CN1293346C - Energy-saving central air conditioning system - Google Patents

Abstract

The invention relates to an energy-saving central air-conditioning system, which includes a main machine for providing cold (hot) water sources required for air conditioning, for transporting unit chilled water to air treatment equipment or terminal chilled water devices, and for air conditioning Terminal devices for cooling, heating, humidification, dehumidification, and purification and filtration, and an air-conditioning control system for manual or automatic adjustment and monitoring of the unit, air-handling equipment, and air-conditioning process; the air-conditioning control system is based on a large number of dynamic changes collected in real time Through processing, the best dynamic operation command for on-demand cooling can be obtained, and the partial load continuous operation state of each component of the central air-conditioning system can be adjusted in real time to one of the two modes of "cooling storage operation" or "cooling operation". The main unit of the air conditioner runs at high speed in the cool-storage mode, and stops running in the cool-down mode. The system can be widely used in various types of central air-conditioning systems to save electric energy and reduce consumption, and has obvious social and economic benefits.

Description

Energy-saving central air-conditioning system

technical field

The invention relates to a central air-conditioning system, in particular to an energy-saving central air-conditioning system.

Background technique

With the rapid development of social economy, hotels, office buildings, large venues and other places using central air-conditioning systems are becoming more and more widespread. Since the design of the central air-conditioning system is mostly calculated and selected based on peak climate conditions and load capacity. In the actual operation of the system, with the change of season, time and the heat dissipation of the used space, the actual load is far lower than the design value most of the time throughout the year. Take hotels as an example: air-conditioning load generally includes: ① building envelope heat transfer (including solar radiation heat); ② lighting, refrigerators, kettles and other electrical appliances heat dissipation; ③ human body heat dissipation; ④ fresh air load and power equipment heat dissipation . Building heat transfer and fresh air load vary with outdoor meteorological parameters; hotel traffic is also a big variable. Due to the use time and utilization rate of different functional spaces such as lobby, conference hall, restaurant, dance hall and guest room are different. Many factors cause the air-conditioning load to change over time.

The daily load curve of a hotel is shown in Figure 6:

It can be seen from the graph that hotel air conditioners operate more frequently under partial load, and the distribution of low load is uneven, which may occur in transitional seasons or summer. Therefore, almost all central air-conditioning systems work under partial load conditions for a long time. If only relying on the load adjustment method that the air conditioning system equipment already has to save energy, the effect of saving electricity is very small compared with electricity consumption.

At present, the operation of central air-conditioning system equipment is generally operated manually. Due to the inaccuracy, untimelyness and instability of manual adjustment, the energy consumption of the central air-conditioning system increases. And the labor cost increases.

At present, there are four energy-saving methods for central air-conditioning: refrigerant, water pump frequency conversion, waste heat recovery and cold storage.

①Refrigerant: Save electricity consumption by replacing the refrigerant of the chiller. All chillers are said to save energy by using a certain refrigerant, but the refrigerant is expensive. At the same time, the manufacturers of chillers have clear regulations on the refrigerants used in their products, and it is not recommended to replace them with new types of refrigerants.

②Frequency conversion of water pump: According to the reduction of chilled water demand at the end of the air conditioner of the variable flow device, the purpose of reducing energy consumption is achieved by reducing the operating frequency of the water pump motor and reducing the operating current. It is limited by the frequency adjustment range. If the amount of circulating water is reduced to a certain extent, it will not only affect the cooling efficiency of the main engine, but even cause a protection shutdown.

③Waste heat recovery: Use refrigerant to condense high temperature, recover heat through heat exchanger, heat water, save energy for heating cold water, this is suitable for occasions that require hot water supply, not suitable for chillers with lower exhaust temperature.

④ Ice storage technology: Ice storage is to realize the phase change of ice balls to absorb and release cold energy by building ice storage pools. This method needs to increase structural investment and use special units. Applicable to newly built areas with peak and valley electricity price policies (actually an energy consumption reduction plan).

It can be seen that the currently widely used refrigerant, water pump frequency conversion, and waste heat recovery energy-saving technologies are all only modified for a certain part of the central air-conditioning device. However, even if full heat exchange, water pump frequency conversion, waste heat recovery and other methods are adopted, during the use of the central air conditioner, the chiller of the central air conditioner often operates continuously at part load, while the cooling water pump and cooling tower still operate according to the full load of the unit. Continuous operation in the high energy consumption operating state. The analysis shows that the energy efficiency ratio COP (COP-cooling capacity to power consumption ratio) value is the highest when the cooling capacity of air-conditioning chillers (or compressors) is usually high (for example, 70-90%), and is lower than 70-90%. When the load is on, the COP value drops, and the energy efficiency ratio of the air conditioner is greatly reduced at low load. As a result, under the same cooling capacity, the power consumption at low load is much higher than that at high load. Therefore, high energy consumption and large waste The situation is still not resolved.

Contents of the invention

The purpose of the present invention is to provide an energy-saving central air-conditioning system, which solves the problems of high energy consumption and large waste caused by partial load.

The object of the present invention is achieved in this way. An energy-saving central air-conditioning system includes a host for providing cold or hot water sources needed for air conditioning, for delivering the chilled water of the unit to the air handling equipment or the terminal chilled water device, A terminal device for cooling, heating, humidifying, dehumidifying, and purifying and filtering the air, and an air-conditioning control system for manually or automatically adjusting and monitoring the unit, air treatment equipment, and air-conditioning process; it is characterized in that: the air-conditioning control The system processes a large amount of dynamic change data collected in real time, and obtains the best dynamic operation command for on-demand cooling, and adjusts the continuous operation state of each component of the central air conditioning system to "cooling storage operation" or "cooling operation" in real time. One of the two modes, the central air-conditioning host runs at high speed in the cold storage mode, and stops running in the cooling mode.

