Vehicle thermal environment evaluation method and application

Abstract

The invention relates to a vehicle thermal environment evaluation method and application, and the method comprises the steps: calculating the evaluation temperature of a vehicle according to the following formula: # imgabs0 #, T is the evaluation temperature, S is the sunlight radiation density value, alpha is the human body absorptivity, epsilon is the human body emissivity, and the vehicle thermal environment is evaluated according to the evaluation temperature. And sigma is a Stefan-Boltzmann constant. According to the Stefan-Boltzmann law, the concept of temperature evaluation is provided, the provided vehicle thermal environment evaluation method is easy and convenient to operate and suitable for various kinds of glass, meanwhile, the result is easy to understand, and ordinary people can be helped to directly obtain which kind of glass with the best thermal control performance through data; consumers can compare and select glass performance conveniently.

Description

Technical Field

[0001] The present invention relates to the field of thermal environment assessment, and in particular to a vehicle thermal environment assessment method and application. Background Art

[0002] With socioeconomic development, people's demands for vehicle comfort are increasing. Thermal comfort is a key indicator of vehicle comfort, and good thermal comfort has become a must-have for luxury cars. The evaluation of in-vehicle thermal comfort is also gaining increasing attention. However, the vehicle is a very complex thermal environment. In addition to air temperature, human comfort is also affected by factors such as air humidity, air velocity, thermal radiation, and air conditioning performance. These factors contribute to the complexity and instability of the in-vehicle climate. Furthermore, human thermal comfort in a vehicle is not only dependent on the thermal environment but also on the body's subjective perception. Different parts of the body have varying degrees of sensitivity to the thermal environment, which adds complexity and difficulty to thermal comfort assessment.

[0003] Direct methods for evaluating a vehicle's thermal environment include measuring various human responses and come in three forms: subjective, objective, and behavioral. Subjective methods use subjective scales to quantify human responses to the environment. Objective methods quantify a person's physical, physiological, or psychological state through the use of instruments or output measurements (such as performance measurements). Behavioral methods quantify or represent human responses to the environment. Each method is developed based on fundamental principles. The most appropriate method form and combination of methods for thermal environment assessment depends on the assessment objective and the vehicle environment. Evaluating the thermal comfort of automotive glass in summer is crucial for determining the optimal method. Although standards such as GB / T40261 and GB / T 33658 have been established, the test methods are complex, the test equipment is expensive, and the test results are highly specialized. This makes it difficult for the average person to directly determine which glass type has the best thermal management performance based on the data, hindering consumer comparison and selection. Furthermore, the emergence of new smart glass—electrochromic glass—can achieve variable transmittance in the visible and near-infrared, rather than a fixed transmittance, posing new challenges to evaluation methods.

[0004] Therefore, it is of great significance to propose a method for vehicle thermal environment assessment that is simple to operate, has easy-to-understand results, and is applicable to different types of glass. In addition, this method also provides important theoretical support for guiding how to develop more energy-efficient glass, contributing to people's "good houses" and "good cars". Summary of the Invention

[0005] The main purpose of the present invention is to provide a method and application for vehicle thermal environment assessment. The technical problem to be solved is how to propose a method that is simple to operate, applicable to a variety of glasses, and at the same time, the results are easy to understand, which can help ordinary people directly determine which glass has the best thermal control performance through data, which is beneficial for consumers to compare and select glass performance, thereby being more suitable for practical use.

[0006] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions. According to the method of vehicle thermal environment assessment proposed by the present invention, the steps include:

[0007] The vehicle's evaluation temperature is calculated according to the following formula, and the vehicle's thermal environment is evaluated based on the aforementioned evaluation temperature. The aforementioned formula is:

[0008]

[0009] Wherein, T is the aforementioned evaluation temperature,

[0010] S is the solar radiation density value,

[0011] α is the human body absorption rate,

[0012] ε is the human body emissivity,

[0013] σ is the Stefan-Boltzmann constant.

[0014] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0015] Preferably, in the aforementioned vehicle thermal environment assessment method, the human body absorption rate α is simplified to the direct sunlight transmittance of the vehicle glass.

