CN111832111A - Thermal characteristic prediction method and influence factor identification method for thermal activation building system - Google Patents
Thermal characteristic prediction method and influence factor identification method for thermal activation building system Download PDFInfo
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Abstract
The invention discloses a thermal characteristic prediction method and an influence factor identification method for a thermal activation building system, which are used for providing guidance and technical support for design, construction and operation of the thermal activation building system. The thermal characteristic prediction method comprises the following steps: establishing a mathematical model of a three-dimensional dynamic heat transfer process of a thermal activation building system, and predicting thermal characteristics according to the mathematical model; the mathematical model is as follows: the heat transfer boundary of the outer surface is a convection and radiation heat exchange boundary, the heat transfer boundary of the inner surface is a convection heat exchange boundary, the inlet of the embedded pipe is a speed inlet boundary, the outlet of the embedded pipe is a pressure outlet boundary, and the middle interface between the embedded pipes is a symmetrical boundary; the internal surface heat transfer boundary of a thermally activated composite wall is described as:
the heat transfer boundary of the outer surface of the heat-activated composite wall is described as follows:
the method establishes a mathematical model for predicting the thermal characteristics according to the three-dimensional dynamic heat transfer process of the thermal activation building system, is reliable and provides guidance for the thermal activation building system.
Description
Technical Field
The invention relates to the technical field of building energy conservation, in particular to a thermal characteristic prediction method and a thermal characteristic influence factor identification method for a thermal activation building system.
Background
The heat activated building system has good energy-saving potential and design concealment, and meanwhile, can isolate the influence of outdoor climate on indoor environment by using low-grade renewable energy, and is continuously concerned by more and more architects and engineers. In fact, the heat transfer process of a traditional building envelope can be generally simplified to one-way heat transfer from indoor to outdoor or outdoor to indoor, wherein the heat insulation layer generally only plays a role in slowing down and weakening the heat transfer strength between indoor and outdoor, but cannot play a role in completely isolating indoor heat transfer. In contrast, for thermally activated building systems, due to the embedding and integration of fluid pipes in the pipe-inlaid layers and the constant injection of renewable energy, the injected heat is continuously accumulated in the building envelope, and finally a dynamic temperature protection barrier consistent with the indoor temperature is built. Meanwhile, the injected heat is continuously dynamically regulated, the temperature of the temperature protection barrier can be kept dynamically consistent with the indoor set temperature, and the heat transfer between the pipe embedding layer and the indoor space is eliminated, so that the heat load caused by the enclosure structure is finally and completely eliminated. It can be seen that the thermal characteristics of thermally activated building systems, and particularly thermally activated composite walls, are completely different from the thermal characteristics of conventional building envelopes, which directly results in the conventional building envelope design methods being unsuitable for thermally activated building systems.
Due to the embedding and integration of the fluid pipelines, not only can the thermal characteristics of the thermal activation building system be predicted by using a traditional mathematical model, but also the quantity of thermal characteristic influence factors of the thermal activation building system is obviously increased, the interaction mechanism among the influence factors is more complex, and the difficulty of thermal characteristic prediction and influence factor identification of the thermal activation building system is increased greatly. The existing mathematical model related to the traditional wall body cannot be applied to performance prediction of a thermal activation building system, and with the sharp increase of the number of influencing factors, the number of samples required by n influencing factors reaches nnObviously, using conventional orthogonal methodsThe influence of the influencing factors can not have practical operability any more. In addition, although the traditional orthogonal method can obtain the influence of a single influence factor on the thermal characteristics of the wall body, the relative importance degree of the influence factor cannot be effectively identified. Therefore, there is currently no method for predicting thermal characteristics and influencing factors for thermally activated building systems, and the design, construction and operation of thermally activated buildings lacks technical guidance and support.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a thermal characteristic prediction method of a thermal activation building system, which provides guidance and technical support for the design, construction and operation of the thermal activation building system.
Another object of the present invention is to provide a method for identifying thermal characteristic influence factors of a thermally activated building system, which identifies risk variables with different influence degrees and the sequencing results thereof, and provides method guidance and technical support for the design, construction and operation of the thermally activated building system.
