CN115075863A - Heat insulation air pipe for ventilation of high-ground-temperature tunnel and heat insulation efficiency estimation method - Google Patents
Heat insulation air pipe for ventilation of high-ground-temperature tunnel and heat insulation efficiency estimation method Download PDFInfo
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Abstract
The invention discloses a heat insulation air pipe for ventilation of a high-ground-temperature tunnel and a heat insulation efficiency estimation method. In order to solve the technical problems and achieve the corresponding technical effects, the invention combines the air duct cloth, the heat insulation air duct column bag and the aluminum foil cloth heat insulation layer to form a heat insulation air duct structure, increases the thermal resistance value of airflow heat transfer in the heat insulation air duct through the additionally arranged heat insulation air duct column bag, thereby effectively enhancing the heat insulation effect of the heat insulation air duct, effectively solving the problem that cold air is preheated during transmission in the air duct, further ensuring the effective cooling effect of the cold air in the air duct on a tunnel face, simultaneously estimating the heat insulation efficiency of the heat insulation air duct, further providing data support and guiding construction for the construction of the heat insulation air duct and ensuring the effectiveness of the construction of the heat insulation air duct.
Description
Technical Field
The invention relates to the technical field of tunnel construction ventilation, in particular to a heat insulation air pipe for ventilation of a high-ground-temperature tunnel and a heat insulation efficiency estimation method.
Background
In recent years, with the vigorous construction of western regions in China, more and more high-ground-temperature tunnels appear in high-altitude regions. The problem of thermal hazard is endless, and too high temperature not only can influence the physical and mental health and the work efficiency of personnel, but also can cause the influence to the normal operation of equipment and lining intensity etc.. The construction ventilation is one of the most common and most economical cooling means for the high-ground-temperature tunnel.
The traditional ventilation cooling adopts the same air pipe as that in the ventilation of the common tunnel construction, when the high ground temperature section of the tunnel is longer, the air flow is always heated in the air pipe for a longer time before reaching the tunnel face, so that the air temperature reaching the tunnel face is in a higher state, and the cooling efficiency is influenced.
Disclosure of Invention
The invention aims to provide a heat insulation air pipe for ventilation of a high-ground-temperature tunnel and a heat insulation efficiency estimation method, which can effectively enhance the heat insulation efficiency of a heat insulation air pipe structure, avoid cold air from being heated in the air pipe to cause the air temperature of a tunnel face to be too high, ensure the effective cooling effect of the tunnel face, and estimate the heat insulation efficiency of the heat insulation air pipe structure by the heat insulation efficiency estimation method of the heat insulation air pipe, thereby providing data support guidance construction for the construction of the heat insulation air pipe and ensuring the effectiveness of the construction of the heat insulation air pipe.
The invention is realized by the following technical scheme:
the method comprises air duct cloth, a heat insulation column bag and an aluminum foil cloth heat insulation layer, wherein the heat insulation column bag is arranged on the inner side of the air duct cloth, the aluminum foil cloth heat insulation layer is arranged on the inner side of the heat insulation column bag, and heat insulation gas is filled in the heat insulation gas column bag. In order to solve the technical problems and realize corresponding technical effects, the invention adopts the air duct cloth, the heat insulation air duct bag and the combination to form the heat insulation air duct structure, and the added heat insulation air duct bag increases the heat resistance value of airflow heat transfer in the heat insulation air duct, thereby effectively enhancing the heat insulation effect of the heat insulation air duct, effectively solving the problem that cold air is preheated during the transmission of the cold air in the air duct, and ensuring the effective cooling effect of the cold air in the air duct on the tunnel face; meanwhile, the heat insulation efficiency of the heat insulation air pipe can be estimated, so that data support is provided for the construction of the heat insulation air pipe, the construction is guided, and the effectiveness of the construction of the heat insulation air pipe is ensured. The heat conductivity coefficient of the aluminum foil cloth heat insulation layer is about 0.03, and the heat insulation performance is good, so that heat insulation can be effectively realized; simultaneously the aluminium foil cloth insulating layer has good waterproof nature and leakproofness, can effectual reduction dryer air leakage problem the probability of appearance, and its tensile strength can reach 45Mpa greatly, the high static pressure environment in the adaptable dryer.
