阅读说明：本技术 非恒温条件下墙体传热系数的工程现场检测方法及系统 (Engineering field detection method and system for wall heat transfer coefficient under non-constant temperature condition ) 是由 马昕煦 葛杰 冯俊 胡成佑 于 2021-07-21 设计创作，主要内容包括：本发明涉及一种非恒温条件下墙体传热系数的工程现场检测方法及系统,该方法包括如下步骤：采集室内温度、室外温度和室内侧热流密度；建立一维非稳态热传导方程,利用室内外温度作为边界条件,求解得出待测墙体所有材料的温度变化；将墙体传热系数设定为设计值；利用求解得出的待测墙体所有材料的温度变化和设计值计算待测墙体室内侧墙体表面处的热流密度变化；比较计算热流密度和室内侧热流密度的大小,从而判断得出待测墙体的实际传热系数是否满足设计要求。本发明无需确保室内外的温度恒定,即使热流密度会因气温波动而产生波动,其也不会影响对墙体的实际传热系数的检测判断,且能够为工程现场提供快速检验墙体是否满足设计保温要求的功能。(The invention relates to an engineering field detection method and system for wall heat transfer coefficient under non-constant temperature condition, wherein the method comprises the following steps: collecting indoor temperature, outdoor temperature and indoor side heat flux density; establishing a one-dimensional unsteady heat conduction equation, and solving to obtain the temperature change of all materials of the wall body to be measured by using indoor and outdoor temperatures as boundary conditions; setting the heat transfer coefficient of the wall body as a design value; calculating the heat flow density change of the indoor side wall surface of the wall to be detected by using the temperature change and the design value of all the materials of the wall to be detected; and comparing the calculated heat flow density with the indoor heat flow density, and judging whether the actual heat transfer coefficient of the wall to be tested meets the design requirement. The invention does not need to ensure constant indoor and outdoor temperature, even if the heat flow density fluctuates due to temperature fluctuation, the detection and judgment of the actual heat transfer coefficient of the wall body can not be influenced, and the function of quickly detecting whether the wall body meets the design heat preservation requirement or not can be provided for the engineering site.)

1. An engineering field detection method for wall heat transfer coefficient under non-constant temperature condition is characterized by comprising the following steps:

adjusting the indoor temperature to generate temperature difference between the indoor and the outdoor of the wall to be measured;

collecting the indoor temperature, the outdoor temperature and the indoor side heat flux density of the wall body to be measured within a set time to form corresponding actually measured indoor temperature data, actually measured outdoor temperature data and actually measured indoor side heat flux density data;

establishing a one-dimensional unsteady heat conduction equation corresponding to the wall to be measured, and solving to obtain the temperature change of all materials of the wall to be measured by using the collected actually-measured indoor temperature data and the actually-measured outdoor temperature data as boundary conditions;

setting the heat transfer coefficient of the wall body as a design value;

calculating the heat flux density change of the indoor side wall surface of the wall to be detected by using the temperature change of all the materials of the wall to be detected and the design value, and recording the heat flux density change as calculated heat flux density data; and

comparing the magnitude of the calculated heat flow density data with the magnitude of the actually measured indoor side heat flow density data, and if the calculated heat flow density data is more than or equal to the actually measured indoor side heat flow density data, judging that the actual heat transfer coefficient of the wall body to be measured is less than or equal to the set value; and if the calculated heat flow density data is smaller than the actually measured indoor side heat flow density data, judging that the actual heat transfer coefficient of the wall body to be measured is larger than the set value.

2. The method for engineering field testing of wall heat transfer coefficient under non-constant temperature condition according to claim 1, further comprising:

amplifying the design values according to a plurality of set multiples respectively to obtain corresponding amplification values;

calculating the heat flux density change of the indoor side wall surface of the wall to be detected by using the temperature change of all the materials of the wall to be detected and the amplification value, and recording the heat flux density change as amplified heat flux density data;

and finding out data with the highest coincidence degree with the actually measured indoor side heat flow density data from the amplified heat flow density data and the calculated heat flow density data, and outputting a wall heat transfer coefficient corresponding to the data with the highest coincidence degree as a detection result.

3. The method according to claim 2, wherein when finding out data having the highest degree of coincidence with the measured indoor-side heat flux density data, a corresponding curve is drawn on a graph according to the amplified heat flux density data, the calculated heat flux density data, and the measured indoor-side heat flux density data, and a curve having a trend and an amplitude value close to those of the curve corresponding to the measured indoor-side heat flux density data is selected from the graph as the data having the highest degree of coincidence.