The technical scheme adopted for realizing the purpose of the invention is as follows:
a method for predicting thermal characteristics of a thermally activated building system, comprising the steps of: establishing a mathematical model of a three-dimensional dynamic heat transfer process of the thermal activation building system, and predicting the thermal characteristics of the thermal activation building system according to the mathematical model; the mathematical model is as follows: the heat transfer boundary of the outer surface is a convection and radiation heat exchange boundary, the heat transfer boundary of the inner surface is a convection heat exchange boundary, the inlet of the embedded pipe is a speed inlet boundary, the outlet of the embedded pipe is a pressure outlet boundary, and the middle interface between the embedded pipes is a symmetrical boundary;
the heat transfer boundary of the inner surface of the heat activated composite wall is described by the following equation (1):
in the formula: lambda [ alpha ]inThe thermal conductivity coefficient of the plastering layer in the thermally activated composite wall body is expressed by the unit W/(m DEG C),
αinis the convective heat transfer coefficient of the inner surface of a heat-activated composite wall body and has the unit W/(m)2·℃)，
TinThe temperature of the inner surface of the composite wall is thermally activated in unit ℃,
TISsetting the indoor temperature in unit;
the heat transfer boundary of the outer surface of the heat-activated composite wall is described by the following formula (2):
in the formula: lambda [ alpha ]exThe thermal conductivity coefficient of the external plastering layer of the thermally activated composite wall is expressed by the unit W/(m DEG C),
αexis the heat-activated composite wall external surface convection heat transfer coefficient with the unit W/(m)2·℃)，
TaIs the outdoor ambient temperature, in units,
Texin order to thermally activate the temperature of the outer surface of the composite wall body, the unit degree,
ρsin order to thermally activate the radiant heat absorption coefficient of the outer surface of the composite wall body,
i is the intensity of solar radiation, W/m2，
RESFor heat-activated long-wave radiation heat exchange between the outer surface of the composite wall and the surrounding environment, W/m2。
A method for identifying thermal characteristic influence factors of a thermally activated building system comprises the following steps:
(1) extracting a risk variable and a certainty parameter, and determining threshold values of the risk variable and the certainty parameter; the risk variables comprise design risk variables, operation risk variables and material property risk variables;
(2) randomly and hierarchically sampling the risk variables to generate a risk variable sample library;
(3) establishing a mathematical model of a three-dimensional dynamic heat transfer process of a heat activated building system;
(4) checking the obtained mathematical model by using experimental data, and executing the step (5) on the mathematical model meeting the requirements of accuracy and precision;
(5) establishing a geometric model based on deterministic parameters and design-class risk variables for each sample in the risk variable sample library;
(6) loading a mathematical model, an operation risk variable and a material physical property risk variable on the geometric model one by one to obtain a basic model;
(7) initializing the basic model obtained in the step (6) and performing iterative operation to obtain primary result output based on the original data;
(8) performing data processing on the data output based on the primary result of the original data based on the evaluation index to obtain a secondary result output based on the evaluation index;
(9) performing statistical analysis on the secondary result data based on the evaluation indexes, and calculating the total effect index of the risk variable to a single evaluation index; and sorting according to the numerical value of the obtained total effect index; accumulating the ranking orders of the same risk variable in all the evaluation indexes;
(10) determining the influence type of the risk variable according to the sorting order accumulation result;
the mathematical model in the step (3) is as follows: the heat transfer boundary of the outer surface is a convection and radiation heat exchange boundary, the heat transfer boundary of the inner surface is a convection heat exchange boundary, the inlet of the embedded pipe is a speed inlet boundary, the outlet of the embedded pipe is a pressure outlet boundary, and the middle interface between the embedded pipes is a symmetrical boundary;
the heat transfer boundary of the inner surface of the heat activated composite wall is described by the following equation (3):
in the formula: lambda [ alpha ]inThe thermal conductivity coefficient of the plastering layer in the thermally activated composite wall body is expressed by the unit W/(m DEG C),