An energy-saving central air-conditioning system implementing the present invention is based on advanced digital multi-point distributed air temperature data collection, processing, calculation, and control programs implemented by computers, and dynamically adjusts the temperature of refrigeration supply and return water, so that chillers, cooling An intelligent energy-saving control system for water pumps and cooling towers in high-efficiency, full-load operation or intermittent shutdown. The system can effectively improve the comprehensive energy efficiency ratio of the air-conditioning and refrigeration system, and overcome the shortcomings of the existing power-saving methods. The system can be widely used in various types of central air-conditioning systems to save electric energy and reduce consumption, and has obvious social and economic benefits.

Description of drawings

Fig. 1 is the system connection schematic diagram of Embodiment 1 of the energy-saving central air-conditioning system of the present invention;

Fig. 2 is a functional block diagram of the energy-saving central air-conditioning control system shown in Fig. 1;

Fig. 3 is the flowchart of the energy-saving central air-conditioning control system shown in Fig. 1;

Fig. 4a, 4b are the circuit diagrams of the energy-saving central air-conditioning control system shown in Fig. 1;

Fig. 5 is a diagram of the operation mode of the second embodiment.

Detailed ways

Embodiment one:

As shown in Figure 1, a central air-conditioning system consists of a main unit, a chilled water device, a terminal unit, and an air-conditioning control system. If the main unit uses a water-cooled or hot water unit, it also includes a cooling water unit. The function of the main unit is to provide cold or hot water source required by air conditioning, and its composition can be refrigeration equipment such as chiller unit and lithium bromide absorption refrigeration unit. The function of the cooling water device is to transport the heat of the unit to the cooling tower and dissipate the heat into the air. It consists of a cooling water pump, a cooling water tower, pipelines, etc., and the cooling water tower is equipped with devices such as fans and water-cooled condensers. The chilled water device, whose function is to transport the chilled water of the unit to the air treatment equipment or the terminal, is a hydraulic pipeline device, including a chilled pump, a pipeline, and can also include a cold storage tank, a water collector, a water separator, etc. . The function of the terminal device is to cool down, heat, humidify, dehumidify, and purify and filter the air. When cooling, the cold water from the outside enters the heat exchanger to exchange heat with the indoor circulating air, which reduces the air temperature and achieves the purpose of air conditioning; when heating, the heat from the outside The water enters the heat exchanger to exchange heat with the indoor circulating air to increase the air temperature and achieve the purpose of air conditioning. The cold or hot water entering the heat exchanger comes from the main unit of the air conditioner; in order to achieve the required air quality, such as constant temperature, constant humidity, high cleanliness, etc., corresponding devices and control equipment will be added to the terminal equipment. The function of the air conditioning control system is to manually or automatically adjust and monitor the unit, air handling equipment and air conditioning process during the operation of the air conditioning system. The conventional control system includes sensing elements, execution and adjustment mechanisms. The central air-conditioning system described in the utility model can be managed and monitored by a computer.

The refrigeration principle of the central air-conditioning system described in the utility model is that the refrigeration compressor compresses the low-temperature and low-pressure refrigerant vapor into high-temperature and high-pressure steam, and then discharges it into the water-cooled condenser; the cooling water cools the high-temperature and high-pressure steam of the condenser into high-pressure and normal temperature After the cooling water absorbs heat in the condenser, the cooling water is circulated by the cooling water pump to the cooling tower, where it exchanges heat with the air and is cooled by the air; the high-pressure and normal-temperature refrigerant liquid in the condenser is throttled by the expansion valve After decompression, it enters the evaporator to boil and evaporate, absorbing the heat brought back from the user end by the chilled water, and becomes low-temperature and low-pressure steam. These low-temperature and low-pressure refrigerant vapors return to the compressor, and repeat the above process to achieve continuous cooling. The purpose of providing circulating cold water to the air-conditioned area. In short, three cycles: refrigerant cycle system, cooling water cycle system, chilled water cycle system.

The central air-conditioning system described in the utility model is processed by the computer according to a large number of real-time collected data of dynamic load changes caused by factors such as temperature rise and fall caused by different seasons and climates, indoor flow of people and other factors, and the best dynamic operation of on-demand cooling is obtained. According to the instructions, the chillers, cooling water pumps and cooling water towers are adjusted in real time to a new working mode of "cooling storage operation and cooling operation", and the computer program system is used to control the operation of central air-conditioning equipment under high energy efficiency ratio conditions. When the central air-conditioning system is in cold storage operation, the chillers, cooling water pumps and cooling water towers all operate at high speeds, so in this state, the air-conditioning system maintains a high COP value; The cooling water pump and the cooling water tower stop working, and the cold energy accumulated in the air-conditioning circulating cold water device continues to provide cooling for the device, and the entire air-conditioning system is also in an energy-saving working state.

