CN118780019A - A control system and method for a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit - Google Patents

Abstract

The present invention relates to the field of air conditioning and refrigeration technology, and in particular to a control system and method for a dual-refrigeration circuit series reverse flow large temperature difference hot and cold air unit; in the present invention, the filter of the hot and cold air unit is located at the return air outlet; the first evaporator, the first compressor, the first condenser, and the expansion valve are connected in series in sequence to form a first refrigeration circuit; the connection end of the first compressor and the first evaporator is located at the air outlet of the first evaporator; the connection end of the first compressor and the first condenser is located at the air inlet of the first condenser; the first evaporator and the second evaporator are placed vertically front and back according to the air flow direction, and the second evaporator is close to the return air outlet; the evaporator and the condenser are arranged in a cross-arrangement manner, so that the wind on one side can be cooled to a lower temperature in the air conditioner, and the wind on the other side can be heated to a higher temperature in the air conditioner, thereby reducing the air duct area and the air conditioner volume, and solving the problem of installing and using the air conditioner in a narrow space.

Description

A control system and method for a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit

Technical Field

The present invention relates to the technical field of air conditioning and refrigeration, and in particular to a control system and method for a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit.

Background Art

At present, my country is vigorously developing mineral resources and building new underground transportation facilities, in places where underground tunnel operations are required, such as coal mining and construction of roads and railways.

When working in underground tunnels, it is usually impossible to install air-conditioning units because the working space is too small, resulting in difficulties in ventilation and heat dissipation, a poor working environment, and low work efficiency. The hot and cold air units that can be installed in small places such as underground tunnels also have a small cooling capacity and poor cooling effect due to the existing parallel installation method of the evaporator and condenser, and the unit itself and the supply and exhaust air ducts occupy a large space. In addition, in the current hot and cold air units, the refrigeration system usually adopts a single circuit or a parallel double circuit. This type of design has significant limitations in the face of complex requirements (such as when a large temperature difference effect needs to be achieved); specifically, in the parallel double-circuit system, the distribution and flow control of the refrigerant are relatively extensive, relying on the expansion valve setting and static pipeline design, which can easily lead to uneven refrigerant distribution when the load changes, resulting in inconsistent working efficiency of each circuit.

In the existing solutions, in order to achieve uniform cooling effect among multiple circuits, fixed expansion valves or electronic expansion valves are generally used to adjust the refrigerant flow rate, but it is still impossible to monitor and dynamically adjust the actual needs of each refrigeration circuit in real time, which is prone to problems such as circuit imbalance, temperature difference cannot be met, and reduced energy efficiency; some circuits may be over-cooled or have insufficient cooling capacity, resulting in a decrease in overall efficiency, and in applications requiring a large temperature difference, the fixed refrigerant distribution method cannot fully utilize the system capacity and cannot achieve the expected temperature difference effect; similarly, due to the uneven distribution of circuit loads, the compressor and other components cannot operate in the optimal state, resulting in increased energy consumption. Therefore, there is an urgent need for a control system and method for a dual refrigeration circuit series reverse flow large temperature difference hot and cold air unit to solve such problems.

Summary of the invention

To this end, the present invention provides a control system and method for a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit, which is used to overcome the problems of parallel installation of evaporators and condensers in the prior art, small cooling capacity, poor cooling effect, large space occupied by the unit itself and the supply and exhaust air ducts; circuit imbalance, unsatisfactory temperature difference and reduced energy efficiency.

To achieve the above-mentioned object, on the one hand, the present invention provides a control system for a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit, comprising: a cold and hot air unit, comprising a first compressor, a second compressor, a first evaporator, a second evaporator, a first condenser, a second condenser, a fan, an electronic expansion valve and a filter; the cold and hot air unit adopts a cross arrangement of the evaporator and the condenser, so that the wind on one side lowers the temperature in the air conditioner, and the wind on the other side raises the temperature in the air conditioner;

The cold and hot air units adopt a counter-flow double-circuit design, which makes the refrigerant flow in opposite directions in the two refrigeration circuits, and uses the temperature difference to improve efficiency;

The data acquisition module includes a temperature sensor, a pressure sensor, a flow sensor, and a data acquisition device; the data acquisition module uses sensors to monitor the real-time data of each refrigeration circuit in real time, including temperature, pressure, and flow, and transmits the data to the control system;

The data acquisition module provides real-time data as the basis for dynamic adjustment;

Dynamic refrigerant distribution and regulation module, with built-in refrigerant distributor, which cooperates with the electronic expansion valve and uses control algorithm to dynamically adjust the refrigerant flow of each refrigeration circuit based on real-time data;

The dynamic refrigerant distribution and regulation module adjusts the refrigerant flow according to real-time data to achieve precise control;

Intelligent circuit management module controls the start-up sequence and operating frequency of each refrigeration circuit according to the current load and temperature difference requirements of the system;

The modules can shut down some circuits to save energy under low load conditions and work together to improve efficiency under high load conditions;

The intelligent loop management module includes: loop start controller, load analysis unit and loop frequency controller;

The intelligent loop management module intelligently manages the start and stop and frequency of the loop according to load demand;

The load adaptation and large temperature difference adjustment module optimizes the refrigerant distribution and circuit working status based on real-time monitoring data for special application scenarios that require large temperature differences;

The load adaptation and large temperature difference regulation module optimizes the overall operation status of the system for scenarios with large temperature difference requirements.

