WO2021057021A1 - Calculation method for non-steady-state radiant heat transfer load of layered air conditioner in large space building - Google Patents

Abstract

Provided in the present invention is a calculation method for a non-steady-state radiant heat transfer load of a layered air conditioner in a large space building, which is used to perform non-steady-state calculations on a radiant heat transfer load from a non-air conditioner area to an air conditioner area in a layered air conditioner load of a large space building, so as to resolve the problem in which the radiant heat transfer load can only be calculated stably in a layered air conditioner design, and the problem of inaccurate calculations, and so on. The method is characterized in comprising the following steps: step S1, fitting hour-by-hour outdoor air integrated temperatures, and expanding changes in the hour-by-hour outdoor air integrated temperatures into a Fourier series form; step S2, calculating hour-by-hour internal wall temperatures; step S3, calculating hour-by-hour radiant heat transfer amounts; step S4, fitting the hour-by-hour radiant heat transfer amounts; step S5, calculating a non-steady-state radiant heat transfer load.

Description

Calculation method of unsteady-state radiant heat transfer load for layered air-conditioning in large space buildings Technical field

The invention belongs to the technical field of air conditioning load calculation for large space buildings, and specifically relates to a method for calculating the unsteady radiant heat transfer load of a layered air conditioning system for large space buildings.

Background technique

Taking into account the reduction of building energy consumption and the improvement of indoor air quality, large-space buildings often use layered air conditioning. Stratified air-conditioning refers to an air-conditioning method in which only the lower part of a large-space building is air-conditioned, and the upper space is not air-conditioned. Therefore, the stratified air-conditioning load in a large space building refers to the load that is only responsible for the air conditioning in the lower air-conditioning area. The stratified air-conditioning load is the basis for determining the cooling capacity provided by the air-conditioning system to the room, and it is also the key to assessing the energy of the stratified air conditioning.

Under stratified air-conditioning in large space buildings, the indoor thermal environment is characterized by the vertical temperature stratification and obvious gradient of indoor air; the temperature of the inner wall and the air temperature in the non-air-conditioned area are much higher than the temperature of the air-conditioned area, so the non-air-conditioned area will The heat is transferred to the lower air-conditioned area through different forms, thereby forming a load in the air-conditioned area. The layered air-conditioning load of large space buildings increases the radiant heat transfer load and convective heat transfer load on the basis of the conventional air-conditioning load in the air-conditioned area.

The amount of radiant heat transfer is the basis for the calculation of radiant heat transfer load. The amount of radiant heat transfer includes the amount of wall radiant heat transfer and the amount of solar radiant heat transfer. The amount of wall radiant heat transfer is the radiative heat transfer between the walls caused by the temperature difference between each wall of the non-air-conditioned area and each wall of the air-conditioned area. The amount of solar radiant heat transfer is the radiation brought by the solar radiation transmitted through the windows of the non-air-conditioned area reaching the walls of the air-conditioned area. Get hot. The amount of radiant heat transferred into the air-conditioned area is stored and released by the enclosure structure of the air-conditioned area, forming the radiant heat transfer load of the air-conditioned area. The effects of complex indoor air distribution, outdoor environment changes, and indoor heat source distribution in large-space buildings will cause changes in indoor thermal environment parameters and changes in radiant heat transfer load. Therefore, the calculation of radiant heat transfer load has always been a problem for designers.

At present, the calculation method of radiant heat transfer load in the layered air conditioning load of large space buildings adopts the steady-state calculation method mentioned in the "Practical Heating and Air Conditioning Design Manual". The calculation of the radiant heat transfer load is divided into two steps: one is radiant heat transfer The quantity is based on the radiant heat transfer from the non-air-conditioned area to the floor of the air-conditioned area and the solar radiant heat absorbed by the floor through the windows of the non-air-conditioned area, multiplied by the air-conditioned area heat correction coefficient (recommended 1.3) to obtain the non-air-conditioned area direction For the radiant heat transfer volume of the air-conditioned area, the wall radiant heat transfer calculation adopts the direct radiation model; the second is the radiative transfer load formed by the radiant heat transfer volume, which is multiplied by the radiant heat transfer volume by the cooling load coefficient (take 0.45～0.72, Generally take 0.5) method to determine. The specific calculation formula is as follows:

(1) Calculate the amount of radiant heat transfer:

In the formula: Q _R ——the amount of radiant heat transfer from the non-air-conditioned area to the air-conditioned area, in W;

∑Q _i,d ——The radiant heat transfer of the wall i facing the floor in the non-air-conditioned area, in W;

N——Number of walls in non-air-conditioned area;

∑Q _k,d ——The solar heat absorbed by the floor through the non-air-conditioned area k windows, the unit is W;

N’——Number of non-air-conditioning windows;

C ₁ ——Heat gain correction coefficient of air-conditioning zone, generally taken as 1.3;

X _i,d ——the angle coefficient of the wall i of the non-air-conditioned area facing the floor;

F _i ——The calculated area of the wall of non-air-conditioned area i, in m ² ;

ε _i ,ε _d ——respectively the emissivity of the wall and floor of the non-air-conditioned area i;

σ——Stephen-Boltzmann constant, 5.67×10 ^-8 W/(m ² ·K ⁴ );

T _i , T _d ——the absolute temperature of the wall and floor of the non-air-conditioned area i, in K;

ρ _d ——The solar radiation absorption rate of the air-conditioned area floor;

X _k,d ——the angle coefficient of the window of the non-air-conditioned area k to the floor;

F _k —— window area of non-air-conditioned area k, in m ² ;

J _k ——The intensity of solar radiation passing through k windows in the non-air-conditioned area, in W/m ² .

(2) The cooling load formed by the amount of radiant heat transfer, that is, the radiant heat transfer load can be calculated as follows:

CLQ _R = C ₂ Q _R

Where: CLQ _R —— radiant heat transfer load from non-air-conditioned area to air-conditioned area, unit W;

C ₂ —— cooling load coefficient, which is 0.45～0.72, generally 0.5.

The calculation method of the above-mentioned radiant heat transfer load was obtained by scientific researchers in the 1980s through experimental research, theoretical discussion, and on-site testing of the nozzle-splitting stratified air conditioner of a large steam turbine workshop. The research depth of this calculation method is limited by the research conditions of the thermal environment of large-space buildings at that time, many of which use the empirical values summarized by the measured data at that time, and the experimental and measured conditions are single. Based on the current depth of research on the indoor thermal environment of large-space buildings, the shortcomings and deficiencies of this calculation method are:

(1) The direct radiation model is used when calculating the radiant heat transfer, that is, when calculating the radiant heat transfer between the wall of the non-air-conditioned area and the wall of the air-conditioned area, only the direct radiation part is considered, and the reflection and absorption are ignored, and there is a certain error in the calculation result;

(2) Multiply the radiant heat transfer from the wall of the non-air-conditioned area facing the floor of the air-conditioned area by the air-conditioned area heat correction coefficient C ₁ (take 1.3) to determine the radiative transfer heat from the entire non-air-conditioned area to the air-conditioned area, and the heat correction coefficient It has nothing to do with parameters such as stratification height, which is obviously unreasonable, so this coefficient is not universal;

(3) The cooling load coefficient C _{2 is used to} determine the radiant heat transfer load. The recommended value range is 0.45～0.72, generally 0.5, but the specific application range of different values is not given;

(4) The method of using the cooling load coefficient as a constant to determine the cooling load does not meet the modern requirements for non-steady-state load calculations.

Summary of the invention

In order to solve the above problems, the present invention provides a method that can calculate the radiant heat transfer load from the non-air-conditioned area to the air-conditioned area in the air-conditioned area of a large space building, and provides an effective basis for air-conditioning designers when designing layered air-conditioning in large space buildings. The calculation method of unsteady-state radiant heat transfer load, and its technical scheme:

The invention provides a complete calculation method for the unsteady-state radiant heat transfer load of stratified air-conditioning in large space buildings, which is used to calculate the unsteady-state radiant heat transfer load from the non-air-conditioned area to the air-conditioned area in the layered air-conditioning load of large space buildings. The calculation is characterized in that it includes the following steps: step S1, fitting the hourly integrated outdoor air temperature t _Z,τ , and expanding the time-wise change of the outdoor air integrated temperature into a Fourier series; step S2, calculating the The inner wall surface temperature θ _{N,τ at time} ; step S3, calculate the time-to-time radiant heat transfer Q _R,j,τ ; step S4, fit the time-to-time radiant heat transfer Q _R,j,τ ; step S5: Calculate the non-steady-state radiant heat transfer load CLQ _R,τ .

In order to facilitate engineering calculations, the present invention simplifies it on the basis of a complete calculation method, and also provides a simplified engineering calculation method for the unsteady-state radiant heat transfer load of a layered air conditioning system in a large space building, which is characterized in that it includes: Step T1: Fit the hourly comprehensive outdoor air temperature t _Z,τ ; Step T2: Calculate the hourly inner wall temperature θ _N,τ ; Step T3, use the direct radiation model and the model to modify the coefficient C ₀ value and the wall surface of the air-conditioning zone Calculate the hourly radiant heat transfer quantity Q _R,τ by the heat correction coefficient C _1a value and the solar air-conditioning zone heat correction coefficient C _1b value; step T4, fit the hourly radiant heat transfer quantity Q _R,τ ; step T5 , Calculate the non-steady-state radiant heat transfer load CLQ _R,τ .