The further technical scheme is as follows:
the heat insulation gas column bag comprises a plurality of gas columns, and the curved surfaces of the gas columns are connected in sequence.
Further: a connecting section is arranged between the adjacent gas columns, and the adjacent gas columns are communicated through the connecting section.
Further: the air column on one side of the heat insulation air column bag is provided with a button head, the air column on the other side of the heat insulation air column bag is provided with a button hole, and the button head is matched with the button hole.
Further: a plurality of button heads are arranged along the length direction of the air column, and a plurality of button holes are correspondingly arranged;
further: when the button head is buckled with the button hole, the heat insulation air column bag forms a closed heat insulation air column bag ring.
Further: the outer side wall of the heat insulation air column bag ring is tightly attached to the air duct cloth.
Further: connecting ropes are arranged on the air duct cloth and the heat insulation column bag, and the heat insulation column bag is fixedly arranged on the inner side of the air duct cloth through the connecting ropes;
and further: the connecting ropes on the heat insulation column bag are arranged at two ends of the heat insulation column bag;
further: the length of each air column is not more than 2 m.
Further: the heat insulation column bag is made of a PA release film, the maximum using temperature of the PA release film is 160 ℃, the longitudinal tensile strength is 80MPa, and the transverse tensile strength is 60 MPa.
A method for estimating the heat insulation efficiency of a heat insulation air pipe comprises the following steps:
acquiring the external initial temperature T of the air duct cloth by adopting a temperature monitor o And temperature T in the air cylinder cloth i ；
A thermal insulation column bag is not arranged, and the temperature rise delta T in the thermal insulation air pipe at the moment is calculated;
arranging a heat insulation column bag and calculating the temperature rise delta T' in the heat insulation air pipe at the moment;
calculating the thermal insulation efficiency of the thermal insulation air pipe
A method for estimating the heat insulation efficiency of a heat insulation air pipe comprises the steps of dividing the air pipe into n calculation sections when heat insulation efficiency calculation is carried out, wherein the length of each section is l, and obtaining the temperature rise in the heat insulation air pipe in an iterative calculation mode;
the calculation process and formula of the heat insulation efficiency are as follows: when the heat-insulating gas column bag is not arranged,
convection heat exchange quantity from hot fluid to the outer surface of the air duct cloth:
heat conduction from the outer surface to the inner surface of the air duct cloth:
convection heat exchange from the inner surface of the air duct cloth to the cold fluid in the air duct:
(S1), (S2) and (S3)
And
equal, the three simultaneous equations are solved to obtain the heat transfer capacity per unit ventilation length as follows:
heat transfer amount of the high ground temperature ventilation section:
raising the temperature of air in the air pipe:
the iterative operation formula is as follows:
heat transfer amount of single calculation section:
internal air temperature rise temperature of single calculation section:
wind temperature in the wind pipe: tij ═ Δ T j +Ti(j-1) (S9)
Using the formulas (S7), (S8) and (S9), iterating from j to 1, and obtaining a final air duct internal temperature Tin when j is n, wherein Δ T is Tin-Ti 0;
in each formula: t is o K is the air temperature outside the air pipe; t is i The air temperature in the air pipe is K; t is W1 The temperature of the outer surface of the air duct cloth is K; t is W2 The temperature of the inner surface of the air duct cloth is K; d is the diameter of the air pipe, m; a is the area of the cross section of the air pipe and square meter; and L is the ventilation distance of the high ground temperature section, m. l is the length of the unit calculation segment, m; j is the unit calculation segment number; delta is the thickness of the air duct cloth, m; lambda is the heat conductivity coefficient of the air duct cloth, W/(m.K); h is 1 Is the heat exchange coefficient of air and the outer surface of the air barrel, W/(m) 2 ·K)；h 2 Is the heat exchange coefficient of air and the inner surface of the wind barrel, W/(m) 2 ·K)；
When the heat-insulating gas column bag is arranged,