αinis the convective heat transfer coefficient of the inner surface of a heat-activated composite wall body and has the unit W/(m)2·℃)，
TinThe temperature of the inner surface of the composite wall is thermally activated in unit ℃,
TISsetting the indoor temperature in unit;
the heat transfer boundary of the outer surface of the heat-activated composite wall is described by the following formula (4):
in the formula: lambda [ alpha ]exThe thermal conductivity coefficient of the external plastering layer of the thermally activated composite wall is expressed by the unit W/(m DEG C),
αexis the heat-activated composite wall external surface convection heat transfer coefficient with the unit W/(m)2·℃)，
TaIs the outdoor ambient temperature, in units,
Texin order to thermally activate the temperature of the outer surface of the composite wall body, the unit degree,
ρsin order to thermally activate the radiant heat absorption coefficient of the outer surface of the composite wall body,
i is the intensity of solar radiation, W/m2，
RESFor thermally activating the long-wave radiant heat between the outer surface of the composite wall body and the surrounding environment,W/m2。
the evaluation indexes in the evaluation system of the thermal activation building system comprise pipe-embedded layer injection heat, pipe-embedded layer energy density, inner surface heat load, outer surface loss, inner surface accumulated supercooling duration and inner surface supercooling discomfort, and are calculated by adopting the following formulas respectively:
in the formula:
HLinthe heat load of the heat-activated composite wall body on the unit area of the coldest month is the unit kWh/m2，
QinThe heat load, in kWh,
a is the surface area of the thermally activated composite wall in m2，
qinThe thermal load, in units of W,
HLexthe heat loss of the heat-activated composite wall body in unit area of the coldest month is unit kWh/m2，
QexIn order to thermally activate the external surface heat loss of the composite wall in the coldest month, in kWh,
qexthe heat loss of the exterior surface of the thermally activated composite wall is gradually increased in the coldest month, unit W,
tsumthe total supercooling duration in unit h for the thermally activated composite wall body on the inner surface of the coldest month,
Isumin order to ensure that the thermally activated composite wall has the internal surface supercooling discomfort degree in the coldest month at the unit of DEG C.h,
QIHheat is injected into the pipe-embedding layer of the coldest month for thermally activating the composite wall body, and the unit MJ,
qpipethe heat is injected into the heat activated composite wall body when the pipe is embedded in the coldest month, the unit W,
ED is the energy density of the heat-activated composite wall in the coldest month, and the unit MJ/m3，
QsThe total heat stored in the coldest month, in units MJ,
Tstopthe average temperature of the thermally activated composite wall body after heat injection is unit ℃,
Tstartthe average temperature at the beginning of heat injection of the heat activated composite wall body is unit ℃,
ρcthe density of the pipe embedding layer of the thermally activated composite wall body is unit kg/m3，
ccThe specific heat capacity of the pipe embedding layer of the thermally activated composite wall is expressed by the unit J/(kg ℃);
ti,startthe initial injection time;
ti,stopstopping the injection time;
VCis the volume of a thermally activated composite wall body in m3。
The design risk variables comprise pipe-inserting distance, pipe-inserting diameter, pipe-inserting position, climate zone and orientation; the operation risk variables comprise heat source temperature, indoor set temperature and heat injection duration; the material physical property class risk variables comprise a heat conductivity coefficient of the embedded pipe layer, a specific heat capacity of the embedded pipe layer, a heat conductivity coefficient of the embedded pipe and an absorption coefficient of radiant heat of the outer surface.
Compared with the prior art, the invention has the beneficial effects that:
1. the thermal characteristic prediction method of the thermal activation building system is reliable and provides method guidance and technical support for design, construction and operation of the thermal activation building system.
2. The thermal characteristic influence factor identification method of the thermal activation building system is based on a mathematical model of a three-dimensional dynamic heat transfer process of the thermal activation building system, takes a design-class risk variable, an operation-class risk variable and a material physical property-class risk variable as risk variables, and takes an evaluation system comprising pipe-embedded layer injection heat, pipe-embedded layer energy density, inner surface heat load, outer surface loss, inner surface accumulated supercooling duration and inner surface supercooling discomfort level as evaluation indexes to obtain a thermal characteristic prediction model, thereby providing a basis for the design of the thermal activation building system.