The simplified calculation method for the unsteady-state radiant heat transfer load engineering of the stratified air-conditioning in the large space building provided by the present invention may also have such technical characteristics, wherein the model correction coefficient C ₀ is the non-air-conditioned area calculated by the Gebhart radiation model The ratio of the radiant heat transfer from each wall to the floor of the air-conditioned area and the direct radiation model to calculate the ratio of the radiant heat from each wall to the floor of the air-conditioned area in the non-air-conditioned area. The wall heat correction coefficient C _{1a of the} air-conditioned area is the air conditioner calculated by the Gebhart radiation model. The ratio of the sum of the amount of radiant heat transfer from each wall of the zone to the amount of radiant heat transfer from the floor of the air-conditioned zone. The solar heat gain correction coefficient C _1b of the air-conditioned zone is the sum of the amount of solar radiant heat transfer from the non-air-conditioned zone absorbed by each wall of the air-conditioned zone and the air-conditioned zone The floor absorbs the ratio of solar radiation heat transfer from non-air-conditioned areas.

Invention function and effect

According to the method for calculating the non-steady-state radiant heat transfer load of the stratified air conditioner in the large space building of the present invention, the method first calculates the inner wall surface of the non-air-conditioned area and the air-conditioned area under the action of the outdoor periodic disturbance. In the calculation, use the harmonic response method to consider the heat storage characteristics of the envelope structure; then calculate the time-by-time wall radiant heat transfer between each wall in the non-air-conditioned area and each wall in the air-conditioned area according to the time-by-time inner wall temperature, which is used in the calculation Gebhart radiation model (considering direct radiation absorption and primary reflection absorption) replaces the direct radiation model for calculation; then calculates based on the hourly solar radiation intensity through the outer window of the non-air-conditioned area, and the angle of each outer window of the non-air-conditioned area to each wall of the air-conditioned area The coefficient, the absorption rate of each wall material in the air-conditioned area to the solar radiation, the hourly solar radiant heat transfer amount is calculated; the sum of the hourly wall radiant heat transfer amount and the hourly solar radiant heat transfer amount can be obtained from the non-air-conditioned area to the air-conditioned area Finally, on the basis of the hourly radiant heat transfer amount, according to the heat release attenuation and delay characteristics of each wall of the air-conditioned area, the harmonic response method is used to calculate the non-steady-state non-air-conditioned area to the air-conditioned area. Radiant heat transfers the load. Therefore, the unsteady-state radiant heat transfer load calculation method of the present invention can accurately calculate the unsteady-state radiant heat transfer load in each time period in a large space building, and solves the problem that the radiant heat transfer load in the air-conditioned space can only be stabilized in the past. The state calculation leads to the problem that the calculated load does not conform to the actual situation, which provides a stronger numerical basis for the air-conditioning designer in the air-conditioning design, and finally makes the cooling equipment power consumption provided by the hierarchical air-conditioning equipment system design closer to the actual situation.

In addition, the present invention also provides a simplified engineering calculation method for the unsteady-state radiant heat transfer load of a stratified air conditioner in a large space building. The method obtains the model correction coefficient C ₀ value and the heat gain of the wall air-conditioning zone by looking up the line calculation graph. Correction coefficient C _1a value and solar air-conditioning zone heat correction coefficient C _1b value, and then calculate the radiant heat transfer amount of the air-conditioning zone, making the calculation process more simplified and in line with engineering needs; on this basis, according to the enclosure structure of the air-conditioning zone Calculate the radiant heat transfer load of the air-conditioned area based on the heat release characteristics of the air-conditioning area, that is, as long as the heat release attenuation degree and the heat release delay time of the envelope structure are known, the unsteady-state radiant heat transfer load can be calculated. The present invention is based on the large-space building air-conditioning area The heat release characteristics of the five walls are obtained by the superposition calculation of the harmonic method, which is different from the room with the 6 walls of the small room by calculation of the overall heat release characteristics of the room. Compared with the traditional method, the correction coefficient used in the engineering simplification method of the present invention takes into account a variety of factors, so that the correction coefficient can be checked according to the actual situation, and the result of the radiant heat transfer amount obtained is more accurate. The calculation of the radiant heat transfer load adopts the method of the present invention, so that the result is more in line with the actual situation and meets the requirements of calculating the dynamic load.

Description of the drawings

Fig. 1 is a flowchart of a method for calculating unsteady-state radiant heat transfer load in the first embodiment of the present invention;

2 is a schematic diagram of the division of ground heat transfer zones in the first embodiment of the present invention;

Fig. 3 is a schematic diagram of a typical structure of a large-space building in the first embodiment of the present invention;

4 is a calculation diagram of the value line of the model correction coefficient C _{0 in the second embodiment of the present invention;}

Fig. 5 is a calculation diagram of the value line of the _{heat gain correction coefficient C 1a} of the wall air-conditioning zone in the second embodiment of the present invention;

Fig. 6 is a calculation diagram of the value line of the _{heat gain correction coefficient C 1b} of the solar air-conditioning zone in the second embodiment of the present invention;

Fig. 7 is a flowchart of a method for calculating an unsteady-state radiant heat transfer load in the second embodiment of the present invention;

Fig. 8 is a plan layout diagram of a scaled model laboratory in an embodiment of the present invention;

Figure 9 is a schematic diagram of a scaled model laboratory air conditioning system in an embodiment of the present invention;

Figure 10 is a layout diagram of experimental measuring points in an embodiment of the present invention;

Fig. 11 is a layout diagram of the tuyere and duct of the scaled model laboratory in the embodiment of the present invention;

Figure 12 is a photo of the wind pipe arrangement site in the embodiment of the present invention;

FIG. 13 is a technical roadmap of a method for calculating unsteady-state radiant heat transfer load of a layered air conditioner in a large space building in an embodiment of the present invention;

14 is a graph of the measured value and the fitted value of the radiant heat transfer amount in the embodiment of the present invention;

15 is a curve diagram of the relative deviation between the measured value of the radiant heat transfer amount and the fitted value in an embodiment of the present invention;

FIG. 16 is the verification result of the complete calculation method of the unsteady-state radiant heat transfer load in the embodiment of the present invention; and

FIG. 17 is the verification result of the simplified calculation method of the unsteady-state radiant heat transfer load engineering in the embodiment of the present invention.

detailed description

In order to make it easy to understand the technical means, creative features, objectives and effects achieved by the present invention, the method for calculating the unsteady radiant heat transfer load of the large-space building layered air conditioner of the present invention will be described in detail below with reference to the embodiments and drawings.

<Example One>

The first embodiment provides a complete calculation method for the non-steady-state radiant heat transfer load of a stratified air conditioner in a large space building. In the complete calculation method, first calculate the time-by-time temperature of the inner wall surface of the non-air-conditioned area and the air-conditioned area under the action of the outdoor periodic disturbance, and use the harmonic response method to consider the heat storage characteristics of the enclosure during the calculation; Then calculate the time-by-time wall radiant heat transfer between each wall of the non-air-conditioned area and each wall surface of the air-conditioned area according to the time-by-time inner wall temperature. The Gebhart radiation model (considering direct radiation absorption and one-time reflection absorption) is used in the calculation instead of the direct radiation model. Calculate; then calculate the hourly solar radiation intensity through the external windows of the non-air-conditioned area, and the angle coefficients of each external window of the non-air-conditioned area to each wall surface of the air-conditioned area, and the solar radiation absorption rate of each wall material in the air-conditioned area. The amount of solar radiant heat transfer; the sum of the time-by-time wall surface radiant heat transfer and the time-by-hour solar radiant heat transfer can then get the time-by-time radiant heat transfer from the non-air-conditioned area to the air-conditioned area; finally, the time-by-hour radiant heat transfer is obtained On the basis, according to the heat release attenuation and delay characteristics of each wall of the air-conditioned area, the harmonic response method is used to calculate the radiant heat transfer load from the non-steady-state non-air-conditioned area to the air-conditioned area.

Fig. 1 is a flowchart of a method for calculating unsteady-state radiant heat transfer load in the first embodiment of the present invention.

As shown in Figure 1, the complete calculation method of the unsteady-state radiant heat transfer load calculation method for the layered air-conditioning of large space buildings includes the following steps:

Step S1, fitting the hourly integrated outdoor air temperature.

Using the time-to-time change data of the outdoor air comprehensive temperature, it is fitted into a Fourier series form, as shown in formula (1):

In the formula: t _{Z,τ ——Calculate the hourly} integrated outdoor air temperature of the day, in ℃;

t _Z,p ——Calculate the average value of daily outdoor air temperature, in ℃;

Δt _Z,n ——the comprehensive temperature change amplitude of outdoor air at the nth order, in ℃;

ω _n ——the frequency of the comprehensive temperature change of outdoor air of the nth order, in °/h or rad/h;

φ _n ——the initial phase of the nth-order outdoor air comprehensive temperature change, in ° or rad.

Step S2: Calculate the hourly temperature of the inner wall surface.

Because the comprehensive outdoor air temperature fluctuates periodically, the envelope structure fluctuates layer by layer from the outer surface to the inner surface. Therefore, when calculating the wall temperature of the non-air-conditioned area and the air-conditioned area of a large-space building, it needs to be based on the suction of the envelope structure. Heat, heat storage and heat release characteristics, and consider the heat transfer attenuation and heat transfer delay time of the envelope structure.

Among them, the heat transfer attenuation is the ratio of the amplitude of the integrated temperature outside the envelope to the amplitude of the internal surface temperature, and the heat transfer delay time is the time delay of the internal surface temperature wave lagging behind the outside integrated temperature wave.

