A method for evaluating the effect of local ventilation under clothing on human thermal regulation

Abstract

The present invention discloses a method for evaluating the effects of localized ventilation under clothing on human thermal regulation. The method provides a locally ventilated garment with adjustable and controllable ventilation temperature and speed to evaluate the overall thermal physiological and psychological effects of localized ventilation on the human body. The method can estimate differences in the skin's preference for air temperature and speed when subjected to ventilation and cooling in a thermal environment, as well as differences in the cooling effect and subjective perception of the individual when ventilation and cooling are applied to a specific area of the body. This method comprehensively determines the ventilation location with the lowest energy consumption and the best cooling efficiency, thereby enabling the design of appropriate ventilation locations and parameters for individual ventilation equipment.

Description

Technical Field

[0001] The invention relates to a method for evaluating the overall thermal physiological and psychological effects of local under-clothing ventilation in a high-temperature environment on a human body, and belongs to the technical field of thermal and moisture comfort of clothing. Background Art

[0002] Individual ventilation devices are often used to enhance thermal comfort in high-temperature, high-humidity environments. While the convection and evaporative cooling provided by the cool airflow can effectively improve thermal comfort, it can also cause discomfort such as a "draughty" sensation on the skin due to differences in skin sensitivity to airflow across different parts of the body. The cooling effect and subjective comfort of under-clothing ventilation can vary across different areas of the body. Previous research by the research team has demonstrated that different parts of the human body exhibit varying sensitivities to airflow stimulation: the upper back and front thighs are most sensitive to hot airflow, while the lower back and back thighs are most sensitive to cold airflow. However, the cooling effect of localized ventilation on the entire body remains unclear. This present invention, using subjects to autonomously adjust ventilation temperature and wind speed, determines the ventilation parameter preferences of different parts of the human body in hot environments. It also analyzes the impact of localized ventilation on the body's overall physiological characteristics and thermal and hygroscopic comfort, identifying the most suitable ventilation areas on the human body while balancing the dual benefits of thermal regulation and energy conservation. This invention can provide guidance for parameter design and comfort optimization of ventilation-based individual thermal management devices. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for evaluating the effect of local under-clothing ventilation on human thermal regulation, which is suitable for guiding the parameter design of ventilation and cooling clothing in high-temperature environments and clarifying the appropriate ventilation parts of the human body.

[0004] To achieve the above objectives, the technical solution of the present invention is to provide a method for evaluating the effect of local ventilation under clothing on human thermal regulation, characterized in that a local ventilation garment with adjustable and controllable ventilation temperature and speed is provided to evaluate the effect of local ventilation on the overall thermal physiology and psychology of the human body, comprising the following steps:

[0005] Step 1: Establish a local under-garment ventilation system with adjustable wind temperature and wind speed, including an air supply device and a local ventilation suit;

[0006] Step 2: Conduct an experiment to evaluate the effect of local under-clothing ventilation on human thermal regulation:

[0007] The local ventilation parts of the local ventilation suit are opened symmetrically on both sides. Each local ventilation only ventilates the symmetrical openings on the left and right sides of one part, and the non-ventilated parts are covered by the clothing fabric. For the human body in a high-temperature environment, local ventilation is performed on the front chest, upper back, lower back, front thigh, and back thigh. During the process, the wind temperature and wind speed parameters adjusted by the subjects themselves are recorded, as well as physiological parameters including average skin temperature and humidity under the clothes, and psychological parameters including subjective thermal sensation, comfort, and wind blowing sensation. Indicators representing the ventilation and cooling effect are calculated, including:

[0008] Total energy consumption E when ventilating a certain part:

[0009]

[0010] Where P is the theoretical power; c is the specific heat capacity of air, ρ is the air density, T is the ambient temperature, T a is the ventilation temperature;

[0011] Actual cooling efficiency η a :

[0012] η a =Q / E

[0013] Where Q is the total heat dissipation during the entire ventilation process, which is calculated by the following formula:

[0014]

[0015] In the formula, η is the equipment power, m is the ventilation speed, h a is the enthalpy of the dry air component in the airflow, h v is the enthalpy of the moist air component in the airflow, T sk is the skin temperature, T a is the ventilation temperature, is the relative humidity of the air flow;

[0016] The local ventilation energy consumption E consumed when the whole body thermal comfort is improved by 1 unit OTC :

[0017] E OTC =E / (OTC S -OTC E )

[0018] Where, OTC S The OTC is the overall thermal comfort of the subjects at the start of ventilation. E E is the overall thermal comfort of the subject at the end of ventilation; OTC The smaller it is, the less energy is consumed in ventilation of that part to achieve the same thermal comfort improvement effect, and the cooling can be achieved more energy-efficiently.

