CN113757908B

CN113757908B - Thermal characteristic measurement method, system, terminal and storage medium of air conditioning system

Info

Publication number: CN113757908B
Application number: CN202111148688.4A
Authority: CN
Inventors: 化振谦; 杨雨瑶; 潘峰; 黄友朋; 宋睿; 叶佑春
Original assignee: Guangdong Power Grid Co Ltd; Measurement Center of Guangdong Power Grid Co Ltd
Current assignee: Guangdong Power Grid Co Ltd; Measurement Center of Guangdong Power Grid Co Ltd
Priority date: 2021-09-28
Filing date: 2021-09-28
Publication date: 2023-07-07
Anticipated expiration: 2041-09-28
Also published as: CN113757908A

Abstract

The invention provides a thermal characteristic measurement method, a system, a terminal and a storage medium of an air conditioning system, wherein the air conditioning system comprises: the water chiller, coil pipe and pipeline; the thermal property measurement method includes: acquiring various initial parameters of thermal characteristics of an air conditioning system in real time, and acquiring the outlet water temperature of a water chilling unit according to the initial parameters of the thermal characteristics of the air conditioning system; acquiring the outlet water temperature of the pipeline according to the outlet water temperature of the water chilling unit; obtaining the air supply temperature of the coil pipe according to the outlet water temperature of the pipeline; obtaining a thermal characteristic measurement result of the air conditioning system according to the outlet water temperature of the water chilling unit, the outlet water temperature of the pipeline and the air supply temperature of the coil; and the thermal characteristic measurement result is a dynamic change process of the indoor cold energy delivery of the air conditioning system after the cold side control strategy is implemented. According to the invention, the measuring results of the water chilling unit, the coil pipe and the pipeline are combined, so that the method has the applicability and universality of scenes and is more effective and quicker than the prior art.

Description

Thermal characteristic measurement method, system, terminal and storage medium of air conditioning system

Technical Field

The present invention relates to the field of air conditioning systems, and in particular, to a method, a system, a terminal, and a storage medium for measuring thermal characteristics of an air conditioning system.

Background

With the development of science and technology, the requirements of the national policy and the social layer on environmental protection and energy conservation are increasingly higher. In the aspect of air conditioning systems, the prior art often adopts an end control strategy to realize the reduction of the cooling load during the peak-to-peak air conditioning, thereby achieving the response effect of reducing the power consumption requirement during the peak-to-peak air conditioning. These end control strategies essentially take advantage of the thermal characteristics of the building itself to effect the storage and release of cold to accomplish the transfer of the cold load. However, the existing strategies have the technical problems of slow response, no control only, simplification or neglect of dynamic thermal characteristics of an air conditioning system and the like. Meanwhile, the description of the compressor, the expansion valve and the condenser in the water chiller unit in the prior art is complex, and the water chiller unit is limited by the form of the cooling side, so that the water chiller unit has no universality.

Disclosure of Invention

The invention provides a thermal characteristic measuring method, a system, a terminal and a storage medium of an air conditioning system, which can rapidly measure the dynamic thermal characteristic of the air conditioning system and improve the universality and the multi-scene adaptability.

In order to solve the above technical problems, an embodiment of the present invention provides a method for measuring thermal characteristics of an air conditioning system, which is applied to an air conditioning system after implementation of a control strategy on a chiller side, the air conditioning system including: the water chiller, coil pipe and pipeline;

the thermal property measurement method includes:

acquiring initial parameters of thermal characteristics of the air conditioning system in real time; wherein the thermal property initiation parameters include: the average temperature of the evaporator material in the water chiller, the average temperature of the refrigerant in the water chiller, the average temperature of the chilled water in the water chiller, the average temperature of the pipeline material, the average temperature of the chilled water in the pipeline, the average temperature of the heat insulation material outside the pipeline, the average temperature of the outside air, the outlet water temperature of the coil and the inlet water temperature of the coil;

according to the average temperature of the evaporator material in the water chilling unit, the average temperature of the refrigerant in the water chilling unit and the average temperature of the chilled water in the water chilling unit, combining a preset heat exchange coefficient between the refrigerant and the evaporator wall and a preset heat exchange coefficient between the evaporator wall and the chilled water to obtain the outlet water temperature of the water chilling unit;

According to the outlet water temperature of the water chiller, the outlet water temperature of the pipeline is obtained by combining the average temperature of the pipeline material, the average temperature of chilled water in the pipeline, the average temperature of the external heat insulation material of the pipeline and the average temperature of external air;

according to the outlet water temperature of the pipeline, combining a preset saturation enthalpy value of air at the average temperature of the coil, the outlet water temperature of the coil, the inlet water temperature of the coil, the number of rows of the coil and a preset heat exchange area of water to obtain the air supply temperature of the coil;

obtaining a thermal characteristic measurement result of the air conditioner according to the outlet water temperature of the water chilling unit, the outlet water temperature of the pipeline and the air supply temperature of the coil; the thermal characteristic measurement result is a dynamic change process of the indoor cooling capacity delivered by the air conditioning system after the control strategy of the cold machine side is implemented.

The method for acquiring the initial parameters of the thermal characteristics of the air conditioning system in real time comprises the following steps: the method comprises the steps of acquiring the average temperature of evaporator materials in a water chilling unit, the average temperature of refrigerant in the water chilling unit, the average temperature of chilled water in the water chilling unit, the average temperature of pipeline materials, the average temperature of chilled water in a pipeline, the average temperature of heat insulation materials outside the pipeline, the average temperature of outside air, the outlet water temperature of a coil and the inlet water temperature of the coil in real time through a plurality of sensors.

Further, the step of obtaining the air supply temperature of the coil pipe comprises the steps of obtaining the air supply temperature of the coil pipe under a dry working condition and obtaining the air supply temperature of the coil pipe under a wet working condition; the coils are formed by a plurality of rows, and the coils in different rows can be in different dry and wet working conditions.

Further, the cold side control strategy comprises an intermittent shutdown strategy, a partial cold shutdown strategy and a chilled water temperature increasing strategy; after the thermal characteristic measurement method is applied to the cold side control strategy, a new steady state is formed.