In order to calculate the hourly inner wall surface temperature, first calculate the hourly integrated outdoor air temperature. Therefore, through the above step S1, use the outdoor air integrated temperature time-to-time change data to fit into the Fourier series form, where the series can be decomposed There are two items: the first item is the average value of the outdoor air temperature; the second item is the fluctuation value of the outdoor air temperature from time to time. The time-by-time inner wall temperature can also be decomposed into an average value and a fluctuation value. The average value of the inner wall temperature can be obtained by the heat balance equation of the steady-state heat transfer of the wall; the fluctuation value of the inner wall temperature is derived from the external disturbance fluctuation value, that is, outdoor The fluctuating value of the air comprehensive temperature is calculated according to the heat transfer attenuation and the heat transfer delay time of the envelope structure. In step S2 of this embodiment, the hourly temperature calculation of the inner wall surface of the non-air-conditioned area and the air-conditioned area is specifically completed by the following sub-steps:

Step S2-1, the average temperature θ _{N,p of the} inner wall surface of the enclosure structure can be calculated according to formula (2):

In the formula: θ _N,p ——the average temperature of the inner wall surface, in ℃;

t _Z,p ——Calculate the average value of daily outdoor air temperature, in ℃;

t _N,p ——Average temperature of indoor air in air-conditioned or non-air-conditioned area, in ℃;

α _W ——The heat release coefficient of the outer surface of the enclosure structure, in W/(m ² ·K);

δ _k ——the thickness of the k-th layer of the enclosure structure, in m;

λ _k ——The thermal conductivity of the k-th layer of the enclosure structure, in W/(m·K);

K——the number of layers of enclosure structure material;

α _N ——The heat transfer coefficient of the inner surface, in W/(m ² ·K).

There are many ways to solve the surface temperature of the floor. In this case, a steady-state calculation method is adopted. This method considers that the heat transfer coefficient of the indoor ground changes with the distance from the outer wall. The intersection line between the inner surface of the outer wall and the ground is taken as the outer contour of the ground, from the outer contour to the inside. As a zone every 2m, the ground is divided into four calculation zones along the direction parallel to the outer wall. Among them, the ground area of the first zone near the corner of the wall needs to be calculated twice, as shown in Figure 2. The steady-state heat transfer coefficient of each zone is shown in Table 1.

The ground temperature θ _{d,y of} each calculation zone can be calculated according to the general formula (3) through the heat balance equation:

In the formula, θ _d,y ——the ground temperature of the y-th zone, the value of y is from one to four, and the unit is ℃;

K _d,y ——The ground heat transfer coefficient of the y-th zone, the specific values are shown in Table 1, the unit is W/(m ² ·K);

t _W,p ——Calculated daily average temperature outside the air conditioner in summer, in ℃;

t _N,p ——The average temperature of indoor air in the air-conditioned area, in ℃.

Table 1 Ground heat transfer coefficient of each calculation zone

Computing zone	K d,y (W/(m 2 ·K))
First zone	0.47
Second zone	0.23
Third zone	0.12
Fourth zone	0.07

The average temperature of the entire ground can be calculated according to formula (4):

In the formula, θ _d —— the average temperature of the entire ground, in ℃;

θ _d,y ——the ground temperature of the y-th zone, in ℃;

F _d,y ——the ground area of the y-th zone, in m ² ;

F _d ——the entire ground area, in m ² .

Step S2-2, the temperature fluctuation value Δθ _N,τ of the inner wall surface is the frequency response of the envelope structure under the _{action of the disturbance quantity Δt Z,n of} each order, that is to say, Δt _{Z,n is the} result of the attenuation and delay of the envelope structure. The reflected fluctuation, the temperature fluctuation value of the inner wall surface can be calculated according to formula (5):

In the formula, Δθ _N,τ ——the fluctuation value of the temperature of the inner wall surface at time τ, in ℃;

ν _n ——The heat transfer attenuation degree of the enclosure structure to the n-th order outdoor air comprehensive temperature disturbance;

ε _n ——The heat transfer delay time of the envelope structure to the comprehensive temperature disturbance of outdoor air of nth order, in ° or rad.

Step S2-3, add the calculated average temperature of the inner wall surface and the fluctuation value (ie the average temperature of the inner wall surface and the temperature fluctuation value of the inner wall surface) to obtain the hourly inner wall surface temperature θ _N,τ as the formula (6 ) Shows:

θ _N,τ =θ _N,p +Δθ _N,τ (6)

In the formula, θ _N,τ ——the temperature of the inner wall surface at time τ, in ℃.

Step S3: Calculate the hourly radiant heat transfer amount.

Hourly radiant heat transfer amount includes time-by-time wall radiant heat transfer and hourly solar radiant heat transfer.

The amount of wall radiant heat transfer is the radiant heat transfer between the walls caused by the fourth-order variance of the temperature of each wall in the non-air-conditioned area and each wall in the air-conditioned area. It is mainly related to the angular coefficient, the temperature of the inner wall surface by time and the emissivity. The present invention approximates a large-space building to a rectangular structure (as shown in Figure 3, the structure is a typical structure of a large-space building), and then the non-air-conditioning building can be calculated according to the length, width, height and layer height of the building The angle coefficient between each wall surface of the zone and each wall surface of the air-conditioning zone and the corresponding wall surface area. At the same time, the windows are arranged in multiple groups in parallel, and are approximately regarded as a lighting belt with the same length as the wall of the large space building. Therefore, according to the height of the window and the bottom elevation of the window, the angle between the window of the non-air-conditioned area and each wall of the air-conditioned area can be obtained. coefficient.

In this embodiment, the Gebhart radiation model is used to calculate the wall radiant heat transfer, and the Gebhart absorption coefficient can be calculated according to the wall emissivity and the angle coefficient between each wall of the non-air-conditioned area and each wall of the air-conditioned area, and then the non-air-conditioned area can be calculated The heat exchange of radiation absorbed by one reflection is considered between each wall surface and each wall surface of the air-conditioning area.

The amount of solar radiant heat transfer is the radiant heat that the solar radiation transmitted through the windows of the non-air-conditioned area reaches each wall of the air-conditioned area and is absorbed. For hourly solar radiant heat transfer, it is necessary to calculate the hourly solar radiant heat passing through non-air-conditioned windows, and distribute it according to the angle coefficients of the windows to each wall of the air-conditioned area. Multiply the hourly solar radiation intensity through the outer window of the non-air-conditioned area, the window area, the angle coefficient of the outer window of the non-air-conditioned area to each wall of the air-conditioned area, and the solar radiation absorption rate of the wall of the air-conditioned area. The amount of time-by-hour solar radiant heat transfer that the solar radiant heat transmitted through the air-conditioning window is absorbed by the walls of the air-conditioned area.

According to the above conclusion, step S3 of this embodiment specifically includes the following sub-steps:

In step S3-1, the radiation heat transfer model between the non-air-conditioned area and the wall of the air-conditioned area adopts the Gebhart radiation model, and the Gebhart absorption coefficient matrix form can be calculated by a matrix formula. As shown in the schematic diagram of the typical structure of a large space building in Figure 3, the non-air-conditioned area and the air-conditioned area each have 5 walls, so there are 10 walls in total, so there are 10×10 Gebhart absorption coefficients, which can be calculated according to equation (7):

In the formula, G——10×10 Gebhart absorption coefficient matrix;

——10×10 angular coefficient matrix;

ε——10×10 diagonal matrix of wall emissivity;

I——10×10 identity matrix.

Step S3-2, using the Gebhart radiation model to calculate the total wall radiant heat transfer from each wall of the non-air-conditioned area to the wall of the air-conditioned area j can be calculated by equation (8):

In the formula, Q _WR,j,τ ——the total radiant heat transfer from each wall of the non-air-conditioned area to the wall surface of the air-conditioned area j at time τ, in W;

σ——Stephen-Boltzmann constant, 5.67×10 ^-8 W/(m ² ·K ⁴ );

ε _{i ——The wall emissivity of i in} non-air-conditioned area;

G _i,j ——The Gebhart absorption coefficient of the wall of non-air-conditioned area i facing the wall of air-conditioned area j, which can be obtained from the corresponding element in the Gebhart absorption coefficient matrix obtained in equation (7);

T _i,τ ——The thermodynamic temperature of the wall of the non-air-conditioned area i at time τ, in K;

T _j,τ ——The thermodynamic temperature of the wall surface of the air-conditioning zone j at time τ, in K;

S _i ——the area of the wall surface of the non-air-conditioned area i, in m ² ;

N——The number of walls divided into non-air-conditioned areas.

Step S3-3, the hourly total solar radiant heat transfer amount from the external windows of the non-air-conditioned area to the wall surface of the air-conditioned area j can be calculated by equation (9):

In the formula, Q _SR,j,τ ——the hourly total solar radiant heat transfer from the external windows of the non-air-conditioned area to the wall surface of the air-conditioned area j at time τ, in W;

ρ _j ——The solar radiation absorption coefficient of the wall j of the air-conditioned area;

X _k,j ——the angle coefficient of the external window of the non-air-conditioned area k to the wall surface of the air-conditioned area j;

S _k ——outer window area of non-air-conditioned zone k, in m ² ;

J _k,τ ——the solar radiation illuminance through the outside window of k in the non-air-conditioned area at moment ^{τ, in W/m 2} ;

N’——The number of external windows in non-air-conditioned areas.

