Methods and apparatus for calculating the heat transfer coefficient of glass surface

Abstract

This invention relates to the field of rail vehicles, and provides a method and apparatus for calculating the heat transfer coefficient of a glass surface. The method includes: obtaining the actual operating speed of the rail vehicle and the actual length of the side window; and calculating the heat transfer coefficient of the glass surface based on the actual operating speed and the actual length. According to the embodiment of this invention, the method for calculating the heat transfer coefficient of the glass surface can be derived by obtaining the actual operating speed of the rail vehicle and the actual length of the side window, thereby providing guidance for the design stage of rail vehicles. This not only creates a comfortable riding environment for passengers and onboard staff, but also reduces the heat load of the rail vehicle's air conditioning system.

Description

Technical Field

[0001] This invention relates to the field of rail vehicles, and provides a method and apparatus for calculating the heat transfer coefficient of a glass surface. Background Technology

[0002] In related technologies, energy loss in the passenger compartment of rail vehicles is mainly achieved through leakage from door and window gaps, heat transfer through side window glass, and heat transfer through the vehicle body enclosure structure.

[0003] The area of ​​the side window glass is approximately 30% of the area of ​​the train's side walls, therefore its thermal insulation performance has a significant impact on the train's air conditioning load. When calculating thermal insulation performance, the heat transfer coefficients of the inner and outer surfaces of the side window glass have a significant influence on the calculation results.

[0004] Current railway industry standards do not provide a method for calculating the heat transfer coefficient of the outer side window glass. Designers typically use the heat transfer coefficient of the train's exterior when it is stationary. During train movement, this calculation result deviates from reality, especially when calculating the heat transfer of the side window glass in high-speed trains. Summary of the Invention

[0005] This invention provides a method for calculating the heat transfer coefficient of a glass surface, thereby addressing the deficiency in related technologies where the heat transfer coefficient of a glass surface cannot be calculated and verified.

[0006] This invention also provides a device for calculating the heat transfer coefficient of a glass surface.

[0007] This invention also provides an electronic device.

[0008] This invention also provides a non-transitory computer-readable storage medium.

[0009] This invention also provides a computer program product.

[0010] This invention provides a method for calculating the heat transfer coefficient of a glass surface, comprising:

[0011] Obtain the actual operating speed of the rail vehicle and the actual length of the side windows;

[0012] The heat transfer coefficient of the glass surface is calculated based on the actual operating speed and the actual length.

[0013] According to the glass surface heat transfer coefficient calculation method provided in the embodiments of the present invention, the glass surface heat transfer coefficient can be derived by obtaining the actual operating speed of the rail vehicle and the actual length of the side window, thereby providing guidance for the design stage of the rail vehicle. This not only creates a comfortable riding environment for passengers and onboard staff, but also reduces the heat load of the rail vehicle's air conditioning system.

[0014] According to one embodiment of the present invention, the heat transfer coefficient of the glass surface is derived by the following formula:

[0015]

[0016] Where Nu represents the Nusselt number, h represents the heat transfer coefficient of the glass surface, l represents the equivalent dimension, and λ represents the thermal conductivity of air;

[0017]

[0018] Among them, Re f Represents the Reynolds number and Pr at temperature f. f The Prandtl number and Pr represent the temperature f. w The Prandtl number represents the temperature w.

[0019] That is,

[0020] During the operation of the rail vehicle, it is equivalent to the train being stationary, and the air flowing relative to the rail vehicle at a velocity v.

[0021]

[0022] Where ρ represents air density; μ represents air viscosity coefficient;

[0023] Combining the above formulas, the heat transfer coefficient h of the glass surface is obtained as follows:

[0024]

[0025] Where v represents the actual operating speed and l represents the actual length.

[0026] This invention also provides a device for calculating the heat transfer coefficient of a glass surface, comprising:

[0027] The acquisition module is used to acquire the actual operating speed of the rail vehicle and the actual length of the side window;

[0028] The calculation module is used to calculate the heat transfer coefficient of the glass surface based on the actual operating speed and the actual length.

[0029] This invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-described method for calculating the heat transfer coefficient of a glass surface.

[0030] This invention also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the above-described method for calculating the heat transfer coefficient of a glass surface.

[0031] This invention also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method for calculating the heat transfer coefficient of a glass surface.

[0032] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0033] According to the glass surface heat transfer coefficient calculation method provided in the embodiments of the present invention, the glass surface heat transfer coefficient can be derived by obtaining the actual operating speed of the rail vehicle and the actual length of the side window, thereby providing guidance for the design stage of the rail vehicle. This not only creates a comfortable riding environment for passengers and onboard staff, but also reduces the heat load of the rail vehicle's air conditioning system. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in this invention or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic flowchart of the method for calculating the heat transfer coefficient of a glass surface provided by the present invention;

[0036] Figure 2 This is a schematic structural diagram of the glass surface heat transfer coefficient calculation device provided by the present invention;

[0037] Figure 3 This is a schematic structural diagram of the electronic device provided by the present invention.