4. The method for on-site engineering testing of the heat transfer coefficient of the wall body under the non-constant temperature condition as claimed in claim 2, wherein when finding out the data with the highest degree of coincidence with the heat flow density data inside the actual measurement chamber, calculating the deviation values of the amplified heat flow density data and the heat flow density data with the heat flow density data inside the actual measurement chamber;

and selecting the data with the minimum deviation value as the data with the highest coincidence degree.

5. The method for engineering field test of wall heat transfer coefficient under non-constant temperature condition as claimed in claim 1, wherein the heat flow density change at the indoor wall surface of the wall to be tested is calculated by the following formula and recorded as the calculated heat flow density data:

in the formula (I), the compound is shown in the specification,representing the calculated heat flow density value, h, for the corresponding time k_nIndicating wall heat transfer systemThe number of the first and second groups is,the temperature value corresponding to the k moment in the temperature change of the inner wall surface of the wall chamber to be measured is shown,and the temperature value corresponding to the k moment in the actually measured indoor temperature data is shown.

6. An engineering field detection system for wall heat transfer coefficient under non-constant temperature condition is characterized by comprising:

the air conditioner is arranged indoors and used for adjusting the indoor temperature to generate temperature difference between the indoor and the outdoor of the wall body to be measured;

the first temperature sensor is arranged indoors and used for collecting the indoor temperature of the wall body to be measured within a set time to form corresponding actually measured indoor temperature data;

the second temperature sensor is arranged outdoors and used for collecting the outdoor temperature of the wall body to be measured within a set time to form corresponding measured outdoor temperature data;

the heat flow meter is arranged on the indoor side wall surface of the wall body to be measured and is used for collecting indoor side heat flow density of the wall body to be measured within set time to form corresponding actually measured indoor heat flow density data;

the processing module is connected with the air conditioner, the first temperature sensor, the second temperature sensor and the heat flow meter, and is used for establishing a one-dimensional unsteady heat conduction equation corresponding to the wall to be measured, and solving to obtain the temperature change of all materials of the wall to be measured by using the actually measured indoor temperature data and the actually measured outdoor temperature data acquired by the first temperature sensor and the second temperature sensor as boundary conditions; the processing module is also used for calculating the heat flow density change of the indoor side wall surface of the wall body to be detected based on a set value as the heat transfer coefficient of the wall body and combining the temperature change of all the materials of the wall body to be detected obtained by solving and recording the heat flow density change as calculated heat flow density data; and

the detection module is connected with the processing module and the heat flow meter and is used for comparing and judging the magnitude of the calculated heat flow density data and the magnitude of the actually measured indoor side heat flow density data, and if the calculated heat flow density data is more than or equal to the actually measured indoor side heat flow density data, the actual heat transfer coefficient of the wall body to be measured is judged to be less than or equal to the set value; and if the calculated heat flow density data is smaller than the actually measured indoor side heat flow density data, judging that the actual heat transfer coefficient of the wall body to be measured is larger than the set value.

7. The project site detection system of wall heat transfer coefficient under non-constant temperature condition of claim 6, characterized in that, the processing module is further configured to amplify the design values according to a set multiple to obtain corresponding amplification values, and calculate the heat flow density change at the indoor wall surface of the wall to be measured by using the amplification values and the temperature changes of all the materials of the wall to be measured obtained by solving, and record the heat flow density change as amplified heat flow density data;

the detection module is further used for finding out data with the highest coincidence degree with the actually measured indoor side heat flow density data from the amplified heat flow density data and the calculated heat flow density data, and outputting a wall heat transfer coefficient corresponding to the data with the highest coincidence degree as a detection result.

8. The system of claim 7, wherein the detection module is further configured to draw a corresponding curve on a graph according to the amplified heat flux density data, the calculated heat flux density data, and the measured indoor side heat flux density data, and select a curve corresponding to the measured indoor side heat flux density data, the curve having a trend and an amplitude that are close to each other, as the data with the highest degree of coincidence.

9. The system of claim 7, wherein the detection module is further configured to calculate a deviation between the amplified heat flux density data and the measured indoor heat flux density data, and select data with the smallest deviation as the data with the highest degree of coincidence.

10. The system of claim 6, wherein the processing module calculates the heat flux density data by the following equation:

in the formula (I), the compound is shown in the specification,representing the calculated heat flow density value, h, for the corresponding time k_nThe heat transfer coefficient of the wall body is shown,the temperature value corresponding to the k moment in the temperature change of the inner wall surface of the wall chamber to be measured is shown,and the temperature value corresponding to the k moment in the actually measured indoor temperature data is shown.

Technical Field

The invention relates to the field of building construction engineering, in particular to an engineering field detection method and system for wall heat transfer coefficient under a non-constant temperature condition.