Step S3-4, the hourly total radiant heat transfer amount is obtained by adding the hourly total wall radiant heat transfer amount calculated above and the hourly total solar radiant heat transfer amount, as shown in equation (10):

Q _R,j,τ =Q _WR,j,τ +Q _SR,j,τ (10)

In the formula, Q _R,j,τ ——the time-by-hour total radiant heat transfer from the entire non-air-conditioned area to the wall of air-conditioned area j at time τ, in W.

In step S4, the hourly radiant heat transfer amount calculated in step S3 is fitted.

The time-varying change data of the radiant heat transfer amount on the wall of the air-conditioning zone j is fitted into a Fourier series, as shown in equation (11):

In the formula, Q _R,j,τ ——the time-by-hour total radiant heat transfer from the entire non-air-conditioned area to the wall of air-conditioned area j at time τ, in W;

Q _R,j,p ——the average value of the radiant heat transfer from the wall surface of the air-conditioning zone j, in W;

ΔQ _R,j,n ——the amplitude of the n-th order radiant heat transfer change on the wall surface of the air-conditioned area j, in W;

ω _R,j,n ——the frequency of the nth-order radiant heat transfer change on the wall surface of the air-conditioned area j, in °/h or rad/h;

φ _R,j,n ——the initial phase of the n-th order radiant heat transfer change on the wall of the air-conditioned zone j, in ° or rad.

Step S5: Calculate the non-steady-state radiant heat transfer load.

After fitting the time-wise change data of the radiant heat transfer amount into a Fourier series form through step S4, it is decomposed into the average value and fluctuation value of the radiant heat transfer amount. Among them, the average value of the time-wise radiant heat transfer amount will be directly It is transformed into a radiant heat transfer load, and the fluctuation value of the radiant heat transfer amount will be attenuated and delayed by the heat release of each wall of the air-conditioned area, and then transformed into an unstable radiant heat transfer load of the air-conditioned area. That is, it is necessary to calculate the fluctuation value of the radiant heat transfer load based on the fluctuation value of the radiant heat transfer amount, the heat release attenuation degree and the heat release delay time of each wall surface of the air-conditioned area, and add the average value of the radiant heat transfer load and the fluctuation value to that Unsteady state radiant heat transfer load can be obtained. Among them, the degree of heat release attenuation is the ratio of the amount of radiant heat transferred into the air-conditioned area to the amplitude of the radiant heat transfer load in the air-conditioned area; the heat release delay time is the phase lag of the radiant heat transfer load of the air-conditioned area to the amount of radiant heat transfer.

According to the above conclusion, step S5 in this embodiment specifically includes the following sub-steps:

In step S5-1, the stable part of the time-to-time radiant heat transfer directly forms a stable radiant heat transfer load, that is, the average value of the time-to-time radiant heat transfer; the unstable part is formed due to the attenuation and delay of the heat release of the envelope structure Unstable radiant heat transfer load, so the unsteady-state radiant heat transfer load is shown in equation (12):

In the formula, CLQ _R,τ ——the unsteady-state radiant heat transfer load of the stratified air conditioner at time τ, the unit is W;

Q _R,j,p ——the average value of the radiant heat transfer from the wall surface of the air-conditioning zone j, in W;

——The fluctuation value of the radiant heat transfer load on the wall surface of the air-conditioned area j, in W;

M——The number of walls divided by the air-conditioning area.

Step S5-2, the fluctuation value of radiant heat transfer load can be calculated by formula (13):

Where

——The fluctuation value of the radiant heat transfer load on the wall surface of the air-conditioned area j, in W;

ν _f,j,n ——the degree of heat release attenuation of the n-th order radiant heat disturbance on the wall of the air-conditioned area j;

ε _f,j,n ——The heat release phase delay time of the wall of the air-conditioned zone j facing the n-th order radiant heat disturbance, in ° or rad.

Step S5-3, the unsteady-state radiant heat transfer load of the stratified air-conditioning in large space buildings can be calculated according to formula (14):

In the formula, CLQ _R,τ ——the unsteady-state radiant heat transfer load of the stratified air conditioner at time τ, the unit is W;

M——The number of walls divided by the air-conditioning area;

Q _R,j,p ——the average value of the radiant heat transfer from the wall surface of the air-conditioning zone j, in W;

ΔQ _R,j,n ——the amplitude of the n-th order radiant heat transfer change on the wall surface of the air-conditioned area j, in W;

ν _f,j,n ——the degree of heat release attenuation of the n-th order radiant heat disturbance on the wall of the air-conditioned area j;

ω _R,j,n ——the frequency of the nth-order radiant heat transfer change on the wall surface of the air-conditioned area j, in °/h or rad/h;

φ _R,j,n ——the initial phase of the n-th order radiant heat transfer change on the wall of the air-conditioned zone j, in ° or rad.

ε _f,j,n ——The heat release phase delay time of the wall of the air-conditioned zone j facing the n-th order radiant heat disturbance, in ° or rad.

<Example 2>

In order to facilitate engineering calculations, the second embodiment provides a simplified engineering calculation method for the unsteady-state radiant heat transfer load of a stratified air conditioner in a large space building. It first calculates the hourly inner wall surface temperature. The calculation process of the hourly inner wall surface temperature is the same as the complete calculation method in the first embodiment: secondly, the direct radiation model is used to calculate the hourly wall radiant heat of each wall of the non-air-conditioned area facing the ground of the air-conditioned area The amount of transfer and the hourly solar radiant heat transfer from each external window of the non-air-conditioned area to the ground of the air-conditioned area; then according to the corresponding model correction coefficient C ₀ value, the wall air-conditioning area heat correction coefficient C _1a value, and the solar air-conditioning area heat correction The value of the coefficient C _1b obtains the hourly radiant heat transfer from the entire non-air-conditioned area to the air-conditioned area; finally, the harmonic response method is used to calculate the radiant heat transfer load from the non-steady-state non-air-conditioned area to the air-conditioned area.

In this embodiment, in order to obtain the model correction coefficient C ₀ value, the heat correction coefficient C _1a value of the wall air-conditioning area, and the solar air-conditioning area heat correction coefficient C _1b value, a typical large-space building rectangular characteristic structure is adopted. The standard The building size of the working condition is 20m (length) × 20m (width) × 12m (height), the layer height is 4.8m, and the relative layer height is 0.4, as shown in Figure 3.

The model correction coefficient C ₀ is the ratio of the radiant heat transfer between the walls of the non-air-conditioned area calculated by the Gebhart radiation model and the floor of the air-conditioned area calculated by the direct radiation model. This value can be checked by the model correction coefficient C _{0 value line calculation diagram shown in Figure 4, which is based on the change of the C 0} value when the three parameters of the relative height of the building, the width-to-length ratio of the building, and the wall emissivity are changed. Drawn by law. In Figure 4, the ratio of building width to length=building width/building length; relative height (h _x )=actual building height/20. The average wall emissivity refers to the average emissivity of all walls in non-air-conditioned areas. _{C 01} can be obtained directly after checking the line calculation diagram, and then corrected according to the standard working conditions to obtain C ₀₂ , and finally C ₀ =C ₀₁ +C ₀₂ , then the value of the model correction coefficient C _{0 can be obtained.}

The wall heat correction coefficient C _1a of the air-conditioning zone is the ratio of the sum of the radiant heat transfer from each wall of the air-conditioning zone calculated by the Gebhart radiation model to the radiant heat transfer from the floor of the air-conditioning zone. _{This value can be checked by the calculation of the value of the heat correction coefficient C 1a of the} wall air-conditioning zone in Figure 5. The line calculation is based on the relative height of the building, the width-to-length ratio of the building, the relative stratification height, the outdoor dry bulb temperature, and the air-conditioning zone. The change rule of _{C 1a} value when the 6 parameters of design temperature and wall emissivity change are drawn. In Figure 5, the relative layer height=layer height/building height; the relative height and the average wall emissivity have the same meaning as in Figure 4 above. _{C 1a-1} can be directly obtained in the line-checking calculation diagram _{, and then C 1a-2} can be obtained by correcting it according to the standard working conditions, and finally C _1a = C _1a-1 + C _1a-2 , then the heat correction coefficient C of the wall surface of the air-conditioning zone can be obtained _1a value.

The air-conditioned area solar heat correction coefficient C _1b is the ratio of the total amount of solar radiation heat transferred from the non-air-conditioned area absorbed by each wall surface of the air-conditioned area to the amount of solar radiation heat transferred from the non-air-conditioned area absorbed by the floor of the air-conditioned area. _{This value can be checked by the line calculation diagram of the heat gain correction coefficient C 1b} value of the solar air-conditioning zone in Figure 6, which is based on the relative height of the building, the width-to-length ratio of the building, the relative layer height, the relative height of the window, and the relative height of the window. The change rule of _{C 1b} value when these 5 parameters of height change are drawn. In Figure 6, the relative height of the window (h _b ) = the height of the window frame under the window/the height of the building; the relative height of the window (h _z ) = the height of the window/the height of the building; the meaning of other physical quantities is the same as in Figures 4 and 5 above. _{C 1b-1} can be obtained directly after checking the map _{, and then C 1b-2} can be obtained by correcting it according to the standard working conditions. Finally, C _1b = C _1b-1 + C _1b-2 , then the solar heat gain correction coefficient C _{1b in the air-conditioned area can be obtained.} value.

Fig. 7 is a flowchart of a method for calculating unsteady-state radiant heat transfer load of a stratified air conditioner in a large space building in the second embodiment of the present invention.