[0016] Preferably, in the aforementioned method for evaluating the thermal environment of a vehicle, the body absorption rate α is calculated as follows:

[0017]

[0018] Where b is the lower limit of sunlight wavelength,

[0019] c is the upper limit of sunlight wavelength,

[0020] λ is the wavelength of sunlight,

[0021] S λ is the radiation density value corresponding to the wavelength λ in sunlight,

[0022] τ(λ) is the visible light spectral transmittance of the glass corresponding to light with a wavelength of λ in sunlight.

[0023] Preferably, in the aforementioned method for evaluating vehicle thermal environment, b=300 nm and c=2500 nm.

[0024] Preferably, in the aforementioned method for evaluating the vehicle thermal environment, the method for calculating the human body emissivity ε is:

[0025] ε=1-a;

[0026] Where a is the direct absorption rate of sunlight by the vehicle glass.

[0027] Preferably, in the aforementioned method for evaluating the thermal environment of a vehicle, the calculation method for the direct sunlight absorption rate a of the vehicle glass is:

[0028]

[0029] Where d is the lower limit of sunlight wavelength,

[0030] e is the upper limit of sunlight wavelength,

[0031] λ is the wavelength of light,

[0032] S λ is the radiation density value corresponding to the wavelength λ in sunlight,

[0033] a(λ) is the visible light spectrum absorption ratio of the glass corresponding to the light with a wavelength of λ in sunlight.

[0034] Preferably, in the aforementioned method for evaluating vehicle thermal environment, d=300 nm and e=2500 nm.

[0035] The purpose of the present invention and the technical problems solved therein are also achieved by adopting the following technical solutions: The present invention proposes the application of any of the aforementioned vehicle thermal environment assessment methods in vehicle comfort assessment.

[0036] The objectives of the present invention and the technical problems solved therein are also achieved by adopting the following technical solutions: The present invention proposes the application of any of the aforementioned vehicle thermal environment assessment methods in the assessment of glass thermal control performance.

[0037] The purpose of the present invention and the technical problems solved therein are also achieved by adopting the following technical solutions: The present invention proposes the application of any of the aforementioned vehicle thermal environment assessment methods in glass research and development.

[0038] By means of the above technical solution, the vehicle thermal environment assessment method and application of the present invention have at least the following advantages:

[0039] Based on the Stefan-Boltzmann law, the present invention proposes the concept of "evaluation temperature," which allows the vehicle's thermal environment to be assessed based on the body's absorptivity and emissivity. Furthermore, simply testing the vehicle's glass's direct sunlight transmittance and direct sunlight absorptivity yields an evaluation temperature, thereby assessing the glass's thermal control performance and the vehicle's thermal environment. The vehicle thermal environment assessment method provided by the present invention is simple to operate and applicable to a variety of glass types. The results are easily understood, allowing individuals to directly determine, through data, which type of glass offers the best thermal control performance, facilitating consumer comparison and selection of glass performance.

[0040] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a simplified diagram of a simulation test device according to an embodiment of the present invention;

[0042] Figure 2 is a graph showing the relationship between the evaluation temperature of the test glass and the inner surface temperature of the glass in an embodiment of the present invention;

[0043] Figure 3 is a graph showing the relationship between the evaluation temperature and the inner surface temperature of the laminated glass in an embodiment of the present invention;

[0044] Figure 4 is a graph showing the relationship between the direct sunlight transmittance and the inner surface temperature of the glass tested in an embodiment of the present invention;

[0045] Figure 5 1 is a graph showing the relationship between the direct sunlight absorption ratio of the test glass and the inner surface temperature of the glass in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] To further illustrate the technical means and effectiveness of the present invention in achieving its intended objectives, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail a vehicle thermal environment assessment method and its specific implementation, structure, features, and effectiveness. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0047] The present invention provides a method for evaluating a vehicle thermal environment, comprising the steps of calculating an evaluation temperature of the vehicle according to the following formula, and evaluating the vehicle thermal environment based on the evaluation temperature. The formula is:

[0048]

[0049] Wherein, T is the aforementioned evaluation temperature,

[0050] S is the solar radiation density value,

[0051] α is the human body absorption rate,

[0052] ε is the human body emissivity,

[0053] σ is the Stefan-Boltzmann constant.

[0054] Specifically, according to the Stefan-Boltzmann law:

[0055] E=σ*T 4 (1),

[0056] Assuming the human skin is an isothermal sphere, the thermal equilibrium temperature of the human body surface is

[0057]

[0058] Where E is the heat radiated per unit area, T is the temperature, and σ is the Stefan-Boltzmann constant.