convection heat exchange quantity from hot fluid to the outer surface of the air duct cloth is as follows:
heat conduction inside the air duct cloth:
heat conduction inside the heat insulating column bag:
the heat conduction of the aluminum foil cloth heat insulation layer is as follows:
convection heat exchange from the inner surface of the aluminum foil cloth thermal insulation layer to the cold fluid in the air pipe:
(S10), (S11), (S12), (S13) and (14) in the formula
And
equal, simultaneous five-form solutionHeat transfer capacity per ventilation length:
heat transfer amount of the high ground temperature ventilation section:
raising the temperature of air in the air pipe:
the iterative calculation formula is as follows:
heat transfer amount of single calculation section:
internal air temperature rise temperature of single calculation section:
the wind temperature in the wind pipe is as follows: ti 'j ═ Δ T' j +Ti′(j-1) (S20)
Iteratively calculating from j to 1 through equations (S18), (S19) and (S20), and obtaining a final in-duct temperature Ti 'n, Δ T ═ Ti' n-Ti0 when j is equal to n;
substituting Δ T and Δ T' into the formula for calculating the thermal insulation efficiency
Obtaining the heat insulation efficiency of the heat insulation air pipe;
in each formula: t is o The temperature of air outside the air pipe is K; t is a unit of i The air temperature in the air pipe is K; t is W1 The temperature of the outer surface of the air duct cloth is K; t is a unit of W2 The temperature of the inner surface of the air duct cloth is K; t is a unit of w3 The temperature of the outer surface of the heat insulation gas column bag, K; d is the diameter of the air pipe, m; a is the cross-sectional area of the wind pipe and square meter; and L is the ventilation distance of the high ground temperature section, m. l is the length of the unit calculation segment, m; j is the unit calculation segment number; delta is the thickness of the air duct cloth, m; lambda is wind tube cloth heat conduction systemNumber, W/(m.K); h is 1 Is the heat exchange coefficient of air and the outer surface of the air barrel, W/(m) 2 ·K)；h 2 Is the heat exchange coefficient of air and the inner surface of the wind barrel, W/(m) 2 ·K)；h 3 Is the heat exchange coefficient W/(m) of the aluminum foil cloth and the fluid in the air cylinder 2 ·K)；λ a Is the thermal conductivity of air, W/(m.K); delta a Is the equivalent thickness of the air column bag, m; lambda b The thermal conductivity coefficient W/(m.K) of the aluminum foil cloth; delta b Is the equivalent thickness of the aluminum foil cloth, m.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the invention relates to a heat insulation air pipe for ventilation of a high-ground-temperature tunnel and a heat insulation efficiency estimation method.
2. According to the heat insulation air pipe for ventilation of the high-ground-temperature tunnel and the heat insulation efficiency estimation method, the air temperature rise in the air pipe is calculated in an iterative calculation mode, the accuracy of a calculated value can be improved, and the accuracy degree of heat insulation efficiency estimation is ensured.
Drawings
In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and that for those skilled in the art, other related drawings can be obtained from these drawings without inventive effort. In the drawings:
FIG. 1 is a schematic view of the structure of the heat insulation air duct of the present invention;
FIG. 2 is a schematic view of the structure of the heat-insulating gas column bag of the present invention;
FIG. 3 is an enlarged view of a portion A of FIG. 2;
FIG. 4 is a sectional view of the duct;
FIG. 5 is a schematic view of the air duct structure without the heat-insulating air column bag;
FIG. 6 is a schematic view of the structure of the air duct for installing the heat-insulating air column bag;
FIG. 7 is a table of data of a conventional duct calculation process without the provision of the insulating gas column bag;
FIG. 8 is a table of data for a calculation process for setting up the air duct of the insulating column bag.
Reference numbers and corresponding part names in the drawings:
1-air duct cloth, 2-heat insulation column bag, 3-aluminum foil cloth heat insulation layer, 21-air column, 22-connecting section, 23-button head, 24-button hole and 25-connecting rope.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: it is not necessary to employ these specific details to practice the present invention. In other instances, well-known structures, circuits, materials, or methods have not been described in detail so as not to obscure the present invention.
Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the invention. Thus, the appearances of the phrases "one embodiment," "an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In the description of the present invention, the terms "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "upper", "lower", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and therefore, should not be construed as limiting the scope of the present invention.
Example 1
As shown in fig. 1 to 3, the heat insulation air duct for ventilation in high-ground-temperature tunnel construction of the present invention comprises an air duct cloth 1, a heat insulation column bag 2 and an aluminum foil cloth heat insulation layer 3, wherein the heat insulation column bag 2 is arranged on the inner side of the air duct cloth 1, the aluminum foil cloth heat insulation layer 3 is arranged on the inner side of the heat insulation column bag 2, and the heat insulation column bag 2 is filled with heat insulation gas. In this embodiment, constitute thermal-insulated tuber pipe structure with dryer cloth 1, thermal-insulated gas column bag 2 and 3 combinations of aluminium foil cloth insulating layer, increased the thermal resistance value of the wind heat transfer in the thermal-insulated tuber pipe through the thermal-insulated gas column bag 2 that adds to effectual thermal-insulated effect that has strengthened thermal-insulated tuber pipe, the effectual transmission of having solved cold wind is the problem of being preheated in the tuber pipe, thereby guaranteed the effectual cooling effect of cold wind to the face in the tuber pipe. The property that gas is not a good conductor of heat is effectively utilized, and the heat insulation air duct is enhanced by filling the heat insulation air column bag 2 with gas, so that the heat transfer to the air duct is reduced.
In this embodiment, in order to improve the suitability of heat insulating gas column bag 2 for heat insulating gas column bag 2 can adapt to the tuber pipe structure of more different structural style, designs heat insulating gas column bag 2, heat insulating gas column bag 2 includes a plurality of gas columns 21, and is a plurality of the curved surface of gas column 21 links to each other in proper order. Wherein the air column 21 structure that a plurality of curved surfaces link to each other makes whole heat insulating column bag 2 can effectually buckle for heat insulating column bag 2 can set up along with the structure of tuber pipe, thereby better realization is to the separation effect of heat transfer, avoids the inside cold air of tuber pipe to be heated.
A connecting section 22 is arranged between the adjacent air columns 21, and the adjacent air columns 21 are communicated through the connecting section 22. In this embodiment, the connection section 22 is arranged to make the heat insulating column bag 2 have a certain flexibility, so as to ensure better matching with the air pipe structure.
The air column 21 on one side of the heat insulation air column bag 2 is provided with a button head 23, the air column 21 on the other side is provided with a button hole 24, and the button head 23 is matched with the button hole 24. A plurality of button heads 23 are arranged along the length direction of the air column 21, and a plurality of button holes 24 are correspondingly arranged; when the button head 23 and the button hole 24 are fastened, the heat insulation gas column bag 2 forms a closed heat insulation gas column bag ring. The outer side wall of the heat insulation air column bag ring is tightly attached to the air duct cloth 1. In this embodiment, the heat insulating column bag 2 can be connected into a closed loop by the button head 23 and the button hole 24, so as to be conveniently installed in the air duct; meanwhile, the heat insulation column bag 2 is tightly attached to the air duct cloth 1, and the heat insulation column bag 2 has certain sealing property and blocking property, so that the problem of air leakage of the air duct in the ventilation construction process can be effectively solved.
Connecting ropes 25 are arranged on the air duct cloth 1 and the heat insulation column bag 2, and the heat insulation column bag 2 is fixedly arranged on the inner side of the air duct cloth 1 through the connecting ropes 25; in this embodiment, can strengthen the installation fixed effect of heat insulating gas column bag 2 through connecting rope 25, ensure that it can not take place the skew scheduling problem and influence its thermal-conductive separation effect in the use.
The connecting ropes 25 on the heat insulation column bag 2 are arranged at two ends of the heat insulation column bag 2; the length of each air column 21 is not more than 2 m. In this embodiment, the connecting string 25 is disposed at two ends of the heat insulation air column bag 2 for convenient installation, and is inconvenient to install if disposed at a middle position, and at the same time, the length of the air column 21 should not exceed 2m in order to avoid the sagging of the heat insulation air column bag 2 located above due to the influence of gravity.