Furthermore, in the cold and hot air unit, the filter is located at the return air port; the first evaporator, the first compressor, the first condenser, and the expansion valve are connected in series in sequence to form a first refrigeration circuit; the second evaporator, the second compressor, the second condenser, and the expansion valve are connected in series in sequence to form a second refrigeration circuit; the connection end of the first compressor and the first evaporator is located at the air outlet of the first evaporator; the connection end of the first compressor and the first condenser is located at the air inlet of the condenser; the connection end of the electronic expansion valve and the first evaporator is located at the liquid inlet of the first evaporator; the connection end of the electronic expansion valve and the first condenser is located at the liquid outlet of the first condenser; the second refrigeration circuit is similar; the first refrigeration circuit and the second refrigeration circuit are cross-arranged;

The first evaporator and the second evaporator are placed vertically front and back according to the air flow direction, and the second evaporator is close to the return air outlet;

The first condenser and the second condenser are placed vertically front and back according to the air flow direction, and the first condenser is close to the return air outlet;

The cold and hot air unit also includes an air outlet, and the fan is placed at the air outlet; the air outlet on the evaporator side is the cold air outlet, and the air outlet on the condenser side is the hot air outlet.

On the other hand, the present invention also provides a control method for a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit, comprising:

Step S1, dual-circuit series counter-flow deployment, using dual refrigeration circuits in series counter-flow mode to deploy the hot and cold air units, the refrigerants of the two refrigeration circuits flow in opposite directions, thereby maximizing the use of temperature differences, improving the cooling effect and overall system efficiency; the counter-flow mode not only enhances the cooling capacity of the system, but also facilitates dynamic adjustment;

Step S2, dynamic refrigerant distribution, installing real-time monitoring equipment in each refrigeration circuit to collect temperature, pressure, and flow parameters;

Step S3, intelligent circuit startup and load adjustment, adjusts the startup sequence and operating frequency of the refrigeration circuit according to the current load situation and temperature difference requirements; under low load conditions, only one circuit is selected to operate; under high load conditions, the two circuits work together, making full use of the advantages of the reverse flow design. By coordinating with the dynamic refrigerant distribution in step S2, the system can avoid the problem of load imbalance between circuits, thereby improving the overall energy efficiency;

Step S4, load adaptation and large temperature difference adjustment, optimizing the distribution of refrigerant and the coordinated control of the circuit, and providing the maximum temperature difference effect under special needs;

In applications such as tunnel cooling or special industrial cooling, the working state of the circuit is automatically optimized through analysis and adjustment of real-time monitoring data, so that the temperature difference always reaches the optimal value and avoids unnecessary energy consumption increase.

Furthermore, in step S2, the control system dynamically adjusts the refrigerant flow rate using an adjustable electronic expansion valve and a refrigerant distributor based on real-time data in combination with the current load and temperature difference requirements; the dynamic distribution mechanism is combined with a dual-circuit series design to ensure precise control of the refrigerant flow rate, so that the refrigeration effect of each refrigeration circuit is optimized.

Furthermore, in step S2, the dynamic refrigerant distribution method is:

Monitoring parameters include: real-time temperature , real-time pressure , real-time refrigerant flow ,load , target temperature difference and The efficiency of the circuit ;

Construct an objective function to adjust the refrigerant flow rate of each refrigeration circuit Make the control system meet the load demand and temperature difference requirements While optimizing system efficiency , the objective function is: ,in: represents the weight coefficient, Indicates the maximum pressure allowed by the system. Indicates A circuit, Indicates the total number of circuits;

Based on the objective function, the gradient descent method is used to adjust the opening of the electronic expansion valve and the setting value of the refrigerant distributor control , refrigerant flow adjustment method: ,in represents the flow coefficient determined based on fluid characteristics, Indicates the opening area of the expansion valve, Indicates the circuit pressure drop, Indicates Temperature difference of the circuit;

The Lagrange multiplier method is used to solve the objective function and obtain the optimal Corresponding and , the specific steps include:

Calculate the gradient of the objective function ;

Adjustment by gradient descent and Reduce the objective function value.

In each iteration, according to the current Recalculate temperature difference and load , and update and until it converges to the optimal value.

Furthermore, in step S2, the dynamic refrigerant distribution method further includes:

Based on real-time monitoring of load and temperature difference The control target is updated through the feedback mechanism:

,in represents the specific heat capacity of the refrigerant, No. The mass flow rate of the loop, denote the circuit inlet and outlet temperatures respectively;

Dynamically adjust the weight coefficients using an adaptive adjustment mechanism based on multivariable control , so that the system maintains the optimal performance state under different working conditions. This process uses the Bayesian optimization algorithm to gradually approach the global optimal solution through iterative experiments. The Bayesian optimization formula is:

,in represents the expected value of the objective function;

This enables precise control of refrigerant flow under complex load and temperature difference requirements.