3. The thermal characteristic prediction method and the influence factor identification method for the thermal activation building system are simple and efficient, have the advantages of small number of required samples, high precision and the like, can effectively identify and sequence various types of risk variables and complex interaction among the risk variables, and provide guidance and technical support for design, construction and operation of the thermal activation building system.
Drawings
FIG. 1 is a schematic diagram of a three-dimensional unsteady heat transfer process of a heat-activated composite wall;
fig. 2 is a graph showing the temperature response measured values and the simulated response values of the inner and outer surfaces of the heat-activated composite wall body as a function of time.
In the figure: 1-outer plastering layer, 2-insulating layer, 3-tube embedding layer, 4-inner plastering layer, 5-tube embedding outlet and 6-tube embedding inlet.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings, taking the method for predicting the thermal characteristics of a thermally activated composite wall and identifying the influencing factors as an embodiment.
The invention discloses a thermal characteristic prediction method of a thermal activation building system, which comprises the following steps: establishing a mathematical model of a three-dimensional dynamic heat transfer process of the thermal activation building system, and predicting the thermal characteristics of the thermal activation building system according to the mathematical model; the mathematical model is as follows: the heat transfer boundary of the outer surface of the outer plastering layer 1 is a convection and radiation heat exchange boundary, the heat transfer boundary of the inner surface of the inner plastering layer 4 is a convection heat exchange boundary, the embedded pipe inlet 6 is a speed inlet boundary, the embedded pipe outlet 5 is a pressure outlet boundary, and the middle interface between the embedded pipes is a symmetrical boundary. The dynamic simplified heat transfer process of the heat-activated composite wall body is shown in fig. 1, and in the embodiment, a mathematical model of the three-dimensional dynamic heat transfer process of the heat-activated building system is established by using ANSYS software.
The inner surface of the wall body is an energy exchange interface, the wall body transfers heat to the inner surface interface in a heat conduction mode, the heat is transferred to the interface and then dissipated to the indoor environment in a convection mode, and the heat transferred by heat conduction and the heat dissipated by convection are always equal. Namely: the heat transfer boundary of the inner surface of the heat-activated composite wall is described by the following formula (1):
in the formula: lambda [ alpha ]inThe thermal conductivity coefficient of the plastering layer in the thermally activated composite wall body is expressed by the unit W/(m DEG C),
αinis the convective heat transfer coefficient of the inner surface of a heat-activated composite wall body and has the unit W/(m)2·℃)，
TinThe temperature of the inner surface of the composite wall is thermally activated in unit ℃,
TISthe temperature was set indoors in units of ℃.
The outer surface of the wall body is also an energy exchange interface, the wall body transfers heat to the outer surface interface of the wall body in a heat conduction mode, the outer surface of the wall body absorbs heat from solar radiation, meanwhile, the heat is dissipated to the surrounding environment in a long-wave radiation and convection heat exchange mode, and the heat transferred by heat conduction and the heat dissipated by radiation and convection are always equal to each other. Namely: the heat transfer boundary of the outer surface of the heat-activated composite wall is described by the following formula (2):
in the formula: lambda [ alpha ]exThe thermal conductivity coefficient of the external plastering layer of the thermally activated composite wall is represented by the unit W/(m DEG C);
αexis the heat-activated composite wall external surface convection heat transfer coefficient with the unit W/(m)2·℃)，
TaIs the outdoor ambient temperature, in units,
Texin order to thermally activate the temperature of the outer surface of the composite wall body, the unit degree,
ρsin order to thermally activate the radiant heat absorption coefficient of the outer surface of the composite wall body,
i is the intensity of solar radiation, W/m2，
RESFor thermally activating the long-wave radiant heat between the outer surface of the composite wall and the surrounding environment, W/m2。
And checking the obtained mathematical model by using experimental data, wherein the checking process is as follows: firstly, acquiring reference experiment data by using a thermal activation composite wall experiment detection platform, secondly, establishing a virtual physical model completely consistent with the experiment detection platform in size specification by using a Geometry module of ANSYS software, coupling the mathematical model on the basis of the virtual physical model, and finally carrying out numerical solution on the mathematical model to obtain simulation data of the temperature of the inner surface and the outer surface, wherein the checking result of the experiment data and the simulation data is shown in figure 2. The experimental data and the simulation data in fig. 2 show that the maximum error between the measured values of the temperatures of the inner and outer surfaces of the thermally activated composite wall and the simulated values obtained by the mathematical model simulation is within 5%, and the prediction accuracy and precision of the mathematical model meet the requirements.