Since the COP value of the air-conditioning system is the highest when it is 70-90%, when the main engine keeps running under a relatively high load, but the central air-conditioning system is in a low-load demand state, except for a part that meets the cooling capacity of the air-conditioning space, the surplus part of the cooling capacity Adopt cold storage method. At this time, the operating condition of the main engine at low load is changed to two operating stages of cold storage and cooling, so that the main engine can run efficiently in the cold storage stage and save the surplus cooling capacity; in the cooling stage, the main engine stops cooling and uses the stored cold The amount provides cooling for the device.

Since the chilled water device of the air conditioner contains dozens or even hundreds of tons of water, water is one of the substances with a large specific heat capacity, and the temperature of 1 ton of water is lowered by 1 degree, which requires 0.33 tons of cooling capacity. Under the condition of a temperature difference of 7-8 degrees, the cold storage capacity of the chilled water device can reach as much as hundreds of cold tons, plus the cold storage capacity of the pipeline and the surface cooler of the terminal equipment, which is equivalent to the chiller running at 90% load for 40 minutes to 1 hour of cooling capacity. All items in the building, except the heat transfer surface of the enclosure structure and the surface of the human body, other inner walls and object surfaces have cold storage capacity. The thermal insulation capacity of the enclosure structure makes it take 1.65 hours for the outdoor heat to be transmitted to the indoor. Its cold storage energy not only maintains the stability of the room temperature, but also provides a stable guarantee for the large temperature difference operation of the chilled water.

In order to prevent the air-conditioning chilled water temperature from being lower than the set value, the central air-conditioning system described in the utility model also adds energy storage equipment, such as a cold storage tank, and the volume and quantity of the cold storage tank are determined according to the size of the air-conditioning system. When the central air-conditioning system is in a high-load working state, the cold storage tank does not work; as the main engine of the air-conditioning system continues to operate at a high load and meets the cooling capacity required by the air-conditioned space, the air-conditioning system is in a state of partial load demand, and the surplus Part of the cooling capacity is stored in the chilled water device of the air conditioner; when the chilled water temperature of the air conditioner reaches the set value, the chilled water device of the air conditioner is turned off; In the cold tank, until the temperature of the cold storage medium in the cold storage tank begins to drop, when it reaches the set value, the main unit of the air conditioning system and other devices stop running; the air conditioning system enters the cooling operation stage, and the air conditioning chilled water device provides cooling capacity for the air conditioning area ; The water temperature of the air-conditioning chilled water device gradually rises. When it is higher than the set value, the main unit of the air-conditioning system and other devices are still in the state of stopping operation, and the cold storage tank provides cooling capacity for the air-conditioning area; until the temperature of the cold storage tank is also higher than the set value After setting the value, the air-conditioning system host and other devices start to run, and the air-conditioning system enters the cold storage operation stage. When the air conditioning system enters the stage of cooling operation, the whole device is very energy-saving, and this stage often lasts for more than 1 hour each time.

The control system of the central air-conditioning system described in the utility model is a novel central air-conditioning power-saving intelligent control system. It can be specially designed for the central air-conditioning system of a new building, or it can be "tailor-made" according to the selection of equipment and operating conditions of the user's existing central air-conditioning system. The device can automatically process and collect data, calculate the load, and automatically adjust the operating status of chillers, cooling water pumps, cooling water towers and other equipment based on online monitoring data of indoor and outdoor temperatures, human flow and other heat dissipation factors. Avoid the waste of energy caused by man-made inability to timely and accurately control the device. At the same time, rationally adjust the initial temperature of the chilled water outlet, and control the operation of the chiller under high-efficiency conditions.

The core of the basic principle of the control system is to control the air-conditioning system at partial load, and adjust the low-load and low-efficiency operation of the chiller to the high-load and high-efficiency operation of the refrigeration system. Its operating state is divided into two operating stages of cold storage and cooling.

As shown in Figure 2, the principle of the central air-conditioning control system (hereinafter referred to as the power-saving system) of the present invention is described as follows: the power-saving system mainly It is composed of six major systems including metering system and remote monitoring management system.

The composition, connection and functions of the above six major systems are as follows:

(1) Central computing processing system:

"Central operation processing system" is composed of CPU, expansion module, analog output module, touch control panel, power switch, uninterruptible power supply, intermediate relay, software, computer, etc. It is the control command center of the central air-conditioning power-saving system. Implement centralized monitoring, centralized management, and centralized control of the central air-conditioning power saving system.

The operating parameters and operating procedures of the central air-conditioning power saving system are input through the "central computing processing system"; first, the analog signals such as temperature, pressure, pressure difference, flow rate, current, voltage, frequency, and power collected by the "data acquisition system" It is converted into a digital signal, stored, calculated, compared, and processed with the input operating parameters, and the processed data is converted into an analog signal, and the operating command is output; the second is to collect the operating status of each device collected by the "data acquisition system" The digital signal is stored, calculated, compared and processed with the input operation parameters, and the operation command is output.

The instructions issued by the "central processing system" are turned into specific actions through the "flow adjustment system", which automatically adjusts the flow rate on the return pipe of the air-conditioner terminal equipment, the frequency conversion of the chilled water pump, the bypass flow rate of the chilled water system pressure difference and the temperature of the cold storage tank. Operation, etc.; the instructions issued by the "central computing processing system" make the chiller, cooling water tower and the electric valve installed on the chiller and cooling water tower linkage through the "linkage control system", and control the linkage of chiller, chilled water pump, cooling water pump and cooling water tower And switch each other, and the sequence of switching on and off. The "central processing system" sends out operating instructions for the system's regular mode and energy-saving mode according to the set switching and start-stop time, and stores, counts and processes through the "automatic metering system", and accurately calculates the energy saving after power-saving transformation and power saving rate. The instructions issued by the "central computing processing system" can be inquired in different places through the "remote monitoring and management system", and the user's central air-conditioning system operating status and usage can be grasped. At the same time, the operating parameters and operating procedures of the central air-conditioning power saving system can be modified to maintain, optimize and upgrade, so that the central air-conditioning power saving system can operate in a more reasonable state.