[0019] The power of the ventilation equipment corresponding to the period when the subject feels the blowing sensation during the ventilation process is the power consumed when the blowing sensation occurs, P DS :

[0020]

[0021] Where, is the ventilation speed in the current period, is the ventilation temperature of the current period;

[0022] Step 3: Conduct statistical analysis on the experimental results to analyze the differences in ventilation parameter preferences and ventilation effects in different ventilation areas. The independent variable is the ventilation area, and the dependent variables are the preferred wind temperature and preferred air volume, overall and local thermal sensation and thermal comfort, blowing sensation, and indicators that characterize the ventilation and cooling effects. The analysis results in the most suitable part of the human body for ventilation.

[0023] Preferably, for the local ventilation suit, two sets of zippers are installed on the front and back center lines of the upper garment and the left and right side seams of the lower garment, respectively. A total of eight sets of zippers are sewn for each suit, providing an adjustment range of -4 to 4 cm for the torso circumference and an adjustment range of -2 to 2 cm for the leg circumference, so that subjects of different body shapes can have similar clothing looseness when wearing them, thereby controlling the size of the gap under the clothes.

[0024] Preferably, in step 2, in order to explore the effects of local under-clothing ventilation on human thermal comfort in five parts, namely the front chest, upper back, lower back, front thigh and back thigh, each part is subjected to 30 minutes of ventilation cooling with adjustable wind temperature and wind speed, the wind temperature and wind speed are adjusted every 5 minutes, and a subjective evaluation is completed; 30 tests are performed on each subject, and the experimental results are recorded and analyzed.

[0025] Preferably, in step 3, when performing statistical analysis on the experimental results, all subjective evaluation data are first normalized, and then all data are subjected to normal distribution and variance homogeneity tests; subsequently, a two-factor repeated measures variance analysis is applied to detect the effects of ventilation temperature and time on preferred wind temperature, preferred wind speed and each subjective evaluation, and a one-way variance analysis is applied to detect the effects of ventilation position on energy consumption-related indicators; if a significant effect is found, multiple comparisons are further applied to perform pairwise comparisons, and the differences in ventilation under clothing in different positions are further analyzed.

[0026] Due to the adoption of the above-mentioned technical solution, the present invention has the following advantages and positive effects compared with the prior art: the present invention can estimate the differences in the preferences of the skin on the same part for wind temperature and wind speed when ventilation and cooling are performed in a hot environment, as well as the differences in the cooling effect and subjective feeling of the human body when ventilation and cooling are performed on local parts of the human body, and comprehensively obtain the ventilation position with the lowest energy consumption and the best cooling efficiency, and then design the reasonable ventilation position and parameters of individual ventilation equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the structural diagram of the air supply device;

[0028] Figure 2 The subjective evaluation scale is indicated;

[0029] Figure 3 The selected wind temperature and wind speed at the end of ventilation of five parts are shown;

[0030] Figure 4 The overall and local thermal sensations and comfort during ventilation of five parts are shown;

[0031] Figure 5 The energy consumption related indicators of the ventilation process in five parts are illustrated. DETAILED DESCRIPTION

[0032] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0033] The present invention discloses a method for evaluating the effect of local ventilation under clothing on human thermal regulation. The method uses local ventilation clothing with adjustable and controllable ventilation temperature and speed to evaluate the effect of local ventilation on the overall thermal physiology and psychology of the human body. The method specifically includes the following steps:

[0034] Step 1: Establish a local under-garment ventilation system with adjustable wind temperature and wind speed, including an air supply device and a local ventilation suit.