Furthermore, the smart loop startup and load adjustment method in step S3 is:

Define real-time monitoring parameters, including: current system total load demand , target temperature difference , Real-time refrigerant flow rate of the circuit , specific heat capacity of refrigerant , Circuit inlet temperature , Circuit outlet temperature , and Mass flow rate of the loop ;

To perform a total load calculation: ,in, is the number of loops, is the refrigerant flow rate of each circuit;

Assign loop priorities and define priority functions , determines the startup order of the circuit:

,in and Represents the weight coefficient, adjusting the impact of temperature difference and load on priority, Indicates The temperature difference of the circuit, Indicates The load contribution of the circuit;

according to The values are sorted from large to small, and the circuit with the highest priority is started first.

Furthermore, in step S3, the smart loop startup and load adjustment method further includes:

Defining the start threshold : ,in and Indicates the adjustment coefficient, balancing the influence of load and temperature difference, Indicates the maximum load capacity of the system. Indicates the maximum temperature difference that the system can achieve;

When the priority of a circuit Exceeding the threshold , start the circuit.

For the activated circuit , adjust its operating frequency Matching system requirements:

,in represents the fundamental frequency of the loop, Indicates the frequency adjustment coefficient, which controls the frequency change amplitude;

Perform load balancing and dynamic adjustment, and define load balancing indicators :

,in Indicates the total refrigerant flow rate of the system;

when Exceeding a certain threshold When the load is balanced, the frequency or flow of the circuit is dynamically adjusted;

Dynamic adjustment method: real-time monitoring , change the opening of the expansion valve according to the system response and the setting value of the refrigerant distributor To achieve the refrigerant flow and operating frequency Fine-tuning.

Furthermore, in step S3, the smart loop startup and load adjustment method further includes:

Using a closed-loop feedback mechanism, real-time monitoring and changes, including and Dynamic adjustment of internal parameters:

Define the overall optimization objective function :

,in Indicates The efficiency of the circuit, Indicates the temperature difference adjustment weight, balancing energy consumption and temperature difference effect;

Gradient descent method and genetic algorithm are used to gradually adjust the frequency and flow of the loop to achieve the optimal performance of the system as a whole;

Perform system stability and preventive adjustments, and regularly calculate system stability indicators :

,when Early warning when exceeding the set range;

Based on historical data and prediction models, possible load peaks are estimated, and additional circuits are started in advance or the frequency of existing circuits is adjusted to ensure stable system operation.

Further, in step S4, the load adaptation and large temperature difference adjustment method includes:

Continuous monitoring of system parameters, including real-time data of each refrigeration circuit, as well as external environmental conditions (temperature and humidity in the tunnel);

Use historical data and current monitoring data for analysis to identify current system load conditions and temperature difference requirements;

The analysis includes identifying load peaks and temperature demand trends;

Identify special requirements in the current application scenario, including the need for a larger temperature difference during a certain period of time to cope with the sharp rise in temperature in the tunnel;

Automatically set new temperature difference targets and load distribution strategies based on identified demand;

Select the circuit that can provide the largest temperature difference effect, and shut down or reduce the operating frequency of other circuits as needed;

By optimizing the coordination between circuits, the distribution of refrigerant in each circuit is more balanced and efficient;

In step S4, dynamic adjustment and real-time response are performed:

Based on real-time monitoring data, the system dynamically adjusts the refrigerant distribution and circuit working status; temporarily increases the refrigerant flow or working frequency of certain circuits when the load suddenly increases;

The system automatically adjusts the working mode of the loop by balancing the relationship between the temperature difference target and energy consumption; when the temperature difference demand decreases, the system will reduce the working frequency of some loops or close some loops;

The system continuously monitors the load distribution of each circuit to ensure that the refrigerant distribution is balanced among the circuits.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention arranges the evaporator and the condenser in a cross-arrangement manner so that the wind on one side can be cooled to a lower temperature in the air-conditioning unit, while the wind on the other side can be heated to a higher temperature in the air-conditioning unit, thereby improving the cooling and heating capacity per unit air volume, reducing the air duct area and the volume of the air conditioner, and solving the problem of installing and using the air conditioner in a narrow space.

The present invention monitors the temperature, pressure and flow parameters of each circuit in real time, utilizes an adjustable electronic expansion valve and a refrigerant distributor, and dynamically adjusts the refrigerant flow according to actual needs, so that the refrigerant flow of each refrigeration circuit is maintained at an optimal level, thereby improving the efficiency and temperature difference effect of the overall system.