(2) Data acquisition system:

"Data acquisition system" consists of temperature sensors, transmitters, pressure sensors, differential pressure sensors, flow meters, ammeters, voltmeters, frequency meters, power meters, differential pressure switches, pressure switches, auxiliary contacts, shielded control lines, etc. The composition is the sensory mechanism of the central air-conditioning power-saving system. Its function is to detect the parameters of the controlled object and field signals, and convert them into unified digital signals, and transmit the digital signals to the "central processing system" for calculation. deal with.

1. The temperature sensor, pressure sensor and differential pressure sensor installed on the water supply and return pipes of the chilled water system are used to detect the temperature of the chilled water supply and return water of the chilled water system, the pressure of the supply and return water, and the pressure difference. The collected analog signals are transmitted to the "central computing processing system".

2. The temperature sensors installed in each air-conditioning area in the room are used to detect the air temperature in the air-conditioning area, and transmit the collected analog signals to the "central computing processing system.

3. The temperature sensor installed on the main water supply pipe of the cooling water system is used to detect the water supply temperature of the cooling water system, and transmit the collected analog signal to the "central computing processing system".

4. The temperature sensor installed outdoors is used to detect the temperature of the outdoor air, and transmits the collected analog signal to the "central processing system".

5. The flow meter installed on the main water supply pipe of the chilled water system is used to measure the chilled water flow of the chilled water system, and transmit the collected analog signal to the "central processing system".

6. Connect the auxiliary contacts of the air-conditioning equipment control cabinets and boxes to monitor the operating status of the air-conditioning equipment and transmit the collected digital signals to the central processing system.

(3) Flow regulation system:

The "flow regulation system" is composed of electric regulating valves, 24V transformers, frequency converters, differential pressure bypass valves, cold storage tanks, control cables, etc., and is the executive body of the central air conditioning power saving system. The function of the "flow adjustment system" is to turn the instructions sent by the "central computing processing system" into specific actions to achieve the purpose of automatic adjustment and automatic operation.

1. The flow regulating valve installed on the return pipe of the terminal equipment of the air conditioner can automatically adjust the flow of chilled water flowing through the terminal equipment of the air conditioner according to the analog signal command sent by the "central processing system", so as to control the air in the air conditioner area. temperature purpose.

2. The frequency converter automatically adjusts the speed of the chilled water pump and the flow of chilled water according to the analog signal command sent by the "central processing system", so that the pressure difference between the supply and return water of the chilled water system is at the set pressure difference. between lower limits.

3. The chilled water system installed with a differential pressure bypass valve automatically adjusts the opening of the differential pressure bypass valve according to the analog signal command sent by the "central processing system", so that the pressure difference between the supply and return water of the chilled water system is at Set between the upper and lower limits of the pressure difference.

4. Install the chilled water system of the cold storage tank, and automatically adjust the electric regulating valve on the cold storage tank according to the analog signal command sent by the "central computing processing system", so that the cold storage tank can automatically complete cold storage, waiting for release, releasing cold, and waiting for storage cycle process.

(4) Linkage control system:

The "linkage control system" is composed of electric valves, electric valve controllers, auxiliary contacts, control cables, etc., and is the linkage mechanism of the central air-conditioning power-saving system. The function of the linkage control system is to make the chiller, the cooling water tower and the electric valve installed on the chiller and the cooling water tower linkage, so as not to bypass the chiller with chilled water and cooling water; to prevent the chiller with never running cooling water The cooling water tower is bypassed to ensure the chilled water and cooling water flow of other chillers; to ensure the cooling water flow of other cooling water towers. The second is to make chillers, chilled water pumps, cooling water pumps, and cooling water towers interlock and switch between each other, and the programs and sequences are turned on and off. And transmit the digital signals of the chiller, the chilled water pump, the cooling water pump, the cooling water tower, and the electric valve switch to the central processing system.

(5) Automatic metering system:

The "automatic metering system" is composed of a multi-functional electricity meter, a comprehensive power monitor, a computer, a printer, a transformer, and a control cable. The function of the automatic metering system is to measure, record, store, and display the power consumption of the motors of air-conditioning equipment such as chillers, chilled water pumps, cooling water pumps, and cooling water towers. It can accurately calculate the power saving and power saving rate after the power saving transformation.

(6) Remote monitoring and management system:

"Remote monitoring and management system" is composed of network controller, software, network computer, printer, etc., and is the remote control device of the central air-conditioning power-saving system. Through remote query via network computer, the user’s central air-conditioning system’s operating status and usage can be grasped. At the same time, the operating parameters and operating procedures of the central air-conditioning power-saving system can be maintained and optimized, so that the central air-conditioning power-conserving system can operate in a more reasonable state. run.

The system adopts programmable control technology, and through the data acquisition system, the collected analog parameters are converted into input digital quantities, and then transmitted to the central processing processor for processing. Comparing the operation with the design parameters, and then converting the digital command into a control analog output. Precisely control the operation of chillers, cooling water pumps, cooling water towers, air conditioners and refrigerated frequency conversion water pumps to achieve intelligent energy-saving control of the central air-conditioning system.