[0059] According to Kirchhoff's law, the amount of heat radiated per unit area is related to the ratio of absorptivity to infrared emissivity, that is:

[0060]

[0061] Among them, S is the solar radiation density value, α is the human body absorption rate, and ε is the human body emissivity.

[0062] According to the Stefan-Boltzmann law, the present invention proposes a concept of "evaluation temperature", which can evaluate the vehicle thermal environment according to the human body absorption rate and human body radiation rate.

[0063] In a vehicle interior, although human skin absorbs and reflects solar radiation, the reflection is mostly diffuse, and the reflectivity is very low relative to the absorptivity. Furthermore, the sensation of heat is primarily due to absorption, not reflection. Therefore, when calculating the absorption rate, α, the human body's absorptivity can be simplified to the energy entering after solar radiation passes through the glass, i.e., the direct solar transmittance of the vehicle's glass. The wavelength range of sunlight is selected as 300 to 2500 nm, resulting in:

[0064]

[0065] Where λ is the wavelength of light,

[0066] S λ is the radiation density value corresponding to the wavelength λ in sunlight,

[0067] τ(λ) is the visible light spectral transmittance of the glass corresponding to light with a wavelength of λ in sunlight.

[0068] As for infrared emissivity, heat is absorbed and reflected in the vehicle environment. Within the glass size range, both reflection and absorption are completed by the glass, that is, infrared radiation is all radiation other than that absorbed by the glass. Ultimately, all heat will be radiated out to balance with the environment. The wavelength range of sunlight is selected to be 300 to 2500 nm, thus simplifying the human body emissivity ε to:

[0069]

[0070] Where a is the direct absorption rate of sunlight by the vehicle glass,

[0071] λ is the wavelength of light,

[0072] S λ is the radiation density value corresponding to the wavelength λ in sunlight,

[0073] a(λ) is the visible light spectrum absorption ratio of the glass corresponding to the light with a wavelength of λ in sunlight.

[0074] Based on the above analysis, formulas (4) and (5) can be substituted into formula (3) to obtain the evaluation temperature T:

[0075]

[0076] From formula (6), we can see that we only need to test the direct sunlight transmittance and direct sunlight absorptivity of the glass to obtain the evaluation temperature T, thereby evaluating the thermal control performance of the glass and the vehicle thermal environment.

[0077] The present invention proposes the application of any of the aforementioned vehicle thermal environment assessment methods in vehicle comfort assessment.

[0078] The present invention proposes the application of any of the aforementioned vehicle thermal environment assessment methods in the evaluation of glass thermal control performance.

[0079] The present invention proposes the application of any of the aforementioned vehicle thermal environment assessment methods in glass research and development.

[0080] The present invention will be further described below with reference to specific embodiments, but this should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0081] Unless otherwise specified, the materials and reagents mentioned below are commercially available products familiar to those skilled in the art. Unless otherwise specified, the methods described are all well-known methods in the art. Unless otherwise defined, technical or scientific terms used shall have the same meanings as those commonly understood by those skilled in the art.

[0082] Example

[0083] 1. Sample preparation

[0084] Select test glass with a size of 300mm×300mm, 3 pieces of each type, and the specific types are:

[0085] Ordinary float glass (G), thickness 3mm;

[0086] Tempered glass (GH1-GH4), thicknesses are 4mm grey glass, 4mm green glass, and 5mm grey glass respectively;

[0087] Ordinary laminated glass (JC1-JC3), the structures are 2.3mm white glass + 0.38mm PVB + 3mm white glass, 2.3mm green glass + 0.76mm PVB + 2.3mm green glass, 2.5mm green glass + 0.76mm PVB + 2.5mm green glass, 2.1mm grey glass + 0.76mm PVB + 2.1mm grey glass;

[0088] Filmed glass (TM1-TM4) are 1.5mil film + 3mm glass (1.5mil film is applied to the air side of 3mm glass), 2mil film + 3mm glass (2mil film is applied to the air side of 3mm glass), and 3mil film + 3mm glass (3mil film is applied to 3mm glass). The films are commercially available automotive solar films.

[0089] Coated glass (DM1-DM2) are 2.1mm coated glass + 0.76mm PVB + 1.6mm green glass, 2.1mm coated glass + 0.76mm PVB + 2.1mm coated glass respectively. The coated glass is single silver LowE glass.