The invention discloses a method for identifying thermal characteristic influence factors of a thermal activation building system, which comprises the following steps:
1. extracting risk variables and certainty parameters, and determining threshold values of the risk variables and the certainty parameters:
for the heat activated composite wall, the known deterministic parameters in the design stage include the wall composition, wherein the wall composition is as shown in fig. 1, the outer plastering layer 1 is 20mm from outdoor to indoor, the heat insulation layer 2 meeting the thermal parameter limit thickness of four climatic regions in the standard specification, the embedded pipe layer 3 is 200mm, and the inner plastering layer 4 is 20 mm. The thickness of the building insulation layer of the cold climate zone, the hot winter cold climate zone and the hot winter warm climate zone is respectively 88mm, 64mm, 36mm and 22 mm.
And determining the risk variable and the threshold value of the thermally activated composite wall according to the known basic design parameters, the current building energy-saving design standard specification and the field investigation data in the design stage. The total number of risk variables comprising category 3 is 12. Wherein the design class risk variables are: the pipe-inserting distance PS, the pipe-inserting diameter PD, the pipe-inserting position PL, the climate zone CZ and the orientation OT; run class risk variables: heat source temperature HT, indoor set temperature IS and heat injection duration CD; material property class risk variables: the heat conduction coefficient Mtc of the embedded pipe layer, the specific heat capacity Msc of the embedded pipe layer, the heat conduction coefficient Ptc of the embedded pipe and the radiation heat absorption coefficient RA of the outer surface. The information of the range threshold, the name, the abbreviation and the threshold range of the extracted risk variable is shown in table 1.
TABLE 1 Risk variables and their Range thresholds
2. Randomly and hierarchically sampling the risk variables to generate a risk variable sample library:
after the risk variables and the threshold value range thereof are determined, the 12 risk variables are subjected to hierarchical random sampling by using R language software and a Latin Hypercube software package, the sampling frequency is at least not lower than 120 groups, and in order to obtain a more reliable statistical analysis result, a risk variable sample library containing 200 groups of risk variable combinations is finally generated.
3. Establishing a mathematical model of a three-dimensional dynamic heat transfer process of a heat activated building system: the establishment of the mathematical model is the same as the thermal characteristic prediction method of the thermal activation composite wall body.
And after the sample library of the risk variables is generated, establishing a thermal activation composite wall three-dimensional unsteady heat transfer process mathematical model in ANSYS software. The dynamic simplified heat transfer process of the thermally activated composite wall is shown in fig. 1, wherein the outer surface is simplified into convection and radiation heat transfer boundaries, the inner surface heat transfer boundary is a convection heat transfer boundary, the embedded tube inlet 6 is a velocity inlet boundary, the embedded tube outlet 5 is a pressure outlet boundary, and the middle interface between the embedded tubes is a symmetrical boundary.
Wherein the heat transfer boundary of the thermally activated composite wall interior surface is described by formula (1); the heat transfer boundary of the thermally activated composite wall exterior surface is described by equation (2).
4. And checking the mathematical model by using experimental data, wherein the checking process is the same as that in the thermal characteristic prediction method of the thermal activation composite wall body. It can be known from the checking result of fig. 2 that the maximum error between the measured values of the temperatures of the inner and outer surfaces of the thermally activated composite wall and the simulated values obtained by simulation using the prediction model is within 5%, and the prediction accuracy and precision of the mathematical model meet the requirements. Then step 5 is performed.
5. Establishing a geometric model for each sample in the risk variable sample library based on deterministic parameters and design class risk variables: the geometric model is a virtual real object built into the computer according to the dimensions of the object under study.
Based on the deterministic parameters in the step 1 and the design variables in the 200 groups of samples in the risk variable sample library in the step 2, 200 groups of geometric models containing the deterministic parameters and the design risk variables are established one by using a Geometry module in ANSYS software.