[0038] Figure label:

[0039] 10. Acquisition module; 20. Calculation module; 30. Processor; 40. Communication interface; 50. Memory; 60. Communication bus. Detailed Implementation

[0040] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0041] like Figure 1 As shown, an embodiment of the present invention provides a method for calculating the heat transfer coefficient of a glass surface, including:

[0042] Step 100: Obtain the actual operating speed of the rail vehicle and the actual length of the side window;

[0043] Step 200: Calculate the heat transfer coefficient of the glass surface based on the actual operating speed and the actual length.

[0044] According to the glass surface heat transfer coefficient calculation method provided in the embodiments of the present invention, the glass surface heat transfer coefficient can be derived by obtaining the actual operating speed of the rail vehicle and the actual length of the side window, thereby providing guidance for the design stage of the rail vehicle. This not only creates a comfortable riding environment for passengers and onboard staff, but also reduces the heat load of the rail vehicle's air conditioning system.

[0045] In step 100, the actual operating speed of the rail vehicle can be obtained by a speed sensor installed on the rail vehicle, and the actual length of the side window can be obtained by manual measurement.

[0046] In step 200, the heat transfer coefficient of the glass surface can be calculated based on the actual operating speed of the rail vehicle and the actual length of the side window obtained in step 100.

[0047] In this embodiment of the invention, heat exchange between the inner and outer surfaces of the rail vehicle window glass is mainly achieved through convection. Depending on the airflow velocity, it is categorized into laminar and turbulent flow states. The heat flux of convective heat transfer is directly proportional to the temperature difference between the fluid and the solid wall surface, i.e.:

[0048] q = h(t) w -t f );

[0049] Where q represents the heat exchange, in W / m³. 2 t w t represents the exterior surface temperature of the vehicle body, in °C. f The outside air temperature is expressed in °C, and h represents the convective heat transfer coefficient in W / m³. 2 ·℃.

[0050] The external surface temperature of the vehicle body and the outside air temperature are determined based on design experience or comprehensively based on the operating environment of the rail vehicle.

[0051] In this embodiment of the invention, heat exchange q is used to illustrate that the motion state of the rail vehicle needs to be considered during the design of the air conditioning load of the rail vehicle, such as whether the air conditioning load designed under the maximum operating speed of the rail vehicle can meet the design requirements.

[0052] The heat transfer coefficient is related to the shape Φ, dimensions l1, l2, l3, and the external surface temperature t of the vehicle body. w Outside air velocity v, outside air temperature t f And external air properties such as λ, c p A function of factors such as ρ, that is:

[0053] h = f(Φ, l1, l2, l3, t) w , t f v, λ, c p ,ρ…).

[0054] According to one embodiment of the present invention, the heat transfer coefficient of the glass surface is derived by the following formula:

[0055]

[0056] Where Nu represents the Nusselt number, h represents the heat transfer coefficient of the glass surface, l represents the equivalent dimension, and λ represents the thermal conductivity of air;

[0057] When calculating the air conditioning load of rail vehicles, it is necessary to know the heat transfer coefficient between the rail vehicle and the outside environment. Heat transfer between the rail vehicle and the outside environment mainly occurs through the car body and its side windows. The heat transfer through the side windows is typically calculated using the following formula:

[0058]

[0059] Among them, h e h is the heat transfer coefficient of the outer glass surface of the vehicle. t The heat transfer coefficient, h, of all components of the side window glass i The heat transfer coefficient of the glass surface inside the vehicle. In the actual operation of the rail vehicle, it is assumed that the air inside the vehicle is stationary, that is, hi is a fixed value.

[0060] When a rail vehicle is stationary or in motion, the heat transfer coefficient of the inner side window glass does not change significantly, while the heat transfer coefficient of the outer side window glass changes considerably with the vehicle's movement. As shown in the above formula, the heat transfer coefficient of the outer side window glass has a significant impact on the overall heat transfer coefficient of the side window glass.

[0061] The heat transfer coefficient of the side window glass surface of a rail vehicle can be calculated by analogy to air passing over a vertical flat plate in the opposite direction of the rail vehicle's movement, and the heat transfer intensity is expressed by the Nusselt number.

[0062]

[0063] Where Nu represents the Nuschelt number, Re f Represents the Reynolds number and Pr at temperature f. f The Prandtl number and Pr represent the temperature f. w The Prandtl number represents the temperature w.