[0035] The local ventilation suit is available in sizes 170 / 92A for men and 160 / 84A and 165 / 88A for women. It is made of 100% polyester fiber with PU coating and is a close-fitting long-sleeved trouser suit with a fabric weight of 120g / m 2 , air permeability is 0L / (m 2 ·s). 8cm*8cm square openings were symmetrically placed on the left and right sides of the localized ventilation areas. Velcro was sewn around the openings to connect the air ducts to the air supply device. Each localized ventilation session ventilated only the symmetrical openings on the left and right sides of one area. Non-ventilated areas were covered with the aforementioned garment fabric. Two sets of zippers were installed on the front and back center lines of the top and on the left and right side seams of the bottom, for a total of eight sets per garment. These zippers provided a -4 to 4cm adjustment range for the torso and -2 to 2cm for the leg. This allowed subjects of different body shapes to maintain similar garment looseness, thereby controlling the size of the undergarment gap.

[0036] like Figure 1As shown, the heat-insulating box shell 1 wrapped around the outside of the air supply device is made of heat-insulating cotton with a thickness of 2 cm (60*60*40 cm, with a 4*4 cm air inlet on each side of the front and back, and two circular air outlets with a diameter of 8 cm on the right side), and the box is assembled with axial fans 8 (3 diameters 8*8 cm), finned heating tubes 3 (Shengxin, China, 220V, 500W), semiconductor refrigeration plates 4 (2, 12710 type, Jiaxing Tongchuang Electronic Technology, 300W), cooling water circulation machine 6 (Shanghai Yibei), electronic energy-saving voltage regulator 7 (Xingyi Electric, China), digital display electronic temperature controller 5 (Pinyi, China) and two stepless speed regulation blowers 9 (220V, 40W). During the experiment, the local air supply device was connected to the local under-garment ventilation suit at the outlet via a retractable aluminum foil insulated hose (8 cm in diameter, 15 to 150 cm in length). The hose was terminated with three 1*1*1.2 cm cubic silicone pads, evenly attached to the skin-facing side of the air supply duct, ensuring a 1.2 cm distance between the vent and the skin for each subject. The air supply device regulates the air temperature within a set value of ±0.5°C by adjusting the voltage, and the air speed within a set value of ±0.2 m / s by adjusting the speed of the blower. The air temperature and speed can be adjusted within the range of 24°C to 30°C and 0.3 m / s to 1.1 m / s, respectively.

[0037] Step 2: Establish an evaluation method for the effect of local under-clothing ventilation on human thermal regulation. For people in a high-temperature environment, local ventilation is performed on five areas (front chest, upper back, lower back, front thigh, and back thigh). During this period, the subjects' self-regulated wind temperature and wind speed parameters, as well as physiological parameters such as average skin temperature and under-clothing humidity, and psychological parameters such as subjective thermal sensation, comfort, and wind sensation are recorded. The ventilation parameters and subjective evaluation indicators are used to analyze the local under-clothing ventilation preference and cooling effect. The specific method is as follows:

[0038] 1. Subjects

[0039] Recruit subjects with no health or skin problems. Before the experiment, explain the experimental procedures and precautions in detail and have them sign a consent form. Avoid conducting the experiment during menstruation, and ensure that the skin in ventilated areas is free of damage and allergies. Maintain a normal and reasonable diet for 24 hours before the experiment. Avoid alcohol, coffee, or excessive eating. Do not eat within half an hour before entering the laboratory. Subjects should choose ventilated clothing that fits their body shape, as described in Step 1. Wear only similar underwear and thin sneakers underneath.

[0040] In this example, 12 healthy college students aged 24 to 25 were recruited as subjects, including 6 females and 6 males. The subjects were healthy and of standard body shape. The female subjects were 161.8 ± 2.5 cm tall, 51.5 ± 2.3 kg in weight, 19.7 ± 0.6 in body mass index (BMI), and 23.7 ± 0.8 years old; the male subjects were 171.3 ± 1.4 cm tall, 60.3 ± 4.3 kg in weight, 20.5 ± 1.3 in body mass index (BMI), and 22.8 ± 1.3 years old. Before the experiment, each subject was trained to familiarize themselves with the evaluation content and experimental procedures. Subjects were required to maintain a good diet and rest schedule before the experiment, not to drink alcohol within 24 hours before the experiment, and not to eat within 1 hour before the experiment. In addition, the experimental time should avoid the physiological period of female subjects. During the experiment, subjects were required to choose a well-fitting long-sleeved and long-trouser experimental garment, wear only underwear inside the experimental garment, and no other equipment outside the experimental garment. They were required to wear socks and thin sneakers on their feet.