As shown in Figure 3, the flow process of the central air-conditioning control system of the present invention is described as follows:

1. The data acquisition system collects the following data information:

① Chilled water supply flow:

The flow meter installed on the main water supply pipe of the chilled water system is used to measure the chilled water flow of the chilled water system and transmit it to the power saving device (air conditioning control system) through the shielded wire;

② Chilled water supply temperature:

For the operation of a single chiller, the temperature sensor installed on the water supply main pipe of the chilled water system is used to detect the chilled water supply temperature of the chilled water system, and transmit the signal of the chilled water supply temperature change to the power saving device through the shielded wire;

③ Chilled water return temperature

For the operation of a single chiller, the temperature sensor installed on the return water main pipe of the chilled water system detects the chilled water return temperature of the chilled water system, and transmits the signal of temperature change to the power saving device through the shielded wire;

④Pressure difference between supply and return water of chilled water system

The pressure sensor installed on the water supply and return main pipe of the chilled water system detects the pressure of the chilled water system supply and return water, and transmits the signal of pressure change to the power saving device through the shielded wire to determine the pressure difference;

⑤The temperature of each air-conditioning area in the room

The temperature sensor installed in each air-conditioning area in the room detects the air temperature in the air-conditioning area, and transmits the signal of temperature change to the power-saving device through the shielded wire;

⑥Cooling water supply temperature, outdoor temperature

The temperature sensor installed on the main water supply pipe of the cooling water system monitors the water supply temperature of the cooling water system; the temperature sensor installed outside detects the temperature of the outdoor air, and transmits the signals of the water supply temperature of the cooling water system and the outdoor air temperature to the power saving device;

⑦ Indoor and outdoor temperature

The temperature sensor installed indoors and outdoors detects the temperature of the indoor and outdoor air, and transmits the signal of the indoor and outdoor air temperature to the power-saving device through the shielded wire.

2. Real-time cooling capacity output: referred to as the central operation processor in the power-saving device to calculate the chilled water flow rate and the temperature difference between the chilled supply and return water (cooling capacity = flow × temperature difference), and calculate the real-time cooling capacity output of the air conditioning system. It is an important parameter for power-saving system design.

3. Operation of the air conditioning system:

① Chiller shutdown control: The power-saving device outputs commands to determine whether the chiller is shut down; when the chilled water supply temperature is higher than the set temperature value, the chiller unit continues to run; when the chilled water supply temperature is lower than the set temperature value , the chiller shuts down;

② Chiller start-up control: The power-saving device outputs commands to determine whether the chiller needs to be started; when the chilled water return temperature is higher than the set temperature value, or the air temperature in the air-conditioning area is higher than the set temperature value, the chiller is started ;When the chilled water return temperature is lower than the set temperature value and the air temperature in the air-conditioning area is not higher than the set temperature value, the chiller will not start and the cooling water pump will not run;

③Frequency conversion control of the chilled water system: The power-saving device outputs instructions, adjusts the speed of the chilled water pump through the frequency converter, and controls the flow of chilled water. When the pressure difference between the supply and return water of the chilled water system is higher than the upper limit of the set pressure difference, the frequency converter Frequency conversion reduces the speed of the chilled water pump to reduce the flow of chilled water; when the pressure difference between the supply and return water of the chilled water system is between the upper and lower limits of the set pressure difference, the speed of the chilled water pump remains unchanged and the flow of chilled water remains unchanged; When the pressure difference between the supply and return water of the water system is lower than the lower limit of the set pressure difference, the frequency converter will increase the speed of the chilled water pump and increase the flow of chilled water;

④ Cold storage tank control: The power-saving device outputs instructions to store or release excess cooling capacity through the cold storage tank. When the pressure difference between the supply and return water of the chilled water system is higher than the set pressure difference, the electric valve on the cold storage tank is opened to allow Chilled water bypasses the cold storage tank to cool the water chiller at high load while the air conditioner terminal equipment operates at partial load, and store the excess cooling capacity in the cold storage tank; when the pressure difference between the chilled water supply and return water is lower than the set When the pressure difference is fixed, the electric valve on the cold storage tank is closed to ensure the chilled water flow of the terminal equipment of the air conditioner; Cooling of the chilled water system;

⑤Pressure differential bypass control of the chilled water system: The energy-saving device outputs commands to control the chilled water flow through the opening of the differential pressure bypass valve; when the pressure difference between the supply and return water of the chilled water system is higher than the set pressure difference , the differential pressure bypass valve opens to bypass part of the chilled water; when the pressure difference between the supply and return water of the chilled water system is lower than the set pressure difference, the differential pressure bypass valve maintains the original opening;

⑥Control of air-conditioning terminal equipment: the power-saving device outputs instructions to control the air temperature in the air-conditioning area by adjusting the chilled water flow of the air-conditioning terminal equipment; when the air temperature in the air-conditioning area is lower than the set temperature value, the The flow regulating valve on the water pipe is closed to reduce the flow of chilled water flowing through the air-conditioning terminal equipment to achieve the purpose of controlling the air temperature in the air-conditioning area; when the air temperature in the air-conditioning area is higher than the set temperature value, it will The flow regulating valve on the water pipe is opened to increase the flow of chilled water flowing through the air-conditioning terminal equipment to achieve the purpose of controlling the air temperature in the air-conditioning area; if the air temperature in the air-conditioning area is still higher than the set temperature value, it proves that the chilled water system is faulty. If the chilled water temperature is too high, the chiller will start (prioritizing the detection of the return water temperature of the chilled water system) to ensure the accuracy of the air temperature in the air-conditioned area;