Correspondingly, the embodiment of the invention also provides a thermal property measurement system of the air conditioning system, which comprises an acquisition module, a water chilling unit module, a pipeline module, a coil module and a thermal property measurement module; wherein,,

the acquisition module is used for acquiring the initial parameters of the thermal characteristics of the air conditioning system in real time; wherein the thermal property initiation parameters include: the average temperature of the evaporator material in the water chiller, the average temperature of the refrigerant in the water chiller, the average temperature of the chilled water in the water chiller, the average temperature of the pipe material, the average temperature of the chilled water in the pipe, the average temperature of the insulation material outside the pipe, the average temperature of the outside air, the outlet water temperature of the coil, and the inlet water temperature of the coil;

The water chilling unit module is used for acquiring the outlet water temperature of the water chilling unit according to the average temperature of the evaporator material in the water chilling unit, the average temperature of the refrigerant in the water chilling unit and the average temperature of the chilled water in the water chilling unit by combining a preset heat exchange coefficient between the refrigerant and the evaporator wall and a preset heat exchange coefficient between the evaporator wall and the chilled water;

the pipeline module is used for acquiring the outlet water temperature of the pipeline according to the outlet water temperature of the water chilling unit and combining the average temperature of pipeline materials, the average temperature of chilled water in the pipeline, the average temperature of heat insulation materials outside the pipeline and the average temperature of outside air;

the coil module is used for acquiring the air supply temperature of the coil according to the outlet water temperature of the pipeline, and combining the preset saturation enthalpy value of the air at the average temperature of the coil, the outlet water temperature of the coil, the inlet water temperature of the coil, the discharge number of the coil and the preset heat exchange area of water;

the thermal characteristic measurement module obtains a thermal characteristic measurement result of the air conditioning system according to the outlet water temperature of the water chilling unit, the outlet water temperature of the pipeline and the air supply temperature of the coil; the thermal characteristic measurement result is a dynamic change process of the indoor cooling capacity delivered by the air conditioning system after the control strategy of the cold machine side is implemented.

The acquisition module is used for acquiring the initial parameters of the thermal characteristics of the air conditioning system in real time, and specifically comprises the following steps: the method comprises the steps of acquiring the average temperature of evaporator materials in a water chilling unit, the average temperature of refrigerant in the water chilling unit, the average temperature of chilled water in the water chilling unit, the average temperature of pipeline materials, the average temperature of chilled water in a pipeline, the average temperature of heat insulation materials outside the pipeline, the average temperature of outside air, the outlet water temperature of a coil and the inlet water temperature of the coil in real time through a plurality of sensors.

Further, the cold side control strategy comprises an intermittent shutdown strategy, a partial cold shutdown strategy and a chilled water temperature increasing strategy; after the thermal property measurement system is applied to the chiller side control strategy, a new steady state is established.

Correspondingly, the embodiment of the invention also provides a terminal which comprises a processor, a memory and a computer program stored in the memory; wherein the computer program is executable by the processor to implement the method of measuring thermal characteristics of an air conditioning system.

Accordingly, embodiments of the present invention also provide a computer-readable storage medium including a stored computer program; and controlling the equipment where the computer readable storage medium is located to execute the thermal characteristic measurement method of the air conditioning system when the computer program runs.

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

the embodiment of the invention provides a thermal characteristic measurement method, a system, a terminal and a storage medium of an air conditioning system, wherein the air conditioning system comprises: the water chiller, coil pipe and pipeline; the thermal property measurement method includes: acquiring various initial parameters of thermal characteristics of an air conditioning system in real time, and acquiring the outlet water temperature of a water chilling unit according to the initial parameters of the thermal characteristics of the air conditioning system; acquiring the outlet water temperature of the pipeline according to the outlet water temperature of the water chilling unit; obtaining the air supply temperature of the coil pipe according to the outlet water temperature of the pipeline; obtaining a thermal characteristic measurement result of the air conditioning system according to the outlet water temperature of the water chilling unit, the outlet water temperature of the pipeline and the air supply temperature of the coil; and the thermal characteristic measurement result is a dynamic change process of the indoor cold energy delivery of the air conditioning system after the cold side control strategy is implemented. According to the invention, the measuring results of the water chilling unit, the coil pipe and the pipeline are combined, so that the method has the applicability and universality of scenes and is more effective and quicker than the prior art.

Drawings

Fig. 1 is a schematic flow chart of an embodiment of a method for measuring thermal characteristics of an air conditioning system according to the present invention.

Fig. 2 is a schematic diagram of a technical idea of an embodiment of a method for measuring thermal characteristics of an air conditioning system according to the present invention.

Fig. 3 is a simplified schematic diagram of a thermal characteristic of a chiller in the method for measuring thermal characteristics of an air conditioning system according to the present invention.

Fig. 4 is a schematic diagram of an analyzed pipe section of a pipe in the method for measuring thermal characteristics of an air conditioning system according to the present invention.

Fig. 5 is a schematic structural diagram of a thermal property measurement system of an air conditioning system according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of a laboratory construction for experimental verification in the method for measuring thermal characteristics of an air conditioning system according to the present invention.

Fig. 7 is a schematic diagram of an air conditioning system and a test point arrangement of a laboratory table for experimental verification in a thermal characteristic measurement method of an air conditioning system according to an embodiment of the present invention.

Fig. 8 is a graph comparing the temperature of the outlet water of the water chiller module with the experimental result after the control strategy is implemented in the thermal characteristic measurement system of the air conditioning system according to the embodiment of the present invention.

Fig. 9 is a schematic diagram of a result of verifying measurement results of a chiller, a coil, and a pipe in a thermal property measurement system of an air conditioning system according to an embodiment of the present invention.

Fig. 10 is a verification result of the overall thermal characteristics of the air conditioning system according to the embodiment of the present invention.