The heat insulation column bag 2 is made of a PA release film, the maximum using temperature of the PA release film is 160 ℃, the longitudinal tensile strength is 80MPa, and the transverse tensile strength is 60 MPa. In this embodiment, adopt PA to leave thermal-insulated gas column bag 2 that the type membrane made, no matter its heat resistance or tensile strength can both satisfy the requirement of construction ventilation in the present high ground temperature tunnel, can avoid from this because the high temperature leads to thermal-insulated gas column bag 2 self damaged, or because the too big cracked problem of thermal-insulated gas column bag 2 that leads to of wind pressure intensity appears.
Example 2
The method comprises the following steps:
a method for estimating the heat insulation efficiency of a heat insulation air pipe comprises the step of acquiring the external initial temperature T of an air cylinder cloth 1 by a temperature monitor o And the temperature T in the air tube cloth 1 i ；
The heat insulation air pipe is not provided with the heat insulation air column bag 2, and the temperature rise delta T in the heat insulation air pipe is calculated at the moment;
arranging a heat insulation air column bag 2 and calculating the temperature rise delta T' in the heat insulation air pipe at the moment;
calculating the thermal insulation efficiency of the thermal insulation air pipe
When the heat insulation efficiency is calculated, the air pipe is divided into n calculation sections, the length of each section is l, and the temperature rise in the heat insulation air pipe is obtained in an iterative calculation mode;
the calculation process and formula of the heat insulation efficiency are as follows: when the heat insulating gas column bag 2 is not provided,
the convection heat exchange quantity from the hot fluid to the outer surface of the air duct cloth 1 is as follows:
heat conduction from the outer surface to the inner surface of the air duct cloth 1:
convection heat exchange from the inner surface of the air duct cloth 1 to the cold fluid in the air duct:
(S1), (S2) and (S3)
And
equal, the three simultaneous equations are solved to obtain the heat transfer capacity per unit ventilation length as follows:
heat transfer amount of the high ground temperature ventilation section:
raising the temperature of air in the air pipe:
the iterative operation formula is as follows:
heat transfer amount of single calculation section:
internal air temperature rise temperature of single calculation section:
the wind temperature in the wind pipe is as follows: tij ═ Δ T j +Ti(j-1) (S9)
Using the formulas (S7), (S8) and (S9), iterating from j to 1, and obtaining a final air duct internal temperature Tin when j is n, wherein Δ T is Tin-Ti 0;
in each formula: t is o The temperature of air outside the air pipe is K; t is i In the air ductWind temperature, K; t is W1 The temperature of the outer surface of the air duct cloth is K; t is W2 The temperature of the inner surface of the air duct cloth is K; d is the diameter of the air pipe, m; a is the cross-sectional area of the wind pipe and square meter; and L is the ventilation distance of the high ground temperature section, m. l is the length of the unit calculation segment, m; j is the unit calculation segment number; delta is the thickness of the air duct cloth, m; lambda is the heat conductivity coefficient of the air duct cloth, W/(m.K); h is 1 Is the heat exchange coefficient of air and the outer surface of the air barrel, W/(m) 2 ·K)；h 2 Is the heat exchange coefficient of air and the inner surface of the wind barrel, W/(m) 2 ·K)；
When the heat insulating gas column bag 2 is arranged,
the convection heat exchange quantity of the hot fluid to the outer surface of the air duct cloth 1 is as follows:
heat conduction inside the air duct fabric 1:
heat conduction inside the heat insulating column bag 2:
the heat conduction of the aluminum foil cloth thermal insulation layer 3 is as follows:
convection heat transfer from the inner surface of the aluminum foil cloth thermal insulation layer 3 to the cold fluid in the air pipe:
(S10), (S11), (S12), (S13) and (14)
And
and (3) equally, solving the five simultaneous formulas to obtain the heat transfer quantity of the unit ventilation length:
heat transfer amount of the high ground temperature ventilation section:
raising the temperature of air in the air pipe:
the iterative calculation formula is as follows:
heat transfer amount of single calculation section:
internal air temperature rise temperature of single calculation section:
the wind temperature in the wind pipe is as follows: ti 'j ═ Δ T' j +Ti′(j-1)(S20)