As shown in Figure 7, the engineering simplified calculation method of the unsteady-state radiant heat transfer load calculation method for layered air conditioning in large space buildings includes the following steps:

Step T1: Fit the hourly integrated outdoor air temperature.

Step T2: Calculate the hourly temperature of the inner wall surface.

In the second embodiment, the above steps T1 and T2 are the same as the steps S1 and S2 of the complete calculation method in the first embodiment, and will not be repeated here.

Step T3: Calculate the hourly radiant heat transfer amount.

In step T3 of this embodiment, first calculate the time-by-time wall radiant heat transfer between each wall of the non-air-conditioned area and the floor of the air-conditioned area based on the direct radiation model, and then calculate the time-by-time wall radiant heat transfer between the walls of the non-air-conditioned area and the floor of the air-conditioned area. After the heat is superimposed, multiply the _{value of the model correction coefficient C 0} to obtain the time-by-time wall radiant heat transfer of the floor of the air-conditioned area based on the Gebhart radiation model. After obtaining the hourly total radiant heat transfer amount from each wall of the non-air-conditioned area to the floor of the air-conditioned area, the hourly total wall radiant heat of the non-air-conditioned area to each wall of the air-conditioned area can be calculated _{according to the value of the heat correction coefficient C 1a of the wall air-conditioned area} Transfer volume. For hourly solar radiant heat transfer, only the hourly solar radiation absorbed by the floor of the air-conditioned area from the non-air-conditioned area is calculated, and the hourly solar radiation intensity through the external windows of the non-air-conditioned area, the window area, and the solar radiation absorption on the ground are used. It is obtained by multiplying the four factors of the angle coefficient of the outer window of the non-air-conditioned area and the ground of the air-conditioned area. After each window is superimposed, it is multiplied by the heat correction coefficient C _1b value of the solar air-conditioned area to obtain the hourly total of the non-air-conditioned area to the air-conditioned area. The amount of solar radiation heat transfer.

According to the above conclusion, step T3 in this embodiment specifically includes the following sub-steps:

Step T3-1, using the direct radiation model and the model correction coefficient C ₀ value to calculate the total wall radiant heat transfer between the walls of the non-air-conditioned area and the floor of the air-conditioned area, as shown in equation (15):

In the formula, Q _WR,d,τ ——the total wall radiant heat transfer amount from each wall of the non-air-conditioned area to the floor of the air-conditioned area at time τ, in W;

C ₀ ——model correction coefficient, which can be found by calculating the value line of the _{model correction coefficient C 0 in Figure 4;}

S _d ——The floor area of the air-conditioning zone, in m ² ;

ε _d ——The emissivity of the floor in the air-conditioned area;

X _d,i ——the angle coefficient of the floor of the air-conditioned area to the wall surface of the non-air-conditioned area i;

ε _{i ——The wall emissivity of i in} non-air-conditioned area;

T _i,τ ——The thermodynamic temperature of the wall of the non-air-conditioned area i at time τ, in K;

T _d ——Thermodynamic temperature of the floor of the air-conditioned area, K;

N——The number of walls divided into non-air-conditioned areas.

Step T3-2, the hourly total solar radiant heat transfer from the external windows of the non-air-conditioned area to the floor of the air-conditioned area can be calculated by equation (16):

In the formula, Q _{SR, d, τ ——} the total solar radiation heat transfer amount of the solar radiation through the external windows of the non-air-conditioned area to the floor of the air-conditioned area at the moment of τ, in W;

ρ _d ——Solar radiation absorption coefficient on the ground of air-conditioned area;

X _k,d ——the angle coefficient of the external window of the non-air-conditioned area k to the floor of the air-conditioned area;

S _k ——outer window area of non-air-conditioned zone k, in m ² ;

J _k,τ ——the solar radiation illuminance through the outside window of k in the non-air-conditioned area at moment ^{τ, in W/m 2} ;

N’——The number of external windows in non-air-conditioned areas.

Step T3-3, the hourly total radiant heat transfer from the non-air-conditioned area of the stratified air-conditioned area to the air-conditioned area can be calculated by equation (17):

Q _R,τ =C _1a Q _WR,d,τ +C _1b Q _SR,d,τ (17)

In the formula, Q _R,τ ——the total radiant heat transfer from the entire non-air-conditioned area to the air-conditioned area at time τ, in W;

C _1a ——The wall heat gain correction coefficient of the air-conditioning zone, which can be found by calculating the value line of the _{heat correction coefficient C 1a of the wall air-conditioning zone in Figure 5;}

C _{1b ——The} correction coefficient of solar heat gain in air-conditioning area, which can be found by calculating the value line of the _{correction coefficient C 1b of solar air-conditioning area in Figure 6.}

Step T4, fitting the hourly radiant heat transfer amount.

Fit the calculated time-to-time change data of the radiant heat transfer amount of the entire air-conditioned area into a Fourier series, as shown in equation (18):

In the formula, Q _R,τ ——the total radiant heat transfer from the entire non-air-conditioned area to the air-conditioned area at time τ, in W;

Q _R,p ——average value of radiant heat transfer amount from time to time in the entire air-conditioned area, unit W;

ΔQ _R,n ——The amplitude of the n-th order radiant heat transfer change, in W;

ω _R,n ——the frequency of the change of the n-th radiant heat transfer amount, in °/h or rad/h;

φ _R,n ——The initial phase of the nth-order radiant heat transfer change, in ° or rad.

Step T5: Calculate the non-steady-state radiant heat transfer load.

The unsteady-state radiant heat transfer load of layered air conditioning in large space buildings can be calculated according to equation (19):

Where: CLQ _R,τ ——unsteady-state radiant heat transfer load of stratified air conditioner at time τ, unit W;

Q _R,p ——average value of radiant heat transfer amount from time to time in the entire air-conditioned area, unit W;

ΔQ _R,n ——The amplitude of the n-th order radiant heat transfer change, in W;

ν _f,d,n ——the degree of attenuation of heat release from the ground to the n-th order radiant heat disturbance;

ω _R,n ——the frequency of the change of the n-th radiant heat transfer amount, in °/h or rad/h;

φ _R,n ——The initial phase of the nth-order radiant heat transfer change, in ° or rad.

ε _f,d,n ——The heat release delay time of the ground to the n-th order radiant heat disturbance, in ° or rad.

In this embodiment, according to the characteristics of a certain actual large-space building, based on the size of the return air outlet at the end, a large-space building scale model laboratory-scale model laboratory is basically established at a scale of 1:4. The floor plan of the laboratory is shown in Figure 8. The scale model laboratory room 404 is on the right, and the low temperature environment room 406 is on the left. Because the two laboratories share a set of cold and heat source systems, air treatment systems, and electrical Control and test system, so the laboratory air conditioning system is introduced in a unified manner. Both laboratories can realize independent adjustment and control of air volume. In the following this embodiment, the above-mentioned layered air conditioning in large space buildings will be carried out in the 404 laboratory. A verification experiment for unsteady radiant heat transfer load (hereinafter referred to as this experiment).

The aforementioned 404 laboratory is mainly composed of environmental simulation room, cooling water system, cold water system, air treatment system, electrical control system, data measurement and acquisition system, and computer measurement and control software. The principle of the test system is shown in Figure 9. In Figure 9, 1 is the expansion tank, 2 is the electric three-way valve, 3 is the chilled water pump, 4 is the chiller, 5 is the cooling water pump, 6 is the cooling tower, 7 is the plate filter, 8 is the surface cooler, and 9 is the Electric heater, 10 is steam humidification, 11 is nozzle, 12 is blower, 13 is dry steam humidifier, 14 is VAV BOX, 15 is heat and humidity load generator, 16 is exhaust fan, VC is air volume controller, T is Temperature measuring point, H is humidity measuring point, V is speed measuring point, DP is differential pressure measuring point, SP- is static pressure measuring point, VFD is variable frequency control, SSR is solid state relay, M is valve, F is-check Valves, C1-C9 are signal converters.

The 404 laboratory is a sloping roof structure with a length of 4.9m, a width of 3.5m, a height of 1.5m at the lowest point and 2.2m at the highest point. The enclosure structure is made of thermal insulation materials, the surroundings and ceiling are made of 100mm thick polyurethane thermal insulation board, the ground surface is made of 2mm thick stainless steel plates, and the designed air volume is 2000m ³ /h.

In this experiment, the inner wall temperature, heat flux density and air temperature of the laboratory are directly measured and used for the calculation of various heat and load. In this experiment, only periodic harmonic heat is applied to the roof electric heating film to simulate periodicity The rest of the wall is not heated, and the heat and moisture load generator does not work.

The measuring points are arranged as shown in Figure 10, including the inner wall temperature, air temperature, and wall heat flow meter. Two wall temperature measuring points and heat flux measuring points are arranged on both sides of the sloping roof, which are arranged evenly and symmetrically. 4 wall temperature measuring points and 2 heat flux measuring points are arranged on the inner wall of the west wall, and 3 wall temperature measuring points and 2 heat flux measuring points are arranged on the remaining inner walls. Due to the large floor area, 3 heat flux measurement points are arranged symmetrically on the floor to accurately measure the convective heat transfer of the floor. The indoor air temperature measuring points are arranged as a vertical measuring line in the center of the room, and 3 temperature measuring points on the side line, respectively 0.6m, 1.2m, and 1.8m from the floor.