[0064] When calculating the air conditioning load of rail vehicles, it is necessary to know the heat transfer coefficient between the rail vehicle and the outside environment. Heat transfer between the rail vehicle and the outside environment mainly occurs through the car body and its side windows. For heat transfer through the side windows, the coefficient is typically calculated using the formula... Calculate the heat transfer coefficient h of the side window glass, given a fixed window glass structure. t As a fixed value, the heat transfer coefficient h of the inner glass surface is relatively high because the airflow inside the rail vehicle is relatively slow. i The heat transfer coefficient h of the outer glass surface of the vehicle is close to a constant value. e The heat transfer coefficient varies with the speed of the rail vehicle. Therefore, obtaining the surface heat transfer coefficient of the rail vehicle's outer glass is particularly important for accurately calculating the rail vehicle's air conditioning load.

[0065] Combining the above derivation formula for the heat transfer coefficient of the glass surface with the convection heat transfer formula, we can obtain:

[0066]

[0067] For a moving rail vehicle, heat exchange between the vehicle and its surroundings is primarily achieved through airflow. This can be equivalent to the rail vehicle being stationary while the air flows at the same speed as the vehicle's movement; therefore, the Reynolds number can be expressed as:

[0068]

[0069] Where ρ represents air density; μ represents air viscosity coefficient;

[0070] Considering the complexity of temperature changes during the operation of rail vehicles, 20℃ is selected as the external heat transfer coefficient of the side windows during the operation of rail vehicles.

[0071] Combining the above formulas, the heat transfer coefficient h of the glass surface is obtained as follows:

[0072]

[0073] Where v represents the actual operating speed and l represents the actual length.

[0074] Taking 20 degrees as an example, Pr f =Pr w =0.703, ρ=1.205kg / m 3 λ=2.59×10 -2 W / (m·℃), μ=18.1×10 -6 kg / (m·s), therefore the external heat transfer coefficient of the side window of the rail vehicle is obtained:

[0075]

[0076] like Figure 2 As shown, this embodiment of the invention also provides a device for calculating the heat transfer coefficient of a glass surface, comprising:

[0077] Module 10 is used to acquire the actual operating speed of the rail vehicle and the actual length of the side window;

[0078] The calculation module 20 is used to calculate the heat transfer coefficient of the glass surface based on the actual operating speed and the actual length.

[0079] Figure 3 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 3 As shown, the electronic device may include: a processor 30, a communication interface 40, a memory 50, and a communication bus 60, wherein the processor 30, the communication interface 40, and the memory 50 communicate with each other via the communication bus 60. The processor 30 can call logical instructions in the memory 50 to execute the following methods:

[0080] Obtain the actual operating speed of the rail vehicle and the actual length of the side windows;

[0081] The heat transfer coefficient of the glass surface is calculated based on the actual operating speed and the actual length.

[0082] Furthermore, the logical instructions in the aforementioned memory 50 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to related technologies, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0083] This invention discloses a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions, and when the program instructions are executed by a computer, the computer can perform the methods provided in the above-described method embodiments, such as including:

[0084] Obtain the actual operating speed of the rail vehicle and the actual length of the side windows;

[0085] The heat transfer coefficient of the glass surface is calculated based on the actual operating speed and the actual length.

[0086] On the other hand, embodiments of the present invention also provide a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by processor 30, is implemented to perform the transmission methods provided in the above embodiments, including, for example:

[0087] Obtain the actual operating speed of the rail vehicle and the actual length of the side windows;

[0088] The heat transfer coefficient of the glass surface is calculated based on the actual operating speed and the actual length.

[0089] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0090] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of software products. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the heat transfer coefficient of a glass surface, characterized in that, include: Obtain the actual operating speed of the rail vehicle and the actual length of the side windows; The heat transfer coefficient of the glass surface is calculated based on the actual operating speed and the actual length; the heat transfer coefficient of the glass surface is derived by the following formula: ； in, Nu Indicates the nussert number, h Indicates the heat transfer coefficient of the glass surface, l Indicates equivalent dimensions, λ Indicates the thermal conductivity of air; ； Among them, Re f Represents the Reynolds number and Pr at temperature f. f Indicates temperature f The Prandtl number at that time, Pr w Indicates temperature as w Prandtl number at that time; Also, ; During the operation of the rail vehicle, it is equivalent to the train being stationary, and the air relative to the rail vehicle is at an angle of... v To flow; ； in, ρ Indicates air density; μ Indicates the air viscosity coefficient; Combining the above formulas, we obtain the heat transfer coefficient of the glass surface. h for: ； in, v Indicates the actual operating speed, l This indicates the equivalent size.

2. A glass surface heat transfer coefficient calculation device for implementing the glass surface heat transfer coefficient calculation method as described in claim 1, characterized in that, include: The acquisition module is used to acquire the actual operating speed of the rail vehicle and the actual length of the side window; The calculation module is used to calculate the heat transfer coefficient of the glass surface based on the actual operating speed and the actual length.

3. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the glass surface heat transfer coefficient calculation method as described in claim 1.

4. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the method for calculating the heat transfer coefficient of the glass surface as described in claim 1.

5. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the method for calculating the heat transfer coefficient of the glass surface as described in claim 1.

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