The present invention intelligently determines the start-up sequence and operating frequency of each circuit according to the current load conditions and temperature difference requirements; when the load is low, only one circuit is operated to save energy; when the load is high, the two circuits work together; and by accurately controlling the refrigerant distribution, the load imbalance problem in the existing system is avoided.

The present invention can achieve the maximum temperature difference under special requirements by optimizing the distribution of refrigerant, which plays a key role in certain specific application scenarios (such as tunnel cooling, special industrial cooling, etc.); according to real-time monitoring data, the circuit working state is automatically adjusted to ensure that the temperature difference always reaches the optimal value.

The present invention adopts a dual-circuit coordinated control method based on refrigerant distribution optimization, introduces dynamic refrigerant distribution and circuit collaborative control mechanism, and realizes a more efficient and intelligent refrigeration process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the control system structure of a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit of the present invention;

FIG2 is a flow chart of a control method of a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit according to the present invention;

FIG3 is a schematic diagram of the structure of a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit of the present invention.

Legend:

1. First compressor; 2. Second compressor; 3. First evaporator; 4. Second evaporator; 5. First condenser; 6. Second condenser; 7. Air blower; 8. Electronic expansion valve; 9. Filter.

DETAILED DESCRIPTION

In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

The present invention is further described in detail below in conjunction with the accompanying drawings:

Example 1

Please refer to Figures 1 to 3. The present invention provides a control system for a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit, comprising:

The hot and cold air unit comprises a first compressor, a second compressor, a first evaporator, a second evaporator, a first condenser, a second condenser, a fan, an electronic expansion valve and a filter; the hot and cold air unit adopts a cross arrangement of the evaporator and the condenser, so that the wind on one side lowers the temperature in the air conditioner, and the wind on the other side raises the temperature in the air conditioner;

The cold and hot air units adopt a counter-flow double-circuit design, which makes the refrigerant flow in opposite directions in the two refrigeration circuits, and uses the temperature difference to improve efficiency;

The data acquisition module includes a temperature sensor, a pressure sensor, a flow sensor, and a data acquisition device; the data acquisition module uses sensors to monitor the real-time data of each refrigeration circuit in real time, including temperature, pressure, and flow, and transmits the data to the control system;

The data acquisition module provides real-time data as the basis for dynamic adjustment;

Dynamic refrigerant distribution and regulation module, with built-in refrigerant distributor, which cooperates with the electronic expansion valve and uses control algorithm to dynamically adjust the refrigerant flow of each refrigeration circuit based on real-time data;

The dynamic refrigerant distribution and regulation module adjusts the refrigerant flow according to real-time data to achieve precise control;

Intelligent circuit management module controls the start-up sequence and operating frequency of each refrigeration circuit according to the current load and temperature difference requirements of the system;

The modules can shut down some circuits to save energy under low load conditions and work together to improve efficiency under high load conditions;

The intelligent loop management module includes: loop start controller, load analysis unit and loop frequency controller;

The intelligent loop management module intelligently manages the start and stop and frequency of the loop according to load demand;

The load adaptation and large temperature difference adjustment module optimizes the refrigerant distribution and circuit working status based on real-time monitoring data for special application scenarios that require large temperature differences;

The load adaptation and large temperature difference regulation module optimizes the overall operation status of the system for scenarios with large temperature difference requirements.

In the cold and hot air unit, the filter is located at the return air port; the first evaporator, the first compressor, the first condenser, and the expansion valve are connected in series in sequence to form a first refrigeration circuit; the second evaporator, the second compressor, the second condenser, and the expansion valve are connected in series in sequence to form a second refrigeration circuit; the connection end of the first compressor and the first evaporator is located at the air outlet of the first evaporator; the connection end of the first compressor and the first condenser is located at the air inlet of the condenser; the connection end of the electronic expansion valve and the first evaporator is located at the liquid inlet of the first evaporator; the connection end of the electronic expansion valve and the first condenser is located at the liquid outlet of the first condenser; the second refrigeration circuit is similar; the first refrigeration circuit and the second refrigeration circuit are cross-arranged;

The first evaporator and the second evaporator are placed vertically front and back according to the air flow direction, and the second evaporator is close to the return air outlet;

The first condenser and the second condenser are placed vertically front and back according to the air flow direction, and the first condenser is close to the return air outlet;

The cold and hot air unit also includes an air outlet, and the fan is placed at the air outlet; the air outlet on the evaporator side is the cold air outlet, and the air outlet on the condenser side is the hot air outlet.

Specifically, when the hot and cold air units are started, the two fans are started first, and then the first refrigeration circuit is started. After it runs stably, the other group is started to avoid excessive circuit current during parallel startup. At this time, the evaporator is in contact with the high-temperature heat source, and the liquid working medium is heated by the high-temperature heat source in the evaporator and evaporates into gas, and absorbs heat. The evaporated gas is extracted and compressed by the compressor to become a high-temperature and high-pressure state and is transported to the condenser. The high-temperature and high-pressure gaseous refrigerant dissipates heat in the condenser and becomes a liquid refrigerant, and then returns to the evaporator through the electronic expansion valve 8 for the next cycle.