6. Loading a mathematical model and operating risk variables and material property risk variables:
on the basis of the 200 groups of geometric models obtained in the step 5, grid division is carried out on more than one pair of geometric models by means of a Meshing module in ANSYS, heat transfer boundaries are named one by one according to the setting principle of the heat transfer boundaries in the mathematical models, then the mathematical models and the operation type and material property type risk variables are loaded on the heat transfer boundaries of each geometric model in a solver, and 200 groups of basic models based on the mathematical models and the geometric models are obtained.
7. And (4) initializing the basic model obtained in the step (6) based on meteorological factors in the uncertainty parameters, giving the initial temperature required by the iterative computation of the thermally activated composite wall, and performing iterative simulation computation on the basic model after the computation time and the iteration steps are set. And (4) completing simulation calculation on all samples, then deriving a simulation calculation result based on the original data, and obtaining a result output based on the original data.
8. And importing the primary result based on the original data into Excel software by writing macro statements, and performing data processing on the data of the primary result based on the original data based on evaluation indexes to obtain and output a secondary result based on the evaluation indexes. The evaluation indexes in the evaluation system of the thermal activation building system comprise inner surface heat load, outer surface heat loss, inner surface accumulated supercooling duration, inner surface supercooling discomfort, pipe embedding layer injection heat and pipe embedding layer energy density. The calculation formulas of the above 6 evaluation indexes are as follows in sequence:
in the formula:
HLinthe heat load of the heat-activated composite wall body on the unit area of the coldest month is the unit kWh/m2，
QinThe heat load, in kWh,
a is the surface area of the thermally activated composite wall in m2，
qinThe thermal load, in units of W,
HLexthe heat loss of the heat-activated composite wall body in unit area of the coldest month is unit kWh/m2，
QexIn order to thermally activate the external surface heat loss of the composite wall in the coldest month, in kWh,
qexthe heat loss of the exterior surface of the thermally activated composite wall is gradually increased in the coldest month, unit W,
tsumthe total supercooling duration in unit h for the thermally activated composite wall body on the inner surface of the coldest month,
Isumin order to ensure that the thermally activated composite wall has the internal surface supercooling discomfort degree in the coldest month at the unit of DEG C.h,
QIHheat is injected into the pipe-embedding layer of the coldest month for thermally activating the composite wall body, and the unit MJ,
qpipethe heat is injected into the heat activated composite wall body when the pipe is embedded in the coldest month, the unit W,
ED is heatActivating the energy density of the composite wall in the coldest month in MJ/m3，
QsThe total heat stored in the coldest month, in units MJ,
Tstopthe average temperature of the thermally activated composite wall body after heat injection is unit ℃,
Tstartthe average temperature at the beginning of heat injection of the heat activated composite wall body is unit ℃,
ρcthe density of the pipe embedding layer of the thermally activated composite wall body is unit kg/m3，
ccThe specific heat capacity of the pipe embedding layer of the thermally activated composite wall is expressed by the unit J/(kg ℃);
ti,startthe initial injection time;
ti,stopstopping the injection time;
VCis the volume of a thermally activated composite wall body in m3。
9. Performing statistical analysis on secondary result output data based on the evaluation indexes, and calculating the total effect index of the risk variable to a single evaluation index; and sorting according to the numerical value of the obtained total effect index; and accumulating the ranking order of the same risk variable in all the evaluation indexes. The ranking results of the risk variables for a single evaluation index and the cumulative results of the ranking orders of the single risk variables in different evaluation indexes are shown in table 2.
TABLE 2 Risk variables ranking results
Note: with "+" signs "the effect is" greater "; unsigned notation represents "impact"; the sign with "#" represents little or no effect.
10. And determining the influence type of the risk variable according to the sorting order accumulation result.
Through the sorting results of the risk variables in table 2, it can be identified that four input variables, namely heat source temperature (HT), indoor set temperature (IS), heat injection time (CD) and embedded pipe layer heat conductivity coefficient (Mtc), are key influence factors of thermal characteristics of the thermally activated composite wall, and the influence of four input variables, namely embedded Pipe Diameter (PD), Orientation (OT), embedded pipe layer heat capacity (Msc) and embedded pipe heat conductivity coefficient (Ptc), on the thermal characteristics of the thermally activated composite wall IS basically negligible.
