Research on hot and comfort of double thermal underwear based on warm body sweating

The air layer volume between clothing and the human body has an important impact on the thermal resistance and wet resistance of the clothing. McCullough EA has used stand-alone people to measure the thermal resistance of loose trousers and tight trousers, respectively, and found that the thermal resistance of loose trousers is greater than the tight under the same conditions body trousers, and believes in clothing The thermal layer thickness is an important factor in determining the thermal resistance of clothing. Y.s.chen et al., Using a sweat-free body dummy, the impact of jackets on the release of the jacket on thermal resistance and wet resistance were found that the thermal resistance and wettulation of the jacket gradually increased within the smaller air layer. In the study of the impact of clothing looseness on its thermal comfort, most of them are limited to measurement of thermal resistance of clothing, and the measurement of wet resistance of clothing is limited. In this study, the use of warm body sweating in the student, using a warm body sweating, and the thermal resistance and wet resistant were measured, and the air layer volume of the underwear and the dummy surface was also carried out using the three-dimensional body scanner. Measurement, in this way, the impact of the air layer thickness between the thermal underwear and the human body on its thermal comfort.

1 Experimental Scheme

1. Treatment of clothing

In this study, numbering Four men's double-layer warm knitted underwear for M, L, XL, XXL were measured. Among them, M, L, XL and XXL numbers correspond to tight, fit, relaxed, loose. 4 pieces of underwear are round neck long sleeves, and as the number increases in the bust, waist circumference, the shoulder width indicator is evenly increased, but the length, sleeve is long, and the indicator is consistent. The size of the underwear is shown in Table 1.

Table 2 shows the fiber composition and physical properties of the thermal endo fabric. Among them, the thickness of the fabric was measured by FAST-1 at low load (196 PA), and the curved stiffness was completed by FAST-2 measurement, and the thermal resistance of the fabric itself was completed by PremeTest.

1.2 Warm fake people

This study uses standing warm body sweating false people Walter to thermal resistance and wet resistance of thermal underwear Perform measurement. When the measuring, the dummy is in the upper body wearing different types of thermal underwear, and the lower body is wearing the same tight knit trousers.

1.3 3D human body scanner

3D body scanner Vitus is used for this human body measurement. According to standard ISO 20185: 2005, the measurement is corrected before measurement. The human body was measured in a temperature environment (25 plusmn; 2) ° C.

When the human body is scanned, the fake person is fixed, the foot is blocked. When scanning, the bare dummy is measured first to obtain the volume of the dummy's nude, and then the fake wearing different type underwear.People are measured to get the volume of dummy wearing underwear. To ensure the reliability of the measurement data, the measurement of each state is scanned 3 times from the 3 different angles of the fake.

1. Determination of thermal resistance, wet resistance and moisturectation index

1.6 thermal resistance and wet resistance measurement

(1) Measurement in a constant temperature and humidity artificial climulation, ambient temperature, humidity is (25 plusmn; 2) ° C, 65% Plusmn; 5%; (2) The entire measurement process The average skin temperature was maintained at 35 ° C; (3) All underwear was placed 24 h before the measurement was measured; (4) Each undergarment was measured 3 times, and the next measurement was taken off and then put it back to measurement; (5) At least 8 h at least 8 h during the measurement of thermal resistance and wet resistance, it is taken after the increasing rate of underwear is stable.

2 Results and Discussion

2.1 thermal resistance and wet resistance measurement

Table 3 is shown in different types The overall thermal resistance of the thermal underwear in the volume of different air layers and the measured value of the wet resistance.

As can be seen from Table 3, in the range of thermal underwear, its overall thermal resistance increases after the increase of numbers small. When the number is increased to XL, its thermal resistance is the largest, indicating that the warm performance of the underwear is best. This is because the volume of the air layer between the underwear and the dummy is also increasing with the increase in the underwear type, and the thermal resistance of the underwear has gradually increased due to the high thermal resistance of the stationary air. However, as the volume of the air layer is further increased, the thermal loss of air convection is increased, so the thermal resistance will gradually decrease. As can be seen from Table 3, in the range of the measured type, the wet resistance of the thermal underwear has gradually increased with the increase of the underwear type, and when it increases from the M number to the L, it is more obvious, but from L When the number to the XXL number, the increase is slow, and the increase rate is gradually reduced. This is related to the fiber component of the thermal underwear, which is made of 100% cotton fiber, good hygroscopic, and the moisture absorbed is not easy to dissemble, so the wet resistance is also large.

2.2 Mandip Wetting Index

in Table 3, the measured value and formula (3) of the thermal resistance and the equation of the wet resistant in Table 3 can be calculated . Figure 1 shows that the moisture absorbing index of the thermal underwear gradually decreases with the increase in underwear type, and its moisturectation index is almost consistent at the L-XL number. Note In the range of thermal underwear, the M is hot comfort, at which point the air layer volume is 3 283 cm3; the XXL number is the worst, the corresponding air layer volume is 11 068 cm3. Description air layer volumeIt is an important factor affecting the thermal comfortability of underwear.

Among them, Y is the overall thermal resistance of the underwear, X is the air layer volume between the underwear and the dummy.

From the regression model, the thermal resistance of the thermal underwear gradually increases within a certain air layer volume, and when the thermal resistance reaches a certain value, gradually decreases as the air layer volume increases. .

2. The relationship between air layer volume and wet resistance

Fig. 3 shows the change of wet resistance of thermal underwear with air layer volume. In order to further analyze the influence of the air layer volume on the warm internal wett resistance, the polynomial regression model between air layer volume and wet resistant (R2 u003d 0.91, P u003c0.05), and its regression model is shown in formula (6).

In the formula (6), Y is the wet resistance of the thermal underwear, X is the air layer volume between the underwear and the dummy.

From the regression model, the wett of thermal underwear gradually increases within a certain air layer volume, and when the wet resistance reaches a certain value, gradually decreases as the air layer volume increases. .

3 Conclusion

On the one hand, in the measured range, the thermal resistance of the thermal underwear increases with the increase of the volume of the air layer. Decrease, and its wett is gradually increased within the measured range. From the established regression model, both thermal resistance and wetbing increase the maximum value of the air layer volume, and then gradually decrease. On the other hand, the moisture absorbing index of thermal underwear gradually decreases with the increase in the underwear type, indicating that the thermal comfortability is gradually weakened. Based on this, this topic will further measure and evaluate the thermal luggage of thermal underwear to determine the appropriate release of thermal comfort and aesthetics of warm underwear.