[0090] Smart dimming glass: inorganic electrochromic glass (EZ, ET) and polymer dispersed liquid crystal glass (PZ, PT).

[0091] 2. Simulation test device

[0092] In order to better evaluate the thermal control performance of automotive glass, we tested the inner surface temperature of the glass under simulated solar radiation to reflect the difference in light and heat comfort. For details of the test device, please refer to the "Automotive Glass Light and Heat Comfort Test and Evaluation Method". The simulation test device mainly consists of two parts: the experimental box and the test box. Figure 1As shown, the test chamber is primarily used to simulate solar radiation and minimize external environmental influences. A light source is mounted on top of the chamber, and its spectral distribution matches the solar spectrum of air quality AM1.5G, meeting Class B requirements specified in JJF 1615. The chamber measures 300mm × 300mm × 300mm (length × width × height), with an internal volume (length × width × height) of 180mm × 180mm × 240mm. The specimen irradiation area is 180mm × 180mm. The chamber is constructed of stainless steel and is completely sealed, filled with polyurethane foam insulation and affixed with black velvet.

[0093] 3. Test methods

[0094] 3.1 Measurement of glass inner surface temperature

[0095] First, the thermocouple of the external temperature recorder was attached to the geometric center of the glass. The specimen was then mounted on the test chamber (with the test surface of the thermocouple facing the inside of the test chamber) and the glass was sealed with polyurethane foam material. The test chamber was placed in the irradiation chamber, and the light source of the experimental chamber was turned on. The irradiation was continuous for 5 hours. The temperature was recorded every 30 seconds by the temperature recorder. The temperature in the experimental chamber was maintained at (35±2)°C during the test. The temperature recorded by the thermocouple was defined as the inner surface temperature of the glass, T-glass, when the temperature change of the glass within 15 minutes was less than ±0.2°C. The test results are shown in Table 1.

[0096] 3.2 Evaluation temperature measurement

[0097] The transmittance and reflectance spectra of the sunlight band were measured using a U4100 UV-visible-near-infrared spectrophotometer from Hitachi, Japan. The visible light transmittance, direct sunlight transmittance, and direct sunlight absorption ratio were calculated according to the national standard GB / T11942. The evaluation temperature T was calculated according to the aforementioned formula (6). The results are shown in Table 1.

[0098] Table 1 Summary of test results and evaluation temperature

[0099]

[0100]

[0101]

[0102] 4. Results Analysis

[0103] Under the scorching sun in summer, the temperature inside a car rises sharply, and local temperatures may reach above 80°C. At this time, skin (fingers) touching the glass may cause burns. Therefore, we verify the applicability of the evaluation temperature by comparing the inner surface temperature of the glass with the evaluation temperature, providing theoretical guidance for the evaluation of the light and heat comfort of automobiles. Figure 2To evaluate the relationship between temperature and glass inner surface temperature, Figure 2 It can be seen that the evaluation temperature and the inner surface temperature of the glass are basically consistent in their changing trends, especially for tempered glass, filmed glass, electrochromic glass and polymer dispersed liquid crystal glass. By plotting the evaluation temperature and inner surface temperature data of laminated glass separately, as shown in the following figure: Figure 3 As shown, the evaluation temperature of laminated glass also changes in line with the temperature of the glass's inner surface. This suggests that our formula is applicable to a wide range of applications when comparing the thermal management performance of the same type of glass, encompassing essentially all types of automotive glass currently on the market: tempered glass, laminated glass, filmed glass, coated glass, and smart dimming glass (inorganic electrochromic glass and polymer dispersed liquid crystal glass).

[0104] For the correlation between the direct sunlight transmittance and direct sunlight absorption and the inner surface temperature of the glass, such as Figure 4 、 Figure 5 As shown. The direct solar transmittance of tempered glass, laminated glass, and smart dimming glass is positively correlated with the inner surface temperature of the glass, but this correlation changes for filmed glass and coated glass. The direct solar transmittance of tempered glass, laminated glass, and polymer dimming glass is inversely correlated with the inner surface temperature of the glass, but this correlation changes for filmed glass, coated glass, and inorganic electrochromic glass. This is related to the spectral characteristics of filmed and coated glass. Their reflection of near-infrared light significantly reduces the direct solar transmittance. Although smart dimming glass also has a certain degree of near-infrared reflectivity, its near-infrared reflectivity is lower than that of filmed and coated glass.