Fig. 11 is a thermal characteristic verification result of a water chiller in an office building according to an embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Embodiment one:

referring to fig. 1, fig. 1 is a schematic diagram illustrating a thermal characteristic measurement method of an air conditioning system according to an embodiment of the present invention, which is applied to an air conditioning system after a chiller side control strategy is implemented, the air conditioning system includes: the water chiller, coil pipe and pipeline;

referring to fig. 2, fig. 2 is a schematic diagram illustrating a technical idea of an embodiment of a method for measuring thermal characteristics of an air conditioning system according to the present invention.

The thermal characteristics measuring method includes steps S1 to S5; wherein,,

step S1, acquiring initial parameters of thermal characteristics of the air conditioning system in real time; wherein the thermal property initiation parameters include: the temperature control system comprises an evaporator material in the water chilling unit, a refrigerant in the water chilling unit, chilled water in the water chilling unit, a pipeline material, chilled water in the pipeline, an external heat insulation material of the pipeline, external air, outlet water temperature of the coil and inlet water temperature of the coil.

In this embodiment, the acquiring, in real time, the initial parameters of the thermal characteristics of the air conditioning system specifically includes: the method comprises the steps of acquiring the average temperature of evaporator materials in a water chilling unit, the average temperature of refrigerant in the water chilling unit, the average temperature of chilled water in the water chilling unit, the average temperature of pipeline materials, the average temperature of chilled water in a pipeline, the average temperature of heat insulation materials outside the pipeline, the average temperature of outside air, the outlet water temperature of a coil and the inlet water temperature of the coil in real time through a plurality of sensors.

And S2, according to the average temperature of the evaporator material in the water chilling unit, the average temperature of the refrigerant in the water chilling unit and the average temperature of the chilled water in the water chilling unit, combining a preset heat exchange coefficient between the refrigerant and the evaporator wall and a preset heat exchange coefficient between the evaporator wall and the chilled water to obtain the outlet water temperature of the water chilling unit.

In this embodiment, fig. 3 is a simplified framework of thermal characteristics of a water chiller, and we first make some simplifications to the water chiller, including:

the adjustment of the chilled water temperature is accomplished by the loading and unloading of the compressor, with negligible delay in the compressor adjustment relative to the thermal characteristics of the air conditioning system; the refrigerant flow rate throughout the cycle remains constant, and the amount of refrigerant in the evaporator and condenser remains constant; the relative flow between the coolant (i.e., chilled water) and the refrigerant can be reduced to pure convection; the chilled water temperature varies linearly along the evaporator and the evaporator shell temperature is described by an average temperature; the mass of the superheated steam portion, i.e. the stored energy, is negligible; the two-phase flow may be represented by a hypothetical single-phase fluid having average physical properties.

After the above simplification, the present embodiment focuses on the dynamic change process of the chilled water side at the time of chiller adjustment, so that the modeling process of the chilled water side, the compressor, and the expansion valve can be simplified. The influence of the dynamic change of the cooling water side, the compressor and the expansion valve on the freezing side is classified as the refrigerating capacity of the refrigerant

Dynamic changes in (2).

Representing the dynamic change in the amount of refrigeration provided by the refrigerant in the evaporator, describes the amount of refrigeration transferred to the evaporator shell by the refrigerant in the evaporator. The water chilling unit module has higher universality and is not limited by the form of the cooling side.

Common chiller side demand response strategies typically have intermittent shut down, shut down of a portion of the chiller, and increase chilled water temperature. These strategies achieve chiller power cutoffs by unloading chillers or reducing chiller cooling loads. After policy enforcement, the refrigerant cooling capacity

The course of change of (2) can be described as +.>

Become dynamic cold energy->

Until a new steady state.

The dynamic heat balance of the refrigerant, the evaporator shell and the chilled water are as follows, respectively, and are mainly used for describing the dynamic change of the cold energy transferred by the chiller to the chilled water after the implementation of the demand response strategy and before the formation of a new stable state.

Dynamic balance of refrigerant:

（1）

dynamic balancing of evaporator housing:

（2）

dynamic balance of chilled water:

（3）

wherein, superscriptch represents chiller related parameters to distinguish between coil (co) and pipe (pipe) related parameters.

、

And +.>

The average temperature of the evaporator material, refrigerant and chilled water within the object being analyzed is shown.

Is the heat exchange coefficient between the refrigerant and the evaporator wall, and (2)>

Is the heat exchange coefficient between the evaporator wall and the chilled water.

For the heat exchange area between evaporator wall and chilled water, < > water>

Is the heat exchange area between the refrigerant and the evaporator wall.

、

And +.>

The specific heat capacity of the evaporator material, refrigerant and chilled water in the chiller is shown.

、

And +.>

Indicating the mass of evaporator material, refrigerant and chilled water in the chilled water unit.

Is the refrigeration capacity of the refrigerant.

、

The temperature of the water supply and return of the chilled water in the chiller.

For chilled water mass flow, it can be obtained by a cold gauge (consisting of a temperature sensor and a flow meter) installed in the building.

The heat exchange coefficient can be calculated according to an empirical formula.

（4）

（5）

（6）

Wherein,,

、

、

、

is constant.

For freezing water in a chillerNumber of knoevenagel criteria.

Is the Reynolds number of the chilled water. / >

Is the coefficient of heat conductivity of chilled water.

Is the sizing size of the chilled water pipeline.

And step S3, according to the outlet water temperature of the water chilling unit, the outlet water temperature of the pipeline is obtained by combining the average temperature of the pipeline material, the average temperature of the chilled water in the pipeline, the average temperature of the heat insulation material outside the pipeline and the average temperature of the external air.

In this embodiment, the description of the pipe includes three parts, chilled water inside the pipe, pipe material, and insulation outside the pipe. Likewise, the pipeline is first simplified:

assuming that the heat capacity of the external heat insulation material is negligible, the heat insulation material outside the pipeline can be described in a steady state; all the delivery and distribution pipelines are divided into a plurality of pipe sections, and the temperature of the chilled water and the pipe materials in the cross section direction of the analyzed pipe sections is assumed to be uniformly distributed, and the temperature in the length direction is changed linearly.