When the air outside the air-conditioning unit enters the unit through the filter 9, the air will be divided into two paths and enter the evaporation side and condensation side of the air-conditioning unit respectively; the air entering the evaporation side will first pass through the second evaporator 4 to cool down, and then pass through the first evaporator 3 to continue to cool down to a lower temperature before being sent to the cooling area by the evaporation side air supply fan; the air entering the condensation side will first pass through the first condenser 5 to heat up, and then pass through the second condenser 6 to continue to heat up to a higher temperature before being sent to the heat dissipation area by the condensation side air supply fan.

At this time, the evaporation temperature of the second evaporator 4 is higher than that of the first evaporator 3, and the condensation temperature of the second condenser 6 is higher than that of the first condenser 5, that is, the evaporation temperature and the condensation temperature in the second refrigeration circuit are relatively high, and the condensation temperature and the evaporation temperature in the first refrigeration circuit are relatively low, thereby effectively balancing the temperature difference between the evaporation temperature and the condensation temperature in different refrigeration circuits, and making the evaporation and condensation pressure differences of the two refrigeration circuits close, so that the power consumption of the two compressors is close.

Finally, the processed hot and cold air are discharged by the fans on the evaporation side and the condensation side respectively. The two-stage evaporator and condenser are placed vertically, which can reduce the supply air temperature on the evaporator side to a lower temperature and raise the return air temperature on the condenser side to a higher temperature, so that the same size unit can take away more heat.

The present invention also provides a control method for a dual refrigeration circuit series reverse flow large temperature difference cold and hot air unit, comprising:

Step S1, dual-circuit series counter-flow deployment, using dual refrigeration circuits in series counter-flow mode to deploy the hot and cold air units, the refrigerants of the two refrigeration circuits flow in opposite directions, thereby maximizing the use of temperature differences, improving the cooling effect and overall system efficiency; the counter-flow mode not only enhances the cooling capacity of the system, but also facilitates dynamic adjustment;

Specifically, the dual-circuit series counter-flow design maximizes the use of temperature differences, significantly improving the cooling effect and overall efficiency. The counter-flow design not only enhances the cooling capacity of the system, but also facilitates dynamic adjustment, allowing the system to maintain efficient operation under different load conditions. When faced with large temperature difference requirements, it can fully tap the potential of each refrigeration circuit to achieve the best cooling effect.

Step S2, dynamic refrigerant distribution, installing real-time monitoring equipment in each refrigeration circuit to collect temperature, pressure, and flow parameters;

In step S2, the control system dynamically adjusts the refrigerant flow rate using an adjustable electronic expansion valve and a refrigerant distributor according to real-time data, combined with the current load and temperature difference requirements; the dynamic distribution mechanism is combined with the dual-circuit series design to ensure accurate control of the refrigerant flow rate, so that the refrigeration effect of each refrigeration circuit is optimized;

In step S2, the dynamic refrigerant distribution method is:

Monitoring parameters include: real-time temperature , real-time pressure , real-time refrigerant flow , load demand , target temperature difference and The efficiency of the circuit ;

Construct an objective function to adjust the refrigerant flow rate of each refrigeration circuit Make the control system meet the load demand and temperature difference requirements While optimizing system efficiency , objective function: ,in: represents the weight coefficient, Indicates the maximum pressure allowed by the system. Indicates A circuit, Indicates the total number of circuits;

Based on the objective function, the gradient descent method is used to adjust the opening of the electronic expansion valve and the setting value of the refrigerant distributor control , refrigerant flow adjustment method: ,in represents the flow coefficient determined based on fluid characteristics, Indicates the opening area of the expansion valve, Indicates the circuit pressure drop, Indicates Temperature difference of the circuit;

The Lagrange multiplier method is used to solve the objective function and obtain the optimal Corresponding and , the specific steps include:

Calculate the gradient of the objective function ;

Adjustment by gradient descent and Reduce the objective function value.

In each iteration, according to the current Recalculate temperature difference and load , and update and until it converges to the optimal value.

Furthermore, in step S2, the dynamic refrigerant distribution method further includes:

Based on real-time monitoring of load and temperature difference The control target is updated through the feedback mechanism:

,in represents the specific heat capacity of the refrigerant, No. The mass flow rate of the loop, denote the circuit inlet and outlet temperatures respectively;

Dynamically adjust the weight coefficients using an adaptive adjustment mechanism based on multivariable control , so that the system maintains the optimal performance state under different working conditions. This process uses the Bayesian optimization algorithm to gradually approach the global optimal solution through iterative experiments. The Bayesian optimization formula is:

,in represents the expected value of the objective function;

Specifically, the dynamic refrigerant distribution mechanism is one of the cores of this control method. By installing real-time monitoring equipment in each refrigeration circuit, the operating status of each circuit can be accurately grasped, including real-time data such as temperature, pressure, and flow. The control system is based on real-time data, combined with the current load and temperature difference requirements, and uses adjustable electronic expansion valves and refrigerant distributors to dynamically adjust the refrigerant flow. This adjustment method based on the optimization control objective function provides the best cooling effect for each refrigeration circuit, which not only meets the load requirements, but also significantly improves the system efficiency. Under complex and changeable working conditions, the refrigerant flow can be accurately controlled to reduce energy consumption.