[0041] 2. Experimental Instruments

[0042] In addition to the air supply equipment and partial under-garment ventilation suit described in Step 1, an integrated temperature and humidity electronic button temperature recorder (iButton, MAX, USA) was required to measure the subject's skin temperature in the ventilated area and the humidity under the garment during the experiment. The recorder was affixed to the skin using 3M medical tape, with the non-perforated side of the recorder in contact with the skin.

[0043] 3. Experimental Design

[0044] The experiment was conducted in an artificial climate chamber (air temperature: 35±2°C, relative humidity: 40±5%, wind speed <0.4 m / s). To investigate the influence of ventilation location on ventilation parameter preferences for local undergarment ventilation and the subjective local and overall human perception (thermal sensation, thermal comfort, and wind sensation), the experimental equipment and clothing described in Step 1 were used. Undergarment ventilation was continuously applied to a specific area using adjustable local undergarment ventilation. The wind temperature and speed were adjusted at fixed intervals according to the subject's preferences during the experiment. Skin temperature and undergarment humidity at the ventilation location were measured throughout the experiment, and the subject's subjective perception at each stage was collected.

[0045] 4. Experimental Procedure

[0046] The experiment was conducted in an artificial climate chamber (air temperature: 35±2°C, relative humidity: 40±5%, wind speed <0.4m / s). During ventilation, the wind temperature and speed were adjustable within the following ranges: wind temperature 24°C to 30°C, in 1°C increments; wind speed 0.3m / s to 1.1m / s, in 0.2m / s increments. The experiment was divided into multiple groups, with each group conducting under-clothing ventilation on both sides of a specific area, with each area tested in a random order. The specific process is as follows:

[0047] (1) The subject puts on the experimental clothing and enters the climate chamber. A ventilation test site is randomly selected, and the operator attaches temperature and humidity sensors to two symmetrical skin points on the left and right of the ventilation site. The subject sits quietly for 20 minutes to adapt to the cabin environment and reach a thermoneutral state. During this time, the operator adjusts the air temperature in the incubator to the initial ventilation temperature of 27°C and explains the basic experimental procedures.

[0048] (2) Connect the left and right sides of the ventilation area to the air supply duct, and the subjects evaluate the initial local and overall thermal sensation and thermal comfort. Turn on the blower and use the stepless speed knob to adjust the air supply volume of the left and right ducts to 0.35m / s at the same time, so the total air supply volume is 0.7m / s. After 4 minutes of continuous ventilation, the subjects need to complete a subjective evaluation within 1 minute to evaluate the thermal sensation, comfort, blowing sensation, and overall thermal sensation and comfort of the ventilation area. The operator adjusts the wind temperature and wind speed according to the subject's wishes. If the adjustment exceeds the limit range, no further adjustment will be made. After continuing ventilation for 4 minutes, repeat the above steps, and so on. The total ventilation time for each area is 30 minutes, during which an adjustment action is performed every 5 minutes. A total of 6 ventilation parameter adjustments are performed throughout the process, and 7 subjective evaluations are completed.

[0049] (3) After the 30-minute ventilation of each part, the subject rests for 15 minutes. After returning to a thermoneutral state, the next part is tested and step (2) is repeated. After all parts are tested, the subject rests for 20 minutes and leaves after confirming that there is no discomfort.

[0050] In this embodiment, the local under-clothing air supply system described in step one and the connected ventilation suit are used to cool the human body in a hot environment by adopting local under-clothing ventilation with adjustable wind temperature and wind speed. Physiological parameters such as skin temperature of the ventilated parts and humidity under the clothes are measured, and the overall and local thermal sensations of the human body under ventilation in different parts, as well as the feeling of blowing, are obtained through subjective evaluation methods as evaluation indicators of comfort.

[0051] To investigate the effects of localized under-garment ventilation on thermal comfort in five areas: the chest, upper back, lower back, front thigh, and back thigh, each area was individually subjected to 30 minutes of ventilation with adjustable air temperature and speed, with the air temperature and speed adjusted every 5 minutes. Subjects were then evaluated. Each subject underwent 30 tests (5 areas × 6 adjustments), and the results were recorded and analyzed.

[0052] Step 3: Analyze and determine the most suitable body parts for ventilation. Considering the local ventilation energy consumption and the effect of local ventilation on the overall thermal regulation of the human body, determine the most suitable ventilation parts.