FIG. 4 is a schematic diagram of a pipe segment being analyzed. The inlet water temperature of each section of pipeline is the outlet water temperature of the upper pipe section or equipment, and the outlet water temperature of the pipe section is the inlet water temperature of the lower pipe section or equipment. The chilled water dynamic thermal balance equation:

（7）

neglecting the heat capacity of the heat insulation material, namely the heat transfer of the heat insulation material is treated according to the steady-state heat transfer, so that the heat exchange amount between the outer side of the heat insulation material and the air is equal to the heat exchange amount between the inner side of the heat insulation material and the outer wall of the pipe, and the heat exchange amount can be obtained:

（8）

Also the dynamic thermal balance of the piping material:

（9）

wherein,,

、

、

and->

The average temperatures of pipeline materials in the analyzed pipeline section, internal chilled water, external heat preservation and external air are respectively.

、

The temperature of the water supply and return of the chilled water in the pipe section to be analyzed.

Is the heat exchange coefficient of the chilled water and the pipeline.

The heat exchange coefficient between the pipeline and the inner side of the heat insulation material.

Is the heat exchange coefficient between the outside ambient air outside the heat insulation material.

Is the heat exchange area of the chilled water and the pipeline.

Is the heat exchange area between the pipeline and the inner side of the heat insulation material.

Is the heat exchange area between the outside of the heat insulation material and the outside ambient air.

Is the specific heat capacity of the pipeline.

Is the pipeline quality.

Coefficient of heat exchange between chilled water and pipeline

And the heat exchange coefficient between the outside of the heat insulation material and the outside ambient air +.>

Can be obtained from the empirical formula:

（10）

（11）

（12）

（13）

wherein,,

、

、

is constant.

A knoop scherter criterion for chilled water in a pipe.

The knoop scherter criterion for air outside the duct.

Is the thermal conductivity of air.

The inner diameter of the pipeline is the pipe section to be analyzed.

Is the outer diameter of the pipeline.

Is the Gray dawn number.

Is the pluronic rule of the pipeline.

And S4, according to the outlet water temperature of the pipeline, combining a preset saturation enthalpy value of air at the average temperature of the coil, the outlet water temperature of the coil, the inlet water temperature of the coil, the number of rows of the coil and a preset heat exchange area of water to obtain the air supply temperature of the coil.

In this embodiment, the obtaining the air supply temperature of the coil includes obtaining the air supply temperature of the coil under the dry working condition and obtaining the air supply temperature of the coil under the wet working condition; the coils are formed by a plurality of rows, and the coils in different rows can be in different dry and wet working conditions.

In this embodiment, too, the coil is simplified to some extent:

the air heat accumulation is not considered; when dehumidification occurs, the effect of the residual chilled water on the fins and pipes is negligible; the temperature distribution inside the rib and in the direction of the rib height conforms to the steady state characteristics, so the rib efficiency can be used to describe the heat and mass transfer process of the rib; the relative flow between chilled water and air is described in terms of pure convection.

The coil is constructed of multiple rows, with any one row of coils being in a fully dry or wet state for each time step, and different rows being in different dry or wet states for calculation separately.

Dynamic thermal equilibrium of coil materials:

（14）

chilled water dynamic thermal balance under dry conditions:

（15）

chilled water dynamic thermal balance under wet conditions:

（16）

wherein,,

、

and->

The coil material, the outside air and the chilled water temperature inside the coil are respectively.

And->

Is the inlet and outlet water temperature of the coil pipe. / >

Indicating the average temperature of the air at the coil>

Lower saturation enthalpy.

Is the enthalpy value of the air outside the coil under the wet working condition.

Heat transfer resistance is provided for the air side of each row of coils.

Total heat and mass transfer resistance between coil material and air.

Heat transfer resistance for the water side of each row of coils.

Is the specific heat capacity of the coil material.

Is the coil pipe material quality.

In coil simplification, the mutual flow between air and water flow is simplified to a purely convective form, and the thermal resistance per discharge side of the coil can be expressed as:

：

（17）

wherein,,

is the total heat exchange area of the water side, +.>

For the heat exchange coefficient between the chilled water and the coil pipe, +.>

Is the number of rows.

Air side heat transfer resistance of each row of coils

：

（18）

Wherein,,

is air specific heat capacity->

For air mass flow, +.>

The "efficiency" of each row of heat exchange of the air side coil can be calculated by the following formula:

（19）

wherein the number of heat transfer units per row

：

（20）

Wherein,,

heat exchange efficiency for each row of coils on the air side, < >>

For each row of heat exchange coefficients on the air side,

is the air side heat exchange area.

Total heat and mass transfer resistance between coil material and air

：

（21）

Wherein the method comprises the steps of

For the total effectiveness of air side heat and mass transfer, one can calculate from the following equation:

（22）

（23）

wherein,,

for the total heat transfer unit number of the coil pipe, < > >

For the total heat exchange efficiency of the air side coil pipe, +.>

To determine the above parameters, three further sets of parameters are required:

、

And->

. These three sets of parameters can be obtained from empirical formulas:

（24）

（25）

（26）

wherein,,

，

，

、

is constant and can be obtained from short-term operating data of the coil by nonlinear regression.

For chilled water mass flow, < >>

Is the air side mass flow. Therefore, a certain time of operation record is needed before a coil uses the module, and parameters such as detailed geometric description information of the coil are not needed. For coils that have been put into operation (coils in demand response), detailed factory information and geometric descriptions are difficult to obtain, but the operating parameters can be obtained through short-term testing.

S5, obtaining a thermal characteristic measurement result of the air conditioning system according to the outlet water temperature of the water chilling unit, the outlet water temperature of the pipeline and the air supply temperature of the coil; the thermal characteristic measurement result is a dynamic change process of the indoor cooling capacity delivered by the air conditioning system after the control strategy of the cold machine side is implemented.

In this embodiment, the chiller side control strategy includes an intermittent shutdown strategy, a shutdown partial chiller strategy, and a chilled water temperature increase strategy; after the thermal characteristic measurement method is applied to the cold side control strategy, a new steady state is formed.