Background

The heat transfer coefficient of the outer wall (building envelope) is an important index influencing the energy saving of the building. At present, the detection of the heat transfer coefficient of an external wall is mainly limited in a laboratory, the testing principle is that constant temperature difference is kept on two sides of the wall, temperature difference delta T of two side wall surfaces of the wall is measured through a temperature sensor, and heat flow Q is measured through a heat flow meter, so that the heat transfer coefficient K of the wall can be obtained as Q/delta T.

However, the laboratory measurement has the defects that the real engineering cannot be reflected and a test piece needs to be additionally manufactured, so that another method for measuring the heat transfer coefficient on the engineering site is provided in China, and the measurement principle is the same as that of the laboratory method. The method comprises the steps of arranging a heat flow meter on the surface of an indoor side wall body of an engineering site to measure heat flow Q, arranging temperature sensors on the surfaces of the indoor side wall body and the outdoor side wall body to measure wall surface temperature difference delta T, arranging an air conditioner indoors to ensure indoor constant temperature, avoiding the weather with severe temperature change during measurement, and recording heat flow density and the temperature of the inner surface and the outer surface. Since Q and Δ T change with the change of the indoor and outdoor air temperature, the wall heat transfer coefficient K calculated at each moment, Q/Δ T, is not a constant value, and a section with relatively stable heat flow needs to be selected, and the average value is taken as the final measurement result. Practice has shown, however, that the measured heat flow Q fluctuates greatly in most cases, mainly because: the heat flow measurement value is sensitive to temperature fluctuation, and the indoor and outdoor constant temperature condition is required to be met in order to obtain stable heat flow, so that the measurement result depends on the weather condition and the indoor constant temperature condition to a great extent, but the two conditions are difficult to control manually, and more time and money are required to be paid when the condition is reached. Thus, the method for measuring the heat transfer coefficient on the engineering site requiring constant temperature conditions has obvious limitations.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a method and a system for engineering field detection of a wall heat transfer coefficient under a non-constant temperature condition, and solves the problems that the existing method for measuring the heat transfer coefficient on the engineering field can obtain a more accurate measurement result only by ensuring indoor and outdoor constant temperature conditions, and the indoor and outdoor constant temperature conditions are difficult to realize artificial control, so that the method has obvious limitations.

The technical scheme for realizing the purpose is as follows:

the invention provides an engineering field detection method for a wall heat transfer coefficient under a non-constant temperature condition, which comprises the following steps:

adjusting the indoor temperature to generate temperature difference between the indoor and the outdoor of the wall to be measured;

collecting the indoor temperature, the outdoor temperature and the indoor side heat flux density of the wall body to be measured within a set time to form corresponding actually measured indoor temperature data, actually measured outdoor temperature data and actually measured indoor side heat flux density data;

establishing a one-dimensional unsteady heat conduction equation corresponding to the wall to be measured, and solving to obtain the temperature change of all materials of the wall to be measured by using the collected actually-measured indoor temperature data and the actually-measured outdoor temperature data as boundary conditions;

setting the heat transfer coefficient of the wall body as a design value;

calculating the heat flux density change of the indoor side wall surface of the wall to be detected by using the temperature change of all the materials of the wall to be detected and the design value, and recording the heat flux density change as calculated heat flux density data; and

comparing the magnitude of the calculated heat flow density data with the magnitude of the actually measured indoor side heat flow density data, and if the calculated heat flow density data is more than or equal to the actually measured indoor side heat flow density data, judging that the actual heat transfer coefficient of the wall body to be measured is less than or equal to the set value; and if the calculated heat flow density data is smaller than the actually measured indoor side heat flow density data, judging that the actual heat transfer coefficient of the wall body to be measured is larger than the set value.

The engineering field detection method disclosed by the invention only needs to generate temperature difference indoors and outdoors, does not need constant temperature difference, realizes the detection of the heat transfer coefficient of the wall body under the non-constant temperature condition, and specifically, during the detection, the indoor and outdoor temperature and the indoor side heat flow density are obtained, the corresponding heat flow density is calculated based on the indoor and outdoor temperature and the set wall body heat transfer coefficient, the calculated heat flow density data is compared with the collected actually measured indoor side heat flow density data, if the calculated heat flow density data is more than or equal to the actually measured indoor side heat flow density data, the fact that the actual heat transfer coefficient of the wall body to be detected is less than or equal to the set value is shown, and the design requirement is met; if the calculated heat flow density data is smaller than the actually measured indoor side heat flow density data, the fact that the actual heat transfer coefficient of the wall body to be measured is larger than a set value is shown, and the design requirement is not met. Therefore, the field detection method does not need to ensure constant indoor and outdoor temperature, even if the heat flow density fluctuates due to temperature fluctuation, the detection and judgment of the actual heat transfer coefficient of the wall body cannot be influenced, and the function of quickly detecting whether the wall body meets the design heat preservation requirement or not can be provided for the engineering field.