[0053] To identify the most suitable ventilation locations, first determine the ventilation parameter preferences for different parts of the human body in a thermal environment. Considering local ventilation energy consumption and its effects on thermal comfort and wind comfort, establish comfort-related energy consumption indicators. Compare the local ventilation effects of different locations to identify the most suitable ventilation locations.

[0054] 1. Evaluation indicators

[0055] Evaluation indicators include subjective evaluation indicators and indicators that characterize ventilation and cooling effectiveness. Subjective evaluation indicators are used to assess the subject's local and overall thermal sensation, thermal comfort, and breeze sensation at each stage of the ventilation process. Subjects were required to complete a subjective evaluation scale during the experiment, which directly reflects their feelings at each ventilation stage. The indicators that characterize ventilation and cooling effectiveness are calculated by combining subjective evaluation results with the corresponding equipment's operating energy consumption. They are used to compare the energy consumption of local ventilation in different locations to achieve the same subjective cooling effect.

[0056] (1) Subjective evaluation scale

[0057] Subjective evaluation indicators include local and overall thermal sensation, local and overall thermal comfort, and wind sensation. Local and overall thermal sensations are rated on a 9-point scale with positive and negative bidirectionality, local and overall comfort on a 5-point continuous scale with a middle break, and wind sensation on a 3-point continuous scale with a middle break, such as Figure 2 shown.

[0058] (2) Total energy consumption

[0059] According to the wind temperature and wind speed selected by the subjects during the ventilation process, the total energy consumption E for ventilation of a certain part is calculated as:

[0060]

[0061] Where, E (kJ) is the total energy consumption; P (W) is the theoretical power; c (kJ·kg -1 ℃ -1 ) is the specific heat capacity of air (1.006 kJ·kg under the experimental conditions) -1 ℃ -1 );ρ(kg·m -3 ) is the air density (1.146 kg / m under the experimental conditions) 3 ); T (℃) is the ambient temperature (35℃ under the experimental conditions); T a (℃) is the ventilation temperature.

[0062] (3) Actual cooling efficiency

[0063] During the cooling process under clothing, the body's heat loss is mainly through convection and evaporation. The total heat dissipation Q during the entire ventilation process is expressed as follows:

[0064]

[0065] Where, Q (kJ) is the total heat dissipation during ventilation; η is the equipment power (take 0.3 for ventilation and cooling equipment); P (W) is the theoretical power; ρ (kg·m -3 ) is the specific heat capacity of air (1.006 kJ·kg under the experimental conditions) -1 ℃ -1 );m(m 3 ·s -1 ) is the ventilation speed; h a (kJ·kg -1 ) is the enthalpy of the dry air component in the air flow; h v (kJ·kg -1 ) is the enthalpy of the moist air component in the airflow; T sk (℃) is skin temperature; T a (℃) is the ventilation temperature; is the relative humidity of the airflow (0.4 under the experimental conditions). The first term on the right side of the equation represents convective heat dissipation, and the second term represents evaporative heat dissipation.

[0066] The actual cooling efficiency η of the entire ventilation process is obtained by the total heat dissipation ratio and the total energy consumption a :

[0067] η a =Q / E

[0068] Among them, η a is the actual cooling efficiency; Q (kJ) is the total heat dissipation during the entire ventilation process; E (kJ) is the total energy consumption during the entire ventilation process.

[0069] (4) Energy consumption per unit of thermal comfort

[0070] In order to more intuitively analyze the effect of local ventilation and cooling on overall thermal comfort and establish a connection with ventilation energy consumption, the “energy consumption per unit of thermal comfort improvement E” was defined by comparing ventilation areas with less energy consumption and greater comfort improvement. OTC ”, which is the local ventilation energy consumption when the whole body thermal comfort is improved by 1 unit.

[0071] E OTC =E / (OTC S -OTC E )

[0072] Among them, E OTC (kJ) is the energy consumption per unit of thermal comfort; OTC S The overall thermal comfort of the subjects at the start of ventilation; OTC E E is the overall thermal comfort of the subjects at the end of ventilation; E (kJ) is the total energy consumption during the whole ventilation process. OTcThe smaller it is, the less energy is consumed for ventilation in that part to achieve the same thermal comfort improvement effect, and cooling can be achieved more energy-efficiently.