Although the walls of the laboratory are insulated, and the enclosure structure can be approximated as having no heat storage, under the action of periodic disturbances, the radiation load still has a very weak attenuation and delay relative to the radiant heat. In order to ensure that the periodic disturbance entered in this experiment has a complete periodic change and eliminate the influence of the initial conditions, a pre-experiment for three consecutive cycles of 72 hours was carried out before the experiment to obtain the periodic disturbance to a quasi-steady state. Time required. The quasi-steady-state time of the periodic disturbance is defined as: the average relative error of the roof heat transfer at each hour from (τ+24) to (τ+47) and from τ to (τ+23) is less than 1% , And the maximum relative error between the air temperature and the 24-hour average air temperature at each time from τ to (τ+23) hours is less than 1%. Through preliminary experiments, it is found that after the third hour of the experiment, the periodic disturbance enters a quasi-steady state. Therefore, in the formal experiment process, the experimental measurement starts at the third hour after the experimental system is turned on. The data is automatically read every minute, and the average of the data every 60 minutes is taken as an hourly data value. A total of 24 cycles are selected. Data at a time.

The enclosure structure of the laboratory is made of thermal insulation materials, and the surrounding and ceiling are made of 100mm thick polyurethane insulation board. The emissivity, attenuation coefficient and delay time of the inner wall surface and other enclosure structure parameters are shown in Table 2.

Table 2 Parameters of the enclosure structure of the scaled model laboratory

During the experiment, input periodic heat P to the roof wall, and the experiment set period is 24 hours, then:

During the experiment, the input periodic heat transfer on the inner wall of the roof was used as a variable, and two working conditions were designed. The specific settings of the working conditions are shown in Table 3.

Table 3 Experimental conditions

This experiment is mainly used to obtain the experimental value of hourly radiant heat transfer and the experimental value of radiant heat transfer load to verify the theoretical radiant heat transfer and theoretical radiant heat transfer load calculation results introduced above. In order to facilitate the experiment and control the experiment process, and eliminate the influence of outdoor uncontrollable factors such as environmental temperature and humidity, the enclosure structure adopts thermal insulation materials. This experiment adopts the air supply method of columnar air supply. The air supply port is semi-cylindrical, with a height of 340mm and a diameter of 200mm. There are 3 air outlets evenly arranged in the north and south. There are 6 air outlets in total. Each air supply pipeline is equipped with air volume. Adjust the valve to control the air supply volume. The return air vent and the air supply vent are arranged one by one above the corresponding air supply vent, 1.1m from the floor, and the diameter of the return air vent is 100mm. The area below the top of the air return vent is an air-conditioned area, and the area from the top of the air return vent to the roof is a non-air-conditioned area. The air ducts in the laboratory are all made of double-layer aluminum foil air ducts with insulation materials, and the remaining rigid air ducts, air valves and static pressure boxes are also insulated with 1cm thick insulation foam. There are measuring holes at the air supply pipe and the return air pipe to measure the wind speed and temperature of the return air. Figure 11 and Figure 12 show the layout of the air outlets and pipelines at the middle and return ends of the downward delivery.

In order to simulate the unsteady heat transfer of the envelope structure, the roof and surrounding walls of the scaled model laboratory are glued with electric heating film according to the largest area. The electric heating film is made of carbon fiber heating material, and its maximum heating power is 230W/m ² . The electric heating film on each wall is equipped with an AC transformer and an electric power measuring meter, which can ^{adjust the heating power within the range of 0-230W/m 2} and measure the heating amount of each surface in real time. Since a part of the heating of the electric heating film will enter the wall, a heat flow meter is pasted on the electric heating film to determine the net heat entering the model space.

In this experiment, the electric heating film on the roof is heated periodically through a voltage regulator to simulate the periodic heat transfer outside. The input power of the electric heating film can be adjusted by the voltage regulator of the electric control cabinet, the heating power is set to a sinusoidal form, and the power meter directly reads the data of the input power. In the experiment, it is considered that the indoor temperature is uniformly equal to the return air temperature. At the beginning of the experiment, periodic harmonic heat transfer disturbances are input to the roof, and the air temperature measured by the sensor placed at the return air automatically adjusts the electric heating of the air conditioning unit In order to achieve a stable indoor temperature by changing the supply air temperature, read a cycle of experimental data when the indoor temperature stabilizes.

The inner surface of the building is a compound heat transfer phenomenon in which conduction, convection and radiation coexist. To obtain the experimental data of a period of time-by-period radiant heat transfer and radiant heat transfer load, it is necessary to obtain a period of time-by-period radiant heat and radiation of each inner surface Load experimental data. In this experiment, the radiant heat transfer load is obtained based on the principle of wall surface flow and radiation separation. According to the relationship of heat conduction, convection and radiant heat transfer on the inner wall of the building envelope, this experiment measures the surface heat conduction heat transfer, and calculates each wall surface through the measured inner wall temperature The heat transfer between radiation and convection can be calculated by equation (21).

The heat transfer of heat conduction enters the room. At this time, the heat transfer of heat conduction is equal to the sum of radiant heat transfer and convective heat transfer. The relationship between the three is:

_{q jλ = q jR + q jd} (21)

In the formula, q _jλ —— the heat conduction heat transfer of the wall surface of the air-conditioning zone j, in W/m ² ;

q _{jR ——Radiative} heat transfer on the wall of air-conditioning zone j, in W/m ² ;

q _{jd ——Convective} heat transfer on the wall of air-conditioning zone j, in W/m ² .

The above-mentioned convection-radiation separation method is used to analyze the composite heat transfer process of each wall surface. The heat transfer heat transfer is directly measured through experiments, and the radiation heat transfer calculation formula is:

In the formula, J _j —— the effective radiant heat of the wall of the air-conditioning zone j, W/m ² .

Vertical joint (23) of the N equations to calculate the wall surface of the air-conditioned area j effective radiated heat _{J j,} which is substituted into the formula (22) to calculate the radiation heat transfer q _jR j wall air-conditioned area.

Radiant heat transfer load: Separate convective radiation on each surface of the air-conditioning area to obtain convective heat transfer. Since each surface of the air-conditioning area does not start electric heating film heating, and it is assumed that the surfaces are insulated and the air flow is weak, the convective transfer is conducted after separation by convective radiation. The thermal part is the radiant heat transfer load, which can be calculated by equation (24).

In the formula, q _jd — the convective heat transfer obtained by separating convective radiation on each surface of the air-conditioned area, in W/m ² .

This experiment will verify the two calculation methods of the unsteady-state radiant heat transfer load of the layered air conditioning in large space buildings (ie, the complete calculation method performed in Example 1 and the simplified engineering calculation method performed in Example 2). The technical route used in the calculation method and the comparison between the two are shown in Figure 13.

Through the above experiments, the experimental verification process using the complete calculation method of Example 1 is as follows:

In the experiment, the curve of the experimental value of the radiant heat transfer amount by time can be obtained according to the measured temperature of the inner wall surface by time. According to formula (11), the fitted curve of the fitted value of the hourly radiant heat transfer of the fitted stratified air conditioner is obtained. The curves of the measured radiant heat transfer and the fitted radiant heat transfer of the two working conditions are shown in Figure 14.

It can be seen from Figure 14 that the amount of radiant heat transfer fluctuates in the form of sine waves with time. This is because in this experiment, the roof electric heating film applies periodic sine wave heat to simulate the effect of periodic outdoor temperature on indoor wall temperature. Disturbance, the experimental data measured in this experiment takes 24 hours as the period and the frequency is 0.262rad/h. The standard deviations of the harmonic fitting curves of radiant heat transfer volume obtained in Working Condition 1 and Working Condition 2 are 7.26W and 8.10W, respectively, and the ratios of their standard deviations to the average value of radiant heat transfer volume are 1.38% and 2.10%, respectively, indicating radiation The fitting curve of heat transfer can basically represent the experimental value of radiant heat transfer.

Fig. 15 is a curve of relative deviation between each fitted value of hourly radiant heat transfer amount and the actual measured value. It can be seen that the relative deviation of the two working conditions is basically below 10%, the average absolute relative deviation of case-1 is 1.57%, and the average absolute relative deviation of case-2 is 2.71%. Therefore, it can be said that the hourly radiant heat transfer amount after fitting can better reflect the actual radiant heat transfer amount.

Figure 16 reflects the calculated value of the complete calculation method of the unsteady state radiant heat transfer load of the stratified air conditioner and the verification result of the experimental value of the radiant heat transfer load: both curves have a period of 24 hours, and the fluctuation laws of the curves are the same. The standard deviations between the calculated radiant heat transfer load and the experimental value of the two working conditions are: 48.92W and 20.15W, and the ratio of the standard deviation to the experimental average of the radiant heat transfer load is 10.14% and 5.21%, respectively; the average absolute relative error They are 12.62% and 6.23%, respectively; the peak relative errors of radiant heat transfer load are 0.48% and -2.33%, respectively; the mean relative errors are: 8.91% and -0.52%, respectively. Therefore, the complete calculation method of the unsteady-state radiant heat transfer load of this embodiment is reliable.

Through the above experiments, the experimental verification process using the simplified engineering calculation method of the second embodiment is as follows:

The simplified engineering calculation method used in the second embodiment only considers the radiant heat transfer load of each wall of the non-air-conditioned area facing the floor. The radiant heat transfer load of the _{air-conditioned area is obtained by the correction of the model correction coefficient C 0} and the air-conditioned area heat correction coefficient C ₁ . Figure 17 shows the verification result of the simplified calculation method for the unsteady-state radiant heat transfer load engineering.