The engineering field detection method for the wall heat transfer coefficient under the non-constant temperature condition is further improved in that the method further comprises the following steps:

amplifying the design values according to a plurality of set multiples respectively to obtain corresponding amplification values;

calculating the heat flux density change of the indoor side wall surface of the wall to be detected by using the temperature change of all the materials of the wall to be detected and the amplification value, and recording the heat flux density change as amplified heat flux density data;

and finding out data with the highest coincidence degree with the actually measured indoor side heat flow density data from the amplified heat flow density data and the calculated heat flow density data, and outputting a wall heat transfer coefficient corresponding to the data with the highest coincidence degree as a detection result.

The engineering on-site detection method for the wall heat transfer coefficient under the non-constant temperature condition is further improved in that when data with the highest degree of coincidence with the actually measured indoor side heat flow density data is found out, a corresponding curve is drawn on a graph according to the amplified heat flow density data, the calculated heat flow density data and the actually measured indoor side heat flow density data, and a curve with the trend and the amplitude close to those of the curve corresponding to the actually measured indoor side heat flow density data is selected from the graph to serve as the data with the highest degree of coincidence.

The engineering field detection method for the wall heat transfer coefficient under the non-constant temperature condition is further improved in that when data with the highest degree of coincidence with the actually measured indoor side heat flow density data are found out, the deviation values of the amplified heat flow density data and the heat flow density data with the actually measured indoor side heat flow density data are calculated;

and selecting the data with the minimum deviation value as the data with the highest coincidence degree.

The engineering field detection method for the wall heat transfer coefficient under the non-constant temperature condition is further improved in that the heat flow density change of the indoor side wall surface of the wall to be detected is calculated through the following formula and is recorded as the calculated heat flow density data:

in the formula (I), the compound is shown in the specification,representing the calculated heat flow density value, h, for the corresponding time k_nThe heat transfer coefficient of the wall body is shown,the temperature value corresponding to the k moment in the temperature change of the inner wall surface of the wall chamber to be measured is shown,and the temperature value corresponding to the k moment in the actually measured indoor temperature data is shown.

The invention also provides an engineering field detection system for the wall heat transfer coefficient under the non-constant temperature condition, which comprises the following components:

the air conditioner is arranged indoors and used for adjusting the indoor temperature to generate temperature difference between the indoor and the outdoor of the wall body to be measured;

the first temperature sensor is arranged indoors and used for collecting the indoor temperature of the wall body to be measured within a set time to form corresponding actually measured indoor temperature data;

the second temperature sensor is arranged outdoors and used for collecting the outdoor temperature of the wall body to be measured within a set time to form corresponding measured outdoor temperature data;

the heat flow meter is arranged on the indoor side wall surface of the wall body to be measured and is used for collecting indoor side heat flow density of the wall body to be measured within set time to form corresponding actually measured indoor heat flow density data;

the processing module is connected with the air conditioner, the first temperature sensor, the second temperature sensor and the heat flow meter, and is used for establishing a one-dimensional unsteady heat conduction equation corresponding to the wall to be measured, and solving to obtain the temperature change of all materials of the wall to be measured by using the actually measured indoor temperature data and the actually measured outdoor temperature data acquired by the first temperature sensor and the second temperature sensor as boundary conditions; the processing module is also used for calculating the heat flow density change of the indoor side wall surface of the wall body to be detected based on a set value as the heat transfer coefficient of the wall body and combining the temperature change of all the materials of the wall body to be detected obtained by solving and recording the heat flow density change as calculated heat flow density data; and

the detection module is connected with the processing module and the heat flow meter and is used for comparing and judging the magnitude of the calculated heat flow density data and the magnitude of the actually measured indoor side heat flow density data, and if the calculated heat flow density data is more than or equal to the actually measured indoor side heat flow density data, the actual heat transfer coefficient of the wall body to be measured is judged to be less than or equal to the set value; and if the calculated heat flow density data is smaller than the actually measured indoor side heat flow density data, judging that the actual heat transfer coefficient of the wall body to be measured is larger than the set value.

The engineering field detection system for the wall heat transfer coefficient under the non-constant temperature condition is further improved in that the processing module is further used for amplifying the design values according to set times to obtain corresponding amplification values, calculating the heat flow density change of the indoor side wall surface of the wall to be detected by using the amplification values and the temperature change of all materials of the wall to be detected obtained through solving, and recording the heat flow density change as amplified heat flow density data;

the detection module is further used for finding out data with the highest coincidence degree with the actually measured indoor side heat flow density data from the amplified heat flow density data and the calculated heat flow density data, and outputting a wall heat transfer coefficient corresponding to the data with the highest coincidence degree as a detection result.