Step S3, intelligent circuit startup and load adjustment, adjusts the startup sequence and operating frequency of the refrigeration circuit according to the current load situation and temperature difference requirements; under low load conditions, only one circuit is selected to operate; under high load conditions, the two circuits work together, making full use of the advantages of the reverse flow design. By coordinating with the dynamic refrigerant distribution in step S2, the system can avoid the problem of load imbalance between circuits, thereby improving the overall energy efficiency;

The intelligent loop startup and load adjustment method in step S3 is:

Define real-time monitoring parameters, including: current system total load demand , target temperature difference , Real-time refrigerant flow rate of the circuit , specific heat capacity of refrigerant , Circuit inlet temperature , Circuit outlet temperature , and Mass flow rate of the loop ;

To perform a total load calculation: ,in, is the number of loops, is the refrigerant flow rate of each circuit;

Assign loop priorities and define priority functions , determines the startup order of the circuit:

,in and Represents the weight coefficient, adjusting the impact of temperature difference and load on priority, Indicates The temperature difference of the circuit, Indicates The load contribution of the circuit;

according to The values are sorted from large to small, and the circuit with the highest priority is started first.

Defining the start threshold : ,in and Indicates the adjustment coefficient, balancing the influence of load and temperature difference, Indicates the maximum load capacity of the system. Indicates the maximum temperature difference that the system can achieve;

When the priority of a circuit Exceeding the threshold , start the circuit.

For the activated circuit , adjust its operating frequency Matching system requirements:

,in represents the fundamental frequency of the loop, Indicates the frequency adjustment coefficient, which controls the frequency change amplitude;

Perform load balancing and dynamic adjustment, and define load balancing indicators :

,in Indicates the total refrigerant flow rate of the system;

when Exceeding a certain threshold When the load is balanced, the frequency or flow of the circuit is dynamically adjusted;

Dynamic adjustment method: real-time monitoring , change the opening of the expansion valve according to the system response and the setting value of the refrigerant distributor To achieve the refrigerant flow and operating frequency Fine-tuning.

Using a closed-loop feedback mechanism, real-time monitoring and changes, including and Dynamic adjustment of internal parameters:

Define the overall optimization objective function :

,in Indicates The efficiency of the circuit, Indicates the temperature difference adjustment weight, balancing energy consumption and temperature difference effect;

Gradient descent method and genetic algorithm are used to gradually adjust the frequency and flow of the loop to achieve the optimal performance of the system as a whole;

Perform system stability and preventive adjustments, and regularly calculate system stability indicators :

,when Early warning when exceeding the set range;

Based on historical data and prediction models, possible load peaks are estimated, and additional circuits are started in advance or the frequency of existing circuits is adjusted to ensure stable system operation;

Specifically, the intelligent loop startup and load adjustment strategy enables the system to flexibly respond to different load demands and temperature difference changes. By real-time monitoring of the system's total load demand and temperature difference target, the system intelligently determines the startup sequence and operating frequency of each loop; when the load is low, only the necessary loops are operated to save energy; when the load is high, the two loops work together, making full use of the advantages of the reverse flow design to ensure balanced system load distribution, avoiding the common load imbalance problem in traditional systems, not only improving overall energy efficiency, but also extending the service life of the equipment.

Step S4, load adaptation and large temperature difference adjustment, optimizing the distribution of refrigerant and the coordinated control of the circuit, and providing the maximum temperature difference effect under special needs;

In applications such as tunnel cooling or special industrial cooling, the working state of the circuit is automatically optimized through analysis and adjustment of real-time monitoring data, so that the temperature difference always reaches the optimal value and avoids unnecessary energy consumption increase;

Load adaptation and large temperature difference regulation methods include:

Continuous monitoring of system parameters, including real-time data of each refrigeration circuit, as well as external environmental conditions (temperature and humidity in the tunnel);

Use historical data and current monitoring data for analysis to identify current system load conditions and temperature difference requirements;

The analysis includes identifying load peaks and temperature demand trends;

Identify special requirements in the current application scenario, including the need for a larger temperature difference during a certain period of time to cope with the sharp rise in temperature in the tunnel;

Automatically set new temperature difference targets and load distribution strategies based on identified demand;

Select the circuit that can provide the largest temperature difference effect, and shut down or reduce the operating frequency of other circuits as needed;

By optimizing the coordination between circuits, the distribution of refrigerant in each circuit is more balanced and efficient;

In step S4, dynamic adjustment and real-time response are performed:

Based on real-time monitoring data, the system dynamically adjusts the refrigerant distribution and circuit working status; temporarily increases the refrigerant flow or working frequency of certain circuits when the load suddenly increases;