The thermal characteristic prediction method and the influence factor identification method for the thermal activation building system are simple and efficient, the number of required samples is small, multiple types of risk variables and complex interaction among the risk variables can be effectively identified and sequenced, and guidance and technical support are provided for design, construction and operation of the thermal activation building system.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (4)
1. A method for predicting thermal characteristics of a thermally activated building system, comprising the steps of: establishing a mathematical model of a three-dimensional dynamic heat transfer process of the thermal activation building system, and predicting the thermal characteristics of the thermal activation building system according to the mathematical model; the mathematical model is as follows: the heat transfer boundary of the outer surface is a convection and radiation heat exchange boundary, the heat transfer boundary of the inner surface is a convection heat exchange boundary, the inlet of the embedded pipe is a speed inlet boundary, the outlet of the embedded pipe is a pressure outlet boundary, and the middle interface between the embedded pipes is a symmetrical boundary;
the heat transfer boundary of the inner surface of the heat activated composite wall is described by the following equation (1):
in the formula: lambda [ alpha ]inFor guiding the plastering layer in the thermally activated composite wallThermal coefficient, in units W/(m. DEG C),
αinis the convective heat transfer coefficient of the inner surface of a heat-activated composite wall body and has the unit W/(m)2·℃)，
TinThe temperature of the inner surface of the composite wall is thermally activated in unit ℃,
TISsetting the indoor temperature in unit;
the heat transfer boundary of the outer surface of the heat-activated composite wall is described by the following formula (2):
in the formula: lambda [ alpha ]exThe thermal conductivity coefficient of the external plastering layer of the thermally activated composite wall is expressed by the unit W/(m DEG C),
αexis the heat-activated composite wall external surface convection heat transfer coefficient with the unit W/(m)2·℃)，
TaIs the outdoor ambient temperature, in units,
Texin order to thermally activate the temperature of the outer surface of the composite wall body, the unit degree,
ρsin order to thermally activate the radiant heat absorption coefficient of the outer surface of the composite wall body,
i is the intensity of solar radiation in W/m2，
RESFor heat-activated long-wave radiation heat exchange between the outer surface of the composite wall and the surrounding environment, the unit is W/m2。
2. A method for identifying thermal characteristic influence factors of a thermally activated building system is characterized by comprising the following steps:
(1) extracting a risk variable and a certainty parameter, and determining threshold values of the risk variable and the certainty parameter; the risk variables comprise design risk variables, operation risk variables and material property risk variables;
(2) randomly and hierarchically sampling the risk variables to generate a risk variable sample library;
(3) establishing a mathematical model of a three-dimensional dynamic heat transfer process of a heat activated building system;
(4) checking the obtained mathematical model by using experimental data, and executing the step (5) on the mathematical model meeting the requirements of accuracy and precision;
(5) establishing a geometric model based on deterministic parameters and design-class risk variables for each sample in the risk variable sample library;
(6) loading a mathematical model, an operation risk variable and a material physical property risk variable on the geometric model one by one to obtain a basic model;
(7) initializing the basic model obtained in the step (6) and performing iterative operation to obtain primary result output based on the original data;
(8) performing data processing on the data output based on the primary result of the original data based on the evaluation index to obtain a secondary result output based on the evaluation index;
(9) performing statistical analysis on the secondary result data based on the evaluation indexes, and calculating the total effect index of the risk variable to a single evaluation index; and sorting according to the numerical value of the obtained total effect index; accumulating the ranking orders of the same risk variable in all the evaluation indexes;
(10) determining the influence type of the risk variable according to the sorting order accumulation result;
the mathematical model in the step (3) is as follows: the heat transfer boundary of the outer surface is a convection and radiation heat exchange boundary, the heat transfer boundary of the inner surface is a convection heat exchange boundary, the inlet of the embedded pipe is a speed inlet boundary, the outlet of the embedded pipe is a pressure outlet boundary, and the middle interface between the embedded pipes is a symmetrical boundary;