[0073] (5) Power consumed when producing a blowing sensation

[0074] During local ventilation, the feeling of blowing is also an important factor affecting the overall comfort of the human body. The period during which the subjects felt the feeling of blowing (blowing sense scale evaluation <0) during the ventilation process was counted, and the power of the corresponding ventilation equipment was the power consumed when the blowing feeling was generated, P DS :

[0075]

[0076] Where, P DS (W) is the power that produces the blowing sensation; The ventilation rate for this period; The ventilation temperature during this period; c (kJ·kg -1 ℃ -1 ) is the specific heat capacity of air (1.006 kJ·kg under the experimental conditions) -1 ℃ -1 );ρ(kg·m -3 ) is the air density (1.146 kg / m under the experimental conditions) 3 ).

[0077] 2. Statistical Analysis

[0078] Statistical analysis of the experimental results was conducted to investigate the impact of local under-clothing ventilation on human thermal comfort, analyzing the differences in ventilation parameter preferences and ventilation effectiveness across different ventilation locations. The independent variables were ventilation location, and the dependent variables were preferred air temperature and air volume, overall and local thermal sensation and thermal comfort, the feeling of a breeze, and indicators representing ventilation cooling effectiveness.

[0079] All subjective evaluation data were first normalized and then tested for normal distribution (Shapiro-Wilk test) and homogeneity of variance (Levene's test). Two-way repeated measures analysis of variance (AVONA) was used to examine the effects of ventilation temperature and time on preferred air temperature, preferred air speed, and subjective evaluations. One-way AVONA was used to examine the effect of ventilation location on energy consumption-related indicators. If a significant effect was found, further pairwise comparisons (Bonferroni's post-hoc analysis) were performed to further analyze differences in ventilation between different locations.

[0080] The results and discussion of the local under-clothing ventilation experiment in this embodiment include the following:

[0081] 1) Wind temperature and speed preferences for local under-clothing ventilation

[0082] The wind temperature and wind speed selected by 12 subjects at the end of ventilation of five parts (30 minutes of ventilation) showed that the preferred wind temperature of the five parts were all distributed around 26℃ (25.7±1.8~25.9±1.4℃), while the preferred wind speed of different parts was widely distributed between 0.7~1.1m / s.

[0083] The results of a two-way repeated-measures ANOVA showed that ventilation position had no significant effect on wind temperature and speed preference [F(4.70,51.69)=0.62,P=0.68,F(4,44)=1.69,P=0.17]. However, during the 15- to 30-minute ventilation period, the posterior thigh (0.87±0.09 m / s) preferred a lower wind speed than other parts (0.96±0.18 m / s). Based on previous studies, this may be because the posterior thigh is more sensitive to airflow, resulting in a more draughty sensation, which led to a reduced wind speed in the second half of the ventilation period.

[0084] 2) Physiological effects of local under-clothing ventilation

[0085] The wind temperature and wind speed preferences of the five parts change with ventilation time, and the changes in skin temperature and humidity under clothing at the ventilation parts change with ventilation time. Figure 3 A two-way repeated-measures ANOVA showed no significant effect of ventilation location on the adjustment trend for either wind temperature or wind speed (P>0.05). However, multiple comparisons revealed that the posterior thigh preferred a significantly lower wind speed between 15 and 30 minutes of ventilation, and the posterior thigh gradually adjusted to a lower wind speed during this period. Previous studies have found that the posterior thigh is the most sensitive to cold air among the five locations, suggesting that subjects experienced greater local discomfort in the second half of the ventilation period, leading them to adjust to a lower wind speed.

[0086] Two-way repeated measures ANOVA showed that ventilation location had no significant effect on the change in skin temperature or humidity under clothing at the ventilation locations (P>0.05). However, the interaction effect of time and ventilation location had a significant effect on the change in humidity under clothing [F(5.71,62.78)=6.24, P<0.001]. After 30 minutes of local ventilation, the humidity under clothing decreased more on the anterior chest (21.6±7.2%), upper back (19.5±6.3%), and lower back (19.0±5.4%) than on the anterior thigh (10.3±5.3%) and posterior thigh (14.0±4.8%), possibly due to greater sweating on the anterior chest, upper back, and lower back.