Correspondingly, referring to fig. 5, fig. 5 is a schematic diagram of a thermal property measurement system of an air conditioning system according to an embodiment of the present invention, including an acquisition module 101, a chiller module 102, a pipeline module 103, a coil module 104, and a thermal property measurement module 105; wherein,,

the acquiring module 101 is configured to acquire initial parameters of thermal characteristics of the air conditioning system in real time; wherein the thermal property initiation parameters include: the temperature control system comprises an evaporator material in the water chilling unit, a refrigerant in the water chilling unit, chilled water in the water chilling unit, a pipeline material, chilled water in the pipeline, an external heat insulation material of the pipeline, external air, outlet water temperature of the coil and inlet water temperature of the coil.

In this embodiment, the obtaining module 101 is configured to obtain, in real time, initial parameters of thermal characteristics of the air conditioning system, specifically: the method comprises the steps of acquiring the average temperature of evaporator materials in a water chilling unit, the average temperature of refrigerant in the water chilling unit, the average temperature of chilled water in the water chilling unit, the average temperature of pipeline materials, the average temperature of chilled water in a pipeline, the average temperature of heat insulation materials outside the pipeline, the average temperature of outside air, the outlet water temperature of a coil and the inlet water temperature of the coil in real time through a plurality of sensors.

The chiller module 102 is configured to obtain an outlet water temperature of the chiller according to an average temperature of an evaporator material in the chiller, an average temperature of a refrigerant in the chiller, and an average temperature of chilled water in the chiller, and by combining a preset heat exchange coefficient between the refrigerant and the evaporator wall and a preset heat exchange coefficient between the evaporator wall and the chilled water.

The pipeline module 103 is configured to obtain an outlet water temperature of the pipeline according to an outlet water temperature of the water chiller, in combination with an average temperature of a pipeline material, an average temperature of chilled water in the pipeline, an average temperature of an external heat insulation material of the pipeline, and an average temperature of external air.

The coil module 104 is configured to obtain an air supply temperature of the coil according to an outlet water temperature of the pipeline, in combination with a preset saturation enthalpy value of air at an average temperature of the coil, an outlet water temperature of the coil, an inlet water temperature of the coil, a discharge number of the coil, and a preset heat exchange area of water.

The thermal characteristic measurement module 105 is configured to obtain a thermal characteristic measurement result of the air conditioning system according to an outlet water temperature of the water chiller, an outlet water temperature of the pipeline, and an air supply temperature of the coil; the thermal characteristic measurement result is a dynamic change process of the indoor cooling capacity delivered by the air conditioning system after the control strategy of the cold machine side is implemented.

Correspondingly, the embodiment of the invention also performs experimental verification on the thermal characteristic measurement method of the air conditioner system.

First, common chiller side demand response control strategies fall into two broad categories:

and (3) start-stop control: such control strategies ensure continuous cooling of the room by taking advantage of the amount of cold stored in the chilled water and plant materials by turning off (some or all) of the chiller while keeping the chilled water side other plants continuously running. Shutting down some or all of the chiller, and intermittent shut down belong to such control strategies.

Chilled water temperature control: the control strategy is to improve the efficiency of the chiller and reduce the cooling load of the chiller by improving the temperature of chilled water, thereby realizing the reduction of electricity consumption of the air conditioner. Mainly refers to 'improving the chilled water temperature set value', which can be realized by resetting the backwater temperature or the water supply temperature.

Therefore, the two control strategies are subjected to experimental verification to determine the dynamic change rule of the cooling capacity of the refrigerant after the different demand response control strategies are implemented.

The thermal characteristics of the chilled water side of an air conditioning system consist of the thermal characteristics of the chiller, the thermal characteristics of the coils, and the thermal characteristics of the pipes.

Wherein the chiller module 102 focuses on the dynamic heat transfer characteristics of the chilled water side, i.e., the evaporator side, while attributing dynamic changes in other components (condenser, compressor, and expansion valve) to changes in refrigerant cooling capacity in the evaporator, by

And (3) representing. And the change rule of the refrigerant cold after the implementation of different demand response control strategies needs to be obtained and verified through experiments.

Therefore, in experimental investigation of the thermal characteristics of an air conditioning system, first, the refrigerant cooling capacity curve of the investigated control strategy is determined by means of a "training set" experiment. And selecting two basic strategies of the cold machine side to carry out experimental solution, namely strategy type 1-start-stop control and strategy type 2-chilled water temperature control.

Then, the cold water unit and the cold energy of the refrigerant are respectively verified through a verification group experiment

Accuracy of description of the overall thermal characteristics, coil, tubing. The evaluation was performed by means of root mean square error (root mean square error, RMSE).

（27）

And finally, verifying the cooling capacity of the refrigerant under different control strategies again through a water chilling unit module in a certain practical office building. The refrigerant cold change law obtained by the experiment table is proved to have certain universality. The chiller module 102, coil module 104, and pipe module 103 are solved by discrete equations using MATLAB programming. The discrete form used for the numerical solution is shown in table 1.

Table 1 discrete modes of thermal characteristics of air conditioning systems

The experimental air conditioning system is located on a 'building full-energy-efficiency test platform' (as shown in fig. 6, fig. 6 is a schematic diagram of laboratory construction for experimental verification), and the whole laboratory is composed of two identical rooms and an environmental control cabin. The environment control cabin and the room are provided with two sets of completely independent air conditioning systems which are respectively used for controlling the indoor temperature in the room and the outdoor environment of the room. During the experiment, the air conditioning system of the room external environment experiment cabin is started, so that the external environment of the test room can be ensured to be basically in a stable state, namely, the external disturbance is constant. The test chamber is in an idle state, and no internal disturbance of personnel, equipment and the like exists, i.e. the internal disturbance of the test chamber is constant and zero. Thus, the indoor temperature change of the room is mainly influenced by the change of the cooling capacity of the air conditioner, and the stable operation of the air conditioning system in a non-regulation period is ensured.

During the experiment, only the air conditioning end of one room was turned on, and the air conditioning end of the other room was in a normally closed state. For a single room, the schematic construction of the system and the arrangement of main measuring points in the experiment are shown in fig. 7 (fig. 7 is a schematic diagram of the arrangement of the air conditioning system and the measuring points of the experiment table), and the measuring point list is shown in table 2.