Further analysis, the complete calculation method, the calculation value of the simplified engineering calculation method and the experimental value are verified, and the results of the two calculation methods and the experimental errors are shown in Table 3.

Table 3 Error analysis of the complete calculation method, the calculation value of the engineering simplified calculation method and the experimental value

According to Figure 17, it is found that the time-to-time radiant heat transfer load curve calculated by the simplified engineering calculation method of case-1 is more consistent with the experimental value curve, while the time-to-day radiant heat transfer load value of the simplified engineering calculation method under case-2 fluctuates more. Big. According to Table 3, it is found that the average relative error and average absolute relative error of the radiant heat transfer load of the simplified calculation method of case-1 project are smaller than those of the complete calculation method, and the peak relative error is larger than the complete calculation method, while the radiation of the simplified calculation method of case-2 project The average relative error, peak relative error and average absolute relative error of heat transfer load are all larger than the complete calculation method. This is because the floor radiant heat transfer amount of case-2 is small, and the fitted fluctuations have a large deviation from the experimental value, which leads to a large deviation between the calculated radiant heat transfer load value and the experimental value. In most cases, the result of the complete calculation method is closer to the experimental value. This is because the simplified calculation method of the project only calculates the radiant heat transfer load of the floor and multiplies it by the correction coefficient to convert the radiant heat transfer load of the air-conditioned area, ignoring the attenuation and delay of the other four walls in the air-conditioned area, so the calculation result Compared with the experimental value, the error is larger. However, in engineering applications, the calculation process of the simplified engineering model is simple and easy to implement, and the calculation results can also reflect the fluctuation of the actual radiant heat transfer load.

Example function and effect

According to the method for calculating the unsteady radiant heat transfer load of a layered air conditioner in a large space building provided by this embodiment, the method can calculate the unsteady radiant heat transfer load of each time period in a large space building, which solves the problem of the past bisection The radiant heat transfer load in the layered air-conditioning load can only be calculated in a steady state, which leads to the problem that the calculated load does not conform to the actual situation, so as to provide a stronger numerical basis for the air-conditioning designer in the air-conditioning design, and finally make the design of the layered air-conditioning equipment system The power consumption of the cooling equipment provided is closer to the actual situation.

In addition, this embodiment also provides a simplified engineering calculation method for the unsteady-state radiant heat transfer load of a stratified air conditioner in a large space building. The method obtains the model correction coefficient C ₀ value and the wall air-conditioning area by looking up the line calculation graph. The thermal correction coefficient C _1a value and the solar air-conditioning zone heat correction coefficient C _1b value, and then calculate the radiant heat transfer amount of the air-conditioning zone, making the calculation process more simplified; then calculate the air-conditioning zone’s heat release characteristics based on the heat release characteristics of the air-conditioning zone enclosure structure The radiant heat transfer load, that is, as long as the heat release attenuation degree and the heat release delay time of the envelope structure are known, the unsteady radiant heat transfer load can be calculated. Compared with the traditional method, the correction coefficient used in the engineering simplification method of this embodiment takes into account multiple factors, so that the correction coefficient can be checked according to the actual situation, and the result obtained is more accurate, from radiant heat transfer to radiant heat The calculation of the transferred load is more in line with the actual situation, which not only satisfies the needs of simplified calculation, but also meets the requirements of calculating dynamic loads.

The above-mentioned embodiments are only used to illustrate specific implementations of the present invention, and the present invention is not limited to the description scope of the above-mentioned embodiments.

Claims (3)

1. A method for calculating unsteady-state radiant heat transfer load of layered air-conditioning in large space buildings, which is used for unsteady calculation of radiant heat transfer load from non-air-conditioned area to air-conditioning area in layered air-conditioning load of large space buildings. It is characterized in that: Including the following steps:

   Step S1, fitting the hourly comprehensive outdoor air temperature t _Z,τ ,

   Using the time-to-time change data of the outdoor air comprehensive temperature, it is fitted into a Fourier series form:

   

   In the formula, t _Z,τ is the comprehensive temperature of outdoor air hour by day, t _Z,p is the average value of the comprehensive outdoor air temperature of the calculation day, Δt _Z,n is the comprehensive temperature change amplitude of the n-th order outdoor air, and ω _n is The frequency of the nth-order outdoor air comprehensive temperature change, φ _n is the initial phase of the nth-order outdoor air comprehensive temperature change;

   Step S2, calculate the hourly inner wall surface temperature θ _N,τ ,

   The time-by-time inner wall surface temperature θ _{N, τ} can be decomposed into the inner wall surface average temperature θ _N,p and the inner wall surface temperature fluctuation value Δθ _N,τ , the inner wall surface average temperature θ _{N,p of the} enclosure structure is according to the formula ( 2) Obtained by calculation:

   

   In the formula, θ _N,p is the average temperature of the inner wall surface, t _Z,p is the average value of the calculated daily outdoor air temperature, t _N,p is the average temperature of the indoor air in the air-conditioned or non-air-conditioned area, and α _W is the envelope structure The heat transfer coefficient of the outer surface, δ _k is the thickness of the _k -th layer of the enclosure structure, λ k is the thermal conductivity of the k-th layer of the enclosure structure, α _N is the heat transfer coefficient of the inner surface, and K is the number of layers of the enclosure structure. ,

   The temperature fluctuation value Δθ _N,τ of the inner wall surface is the frequency response of the envelope structure under the _{action of each step disturbance Δt Z,n} , and the temperature fluctuation value Δθ _{N,τ of the} inner wall surface is calculated according to formula (3):

   

   In the formula, Δθ _N,τ is the fluctuation value of the inner wall surface temperature at time τ, ν _n is the heat transfer attenuation degree of the envelope structure to the n-th order outdoor air comprehensive temperature disturbance, and ε _n is the n-th order of the envelope structure The heat transfer delay time of the comprehensive temperature disturbance of outdoor air,

   Adding the average temperature θ _N,p of the inner wall surface and the temperature fluctuation value Δθ _N,τ of the inner wall surface can obtain the time-wise inner wall surface temperature θ _N,τ :

   θ _N,τ =θ _N,p +Δθ _N,τ (4)

   In the formula, θ _N,τ is the temperature of the inner wall surface at time τ;

   Step S3, calculate the hourly radiant heat transfer amount Q _R,j,τ ,

   The time-by-time radiant heat transfer Q _R,j,τ can be decomposed into the time-by-time wall radiant heat transfer Q _WR,j,τ and the time-by-time solar radiant heat transfer Q _SR,j,τ ,

   The Gebhart radiation model is used to establish the radiative heat transfer model between the non-air-conditioned area and the wall of the air-conditioned area. Since the non-air-conditioned area and the air-conditioned area each have 5 walls, there are 10 walls in total, so there are 10×10 in total. Gebhart absorption coefficient, the Gebhart absorption coefficient matrix is calculated according to formula (5):

   

   In the formula, G is a 10×10 Gebhart absorption coefficient matrix,

   

   Is a 10×10 corner coefficient matrix, ε is a 10×10 wall emissivity diagonal matrix, I is a 10×10 identity matrix,

   Further, the total wall surface radiant heat transfer amount from each wall of the non-air-conditioned area to the wall surface of the air-conditioned area j is calculated by the Gebhart radiation model:

   

   In the formula, Q _WR,j,τ is the total wall radiant heat transfer from each wall of the non-air-conditioned area to the wall of the air-conditioned area j at time τ, σ is the Stephen-Boltzmann constant, and ε _{i is the} emissivity of the wall of the non-air-conditioned area i , G _{i,j is} the Gebhart absorption coefficient of the wall of the non-air-conditioned area i facing the wall of the air-conditioned area j, which is obtained by the corresponding Gebhart absorption coefficient matrix, T _i,τ is the thermodynamic temperature of the wall of the non-air-conditioned area i at time τ, T _{j, τ} j is the thermodynamic temperature wall surface of the air-conditioned area moment τ, _i S i the wall surface area of non-air-conditioned area, N the number of non-air-conditioned area division wall,

   At the same time, the hourly total solar radiant heat transfer from the external windows of the non-air-conditioned area to the wall of the air-conditioned area j is calculated by equation (7):

   

   In the formula, Q _SR,j,τ is the hourly total solar radiation heat transfer from the external windows of the non-air-conditioned area to the wall surface of the air-conditioned area j at time τ, and ρ _j is the solar radiation absorption coefficient of the wall surface j of the air-conditioned area, X _{k,j is} the angle coefficient of the external window of the non-air-conditioned zone k to the wall surface of the air-conditioned zone j, S _{k is the} area of the external window of the non-air-conditioned zone k, J _k,τ is the solar radiation illuminance through the external window of the non-air-conditioned zone k at time τ , N'is the number of external windows in non-air-conditioned areas,

   Then, the hourly total radiant heat transfer amount is obtained by adding _{the hourly total wall radiant heat transfer amount Q WR,j,τ} and the hourly total solar radiant heat transfer amount Q _SR,j,τ:

   Q _R,j,τ =Q _WR,j,τ +Q _SR,j,τ (8)

   In the formula, Q _R,j,τ is the time-by-hour total radiant heat transfer from the entire non-air-conditioned area to the wall of air-conditioned area j at τ;

   Step S4, fitting the hourly radiant heat transfer quantity Q _R,j,τ ,

   Fit the time-wise change data of the radiant heat transfer amount into a Fourier series form:

   