Iteratively calculating from j to 1 through equations (S18), (S19) and (S20), and obtaining a final in-duct temperature Ti 'n, Δ T ═ Ti' n-Ti0 when j is equal to n;
substituting Δ T and Δ T' into the formula for calculating the thermal insulation efficiency
Obtaining the heat insulation efficiency of the heat insulation air pipe;
in each formula: t is o The temperature of air outside the air pipe is K; t is i The air temperature in the air pipe is K; t is W1 The temperature of the outer surface of the air duct cloth is K; t is W2 The temperature of the inner surface of the air duct cloth is K; t is w3 The temperature of the outer surface of the heat insulation gas column bag, K; d is the diameter of the air pipe, m; a is the cross-sectional area of the wind pipe and square meter; l is ventilation distance of high ground temperature section, m. l is the length of the unit calculation segment, m; j is the unit calculation segment number; delta is the thickness of the air duct cloth, m; lambda is the heat conductivity coefficient of the air duct cloth, W/(m.K); h is 1 Is air and a wind tubeCoefficient of heat transfer from the outer surface, W/(m) 2 ·K)；h 2 Is the heat exchange coefficient of air and the inner surface of the wind barrel, W/(m) 2 ·K)；h 3 The heat exchange coefficient of the aluminum foil cloth and the fluid in the air cylinder is adopted; lambda [ alpha ] a Is the thermal conductivity of air, W/(m.K); delta a Is the equivalent thickness of the air column bag, m; lambda [ alpha ] b The thermal conductivity coefficient W/(m.K) of the aluminum foil cloth; delta b Is the equivalent thickness of the aluminum foil cloth, m. In this embodiment, it is found by comparing the formulas (S4) and (S15) that the total thermal resistance value (denominator) of the thermal insulation air duct provided with the thermal insulation air duct 2 is larger due to the existence of the thermal insulation air column bag 2, so that the heat quantity transferred to the cooling fluid in the air duct by the hot fluid outside the air duct is smaller, and the temperature rise in the air duct is smaller because the transferred heat quantity is smaller.
Example 3
The embodiment provides an estimation situation of the heat insulation efficiency in an actual scene on the basis of the embodiment 2.
The length of a high ground temperature section of a certain section of tunnel is 3000m, and the initial temperature T in the section of air pipe i At 20 ℃ and the temperature T outside the air duct o The wind speed v is 15m/s at 50 ℃, the diameter d of the wind pipe is 2m, and the thickness delta of the wind pipe cloth 1 is 4mm (4 x 10) -3 m), the heat conductivity coefficient lambda of the air duct cloth is 0.038W/(m.k), and the equivalent thickness delta of the heat insulation air column bag a Is 4cm (4 x 10) -2 m), thermal conductivity of air lambda a 0.0244W/(m.K), and the surface heat exchange coefficient h of air and air-duct cloth is 10W/(m.K) 2 K) thickness of the aluminium foil cloth heat-insulating layer delta b Is 3mm (3 x 10) -3 m), heat conductivity coefficient lambda of aluminum foil cloth b The surface heat exchange coefficient h is 0.03W/(m.K) 1 Take 5W/(m) 2 ·K),h 2 And h 3 Take 20W/(m) 2 ·K)。
Calculating the temperature rise of the traditional air pipe without the heat insulation column bag, obtaining a process data result as shown in fig. 7, and determining that delta T is 17.6 ℃; calculating the temperature rise of the air pipe of the non-heat-insulating air column bag 2, obtaining a process data result shown in fig. 8, and determining that delta T' is 4.1 ℃; the heat insulation efficiency of the air pipe provided with the heat insulation column bag 2 compared with the traditional air pipe is obtained by calculation
Compared with the temperature rise before and after the arrangement of the heat insulation gas column bag 2, the heat insulation efficiency of the heat insulation air pipe exceeds 75 percent. The heat insulation effect is better, and the ventilation effect of the high-ground-temperature tunnel construction can be effectively guaranteed.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. The utility model provides a thermal-insulated tuber pipe for ventilation of high ground temperature tunnel, its characterized in that, includes dryer cloth (1), thermal-insulated gas column bag (2) and aluminium foil cloth insulating layer (3), thermal-insulated gas column bag (2) set up in dryer cloth (1) is inboard, aluminium foil cloth insulating layer (3) set up in the inboard of thermal-insulated gas column bag (2), just fill in thermal-insulated gas column bag (2).