The engineering on-site detection system for the wall heat transfer coefficient under the non-constant temperature condition is further improved in that the detection module is further used for drawing a corresponding curve on a graph according to the amplified heat flow density data, the calculated heat flow density data and the actually measured indoor side heat flow density data, and selecting a curve with the trend and the amplitude close to each other of the curve corresponding to the actually measured indoor side heat flow density data from the graph as data with the highest coincidence degree.

The engineering field detection system for the wall heat transfer coefficient under the non-constant temperature condition is further improved in that the detection module is further used for calculating the deviation values of the amplified heat flow density data and the heat flow density data with the actually measured indoor side heat flow density data, and selecting the data with the minimum deviation value as the data with the highest coincidence degree.

The engineering field detection system for the wall heat transfer coefficient under the non-constant temperature condition is further improved in that the processing module calculates the heat flow density data through the following formula:

in the formula (I), the compound is shown in the specification,representing the calculated heat flow density value, h, for the corresponding time k_nThe heat transfer coefficient of the wall body is shown,the temperature value corresponding to the k moment in the temperature change of the inner wall surface of the wall chamber to be measured is shown,and the temperature value corresponding to the k moment in the actually measured indoor temperature data is shown.

Drawings

FIG. 1 is a schematic view of the measurement conditions of the method and system for engineering on-site detection of the heat transfer coefficient of the wall under non-constant temperature conditions.

Fig. 2 is a schematic structural diagram of a wall of an engineering example.

FIG. 3 is a graph of measured heat flux density measurements in an example of a process.

Fig. 4 is a graph showing the measurement results of indoor and outdoor temperatures actually measured in an example of the process.

FIG. 5 is a comparison graph of two calculated heat flow density curves and an actually measured heat flow density curve calculated by the detection system and method of the present invention.

Detailed Description

The invention is further described with reference to the following figures and specific examples.

Referring to fig. 1, the invention provides an engineering field detection method and system for wall heat transfer coefficient under non-constant temperature condition, which solves the bottleneck problem that the traditional field measurement method for wall heat transfer coefficient must depend on stable temperature environment; and a strict indoor constant-temperature environment is not required to be provided, the test cost is saved, and the measurement result can reflect the actual engineering and is more representative. The invention relates to a method and a system for detecting the heat transfer coefficient of a wall body under the non-constant temperature condition in an engineering field, which are disclosed by the invention.

Referring to fig. 1, there is shown a schematic view of fig. 1 illustrating the measurement conditions of the method and system for engineering field testing of wall heat transfer coefficient under non-constant temperature condition according to the present invention. The engineering site detection system for the wall heat transfer coefficient under the non-constant temperature condition of the invention is explained with reference to fig. 1.

As shown in fig. 1, the engineering site detection system for the wall heat transfer coefficient under the non-constant temperature condition of the invention includes an air conditioner 21 disposed indoors, a first temperature sensor 22 disposed indoors, a second temperature sensor 23 disposed outdoors, a heat flow meter 24 disposed on the wall surface of the indoor side wall of the wall 10 to be detected, a processing module and a detection module, wherein the processing module is connected with the air conditioner 21, the first temperature sensor 22, the second temperature sensor 23 and the heat flow meter 24, and the detection module is connected with the processing module and the heat flow meter 24. The air conditioner 21 is used for adjusting the indoor temperature to enable the indoor and outdoor temperature difference of the wall 10 to be measured, preferably, the processing module can control the operation of the air conditioner 21 through a control command, the air conditioner 21 can refrigerate and heat, and as long as the indoor and outdoor temperature difference can be formed, the temperature difference is not required to be ensured to be constant, and the indoor temperature is not required to be ensured to be kept constant. The first temperature sensor 22 is arranged near the heat flow meter 24, and the first temperature sensor 22 is used for acquiring the indoor temperature of the wall 10 to be measured within a set time to form corresponding measured indoor temperature data; a second temperature sensor 23 is also disposed near the heat flow meter 24, and the second temperature sensor 23 is configured to collect the temperature of the outdoor side of the wall 10 to be measured within a set time period to form corresponding measured outdoor temperature data. The heat flow meter 24 is used for acquiring indoor heat flow density of the wall to be measured within a set time to form corresponding actually measured indoor heat flow density data.

The processing module is configured to establish a one-dimensional unsteady heat conduction equation corresponding to the wall 10 to be measured, and solve temperature changes of all materials of the wall 10 to be measured, that is, temperature fields of all materials in the wall 10 to be measured at all times, by using the measured indoor temperature data and the measured outdoor temperature data acquired by the first temperature sensor 22 and the second temperature sensor 23 as boundary conditions. Further, the processing module is used for calculating the heat flow density change of the indoor side wall surface of the wall body 10 to be detected by combining the temperature change of all the materials of the wall body to be detected, which is obtained by solving, and recording the heat flow density change as the calculated heat flow density data; preferably, the set value is the designed heat transfer coefficient of the wall to be tested, the designed heat transfer coefficient is determined according to the parameters of the wall design structure, and the purpose of detecting the heat transfer coefficient of the wall in the engineering field is to judge whether the actual heat transfer coefficient of the wall meets the requirements of the designed heat transfer coefficient.