⑦Cooling water tower control: The power-saving device outputs instructions to determine whether the cooling water tower fan needs to stop running; when the temperature of the water supplied by the chilled water system and the outdoor air temperature are higher than the set temperature value, the cooling water tower fan continues to run; when the chilled water system When the temperature of the water supply and the outdoor air temperature are lower than the set temperature value, the cooling tower fan stops running;

⑧ Chilled water pump control: The power-saving device outputs instructions, the chilled water pump runs normally when the machine is turned on, and the speed of the water pump is adjusted by comprehensive frequency conversion according to the pressure difference between the supply and return water, the return water temperature and the end return air temperature after the machine is turned off;

⑨Control of chilled water return temperature: temperature sensors installed indoors and outdoors are used to detect the outdoor air temperature, and the signals of indoor and outdoor air temperature changes are transmitted to the power-saving device through shielded wires as power-saving devices The important calculation basis of the internal central processing processor is to output instructions from the power saving device to set the return water temperature of the chilled water.

As shown in Fig. 4a, 4b, it is the circuit diagram of the air conditioning control system of the present invention:

1 is the analog output module, the model specification is EM232, the parameter is 148g 2W 24V DCAQ2×12Bit, the performance is: 2 analog output points, the function is to convert the digital information of the points into standard current and voltage signals and output them to the execution equipment ( Valve, frequency converter), adjust its working status. The "M" and "L+" at the bottom of the module are respectively connected in parallel to the power from the "M" and "L+" at the bottom of the CPU 226XM, and the grounding mark needs to be connected in parallel to the ground. There are two sets of outputs on the top of the module, and each set can select current (Ix and common M) or voltage (Vx and common M) output. The public M is connected to the negative pole of the signal input point of the executive device (valve, frequency converter), and Ix or Vx is connected to the positive pole.

2 is the analog module, the model specification is EM231, the parameter is 183g 2W 24V DCAI4×12Bit, the performance is: 4 analog input points, the function is to convert the current or voltage signal of the point into digital information for CPU 226XM to read, the current Or the voltage signal comes from various external sensors. The "M" and "L+" at the bottom of the module are respectively connected in parallel to the power from the "M" and "L+" at the bottom of the CPU 226XM, and the grounding mark needs to be connected in parallel to the ground. There are four sets of inputs on the top of the module. A single module can only choose to use current or voltage signal inputs. Here we all use current inputs (the signal type is determined by the bottom switch). Take group A as an example: the input from "L+" The 24V DC power supply is positively output to the positive pole of the external sensor, and then the signal from the negative pole of the sensor is connected in parallel to the "A+" and "RA" points of the module, and the "A-" point is connected to "M".

3 is the modulus expansion module, the model specification is EM223, the parameter is 360g 6W DC/RLY, the performance is: 16 input sink type/source type (IEC Typel sink type), 16 digital output relays, dry contacts, the function is according to " "CPU" commands control the start and stop of external air-conditioning equipment, and receive the operation and fault signals of these equipment and return them to the "CPU". , The power supply at "L+". "xM" is connected to the negative pole of the DC power supply, and the positive pole of the DC power supply returns to ".x" through the normally open contact of the 220V intermediate relay. The top of the module is the output part, "xL" is connected to the positive pole of the DC power supply, and ".x" is output to the coil of the 24V intermediate relay when it is turned on.

4 is the central processing unit, the model specification is CPU226XM, the parameter is 550g 11W AC/DC/RLY relay output, the performance is: 24 digital inputs, 16 digital outputs, the functions include calculation, storage, clock, communication, power supply, Same input and output as EM223. The "LAC" and "N" on the top of the module are respectively connected to the "fire" and "zero" of single-phase AC, and the grounding marks need to be connected to the ground in parallel, and the "M" and "L" at the bottom are DC 24V output. The functional connections of other points are the same as EM 223.

5 is a 485 connection line for transmitting data signals;

6 is a fuse isolator, the model specification is RT18-32X, and the parameter is 5A;

7 is a high-section miniature circuit breaker, the model specification is DZ47-60, and the parameter is 220V/5A 50HZ;

8 is a small medium-power electromagnetic relay, the model specification is JZX-22F, and the parameter is 220VAC. The function is to convert the 220V "on" and "off" signals from the external air-conditioning equipment Return "CPU 226XM" and "EM 223". The coils are respectively connected to "zero" and "fire" from the external air-conditioning equipment, one end of the normally open point is connected to the positive output of the DC power supply, and the other end is connected to the input part ".x" of the module.

9 is a small medium-power electromagnetic relay, the model specification is JZX-22F, and the parameter is 24VDC. Its function is to convert the 24V output signal from "CPU 226XM" and "EM223" to 220V and transmit it to the external air conditioning equipment. The coil is respectively connected to the negative output of the DC power supply and the ".x" output part of the module. One end of the normally open point is connected to "fire", and the other end is connected to the external air conditioning equipment.

10 is the RVV1×1.0 wire.