2. The thermal insulation air duct for ventilation of high-ground-temperature tunnels according to claim 1, characterized in that the thermal insulation air column bag (2) comprises a plurality of air columns (21), and the curved surfaces of the plurality of air columns (21) are connected in sequence.
3. The insulated air duct for ventilation of high-ground-temperature tunnels according to claim 2, characterized in that a connecting section (22) is provided between adjacent air columns (21), and the adjacent air columns (21) are communicated through the connecting section (22).
4. The thermal insulation air duct for ventilation of high-ground-temperature tunnels according to claim 1, characterized in that the air column (21) on one side of the thermal insulation air column bag (2) is provided with a button head (23), the air column (21) on the other side is provided with a button hole (24), and the button head (23) is matched with the button hole (24).
5. The insulated air duct for ventilation of high-geothermal tunnels according to claim 4, characterized in that a plurality of button heads (23) are provided along the length direction of the air column (21) and a plurality of button holes (24) are correspondingly provided;
when the button head (23) is buckled with the button hole (24), the heat insulation gas column bag (1) forms a closed heat insulation gas column bag ring.
6. The insulating air duct for ventilation of high-ground-temperature tunnels according to claim 5, characterized in that the outer side wall of the insulating air column bag ring is tightly attached to the air duct cloth (1).
7. The heat insulation air duct for ventilating the high-ground-temperature tunnel according to claim 1, wherein the air duct cloth (1) and the heat insulation air column bags (2) are provided with connecting ropes (25), and the heat insulation air column bags (2) are fixedly arranged on the inner side of the air duct cloth (1) through the connecting ropes (25);
the connecting ropes (25) on the heat insulation column bag (2) are arranged at two ends of the heat insulation column bag (2);
the length of each air column (21) is not more than 2 m.
8. The heat insulation air pipe for ventilation of the high-ground-temperature tunnel according to claim 1, wherein the heat insulation column bag (2) is made of a PA release film, the maximum service temperature of the PA release film is 160 ℃, the longitudinal tensile strength is 80MPa, and the transverse tensile strength is 60 MPa.
9. The method for estimating the heat insulation efficiency of the heat insulation air duct according to any one of claims 1 to 8, characterized by comprising the following steps:
the temperature monitor is adopted to obtain the external initial temperature T of the air cylinder cloth (1) o And the temperature T in the air cylinder cloth (1) i ；
The heat insulation column bag (2) is not arranged, and the temperature rise delta T in the heat insulation air pipe is calculated at the moment;
arranging a heat insulation air column bag (2) and calculating the temperature rise delta T' in the heat insulation air pipe at the moment;
calculating the thermal insulation efficiency of the thermal insulation air pipe
10. The method for predicting the heat insulation efficiency of the heat insulation air duct according to claim 9, wherein the air duct is divided into n calculation sections during the calculation of the heat insulation efficiency, each section is l, and the temperature rise in the heat insulation air duct is obtained in an iterative calculation manner;
the calculation process and the formula of the heat insulation efficiency are as follows: when the heat insulation column bag (2) is not arranged,
convection heat exchange quantity of hot fluid to the outer surface of the air cylinder cloth (1):
heat conduction from the outer surface to the inner surface of the air duct cloth (1):
the convection heat exchange from the inner surface of the air duct cloth (1) to the cold fluid in the air duct is as follows:
(S1), (S2) and (S3)
And
equal, the three simultaneous equations are solved to obtain the heat transfer capacity per unit ventilation length as follows:
heat transfer amount of the high ground temperature ventilation section:
raising the temperature of air in the air pipe:
the iterative operation formula is as follows:
heat transfer amount of single calculation section:
internal air temperature rise temperature of single calculation section:
the wind temperature in the wind pipe is as follows: tij ═ Δ T j +Ti(j-1) (S9)
Using the formulas (S7), (S8) and (S9), iterating from j to 1, and obtaining a final air duct internal temperature Tin when j is n, wherein Δ T is Tin-Ti 0;
in each formula: t is o The temperature of air outside the air pipe is K; t is i The air temperature in the air pipe is K; t is W1 The temperature of the outer surface of the air duct cloth is K; t is W2 The temperature of the inner surface of the air duct cloth is K; d is the diameter of the air pipe, m; a is the cross-sectional area of the wind pipe and square meter; l is ventilation distance of high ground temperature section, m. l is the length of the unit calculation segment, m; j is the unit calculation segment number; delta is the thickness of the air duct cloth, m; lambda is the heat conductivity coefficient of the air duct cloth, W/(m.K); h is 1 Is the heat exchange coefficient of air and the outer surface of the air barrel, W/(m) 2 ·K)；h 2 Is the heat exchange coefficient of air and the inner surface of the wind barrel, W/(m) 2 ·K)；
When the heat insulation gas column bag (2) is arranged,
convection heat exchange quantity of hot fluid to the outer surface of the air cylinder cloth (1):
heat conduction inside the air duct cloth (1):
heat conduction inside the heat insulating gas column bag (2):
the heat conduction of the aluminum foil cloth heat insulation layer (3) is as follows:
the convection heat exchange from the inner surface of the aluminum foil cloth thermal insulation layer (3) to the cold fluid in the air pipe is as follows:
(S10), (S11), (S12), (S13) and (14) in the formula
And
and (3) equally solving the five simultaneous formulas to obtain the heat transfer quantity of the unit ventilation length:
heat transfer amount of the high ground temperature ventilation section:
raising the temperature of air in the air pipe:
the iterative calculation formula is as follows:
single meterCalculating the heat transfer capacity of the section:
internal wind temperature rise temperature of single calculation segment:
the wind temperature in the wind pipe is as follows: ti 'j ═ Δ T' j +Ti′(j-1) (S20)
Iterative operation is started from j ═ 1 through formulas (S18), (S19) and (S20), and when j ═ n, the final in-duct temperature Ti 'n, Δ T ═ Ti' n-Ti0 is obtained;
substituting Δ T and Δ T' into the formula for calculating the thermal insulation efficiency
Obtaining the heat insulation efficiency of the heat insulation air pipe;
in each formula: t is o The temperature of air outside the air pipe is K; t is i The air temperature in the air pipe is K; t is W1 The temperature of the outer surface of the air duct cloth is K; t is W2 The temperature of the inner surface of the air duct cloth is K; t is w3 The temperature of the outer surface of the heat insulation gas column bag, K; d is the diameter of the air pipe, m; a is the cross-sectional area of the wind pipe and square meter; and L is the ventilation distance of the high ground temperature section, m. l is the length of the unit calculation segment, m; j is the unit calculation segment number; delta is the thickness of the air duct cloth, m; lambda is the heat conductivity coefficient of the air duct cloth, W/(m.K); h is a total of 1 Is the heat exchange coefficient of air and the outer surface of the air barrel, W/(m) 2 ·K)；h 2 Is the heat exchange coefficient of air and the inner surface of the wind barrel, W/(m) 2 ·K)；h 3 Is the heat exchange coefficient W/(m) of the aluminum foil cloth and the fluid in the air cylinder 2 ·K)；λ a Is the thermal conductivity of air, W/(m.K); delta a Is the equivalent thickness of the air column bag, m; lambda [ alpha ] b The thermal conductivity coefficient W/(m.K) of the aluminum foil cloth; delta b Is the equivalent thickness of the aluminum foil cloth, m.
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