The system automatically adjusts the working mode of the loop by balancing the relationship between the temperature difference target and energy consumption; when the temperature difference demand decreases, the system will reduce the working frequency of some loops or close some loops;

The system continuously monitors the load distribution of each circuit to ensure that the refrigerant distribution is balanced among the circuits;

Specifically, load adaptation and large temperature difference regulation are suitable for application scenarios that require large temperature difference effects, such as tunnel cooling or special industrial cooling. The system continuously monitors external environmental conditions and internal operating status, automatically identifies special needs, and dynamically adjusts the distribution of refrigerants and the working status of the circuits. This enables the system to quickly increase cooling capacity when the load increases suddenly, and reduce unnecessary energy consumption when the demand decreases, thereby achieving the best balance between energy efficiency and temperature difference. By optimizing the collaborative work between circuits, the system further enhances its performance under high temperature difference requirements, and can stably achieve the expected temperature difference effect even under the most demanding conditions.

So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims (10)

1. The control system of the double-refrigeration loop serial reverse flow large-temperature difference cold-hot air unit is characterized by comprising:

The cold and hot air unit comprises a first compressor, a second compressor, a first evaporator, a second evaporator, a first condenser, a second condenser, a fan, an electronic expansion valve and a filter, wherein a plurality of refrigeration loops are arranged in the cold and hot air unit, and the arrangement mode of the evaporators and the condensers in the cold and hot air unit adopts a cross arrangement mode;

the data acquisition module comprises a temperature sensor, a pressure sensor, a flow sensor and a data acquisition device, and acquires real-time data of each refrigeration loop through the sensor and the data acquisition device;

The dynamic refrigerant distribution adjusting module dynamically adjusts the refrigerant flow of each refrigeration loop based on real-time data by adopting a control algorithm, and is internally provided with a refrigerant distributor which is matched with an electronic expansion valve in the cold and hot air unit;

The intelligent loop management module is used for controlling the starting sequence and the working frequency of each refrigeration loop according to the current load condition and the temperature difference requirement of the control system and comprises a loop starting controller, a load analysis unit and a loop frequency controller;

The load adaptation and large temperature difference adjusting module is used for adjusting the working states of the refrigerant distribution and refrigeration loop based on real-time data and is applied to a large temperature difference scene, namely a scene with the temperature difference exceeding 5 ℃.

2. The control system of a double-refrigeration-circuit serial reverse-flow large-temperature-difference cold and hot air unit according to claim 1, wherein in the cold and hot air unit, the filter is positioned at a return air inlet, the first evaporator, the first compressor, the first condenser and the electronic expansion valve are sequentially connected in series to form a first refrigeration circuit, and the second evaporator, the second compressor, the second condenser and the electronic expansion valve are sequentially connected in series to form a second refrigeration circuit;

The connecting end of the first compressor and the first evaporator is positioned at the air outlet of the first evaporator, the connecting end of the first compressor and the first condenser is positioned at the air inlet of the first condenser, the connecting end of the electronic expansion valve and the first evaporator is positioned at the liquid inlet of the first evaporator, the connecting end of the electronic expansion valve and the first condenser is positioned at the liquid outlet of the first condenser, the first refrigerating loop and the second refrigerating loop are arranged in a crossing way, the first evaporator and the second evaporator are arranged vertically and front and back according to the air flow direction, the second evaporator is close to the air return opening, the first condenser and the second condenser are arranged vertically and front and back according to the air flow direction, and the first condenser is close to the air return opening;

the cold and hot air unit further comprises an air outlet, the fan is arranged at the air outlet, the air outlet at the evaporator side is a cold air outlet, and the air outlet at the condenser side is a hot air outlet.

3. A control method of a double-refrigeration-circuit serial reverse-flow large-temperature-difference cold and hot air unit, which is characterized by using the control system of the double-refrigeration-circuit serial reverse-flow large-temperature-difference cold and hot air unit, comprising the following steps:

step S1, double-loop serial reverse flow deployment is adopted to deploy a cold-hot air unit in a double-refrigeration loop serial reverse flow mode, and the directions of the refrigerants of the two refrigeration loops are opposite;

step S2, dynamic refrigerant distribution, monitoring and collecting real-time data of each refrigeration loop;

step S3, intelligent loop starting and load adjustment are carried out, the starting sequence and the working frequency of the refrigeration loop are adjusted according to the current load condition and the temperature difference requirement, only one loop is operated under the low load condition, and the two loops work cooperatively under the high load condition;

and S4, adjusting load adaptation and large temperature difference, and adjusting the refrigerant distribution and the working state of the refrigeration loop under a large temperature difference scene.

4. The control method of a dual-refrigeration-circuit serial reverse-flow large-temperature-difference cold-hot air unit according to claim 3, wherein in step S2, the flow of the refrigerant is dynamically adjusted by using an electronic expansion valve and a refrigerant distributor according to real-time data and in combination with the current load and the temperature difference requirement.