Adopt the central air-conditioning system of the present invention and adopt the central air-conditioning system of the frequency conversion energy-saving way to compare and control the effect as follows:

Influence Number of starts and stops 3∽4h/time Same as before the transformation   Within the allowable range of the equipment Surge normally not will cause Won't

According to the standard of central air-conditioning cool-storage intelligent energy-saving system, the company organized a test on the operation of the central air-conditioning system described in the present invention in "Fuzhou Jinyuan International Hotel", and the test results are as follows:

Construction area: 81400M2 Installed cooling capacity: 2400RT

Cooling capacity of single unit: 600RT Quantity of units: 4

Cooling capacity per unit area: 148W/M2 Chilled water pump power: 75KW

Energy efficiency ratio of full load system: COP value > 4 Cooling water pump power: 90KW

Monthly power saving > 60000KW/hr System power saving rate: 20.23%

It can be known from the above table and the above example that the central air-conditioning system of the present invention has a very good energy-saving effect, and the overall energy-saving rate can reach about 20%. At the same time, the present invention can be used not only for new engineering design, but also for the transformation of the original central air-conditioning system, and has very wide applicability.

Embodiment two:

The difference between this embodiment and the first embodiment lies in that the main engine adopts multiple chillers.

As shown in Figure 5, the operating mode of the second embodiment is:

When the load of the air-conditioning system increases, the operating sequence of the air-conditioning host is as follows:

The first step: one machine runs with cold storage;

Step 2: One machine runs under high load;

The third step: two machines cold storage operation;

Step 4: The two machines run under high load;

Step 5: Three machines run in cold storage;

Step 6: The three machines are running under high load...

When the load of the air conditioner decreases, the operating sequence of the air conditioner is as follows:

Step 1: The three machines run under high load;

Step 2: The three machines are running in cold storage;

Step 3: The two machines run under high load;

Step 4: The two machines run in cold storage;

Step 5: One machine runs under high load;

Step 6: One machine runs with cold storage.

The linkage system controls the working status of the main engine, pump, cooling tower and flow regulating device according to the instructions. During high-load operation, the main engine runs continuously under higher load conditions; cold storage operation: the main engine cycle is in two stages of cold storage and cooling.

The flow process of the central air-conditioning control system of the present embodiment is as follows:

1. Chilled water supply temperature monitoring and chiller shutdown number control. For multiple chillers running in parallel, the temperature sensor installed on the water supply main pipe of the chilled water system detects the water supply temperature of the chilled water system, and the temperature of the chilled water system changes. The signal is transmitted to the power-saving device through the shielded wire, and the power-saving device outputs instructions to determine the number of chillers to stop running. When the water supply temperature of the chilled water system is higher than the set temperature value, the chiller will continue to run; when the water supply temperature of the chilled water system does not drop continuously, one more chiller will run; when the water supply temperature of the chilled water system is lower than the set temperature value, and the air temperature in the air-conditioned area is not higher than the set temperature value, one chiller will stop running.

2. Chilled water return temperature monitoring and chiller number control. For multiple chillers running in parallel, the temperature sensor installed on the return water main pipe of the chilled water system detects the return water temperature of the chilled water system and returns the chilled water system to The signal of water temperature change is transmitted to the power-saving device through the shielded wire, and the power-saving device outputs instructions to determine the number of chillers to start and run. When the temperature of the return water of the chilled water system is higher than the set temperature value, an additional chiller will run.

3. When multiple chillers are running in parallel, electric valves are installed on the water supply pipes of the freezing and cooling water systems of each chiller. When the chillers need to be turned on, first open the water supply pipes of the freezing and cooling water systems of the chiller When the chiller is shut down, close the electric valve on the water supply pipe of the freezing and cooling water system of the chiller to prevent the freezing and cooling water from bypassing the chiller to ensure the freezing and cooling of other chillers water flow.

4. The operating quantity of the cooling water tower corresponds to the operating quantity of the chiller unit and the cooling water pump. When multiple cooling water towers are running in parallel, an electric valve is installed on the water inlet pipe of each cooling water tower. When the cooling water tower needs to be put into operation, turn on the corresponding cooling water pump, open the electric valve on the water inlet pipe of the cooling water tower, Turn off the cooling tower fan, and then turn on the chiller; when the cooling tower does not need to run, first turn off the chiller, turn off the cooling tower fan, turn off the electric valve on the water inlet pipe of the cooling tower, and then turn off the cooling water pump.

Claims (17)

