temperature change value, whether the heating capacity of the unit meets a preset second condition or not is determined; and if the heating capacity of the unit meets the preset second condition, the air source heat pump unit is controlled to execute a preset defrosting action. The defrosting reliability of the air source heat pump unit can be effectively improved.

This application relates to the field of refrigeration, and more particularly to an adjustable refrigeration device. The technical solution includes an evaporator, a compressor, a condenser, and a solenoid valve disposed between the condenser and the evaporator. The evaporator outlet has a first pipe, the end of which, away from the evaporator, is connected to the compressor's suction port. The compressor discharge port has a second pipe, the end of which, away from the compressor, is connected to the condenser's inlet. The condenser outlet has a third pipe, the end of which, away from the condenser, is connected to the solenoid valve's inlet. The solenoid valve outlet has a fourth pipe connected to the evaporator inlet. An adjusting component is provided on the fourth pipe. This application allows for real-time control of the evaporation temperature as needed, reducing energy waste and improving the device's environmental performance. Furthermore, this application has fewer structural components, is easy to install, and effectively improves the device's installation efficiency.

The application discloses a method for dry-wet separation operation of terminal air conditioners and a multi-air-conditioning system, which is used for dividing the terminal air conditioners into dry air conditioners and wet air conditioners, controlling the dry air conditioners which are sensitive to water leakage to carry out refrigeration, and controlling the wet air conditioners which are not sensitive to water leakage to carry out dehumidification, so that the influence of air conditioner water leakage on the safety of a data machine room is effectively reduced. The method comprises the following steps: dividing the terminal air conditioners in a multi-air-conditioning system of a data machine room into dry air conditioners and wet air conditioners, wherein the sensitive degree of the installation position of the dry air conditioners to water leakage is higher than the sensitive degree of the installation position of the wet air conditioners to water leakage; controlling the target evaporation temperature of the dry air conditioners to be higher than the air dew point temperature, so that the dry air conditioners are in a refrigeration mode without condensate water; and controlling the target evaporation temperature of the wet air conditioners to be not higher than the air dew point temperature, so that the wet air conditioners are in a dehumidification mode.

This invention discloses an intelligent control method and device for a high-temperature water source heat pump unit. The method is differential pressure interval intelligent control, which divides the suction and exhaust pressure difference ΔP into three intervals based on a first and a second differential pressure threshold, and implements differentiated opening control of the electronic expansion valve (EEV) to actively utilize the high evaporation temperature characteristics of the high-temperature heat pump to increase the pressure difference. The device is a falling film evaporator with a bottom-inclined oil return port of 3-7°. Through differential pressure interval intelligent control and equipment structure optimization, this invention eliminates the pressure maintaining valve and regenerator required in existing technologies, achieving a comprehensive effect of improving energy efficiency by more than 5%, reducing failure points by more than 40%, and reducing the total life cycle cost by more than 7%. It can balance safety and energy efficiency, and also has the advantages of reducing costs, improving reliability, and expanding the unit's load adjustment range.

The temperature control system comprises an upper-layer heat exchanger and a lower-layer heat exchanger, the upper portion of a heat pipe is arranged in the upper-layer heat exchanger, the lower portion of the heat pipe is arranged in the lower-layer heat exchanger, and a medium C in the heat pipe is communicated to a balance tank through a vapor-phase balance pipe and a liquid-phase balance pipe. The energy accumulator communicates with the upper portion of the balance tank through a pipeline and is provided with a pressure adjusting device used for dynamically adjusting system pressure to control the evaporation temperature of the medium C. The system is simple in structure, convenient to use and capable of adjusting the system pressure in a self-adaptive mode, so that the evaporation temperature of the medium C is always higher than the freezing temperature of the working medium B, and the working medium B cannot be frozen in the heat exchange process; the temperature control precision is high, the response is fast, the system stability is high, the safety and the heat exchange efficiency of the system are improved, and high practical value is achieved in industrial application.

The invention discloses a cascade heat extraction mode high-temperature heat pump system with pre-heaters for serial evaporators, which belongs to the technical field of compression heat pumps and comprises a condenser, a first pre-heater, a jet evaporation module and a compression buffer module. The problems that the heat exchange effect of the condensation side is poor and the ejection efficiency of an ejector is low are solved, and meanwhile interstage liquid spraying cooling is achieved. The evaporation side is in an evaporator series connection mode, and gradient utilization of the evaporation temperature is achieved; the preheater is arranged at an outlet of the condenser, structural optimization of graded heating is formed, the heat exchange efficiency and heating power matching performance of the system can be improved, meanwhile, after a main flow refrigerant entering the ejector is cooled, the ejection capacity of the ejector can be further improved, and the good intermediate cooling effect is achieved; or a preheater is further additionally arranged, the heating temperature interval is expanded, and the system performance is improved.