Table 2 test point list of air conditioning system laboratory table

Sensor naming rules: "S" -sensor, "1 to 8" -number, "T" -temperature, "M" -flow, "TH" -temperature and humidity.

The detailed parameters of the chilled water units, coils and distribution lines in the laboratory are shown in table 3. The parameters as presented in formulas (4) to (6), (10) to (13) and (24) to (26) can be obtained from short-term experimental test data by nonlinear regression. Therefore, before the formal experiment, the unit operation parameters under different working conditions are obtained through short-term test, and each obtained constant is shown in table 4.

Table 3 detailed parameters of various devices of the air conditioning system laboratory bench

Table 4 values of various constants in experimental air conditioning system

As described above, the present study conducted experimental studies on two broad classes of common cold side control strategies. Details of the individual control strategies in the laboratory verification are shown in table 5.

Table 5 details of control strategy in experiments

Two common cold machine side strategies are researched in experiments, so that the cold energy of the refrigerant after the implementation of the two control strategies is determined

Dynamic changes in (2).

Refrigerating capacity of refrigerant

Solving:

experiments under each control strategy are divided into two groups, wherein a training group is used for solving the cold energy of the refrigerant, and a verification group is used for verifying the accuracy of the cold energy of the refrigerant and the overall thermal characteristics of the water chiller, the coil, the pipeline and the air conditioning system. The following first describes the solution of the refrigeration capacity of the training set.

Wherein, start-stop control strategy:

in the experiment of start-stop control, after the air conditioning system is operated for a period of time to reach stable operation, the refrigerating machine is closed, and meanwhile, the chilled water pump and the tail end are kept to continue to operate, and the operation parameters are unchanged. The refrigerating capacity reserved in the evaporator, the chilled water and the materials of all the components can still have a certain refrigerating effect, so that the indoor temperature rise is delayed.

After the unit closing strategy is implemented, the whole unit has certain adjustment delay and heat transfer delay, so that whether the refrigerating capacity of the refrigerating fluid can be directly regarded as zero after the unit is closed or not needs to be further verified through experiments. If the effect of the adjustment delay is negligible, the refrigeration capacity of the unit immediately after the chiller is turned off falls to zero, and the refrigeration capacity of the refrigerant in the evaporator should be zero. Adopts a trial calculation method

Substituting 0 into the thermal characteristics of the water chilling unit after the implementation of the chiller control strategy, and comparing the thermal characteristics with experimental results to verify the rationality of the assumption.

And taking the operation parameters of the stable operation state before the cold machine is closed as the initial state parameters of the dynamic solving of the whole system. The dynamic process after the cold machine is shut down is shown as formulas (1) to (3), and the discrete form used for numerical solution is shown as formulas (28) to (30). The result of the first time step is used as the initial parameter of the second time step in the calculation, and the like. The chiller module 102 may accurately predict changes in the water inlet status parameters when they change. Because the cold water flow rate in the experiment is not regulated, the outlet water temperature of the water chilling unit is selected as a verification parameter.

Will be

The measured chilled water outlet temperature was compared with the experimental test result with zero, as shown in fig. 8 (a). The outlet temperature of chilled water of the chiller gradually rises after the chiller is turned off, and the water temperature is still lower than the indoor air temperature by 20 minutes and is about 14 ℃, which indicates that the whole air conditioning system still has certain refrigerating capacity at the moment. As can be seen from fig. 8 (a), the outlet water temperature obtained by the water chiller according to the measurement method of the present embodiment matches with the variation trend of the experimental result, and the root mean square error RMSE between the result obtained by the water chiller according to the thermal characteristic measurement method and the experimental result is 0.21 ℃. This means that the refrigerant cooling capacity after the chiller is turned off +. >

The assumption of direct zero has certain rationality, and the chiller module 102 can also accurately describe the dynamic changes in chilled water temperature.

Chilled water temperature control strategy:

in actual buildings, raising the chilled water temperature set point is also a common chiller side demand response control strategy. The cold machine of the experiment table can reset the return water temperature of the chilled water, and the return water temperature of the chilled water in the experiment is adjusted to 14 ℃ from 12 ℃ when the experiment is initially stably operated, and other operation parameters are kept unchanged.

Likewise, the refrigerant coldness in the chiller modules 102 (1) to (3)

Is an unknown parameter. The operating parameters in the module can be measured experimentally, usually for a new control strategy, in which case the refrigerant cooling capacity +.>

The unique unknown parameters in the module can be obtained through back-calculation of experimental results. However, it was found in the experiment that after the temperature was reset, the temperature rise rate of the chilled water before the new set return water temperature was reached was very close to the temperature rise rate of the chilled water after the unit was turned off, as shown in fig. 8 (b). Therefore, it is now assumed that the refrigerant cooling capacity +_ after the freezing water temperature is reset and before the new set temperature is reached>

And can still be considered zero. The chilled water temperature reset module measures the chiller outlet water temperature as shown in fig. 8 (c). The outlet water temperature measured by the module is similar to the variation trend of the experimental result, and the root mean square error RMSE of the module measurement result and the experimental result is 0.23 ℃. This means that after the chilled water temperature is raised, the chiller will be temporarily shut down for a period of time due to the reduced load. The refrigerant cooling capacity can be set to zero after the chilled water temperature is reset until a new temperature set point is reached.

In addition, the verification of the water chilling unit based on the thermal characteristic measurement method comprises the following steps:

the verification of the thermal characteristic measurement result of the water chiller comprises two purposes, namely, the verification of the refrigeration capacity of the refrigerant under two control strategies

Secondly, verifying the accuracy of the water chilling unit equation sets (1) to (3). The initial parameters of the water chilling unit are stable operation state parameters before the response strategy is implemented, including chilled water supply and return water temperature, flow rate and the like, and can be obtained by the sensors S1-T, S2-M and S5-T. During the module dynamics, the water chilling unit module 102 is verified for accuracy using the water supply temperature (S1-T).