[0087] 3) Subjective response to local under-clothing ventilation

[0088] The overall and local thermal sensation and thermal comfort evaluation of the five parts during ventilation are as follows: Figure 4As shown in the figure, after 30 minutes of localized under-clothing ventilation, the local thermal sensation changed from "warm" (+1.89±0.16) to "slightly cool" (-1.23±0.15), and the local thermal comfort changed from "uncomfortable" (-0.47±0.11) to "comfortable" (+0.66±0.08). However, the overall thermal neutrality and comfort (thermal sensation > 0, thermal comfort < 0) were still not achieved. This indicates that using the ventilation parameters of this experiment to ventilate a single area can effectively alleviate local heat stress, but it still cannot achieve thermal comfort for the entire body.

[0089] A two-way repeated measures analysis of variance showed that ventilation location had no significant effect on any of the four subjective evaluations (P>0.05). However, multiple comparisons revealed that the overall thermal sensation of the anterior chest was significantly lower than that of the upper back (P=0.02), anterior thigh (P=0.02), and posterior thigh (P=0.01). The anterior chest experienced comparable ventilation temperatures and lower air speeds compared to these locations, indicating that ventilation of the anterior chest is more effective in reducing overall thermal sensation.

[0090] 4) Cooling energy consumption of local under-clothing ventilation

[0091] Energy consumption related indicators of 5 parts are as follows Figure 5 The single-factor variance analysis showed that the ventilation position had no significant effect on the four indicators (P<0.05), but the multiple comparison results showed that the power of the wind sensation on the posterior thigh was P<0.05. Ds The E of the lower back was significantly lower (60.2±8.3W) than that of the upper back (87.8±26.7W), indicating that the posterior thigh was more susceptible to wind blowing, which was consistent with the result of gradually lowering the wind speed after 15 minutes of ventilation. OTC The lowest value (223.9±89.1kJ) indicates that ventilation under the lower back can achieve a greater overall comfort improvement with less energy consumption, making it a suitable location for ventilation and cooling under clothing. OTC There were large individual differences, which may be due to the fact that half of the subjects were female and half were male. Women wore bras, which allowed ventilation in that area, resulting in a different overall cooling effect than men.

[0092] in conclusion

[0093] Based on the aforementioned method, the wind temperature and speed preferences for ventilation under clothing on the front chest, upper back, lower back, front thigh, and back thigh of the human body in a thermal environment were evaluated, as well as the effects of ventilation at each location on thermal comfort. The following conclusions were drawn:

[0094] In hot environments, under-garment ventilation of a single location can be used to cool the human body. The preferred air temperature for ventilation is 26°C, and the wind speed preferences vary across different locations, typically ranging from 0.7 to 1.1 m / s. Currently, adjustable-speed ventilation suits used in hot environments typically use ambient air (28 to 35°C). Cooling ventilation at a temperature of 26°C should be designed to enhance the cooling effect, and the wind speed should be adjusted from 0.7 m / s to above to meet user needs. 30 minutes of localized ventilation of a single location can transform the localized thermal sensation and thermal comfort of a person in a hot environment from hot and uncomfortable to slightly cool and comfortable, but achieving overall thermal neutrality and thermal comfort is difficult. Therefore, simultaneous ventilation of two or more locations should be designed to enhance the cooling effect of ventilated suits in hot environments.

[0095] Lower back ventilation consumes the least energy to achieve a unit improvement in overall thermal comfort, making it a suitable primary ventilation area. Ventilation of the front chest can further reduce overall thermal sensation and is also suitable for ventilation and cooling. The upper back is less likely to produce a drafty sensation even during ventilation at higher wind speeds and lower temperatures, making it a viable ventilation area. The posterior thigh, on the other hand, tends to experience lower wind speeds during ventilation parameter adjustment and is more prone to a drafty sensation, making it unsuitable for ventilation and cooling. Therefore, in the design of ventilated and cooling clothing, the primary consideration is to introduce cool airflow into the lower back, followed by increased cooling ventilation of the front chest and upper back. At the same time, ventilation of the posterior thigh should be avoided to prevent local discomfort and reduced overall comfort.