   In the formula, Q _R,j,τ is the hourly total radiant heat transfer from the entire non-air-conditioned area to the wall of air-conditioned area j at time τ, and Q _R,j,p is the average value of hourly radiant heat transfer from the wall of air-conditioned area j , ΔQ _R,j,n is the amplitude of the nth-order radiant heat transfer change on the wall of air-conditioned area j, ω _R,j,n is the frequency of the nth-order radiant heat transfer change on the wall of air-conditioned area j, φ _R,j,n Is the initial phase of the n-th order radiant heat transfer change on the wall of the air-conditioned zone j;

   Step S5: Calculate the non-steady-state radiant heat transfer load CLQ _R,τ ,

   The unsteady-state radiant heat transfer load is shown in equation (10):

   

   In the formula, CLQ _R,τ is the unsteady-state radiant heat transfer load of the stratified air conditioner at time τ, and Q _R,j,p is the hourly average radiant heat transfer of the wall surface of the air-conditioning zone j,

   

   Is the fluctuation value of the radiant heat transfer load on the wall of the air-conditioning zone j, and M is the number of walls divided by the air-conditioning zone,

   The fluctuation value of the radiant heat transfer load

   

   Calculated by formula (11), we can get:

   

   Where

   

   Is the fluctuation value of the radiant heat transfer load on the wall of air-conditioning zone j, ΔQ _R,j,n is the variation amplitude of the n-th order radiant heat transfer amount on the wall of air-conditioning zone j, and ν _f,j,n is the n-th order radiant heat on the wall of air-conditioning zone j The degree of attenuation of the heat release of the disturbance, ω _R,j,n is the frequency of _{the nth-order radiant heat transfer change on the wall of the air-conditioned area j, and φ R,j,n} is the nth-order radiant heat transfer change of the wall of the air-conditioned area j The initial phase, ε _f,j,n is the heat release phase delay time of the n-th order radiant heat disturbance on the wall of the air-conditioned area j,

   Therefore, the unsteady-state radiant heat transfer load CLQ _{R,τ of the} stratified air-conditioning in large space buildings can be calculated according to formula (12):

   

   In the formula, CLQ _R,τ is the unsteady radiant heat transfer load of the stratified air conditioner at time τ.
2. A simplified calculation method for the unsteady-state radiant heat transfer load engineering of layered air-conditioning in large space buildings, which is used to simplify the unsteady state of the engineering simplification of the unsteady-state radiant heat transfer load from the non-air-conditioned area to the air-conditioned area in the layered air-conditioning load of large space buildings The calculation is characterized in that it includes the following steps:

   Step T1, fitting the hourly comprehensive outdoor air temperature t _Z,τ ,

   Using the time-to-time change data of the outdoor air comprehensive temperature, it is fitted into a Fourier series form:

   

   In the formula, t _Z,τ is the comprehensive temperature of outdoor air hour by day, t _Z,p is the average value of the comprehensive outdoor air temperature of the calculation day, Δt _Z,n is the comprehensive temperature change amplitude of the n-th order outdoor air, and ω _n is The frequency of the nth-order outdoor air comprehensive temperature change, φ _n is the initial phase of the nth-order outdoor air comprehensive temperature change;

   Step T2, calculate the hourly inner wall surface temperature θ _N,τ ,

   The time-by-time inner wall surface temperature θ _{N, τ} can be decomposed into the inner wall surface average temperature θ _N,p and the inner wall surface temperature fluctuation value Δθ _N,τ , the inner wall surface average temperature θ _{N,p of the} enclosure structure is according to formula (2) Calculated to obtain:

   

   In the formula, θ _N,p is the average temperature of the inner wall surface, t _Z,p is the average value of the calculated daily outdoor air temperature, t _N,p is the average temperature of the indoor air in the air-conditioned or non-air-conditioned area, and α _W is the envelope structure The heat transfer coefficient of the outer surface, δ _k is the thickness of the _k -th layer of the enclosure structure, λ k is the thermal conductivity of the k-th layer of the enclosure structure, α _N is the heat transfer coefficient of the inner surface, and K is the number of layers of the enclosure structure. ,

   The temperature fluctuation value Δθ _N,τ of the inner wall surface is the frequency response of the envelope structure under the _{action of each step disturbance Δt Z,n} , and the temperature fluctuation value Δθ _{N,τ of the} inner wall surface is calculated according to formula (3):

   

   In the formula, Δθ _N,τ is the fluctuation value of the inner wall surface temperature at time τ, ν _n is the heat transfer attenuation of the n-th order outdoor air temperature disturbance by _{the envelope structure, and ε n} is the pair of envelope structure Heat transfer delay time of n-th order outdoor air comprehensive temperature disturbance,

   Adding the average temperature θ _N,p of the inner wall surface and the temperature fluctuation value Δθ _N,τ of the inner wall surface can obtain the time-wise inner wall surface temperature θ _N,τ :

   θ _N,τ =θ _N,p +Δθ _N,τ (4)

   In the formula, θ _N,τ is the temperature of the inner wall surface at time τ;

   Step T3, calculate the hourly radiant heat transfer Q _R,τ ,

   The hourly radiant heat transfer amount Q _R,τ can be calculated from the hourly total wall radiant heat transfer amount Q _WR,d,τ and the hourly total solar radiant heat transfer amount Q _{SR,d,τ obtained from the floor of the air-conditioned area,}

   Use the direct radiation model and the model correction coefficient C ₀ value to calculate the hourly total wall radiant heat transfer amount from each wall of the non-air-conditioned area to the floor of the air-conditioned area:

   

   In the formula, Q _{WR, d, τ} are the total wall radiant heat transfer from each wall of the non-air-conditioned area to the floor of the air-conditioned area at time τ, C ₀ is the model correction coefficient, S _d is the area of the air-conditioned area floor, and ε _d is The emissivity of the floor of the air-conditioned area, X _d,i is the angle coefficient of the floor of the air-conditioned area to the wall of the non-air-conditioned area i, T _i,τ is the thermodynamic temperature of the wall of the non-air-conditioned area i at time τ, and T _d,τ is The thermodynamic temperature of the floor of the air-conditioned area at time τ, where N is the number of walls divided by the non-air-conditioned area,

   At the same time, the hourly total solar radiant heat transfer from the external windows of the non-air-conditioned area to the floor of the air-conditioned area is calculated by equation (14):

   

   In the formula, Q _{SR, d, τ} is the total solar radiation heat transfer amount of the solar radiation through the external windows of the non-air-conditioned area to the floor of the air-conditioned area at time τ, ρ _d is the solar radiation absorption coefficient of the floor of the air-conditioned area, X _k,d k non-air-conditioned area outside the window coefficients of the angle of the air-conditioned area floor, S _k k outside the window area of the non-air-conditioned _area, J _{k, τ} is the time [tau] k solar radiation through an outer non-air-conditioned area illumination window, N 'non- The number of external windows in the air-conditioned area,

   Then, the hourly radiant heat transfer quantity Q _R,τ is calculated by formula (15):

   Q _R,τ =C _1a Q _WR,d,τ +C _1b Q _SR,d,τ (15)

   In the formula, Q _R,τ is the amount of radiant heat transfer from the entire non-air-conditioned area to the air-conditioned area at time τ, C _1a is the heat gain correction coefficient _{of the air-conditioned area, and C 1b} is the sun heat correction coefficient of the air-conditioned area;

   Step T4, fitting the hourly radiant heat transfer quantity Q _R,τ ,

   Fit the time-wise change data of the radiant heat transfer amount into a Fourier series form:

   

   In the formula, Q _R,τ is the amount of radiant heat transfer from the entire non-air-conditioned area to the air-conditioned area at time τ, Q _R,p is the hourly average radiant heat transfer of the entire air-conditioned area, and ΔQ _R,n is the nth-order radiant heat The amplitude of the change in the transfer amount, ω _R,n is the frequency of the n-th radiant heat transfer change, and φ _R,n is the initial phase of the n-th radiant heat transfer change;

   Step T5, calculate the non-steady-state radiant heat transfer load CLQ _R,τ :

   

   In the formula, CLQ _R,τ is the unsteady-state radiant heat transfer load of the stratified air-conditioning at τ, Q _R,p is the hourly average radiant heat transfer of the entire air-conditioned area, and ΔQ _R,n is the nth-order radiant heat transfer Variation amplitude, ν _{f, d, n} is the attenuation degree of the ground to the nth-order radiant heat disturbance, ω _R,n is the frequency of the n-th radiant heat transfer change, and φ _R,n is the nth-order radiation The initial phase of the heat transfer change, ε _{f, d, n} is the heat release delay time to the n-th order radiant heat disturbance.
3. The simplified calculation method for the unsteady-state radiant heat transfer load engineering of a large-space building stratified air conditioner according to claim 2, characterized in that:

   Wherein, the model correction coefficient C ₀ is the radiant heat transfer between the walls of the non-air-conditioned area calculated by the Gebhart radiation model and the floor of the air-conditioned area, and the direct radiation model is used to calculate the radiant heat transfer between the walls of the non-air-conditioned area and the floor of the air-conditioned area. Ratio of

   The wall heat _{gain correction coefficient C 1a} of the air-conditioning zone is the ratio of the sum of the radiant heat transfer amount of each wall surface of the air-conditioning zone calculated by the Gebhart radiation model to the floor radiant heat transfer amount of the air-conditioning zone.

   The solar heat gain correction coefficient C _1b of the air-conditioned area is the ratio of the total amount of solar radiation heat transfer from the non-air-conditioned area absorbed by each wall surface of the air-conditioned area to the solar radiation heat transfer amount from the non-air-conditioned area absorbed by the floor of the air-conditioned area.

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