The verification result of the module is shown in fig. 9 (a) (b). Under the two control strategies, the water supply temperature measured by the water chilling unit module is consistent with the variation trend of the experimental result. For the strategy of closing the chiller, the Root Mean Square Error (RMSE) of the measurement result and the experimental result of the chiller is 0.39 ℃; for increasing the chilled water temperature, the root mean square error RMSE between the chiller module measurement and the experimental results was 0.38 ℃. Therefore, the method for measuring the thermal characteristics of the water chilling unit provided by the subject can accurately predict the dynamic change process of the chilled water temperature at the side of the chiller after the demand response strategy is implemented to a certain extent, and the obtained refrigerant cold quantity in the dynamic process is reasonable.

And subsequently, the accuracy of the cooling capacity of the water chilling unit and the refrigerant and the applicability of the cooling capacity and the refrigerant in the actual water chilling unit are verified again through the actual building water chilling unit test.

Verification of coil module 104 measurements:

the state parameter during steady operation is used as an initial condition for the coil modules (14) to (16) to measure. The status parameters required for module verification may be measured by the sensors S3-T, S4-T, S-TH, S7-M, and S8-T. The temperature and humidity of indoor air are used as state parameters of return air temperature. Because the air quantity of the fan coil in the experiment is kept unchanged

) Thus, it isThe supply air temperature (S8-T) directly reflects the amount of cooling delivered to the indoor air by the fan coil, where the supply air temperature is selected as the output parameter for verification by the coil module 104.

As shown in fig. 9 (c) and (d), the module test air supply temperature and the experimental test air supply temperature have substantially the same trend. The accuracy of the module was evaluated by the rms error of the module measurements relative to the experimental results, with rms errors RMSE of the two strategies being 0.31 ℃ and 0.28 ℃, respectively. As can be seen from the module verification result, the coil module can accurately predict the dynamic change process of the air supply temperature after the response strategy is implemented.

Verification of the pipeline module 103 measurement:

the initial state parameters of the pipeline module 103 at the time of validation of equation set (7) (9) are steady state operating state parameters prior to the implementation of the response strategy. Parameters required for pipeline verification are measured by the sensors S1-T, S2-M and S3-T. Because the flow of chilled water is not regulated in the experiment, the pipeline module 103 should accurately describe the change of the pipeline outlet water temperature when the pipeline inlet water temperature changes dynamically. The comparison result of the experiment and the module can prove that the root mean square error RMSE of the water outlet temperature predicted by the pipeline module relative to the temperature of the water collected by the experiment under the two control strategies is respectively 0.27 ℃ and 0.34 ℃. As can be seen from fig. 9 (e) and (f), the change trends of the two are basically consistent, which indicates that the pipeline module can more accurately describe the dynamic heat transfer characteristics of the pipeline after the control strategy is implemented.

Verification of measurement results of the overall thermal characteristics of the air conditioning system:

the accuracy of the three modules of the water chiller module 102, the pipeline module 103 and the coil module 104 is respectively verified before, and the accuracy of the three modules in combined operation is more important for evaluating the dynamic change of the indoor cooling capacity of the air conditioning system after the implementation of the demand response control strategy.

When the three modules are operated in combination, the whole system forms a closed loop (as shown in fig. 6), and the output parameter of the previous module is the input parameter of the next module. Taking pipeline module 103 as an example, pipeline module103 is actually the outlet temperature of the chiller module 102 (chilled water supply temperature), while the outlet water temperature of the piping module 103 is the inlet temperature of the coil module 104. The stable operation parameters before the implementation of the demand response strategy are taken as the initial parameters of the module, and the flow rate and the air volume of the refrigerating water and the air volume of the fan are not regulated when the whole control strategy is implemented, so that the flow rate and the air volume of the refrigerating water can be considered to be the same as the initial values

，

608L/h). The discrete form for numerical solution is shown in table 1.

The purpose of the thermal characteristic measurement system is to accurately describe the dynamic change process of the air conditioning system delivering cold to the room after the demand response strategy is implemented. In two groups of experiments, the air quantity of the fan coil is kept unchanged all the time, so that the air supply temperature can directly reflect the change of the cold quantity delivered to the indoor by the tail end of the air conditioning system. Comparison of measured air supply temperature and experimental results of overall thermal characteristics under two control strategies as shown in fig. 10, the overall thermal characteristic system predicts the trend of change of air supply temperature more accurately under two control strategies.

The error of the joint system is slightly larger than the verification result of the single module. The method is characterized in that in the verification of a single module, the input parameter of each step length of the module is the acquisition value of each step length in an experiment, so that the calculation error of the previous step length of the module cannot influence the next step length; in the combined system, the outlet parameter of the last module is used as the inlet parameter of the next module, and the calculation result of the last step is the initial state parameter of the next step, that is, the calculation error of the last module acts on the next module, and the error of the last time step also affects the next step, so that the module deviation is slightly larger. Even so, the root mean square error of the overall system is still small, 0.53 ℃ (shutdown) and 0.36 ℃ (attemperation), respectively.

The verification result of the air conditioning body heat characteristic measurement system can be obtained, and the whole heat characteristic measurement system can accurately predict the dynamic change of indoor cooling capacity of the air conditioning system after the demand response control strategy is implemented.

The root mean square error summary results of the chiller module 102 predicting the outlet water temperature, the coil module 104 predicting the supply air temperature, the pipe module 103 predicting the pipe outlet water temperature and the overall thermal characteristics measurement system predicting the supply air temperature are shown in table 6. Whether the chiller strategy is turned off or the chilled water temperature setpoint strategy is raised, the predicted deviation of the three modules and the overall thermal property measurement system is substantially less than 0.5 ℃.

TABLE 6 root mean square error between the various modules and experimental results

Actual building verification (refrigerant cold general verification) of the chiller module 102:

in laboratory verification, although the accuracy of the chiller module 102 in describing the dynamic changes in chilled water temperature is verified. However, on one hand, the water chilling unit for experiments can only complete the adjustment of the return water temperature of the chilled water due to the limitation of experimental conditions, and the actual air conditioning system often realizes the resetting of the chilled water temperature by adjusting the water supply temperature of the chilled water, on the other hand, the refrigerating capacity of the refrigerant in the dynamic process obtained through the experiments

The universality of the system still needs to be further verified in the water chilling units of the actual buildings.