1. An energy-saving central air-conditioning system, including a host for providing cold or hot water sources required for air conditioning, for transporting unit chilled water to air treatment equipment or terminal chilled water devices, for cooling air, Terminal devices for heating, humidification, dehumidification, and purification and filtration, and an air-conditioning control system for manual or automatic adjustment and monitoring of the unit, air handling equipment, and air-conditioning process; it is characterized in that the air-conditioning control system is based on a large number of dynamic The changing data is processed to obtain the best dynamic operation command for on-demand cooling, and the partial load continuous operation status of each component of the central air-conditioning system is adjusted in real time to one of the two modes of "cooling operation" or "cooling operation". The main engine of the central air conditioner described above operates efficiently in the cold storage operation mode, and stops operation in the cooling operation mode. 2. The energy-saving central air-conditioning system according to claim 1, characterized in that it also includes a cooling water device for dissipating the heat of the unit into the air, and the cooling water device includes a cooling water pump, a cooling water tower, and pipelines. The cooling water tower is provided with a fan and a water-cooled condenser. 3. The energy-saving central air-conditioning system according to claim 1 or 2, characterized in that: when the central air-conditioning system is in cold storage operation, the water chiller, the cooling water pump and the cooling water tower all operate at high efficiency. 4. The energy-saving central air-conditioning system according to claim 1 or 2, characterized in that: when the central air-conditioning system is running in the cold state, except for the chilled water pump running with frequency conversion, the chiller unit, cooling water pump and cooling water tower all stop working, The air-conditioning system continues to provide cooling with the cold energy stored in the air-conditioning circulating chilled water device. 5. The energy-saving central air-conditioning system according to claim 4, wherein the chilled water pump is a variable frequency water pump. 6. The energy-saving central air-conditioning system according to claim 1 or 5, characterized in that: said central air-conditioning system includes energy storage equipment. 7. The energy-saving central air-conditioning system according to claim 6, wherein the energy storage device is a cold storage tank, and the volume and number of the cold storage tanks are determined according to the size of the air-conditioning system. 8. The energy-saving central air-conditioning system according to claim 7, characterized in that: when the central air-conditioning system starts cold storage operation, the energy-saving central air-conditioning system works under high load, and the cold storage tank does not work; the air-conditioning system is in a partial load demand state , the excess cooling capacity is stored in the chilled water device of the air conditioner; when the chilled water temperature of the air conditioner reaches the set value, the chilled water device of the air conditioner is turned off; In the cold storage tank; the temperature of the cold storage medium in the cold storage tank begins to drop. When it reaches the set value, the main engine of the air conditioning system stops running; the air conditioning system enters the cooling operation stage, and the air conditioning chilled water device provides cooling capacity for the air conditioning area; The water temperature of the air-conditioning chilled water device rises gradually. When it is higher than the set value, the cold storage tank will provide cooling capacity for the air-conditioning area; Enter the cold storage operation stage. 9. The energy-saving central air-conditioning system according to claim 1 or 2, characterized in that the control system mainly consists of a central processing system, a data acquisition system, a linkage control system, a flow regulation system, an automatic metering system, and a remote monitoring and management system composition. 10. The energy-saving central air-conditioning system according to claim 9, characterized in that: As the control and command center, the central processing system is composed of CPU, expansion module, analog output module, touch control panel, power switch, uninterruptible power supply, intermediate relay, software, and computer. It implements centralized monitoring, Centralized management and centralized control. 11. The energy-saving central air-conditioning system according to claim 9, characterized in that: The data acquisition system as the sensory mechanism of the central air-conditioning control system consists of a temperature sensor, a transmitter, a pressure sensor, a differential pressure sensor, a flow meter, an ammeter, a voltmeter, a frequency meter, a power meter, a differential pressure switch, a pressure switch, The data acquisition system is composed of auxiliary contacts and shielded control lines. The data acquisition system detects the parameters of the controlled object and field signals, and converts them into unified digital signals, and transmits the digital signals to the "central processing system" for calculation and processing. 12. The energy-saving central air-conditioning system according to claim 9, characterized in that: The flow regulating system as the executive mechanism of the central air-conditioning control system is composed of an electric regulating valve, a 24V transformer, a frequency converter, a differential pressure bypass valve, a cold storage tank, and a control cable. The instructions sent are turned into specific actions, and the central air-conditioning system is automatically adjusted and operated automatically. 13. The energy-saving central air-conditioning system according to claim 9, characterized in that: The linkage control system of the linkage mechanism as the central air-conditioning control system is composed of electric valves, electric valve controllers, auxiliary contacts, and control cables. The electric valve is linked to prevent the chilled water and cooling water from bypassing the non-operating chiller; to prevent the cooling water from bypassing the cooling tower that is not operating, to ensure the chilled water and cooling water flow of other chillers; to ensure the flow of other cooling towers Cooling water flow; the linkage control system also enables the chiller, chilled water pump, cooling water pump, and cooling water tower to be linked and switched each other, and the program and sequence are turned on and off; and the chiller, chilled water pump, cooling water pump, cooling water tower, and electric valve switch The digital signal is transmitted to the central processing system. 14. The energy-saving central air-conditioning system according to claim 9, characterized in that: The automatic metering system as the equipment power metering device in the central air-conditioning control system is composed of a multi-functional electricity meter integrated power monitor, a computer, a printer, a transformer and a control cable, and the function of the automatic metering system is to control the water chiller. , Chilled water pumps, cooling water pumps, and motors of cooling water towers are measured, recorded, stored, and displayed. power saving and power saving rate. 15. The energy-saving central air-conditioning system according to claim 9, characterized in that: The remote monitoring and management system of the remote control device as the central air-conditioning control system is composed of network controllers, software, network computers, and printers. Through the network computer for remote query, the user's central air-conditioning system operating status and usage can be grasped. At the same time, it can Maintain and optimize the operating parameters and operating procedures of the central air-conditioning power-saving system, so that the central air-conditioning power-saving system can operate in a more reasonable state. 16. The energy-saving central air-conditioning system according to claim 9, characterized in that: The control system adopts programmable control technology, and through the data acquisition system, the collected analog parameters are converted into input digital quantities, which are transmitted to the central processing processor for processing; compared with the design parameters, the digital commands are then converted into control Analog output; accurately control the operation of chillers, cooling water pumps, cooling water towers, air conditioners and refrigerated frequency conversion water pump equipment to achieve intelligent energy-saving control of the central air-conditioning system. 17. The energy-saving central air-conditioning system according to claim 1, characterized in that: the host adopts multiple chillers.

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