The detection module is used for comparing and judging the magnitude of the calculated heat flow density data and the actually measured indoor side heat flow density data, if the calculated heat flow density data is larger than or equal to the actually measured indoor side heat flow density data, the actual heat transfer coefficient of the wall body to be detected is judged to be smaller than or equal to a set value, namely the heat transfer coefficient of the wall body meets the design expectation requirement, if the calculated heat flow density data is smaller than the actually measured indoor side heat flow density data, the actual heat transfer coefficient of the wall body to be detected is judged to be larger than the set value, and the actual heat transfer coefficient of the wall body to be detected is judged to be larger than the set value, namely the heat transfer coefficient of the wall body does not meet the design expectation requirement.

The detection of the heat transfer coefficient of the wall body in the engineering site is to judge whether the heat preservation performance of the actually constructed wall body meets the design requirements, namely whether the heat transfer coefficient meets the design requirements, so that the detection system of the invention calculates the heat flow density at the surface of the indoor wall body by utilizing the set heat transfer coefficient and the actually measured indoor and outdoor temperature, and then compares the calculated heat flow density with the actually measured heat flow density.

In a specific embodiment of the present invention, the processing module is further configured to amplify the design values according to a set multiple to obtain corresponding amplification values, and calculate a heat flux density change at the surface of the indoor wall of the wall to be measured by using the amplification values and the temperature changes of all the materials of the wall to be measured obtained by the solution, and record the heat flux density change as amplified heat flux density data; preferably, the magnification is 1.2, 1.5, 2 or 3.

The detection module is also used for finding out data with the highest coincidence degree with the actually measured indoor side heat flow density data from the amplified heat flow density data and the calculated heat flow density data, and outputting a wall heat transfer coefficient corresponding to the data with the highest coincidence degree as a detection result.

The detection system can provide a measured value of the wall heat transfer coefficient, the set wall heat transfer coefficient is amplified, and then the heat flow density change is correspondingly calculated, so that a heat flow density curve can be drawn, the coincidence degree of all the heat flow density curves obtained by calculation and the actually measured heat flow density curve is compared, and the heat flow density curve with the highest coincidence degree is selected, and the heat flow density curve with the highest coincidence degree is closest to the actually measured heat flow density curve, so that the wall heat transfer coefficient corresponding to the heat flow density curve is closest to the actual heat transfer coefficient of the wall.

In one embodiment of the present invention, as shown in fig. 1, a sun visor 25 is placed on the outdoor side of the wall 10 to be measured to prevent solar radiation from affecting the heat flow measurement. When the sun shield cannot be placed, a sunshine sensor is placed on the wall surface of the outdoor side of the wall body 10 to be measured, the sunshine intensity is recorded, and the parameter of the sunshine intensity is added in the subsequent calculation.

In one embodiment of the present invention, the theoretical basis of the one-dimensional unsteady heat conduction equation established by the present invention is a classical heat-source-free heat conduction equation as follows:

where t denotes temperature, x denotes position coordinates (in m), τ denotes time (in s), and α (x, τ) denotes a temperature coefficient (in m)²/s) for walls composed of a combination of layers, the thermal conductivity is considered to be independent of time, i.e.Wherein λ (x) is the thermal conductivity (W/(m.K), C) of the material at position x_p(x) The specific heat capacity (J/(kg. K)) of the material at the position x, and ρ (x) the density (kg/m) of the material at the position x³). This equation is the one-dimensional unsteady heat conduction equation of the present invention.

When the one-dimensional unsteady heat conduction equation is solved, the invention adopts the difference calculation method of the simplest hidden format, the calculation method is unconditionally stable, and the time difference step length can take a larger value, so that the calculation steps are few, the calculation time consumption is short, and the calculation result is more reliable.