[0105] The ability of typical glass to block solar heat gain in the summer is primarily assessed by its ability to block radiation in the 300-2500nm wavelength range. When used as windshield glass, visible light transmittance is mandatory. Improving the thermal management performance of automotive glass requires minimizing near-infrared transmission, thereby reducing direct sunlight transmittance. Furthermore, minimizing absorption of sunlight in these wavelengths is crucial. This is why tinted glass does not insulate: it absorbs sunlight heat, generating secondary radiation and raising surface temperature, creating a strong sense of heat.

[0106] Therefore, based on formula (6), we can propose a direction for improving glass performance in the future. To improve the thermal control performance of glass (reducing the temperature of the inner surface of the glass), we must first reduce the direct transmittance of sunlight, and then reduce the direct absorption of sunlight. Smart dimming glass can change the incident visible light, and by reducing the visible light transmittance, it can further reduce the direct transmittance of sunlight. Inorganic electrochromic glass can also regulate a portion of the near-infrared, so its evaluation temperature and the inner surface temperature of the glass are lower than those of polymer liquid crystal glass. This is also the reason why coated glass and filmed glass have performance advantages (reflecting near-infrared), but their disadvantage is the lack of regulation of visible light. Therefore, the research and development of automotive glass, especially smart dimming glass, should focus on regulating the long-wave band, that is, the near-infrared, while reducing the absorption of the sunlight band and increasing the reflection of the entire sunlight band.

[0107] In addition, through Figure 2 、 Figure 3 It can also be seen that the numerical value of the evaluation temperature is quite different from the numerical value of the inner surface temperature of the glass. This is because we only consider the influence of thermal radiation, but do not consider the factors of thermal convection and heat conduction. However, the above comparison also shows that thermal radiation is one of the important factors of heat source in automobiles.

[0108] The technical features in the claims and / or the specification of the present invention may be combined, and the manner of combination is not limited to the combination obtained by reference in the claims. The technical solutions obtained by combining the technical features in the claims and / or the specification are also within the scope of protection of the present invention.

[0109] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiment based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for evaluating vehicle thermal environment, characterized in that: The steps include: The vehicle's evaluation temperature is calculated according to the following formula, and the vehicle's thermal environment is evaluated based on the evaluation temperature. The formula is: Wherein, T is the evaluation temperature, S is the solar radiation density value, α is the human body absorption rate, ε is the human body emissivity, σ is the Stefan-Boltzmann constant.

2. The vehicle thermal environment assessment method according to claim 1, characterized in that: The human body absorption rate α is simplified to the direct sunlight transmittance of the vehicle glass.

3. The vehicle thermal environment assessment method according to claim 2, characterized in that: The calculation method of the human body absorption rate α is: Where b is the lower limit of sunlight wavelength, c is the upper limit of sunlight wavelength, λ is the wavelength of light, Sλ is the radiation density value corresponding to the light with wavelength λ in sunlight, τ(λ) is the visible light spectral transmittance of the glass corresponding to light with a wavelength of λ in sunlight.

4. The vehicle thermal environment assessment method according to claim 3, characterized in that: b=300nm, c=2500nm.

5. The vehicle thermal environment assessment method according to claim 1, characterized in that: The calculation method of the human body radiation rate ε is: ε=1-a; Where a is the direct absorption rate of sunlight by the vehicle glass.

6. The vehicle thermal environment assessment method according to claim 5, characterized in that: The calculation method of the direct sunlight absorption rate a of the vehicle glass is: Where d is the lower limit of sunlight wavelength, e is the upper limit of sunlight wavelength, λ is the wavelength of light, Sλ is the radiation density value corresponding to the light with wavelength λ in sunlight, a(λ) is the visible light spectrum absorption ratio of the glass corresponding to the light with a wavelength of λ in sunlight.

7. The vehicle thermal environment assessment method according to claim 6, characterized in that: d=300nm, e=2500nm.

8. Application of the vehicle thermal environment assessment method according to any one of claims 1 to 7 in vehicle comfort assessment.

9. Application of the vehicle thermal environment assessment method according to any one of claims 1 to 7 in the evaluation of glass thermal control performance.

10. Use of the vehicle thermal environment assessment method according to any one of claims 1 to 7 in glass research and development.

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