5. The control method of a dual-refrigeration-circuit serial-connection reverse-flow large-temperature-difference cold-hot air unit according to claim 4, wherein the dynamic refrigerant distribution mode in the step S2 is as follows:

data acquisition is performed, wherein the acquired data comprises: real-time temperature Real-time pressureReal-time refrigerant flowLoad ofTarget temperature differenceFirst of allEfficiency of individual circuits；

Constructing an objective function to adjust refrigerant flow in each refrigeration circuitThe objective function is: Wherein: The weight coefficient is represented by a number of weight coefficients, Indicating the maximum pressure in the bearable range,Representing the total loop number;

Based on the objective function, the opening degree of the electronic expansion valve is adjusted by adopting a gradient descent method And the set point of the refrigerant distributorRefrigerant flow adjustment mode: Wherein The flow coefficient is represented by a value representing,Indicating the opening area of the expansion valve,Indicating the pressure drop across the circuit,Represent the firstThe temperature difference of the loop;

solving the objective function by using Lagrangian multiplier method to obtain the optimal Corresponding toAndThe solving step comprises the following steps:

Calculating the gradient of the objective function By gradient descent methodAndDecreasing the objective function value;

Performing iterations, each iteration being based on refrigerant flow Recalculating the temperature differenceAnd loadAnd updateAndUntil convergence to an optimal value.

6. The method for controlling a dual-refrigeration-circuit serial-connection reverse-flow large-temperature-difference cold-hot air unit as set forth in claim 5, wherein in step S2, the dynamic refrigerant distribution manner further includes:

Load based on real-time monitoring And temperature differenceUpdating the control objective by a feedback mechanism:

Wherein Indicating the specific heat capacity of the refrigerant,First, theThe mass flow rate of the circuit is such that,Respectively the loop inlet and outlet temperatures;

Adjusting weight coefficients of objective functions by adopting Bayesian optimization algorithm 。

7. The control method of a dual-refrigeration-circuit serial reverse-flow large-temperature-difference cold-hot air unit according to claim 6, wherein the intelligent circuit starting and load adjusting mode in the step S3 is as follows:

Set total load demand Target temperature differenceFirst, theReal-time refrigerant flow of a circuitSpecific heat capacity of refrigerantFirst, theLoop inlet temperatureFirst, theLoop outlet temperatureAnd (b)Mass flow of circuit; And (3) carrying out total load calculation: Wherein, the method comprises the steps of, wherein, Indicating the number of loops;

performing loop priority assignment and defining a priority function Determining a loop starting sequence:

Wherein AndThe weight coefficient is represented by a number of weight coefficients,Represent the firstThe temperature difference of the loop is equal to the temperature difference of the loop,Represent the firstThe load of the circuit;

According to The values of (2) are ordered from big to small, and the loops with high ordering are started first.

8. The control method of a dual-refrigeration-circuit serial reverse-flow large-temperature-difference cold-hot air unit according to claim 7, wherein in step S3, the intelligent circuit starting and load adjusting mode further comprises:

Defining a start threshold Expressed as: Wherein AndRepresents the adjustment coefficient of the device,Indicating the maximum load capacity of the vehicle,Representing the maximum temperature difference that can be achieved;

When the priority of a certain loop Exceeding a threshold valueStarting the loop when the loop is started;

for started loops Adjusting the working frequencyMatching system requirements:

Wherein Indicating the fundamental frequency of the loop and,Representing the frequency adjustment coefficient;

load balancing and dynamic adjustment are carried out, and load balancing indexes are defined ：

WhereinIndicating the total refrigerant flow;

Preset threshold value When (when)Exceeding a threshold valueAnd dynamically adjusting the working frequency of the loop.

9. The control method of a dual-refrigeration-circuit serial reverse-flow large-temperature-difference cold-hot air unit according to claim 8, wherein in step S3, the intelligent circuit starting and load adjusting mode further comprises:

By real-time monitoring using a closed-loop feedback mechanism AndVariations of (2) includeAndDynamically adjusting internal parameters:

defining an overall optimization objective function ：WhereinRepresent the firstThe efficiency of the loop is such that,Representing temperature difference adjusting weight, and balancing energy consumption and temperature difference effect;

the gradient descent method and genetic algorithm are selected to regulate the frequency and flow rate of the loop.

10. The method for controlling a dual-refrigeration-circuit serial-connection reverse-flow large-temperature-difference cold-hot air unit according to claim 9, wherein in step S4, the load adaptation and large-temperature-difference adjustment mode comprises:

Continuously monitoring operating parameters including real-time data for each refrigeration circuit, and external environmental conditions;

analyzing the current load condition and the temperature difference requirement by using historical data, current real-time data and external environment conditions, and identifying whether special requirements exist in the current scene, namely the temperature difference requirement which needs to exceed 5 ℃;

After the special requirements are identified, a loop starting and load adjusting mode in the step 3 is adopted to set a new temperature difference target and a new load distribution strategy.