the heat transfer boundary of the inner surface of the heat activated composite wall is described by the following equation (3):
in the formula: lambda [ alpha ]inThe thermal conductivity coefficient of the plastering layer in the thermally activated composite wall body is expressed by the unit W/(m DEG C),
αinis the convective heat transfer coefficient of the inner surface of a heat-activated composite wall body and has the unit W/(m)2·℃)，
TinThe temperature of the inner surface of the composite wall is thermally activated in unit ℃,
TISsetting the indoor temperature in unit;
the heat transfer boundary of the outer surface of the heat-activated composite wall is described by the following formula (4):
in the formula: lambda [ alpha ]exThe thermal conductivity coefficient of the external plastering layer of the thermally activated composite wall is expressed by the unit W/(m DEG C),
αexis the heat-activated composite wall external surface convection heat transfer coefficient with the unit W/(m)2·℃)，
TaIs the outdoor ambient temperature, in units,
Texin order to thermally activate the temperature of the outer surface of the composite wall body, the unit degree,
ρsfor thermally activating composite wall surfacesThe absorption coefficient of the surface radiant heat is,
i is the intensity of solar radiation, W/m2，
RESFor heat-activated long-wave radiation heat exchange between the outer surface of the composite wall and the surrounding environment, W/m2。
3. A method for identifying thermal characteristic influencing factors of a thermally activated building system according to claim 2, wherein the evaluation indexes in the evaluation system of the thermally activated building system include the heat quantity injected into the pipe-inlaid layer, the energy density of the pipe-inlaid layer, the heat load of the inner surface, the loss of the outer surface, the cumulative supercooling duration of the inner surface and the supercooling discomfort level of the inner surface, and are calculated by adopting the following formulas respectively:
in the formula:
HLinthe heat load of the heat-activated composite wall body on the unit area of the coldest month is the unit kWh/m2，
QinFor thermally activating the internal surface heat of composite wall in the coldest moonThe load, in kWh units,
a is the surface area of the thermally activated composite wall in m2，
qinThe thermal load, in units of W,
HLexthe heat loss of the heat-activated composite wall body in unit area of the coldest month is unit kWh/m2，
QexIn order to thermally activate the external surface heat loss of the composite wall in the coldest month, in kWh,
qexthe heat loss of the exterior surface of the thermally activated composite wall is gradually increased in the coldest month, unit W,
tsumthe total supercooling duration in unit h for the thermally activated composite wall body on the inner surface of the coldest month,
Isumin order to ensure that the thermally activated composite wall has the internal surface supercooling discomfort degree in the coldest month at the unit of DEG C.h,
QIHheat is injected into the pipe-embedding layer of the coldest month for thermally activating the composite wall body, and the unit MJ,
qpipethe heat is injected into the heat activated composite wall body when the pipe is embedded in the coldest month, the unit W,
ED is the energy density of the heat-activated composite wall in the coldest month, and the unit MJ/m3，
QsThe total heat stored in the coldest month, in units MJ,
Tstopthe average temperature of the thermally activated composite wall body after heat injection is unit ℃,
Tstartthe average temperature at the beginning of heat injection of the heat activated composite wall body is unit ℃,
ρcthe density of the pipe embedding layer of the thermally activated composite wall body is unit kg/m3，
ccThe specific heat capacity of the pipe embedding layer of the thermally activated composite wall is expressed by the unit J/(kg ℃);
ti,startthe initial injection time;
ti,stopstopping the injection time;
VCfor thermally activating composite wallsVolume in m3。
4. A method of identifying thermally activated building system thermal property influencing factors according to claim 2 or 3, wherein the design-like risk variables include slug spacing, slug diameter, slug position, climate zone and orientation; the operation risk variables comprise heat source temperature, indoor set temperature and heat injection duration; the material physical property class risk variables comprise a heat conductivity coefficient of the embedded pipe layer, a specific heat capacity of the embedded pipe layer, a heat conductivity coefficient of the embedded pipe and an absorption coefficient of radiant heat of the outer surface.
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| 朱丽等: "热激活相变复合墙体动态热特性与节能潜力", 《重庆大学学报》 * |
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