Firstly, a differential format is established:

assuming that each material is divided into a plurality of small sections, nodes are also arranged on material interfaces, and n nodes are arranged in total, wherein the node 1 represents the outermost surface of the wall, and the node n represents the wallAt the innermost surface, the temperature of each node is set toWhere j represents the node change and k represents the time step. The basic difference format is then:

namely:

wherein the content of the first and second substances,

in the above formula, α_j,lThe material thermal conductivity coefficient, α, representing the left side of node j_j,rDenotes the material thermal conductivity coefficient on the right side of the node j, Δ τ denotes the differential step of time, Δ x_j,lRepresenting the position coordinate difference step, Δ x, to the left of node j_j,rRepresenting the position coordinate difference step length on the right side of the node j; when j is 1 or n, Δ x_j,l＝Δx_j,r，α_j,l＝α_j,r。

Then, boundary conditions are established:

when the temperature of the inner surface of the wall body is calculated, a third type boundary condition is established according to the following formula:

wherein h is₁Represents the outdoor side heat convection coefficient (m)²·K)，h_nRepresents the heat convection coefficient (m) of the indoor side²·K)，C_p1Represents the specific heat capacity (J/(kg. K), C) of the material of the wall body on the outdoor side_pnRepresents the specific heat capacity (J/(kg. K), ρ, of the material of the wall on the indoor side₁Indicating the density (kg/m) of the material of the wall on the outside of the room³)，ρ_nIndicating the density (kg/m) of the material of the wall on the indoor side³)，ρ_sDenotes the external surface solar radiation absorption coefficient,/^k+1Represents the surface normal total solar radiation intensity (W/m) at the k +1 th time²) Including direct and diffuse radiation, which is calculated as 0 when using a sun visor and as a measured value of a solar radiation sensor when not using a sun visor,represents the outdoor air temperature (. degree. C.) at the time of k +1, which is measured by a temperature sensor on the outdoor side,the room air temperature (. degree. C.) at the time of k +1 is shown, and this value is measured by a room temperature sensor. Lambda [ alpha ]_1,rRepresents the thermal conductivity of the material on the right side of the node 1, i.e. the thermal conductivity of the outermost material of the wall (outside the room), Deltax_1,rThe difference step length of the position coordinate on the right side of the node 1, namely the length of the outermost grid of the wall body, lambda_n,lRepresents the thermal conductivity of the material on the left side of the node n, namely the thermal conductivity of the innermost layer material (indoor side) of the wall, delta x_n,lAnd (4) representing the position coordinate difference step length on the left side of the node n, namely the length of the innermost grid of the wall.

The boundary conditions described above may be rewritten into the following format:

wherein the content of the first and second substances,

and finally, establishing a linear equation set based on the established difference format and the boundary conditions, storing the linear equation set in the processing module, and further inputting the received parameters into the linear equation set to obtain the temperature change condition of each layer of the wall material.

With the temperature field at the k-th time known, the temperature field at the k + 1-th time can be obtained by solving the above equation system. Since the temperature field at the initial moment is known, the temperature fields at all the following moments can be calculated, namely the temperature changes of all the materials of the wall are obtained.

Further, the processing module calculates the heat flux density data by the following formula:

in the formula (I), the compound is shown in the specification,representing the calculated heat flow density value, h, for the corresponding time k_nThe heat transfer coefficient of the wall body is shown,representing the temperature of the wall chamber inner wall surface to be measured at the corresponding k moment in the temperature changeThe value of the one or more of the one,the temperature value corresponding to the k time in the actually measured indoor temperature data is represented by the measured value from the first temperature sensor. Since the temperature change of all the materials of the wall body is obtained in the above step, the temperature change of the inner wall surface of the room can be directly extracted.

In an embodiment of the present invention, the detection module is further configured to draw a corresponding curve on a graph according to the amplified heat flow density data, the calculated heat flow density data, and the actually measured indoor side heat flow density data, and select a curve having a trend and an amplitude close to each other from the graph, as the data with the highest degree of coincidence, the curve corresponding to the actually measured indoor side heat flow density data.

And each heat flow density data is drawn on a graph, and the heat flow curve closest to the actually measured heat flow curve can be directly compared, so that the method is simple and convenient to implement.

In an embodiment of the invention, the detection module is further configured to calculate a deviation value between the amplified heat flow density data and the actually measured indoor side heat flow density data, and select data with the smallest deviation value as data with the highest degree of coincidence.

The deviation value calculation formula is as follows:

wherein Q represents the measured heat flow curve, Q_dRepresenting the calculated heat flow curve, e_jThe calculated heat flow curve corresponding to the minimum value is the curve with the highest goodness of fit with the actually measured heat flow curve.

The following description is given in terms of an engineering case.

As shown in fig. 2, the outer insulation system of ALC board plus I-type STP is adopted in the engineering outer wall, and comprises an outer wall coating layer 1, a veneer base layer 2, a plastering mortar + alkali-resistant coated mesh layer 3, an I-type STP vacuum insulation board 4, a bonding mortar layer 5, a cement mortar leveling layer 6, an ALC board 7, an interface treating agent layer 8, a mixed mortar priming layer 9, a mixed mortar leveling layer 10 and an inner wall coating layer 11 in sequence from outside to inside, wherein the design parameters of each material layer are shown in the following table:

table 1 design parameter table for each material layer of wall

As shown in fig. 3 and 4, measured heat flow measurements and indoor and outdoor temperature measurements are shown.