The invention relates to an air conditioning system of a vehicle and a control method thereof. An air conditioning system of a vehicle may include: an ambient temperature sensor for sensing an ambient temperature; the evaporation temperature sensor is used for sensing the evaporation temperature; and a controller configured to set an upper limit of an evaporation target temperature to a first upper limit value, acquire the evaporation target temperature, determine whether to apply the first upper limit value to limit the evaporation target temperature according to the sensed ambient temperature and the evaporation temperature and the acquired evaporation target temperature, and when the first upper limit value is applied to limit the evaporation target temperature, determine whether to apply the first upper limit value to limit the evaporation target temperature. The evaporation target temperature upper limit is changed according to whether or not a periodic fluctuation occurs in the evaporation temperature, and the evaporation target temperature is limited by applying the changed evaporation target temperature upper limit.

The invention provides an air conditioning unit defrosting control method and system and an air conditioning unit. The method comprises the steps that the environment dry-bulb temperature and the environment wet-bulb temperature are collected in real time, and the dew-point temperature is calculated; the evaporation temperature is obtained; when the evaporation temperature is smaller than a preset threshold value, a defrosting mode is entered, and the defrosting mode comprises an air cooling defrosting mode and a refrigerant defrosting mode; a defrosting mode is selected according to the comparison result of the working current of the frequency conversion fan and the target current; and in the air cooling defrosting mode, the fan frequency is controlled according to the size relation between the evaporation temperature and the dew point temperature. According to the method, through defrosting judgment based on the evaporation temperature, flexible mode switching and dynamic air speed adjustment, on one hand, the reasonability of defrosting control is improved, and unnecessary defrosting operation is avoided; the adaptability and flexibility of the system are enhanced, and the system is suitable for different frosting degrees and operation states; and thirdly, the frequency adjustment of the fan is assisted through the dew point temperature, the efficiency and the energy consumption of the air cooling defrosting mode are optimized, and the overall energy-saving performance of the air conditioning unit is improved.

This invention relates to a design method for a medium-temperature chilled water centralized air conditioning system, belonging to the field of energy-saving air conditioning system design technology, and filling the gap in existing technologies for design methods of medium-temperature chilled water centralized air conditioning systems. The design method includes the following steps: S1, initial data extraction and initial judgment: determining whether adjustments to the selection and design of conventional fresh air handling units and fan coil units are needed; S2, calculating the indoor heat-to-moisture ratio and determining the air supply state point; S3, calculating the dehumidification capacity of the fresh air handling unit and fan coil units; S4, setting equipment selection parameters; S5, evaluating the dehumidification capacity of the fresh air handling unit; S6, evaluating the dehumidification capacity of the fan coil units; S7, determining the system supply water temperature. This invention can design medium-temperature chilled water centralized air conditioning systems with different operating conditions and determined supply water temperatures for different climate zones. Compared with normal temperature systems (7 / 12℃), the medium-temperature system has a higher evaporation temperature of the chiller unit, which can improve the system COP and achieve energy saving in air conditioning.

This application provides a low-temperature refrigeration control method, apparatus, air conditioner, and computer-readable storage medium for controlling an air conditioner. The air conditioner includes a compressor, an expansion valve, an outdoor fan, and an indoor heat exchanger. The low-temperature refrigeration control method includes: controlling the compressor to operate at a preset low-temperature refrigeration frequency and the expansion valve to operate at a preset low-temperature refrigeration opening degree; increasing or decreasing the speed of the outdoor fan according to the current temperature and stable evaporation critical temperature of the indoor heat exchanger until the outdoor fan speed reaches its maximum or minimum speed; after the outdoor fan speed reaches its maximum or minimum speed, adjusting the opening degree of the expansion valve according to the temperature of the indoor heat exchanger and a stable evaporation temperature range, so that the temperature of the indoor heat exchanger is adjusted to be within the stable evaporation temperature range, wherein the stable evaporation temperature range is a temperature range greater than the stable evaporation critical temperature and less than a second preset temperature.

The invention relates to the technical field of machine room air conditioners, and discloses a fluorine pump multi-connected backboard air conditioning system capable of actively preventing condensation and a control method, the fluorine pump multi-connected backboard air conditioning system comprises an outdoor host module, a plurality of indoor backboard air conditioning modules connected in parallel and a host controller; each indoor backboard air conditioning module comprises a backboard controller, a return air temperature and humidity sensor, an air supply temperature and humidity sensor, an evaporation pressure sensor, a temperature sensor, a backboard fan, a first backboard electronic expansion valve and a second backboard electronic expansion valve; the air supply dew point temperature Ts1 is calculated by detecting the air supply temperature and humidity, the evaporation temperature Tp1 is converted according to the evaporation pressure, Ts1 + T and Tp1 are compared, and if the conditions are not met, the anti-condensation actions such as opening a second electronic expansion valve, reducing the rotating speed of a compressor, increasing the output of a draught fan and starting a dehumidifier are progressively executed till the condensation risk is relieved. According to the invention, active predictive condensation prevention is realized, generation of condensate water is fundamentally avoided, and the safety of the server is guaranteed.