The control panel of the water chilling unit for re-verification can realize the resetting of the outlet water temperature of chilled water and the monitoring of the return water temperature of chilled water supply, and the 'energy system monitoring platform' of the building can monitor other operating parameters of the unit in real time. The basic information of the water chiller required in verification is obtained by means of on-site investigation, equipment sample information collection, sample data fitting and short-term operation data acquisition, and is shown in table 7.

Table 7 detailed parameters of a chiller for an office building

In the test, two control strategies are carried out on the unit, and strategy 1: closing the chiller while maintaining the water pump and the end in operation; strategy 2: the chilled water outlet temperature was reset from 10 ℃ to 12 ℃ as in table 8.

TABLE 8 details of control strategies in actual building testing

The pairs of the measurement results and the experimental results of the four water chilling unit modules 102 in the test are as shown in fig. 11, and the change trend of the water outlet temperature of the chilled water in the four working conditions is basically consistent with that of the modules in the test. The root mean square error between the module and the test result is shown in table 9, and is smaller in both shutdown strategy and temperature reset strategy. On one hand, the water chilling unit module provided by the subject has certain accuracy and universality; on the other hand, the refrigerant cold gauge law obtained through laboratory tests and subjected to different strategies has certain universality.

TABLE 9 details of control strategies in actual building testing

The terminal can be a computing device such as a desktop computer, a notebook computer, a palm computer, a cloud server and the like. The terminal may include, but is not limited to, a processor, a memory.

The processor may be a central processing unit (Central Processing Unit, CPU), other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), off-the-shelf programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. The general purpose processor may be a microprocessor or the processor may be any conventional processor or the like, which is a control center of the terminal, connecting various parts of the entire terminal using various interfaces and lines.

The memory may be used to store the computer program, and the processor may implement various functions of the terminal by running or executing the computer program stored in the memory and invoking data stored in the memory. The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program (such as a sound playing function, an image playing function, etc.) required for at least one function, and the like; the storage data area may store data (such as audio data, phonebook, etc.) created according to the use of the handset, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as a hard disk, memory, plug-in hard disk, smart Media Card (SMC), secure Digital (SD) Card, flash Card (Flash Card), at least one disk storage device, flash memory device, or other volatile solid-state storage device.

Wherein the module of the thermal property measuring system/terminal integration of the air conditioning system may be stored in a computer readable storage medium if implemented in the form of a software functional unit and sold or used as a separate product. Based on such understanding, the present invention may implement all or part of the flow of the method of the above embodiment, or may be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer readable storage medium, and when the computer program is executed by a processor, the computer program may implement the steps of each of the method embodiments described above. Wherein the computer program comprises computer program code which may be in source code form, object code form, executable file or some intermediate form etc. The computer readable medium may include: any entity or device capable of carrying the computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth.

The foregoing embodiments have been provided for the purpose of illustrating the general principles of the present invention, and are not to be construed as limiting the scope of the invention. It should be noted that any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art without departing from the spirit and principles of the present invention are intended to be included in the scope of the present invention.

Claims

1. A thermal characteristic measurement method of an air conditioning system, which is applied to an air conditioning system after implementation of a chiller side control strategy, the air conditioning system comprising: the water chiller, coil pipe and pipeline;

the thermal property measurement method includes:

obtaining a thermal characteristic measurement result of the air conditioning system according to the outlet water temperature of the water chilling unit, the outlet water temperature of the pipeline and the air supply temperature of the coil; the thermal characteristic measurement result is a dynamic change process of the indoor cold quantity delivered by the air conditioning system after the cold side control strategy is implemented;

2. The method for measuring thermal characteristics of an air conditioning system according to claim 1, wherein said obtaining the supply air temperature of the coil includes obtaining the supply air temperature of the coil under dry conditions and obtaining the supply air temperature of the coil under wet conditions; the coils are formed by a plurality of rows, and the coils in different rows are in different dry and wet working conditions.

3. The method for measuring thermal characteristics of an air conditioning system according to any one of claims 1 to 2, wherein the chiller side control strategy includes an intermittent shutdown strategy, a partial chiller shutdown strategy, and a chilled water temperature increase strategy; after the thermal characteristic measurement method is applied to the cold side control strategy, a new steady state is formed.

4. The system is characterized by comprising an acquisition module, a water chilling unit module, a pipeline module, a coil module and a thermal property measurement module; wherein,,

the thermal characteristic measurement module is used for obtaining a thermal characteristic measurement result of the air conditioning system according to the outlet water temperature of the water chilling unit, the outlet water temperature of the pipeline and the air supply temperature of the coil; the thermal characteristic measurement result is a dynamic change process of the indoor cold quantity delivered by the air conditioning system after the cold side control strategy is implemented;

5. The system for measuring thermal characteristics of an air conditioning system according to claim 4, wherein said obtaining the temperature of the supply air to the coil includes obtaining the temperature of the supply air to the coil during dry conditions and obtaining the temperature of the supply air to the coil during wet conditions; the coils are formed by a plurality of rows, and the coils in different rows are in different dry and wet working conditions.

6. The thermal characteristics measurement system of an air conditioning system according to any one of claims 4 to 5, wherein the chiller side control strategy includes an intermittent shutdown strategy, a shut down partial chiller strategy, and a raise chilled water temperature strategy; after the thermal property measurement system is applied to the chiller side control strategy, a new steady state is established.

7. A terminal comprising a processor, a memory and a computer program stored in the memory; wherein the computer program is executable by the processor to implement the method of measuring thermal characteristics of an air conditioning system according to any one of claims 1 to 3.

8. A computer readable storage medium, wherein the computer readable storage medium comprises a stored computer program; wherein the apparatus in which the computer-readable storage medium is controlled to execute the thermal characteristic measurement method of the air conditioning system according to any one of claims 1 to 3 when the computer program is run.