The detection system firstly calculates the calculated heat flux density data Q of the surface of the indoor side wall under the designed heat transfer coefficient_d0Then, the heat conductivity coefficient of each layer of material is multiplied by an amplification coefficient of 1.5, and the calculated heat flux density Q of the surface of the indoor side wall is obtained through recalculation_d1。

Calculating heat flux density Q from the heat flux measurement Q_d0And Q_d1Plotted on the same graph, with time on the abscissa and heat flux density on the ordinate. As shown in FIG. 5, the lowest curve is the curve corresponding to the heat flow measurement result, and the heat flow density Q is calculated_d0The corresponding curve is slightly higher than the heat flow measurement result curve, and the heat flow density Q is calculated_d1Much larger than the heat flow measurement curve, from which the heat flow density Q is calculated_d0The curve goodness of fit with the heat flow measurement result is highest, and the actual heat transfer coefficient of the wall body is not higher than the design value of 0.2W/(m)²K), meets design expectations.

The invention also provides an engineering field detection method of the wall heat transfer coefficient under the non-constant temperature condition, and the detection method is explained below.

The engineering field detection method of the wall heat transfer coefficient under the non-constant temperature condition comprises the following steps:

adjusting the indoor temperature to generate temperature difference between the indoor and the outdoor of the wall to be measured;

collecting the indoor temperature, the outdoor temperature and the indoor side heat flux density of the wall body to be measured within a set time to form corresponding actually measured indoor temperature data, actually measured outdoor temperature data and actually measured indoor side heat flux density data;

establishing a one-dimensional unsteady heat conduction equation corresponding to the wall to be measured, and solving to obtain the temperature change of all materials of the wall to be measured by using the collected actually-measured indoor temperature data and the actually-measured outdoor temperature data as boundary conditions;

setting the heat transfer coefficient of the wall body as a design value;

calculating the heat flux density change of the indoor side wall surface of the wall to be detected by using the temperature change and the design value of all the materials of the wall to be detected, and recording the heat flux density change as calculated heat flux density data; and

comparing the calculated heat flow density data with the actually measured indoor side heat flow density data, and if the calculated heat flow density data is larger than or equal to the actually measured indoor side heat flow density data, judging that the actual heat transfer coefficient of the wall body to be measured is smaller than or equal to a set value; and if the calculated heat flow density data is smaller than the actually measured indoor side heat flow density data, judging that the actual heat transfer coefficient of the wall body to be measured is larger than a set value.

In one embodiment of the present invention, the method further comprises:

amplifying the design value according to a plurality of set multiples to obtain corresponding amplification values;

calculating the heat flux density change of the indoor side wall surface of the wall to be detected by using the temperature change and the amplification value of all the materials of the wall to be detected, and recording the heat flux density change as amplified heat flux density data;

and finding out the data with the highest coincidence degree with the actually measured indoor side heat flow density data from the amplified heat flow density data and the calculated heat flow density data, and outputting the wall heat transfer coefficient corresponding to the data with the highest coincidence degree as a detection result.

In an embodiment of the present invention, when finding out the data with the highest degree of coincidence with the actually measured indoor side heat flow density data, drawing a corresponding curve on a graph according to the amplified heat flow density data, the calculated heat flow density data and the actually measured indoor side heat flow density data, and selecting a curve with a trend and an amplitude value close to each other of the curve corresponding to the actually measured indoor side heat flow density data as the data with the highest degree of coincidence.

In a specific embodiment of the present invention, when finding out the data that matches the measured indoor-side heat flow density data to the highest extent, calculating the deviation values of the amplified heat flow density data and the heat flow density data from the measured indoor-side heat flow density data;

and selecting the data with the minimum deviation value as the data with the highest coincidence degree.

In a specific embodiment of the present invention, the heat flux density change at the surface of the indoor wall of the wall to be measured is calculated by the following formula and is recorded as the calculated heat flux density data:

in the formula (I), the compound is shown in the specification,representing the calculated heat flow density value, h, for the corresponding time k_nThe heat transfer coefficient of the wall body is shown,the temperature value corresponding to the k moment in the temperature change of the inner wall surface of the wall chamber to be measured is shown,and the temperature value corresponding to the k moment in the actually measured indoor temperature data is shown.

While the present invention has been described in detail and with reference to the embodiments thereof as illustrated in the accompanying drawings, it will be apparent to one skilled in the art that various changes and modifications can be made therein. Therefore, certain details of the embodiments are not to be interpreted as limiting, and the scope of the invention is to be determined by the appended claims.