Claims

1. A method for evaluating the effect of local ventilation under clothing on human thermal regulation, characterized in that: Provide a local ventilation garment with adjustable and controllable ventilation temperature and speed, and evaluate the effects of local ventilation on the overall thermal physiology and psychology of the human body, including the following steps: Step 1: Establish a local under-garment ventilation system with adjustable wind temperature and wind speed, including an air supply device and a local ventilation suit; Step 2: Conduct an experiment to evaluate the effect of local under-clothing ventilation on human thermal regulation: The local ventilation parts of the local ventilation suit are opened symmetrically on both sides. Each local ventilation only ventilates the symmetrical openings on the left and right sides of one part, and the non-ventilated parts are covered by the clothing fabric. For the human body in a high-temperature environment, local ventilation is performed on the front chest, upper back, lower back, front thigh, and back thigh. During the process, the wind temperature and wind speed parameters adjusted by the subjects themselves are recorded, as well as physiological parameters including average skin temperature and humidity under the clothes, and psychological parameters including subjective thermal sensation, comfort, and wind blowing sensation. Indicators representing the ventilation and cooling effect are calculated, including: Total energy consumption E when ventilating a certain part: E=∫0 t Pdt=∫0 t [cρV a (T-T a )]dt Where P is the theoretical power; c is the specific heat capacity of air, ρ is the air density, T is the ambient temperature, T a is the ventilation temperature; Actual cooling efficiency η a : or a =Q / E Where Q is the total heat dissipation during the entire ventilation process, which is calculated by the following formula: In the formula, η is the equipment power, m is the ventilation speed, h a is the enthalpy of the dry air component in the airflow, h v is the enthalpy of the moist air component in the airflow, T sk is the skin temperature, T a is the ventilation temperature, is the relative humidity of the air flow; The local ventilation energy consumption E consumed when the whole body thermal comfort is improved by 1 unit OTC : E OTC =E / (OTC S -OTC E ) Where, OTC S The OTC is the overall thermal comfort of the subjects at the start of ventilation. E E is the overall thermal comfort of the subject at the end of ventilation; OTC The smaller it is, the less energy is consumed in ventilation of that part to achieve the same thermal comfort improvement effect, and the cooling can be achieved more energy-efficiently. The power of the ventilation equipment corresponding to the period when the subject feels the blowing sensation during the ventilation process is the power consumed when the blowing sensation occurs, P Ds : Where, is the ventilation speed in the current period, is the ventilation temperature of the current period; Step 3: Conduct statistical analysis on the experimental results to analyze the differences in ventilation parameter preferences and ventilation effects in different ventilation areas. The independent variable is the ventilation area, and the dependent variables are the preferred wind temperature and preferred air volume, overall and local thermal sensation and thermal comfort, blowing sensation, and indicators that characterize the ventilation and cooling effects. The analysis results in the most suitable part of the human body for ventilation.

2. The method for evaluating the effect of local ventilation under clothing on human thermal regulation according to claim 1, wherein: For the local ventilation suit, two sets of zippers are installed on the front and back center lines of the upper garment and the left and right side seams of the lower garment, respectively. Each suit has a total of eight sets of zippers, which provide an adjustment range of -4 to 4 cm for the torso circumference and -2 to 2 cm for the leg circumference. This allows subjects of different body shapes to have similar clothing looseness when wearing the suit, thereby controlling the size of the gap under the suit.

3. The method for evaluating the effect of local ventilation under clothing on human thermal regulation according to claim 1, wherein: In step 2, in order to explore the effects of local under-clothing ventilation on human thermal comfort in five areas, namely the front chest, upper back, lower back, front thigh, and back thigh, each area was subjected to 30 minutes of ventilation cooling with adjustable wind temperature and wind speed, with the wind temperature and wind speed adjusted every 5 minutes, and a subjective evaluation was completed; 30 tests were performed on each subject, and the experimental results were recorded and analyzed.

4. The method for evaluating the effect of local ventilation under clothing on human thermal regulation according to claim 1, wherein: In step 3, when performing statistical analysis on the experimental results, all subjective evaluation data are first normalized, and then all data are tested for normal distribution and homogeneity of variance; then, a two-factor repeated measures variance analysis is used to detect the effects of ventilation temperature and time on preferred wind temperature, preferred wind speed, and various subjective evaluations, and a one-factor variance analysis is used to detect the effects of ventilation position on energy consumption-related indicators; if a significant effect is found, multiple comparisons are further used for pairwise comparisons, and the differences in ventilation under clothing in different positions are further analyzed.

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