Study on hot and comfort of warm underwear with warm body sweating

The air layer volume between the 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 trousers under the same conditions, and considers the air layer thickness in the clothing It 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 jacket is studied on the heat resistance and wet resistance. It is found that the thermal resistance and wet resistance of the jacket are gradually increased within a 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

1.1 Measurement of clothing In this study, 4 men with M, L, XL, XXL were selected for measurement. 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 is measured by FAST-1 at low load (196 PA), and the bending stiffness is completed by FAST-2 measurement, and the thermal resistance of the fabric itself is measured by Premetest. Finish.

1.2 Warm fake people

Standing warm body sweating fake people Walter measures thermal resistance and wet resistance of thermal underwear. 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 body scanner

The three-dimensional 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 and the foot is close to the ground. When scanning, the bare dummy is measured first to obtain the volume of the fake people, and then measure the dummy wearing a different type underwear to obtain a dummy in the 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.

1.4 thermal resistance, wet resistance, and moisture absorption index can be obtained according to standard ASTM 1291-10, and the calculation formula is shown in equation (1).

In the formula (2), RE is a wet resistance (Pa MIDDOT; M2 / W), PSS is Saturated moisture vapor pressure (PA) at a skin temperature, PAS is saturated with water at ambient temperature

(PA), and RHA is the environment relative humidity , and RES is a skin wet resistance (8.6 Pa MIDDOT; M2 / W), HE is evaporation heat loss (W). HE lambda; q, where Q is sweating rate, lambda; evaporation heat. The Mandip Wetting Index (IM) can be calculated according to standard ISO 9920: 2007 (ISO2007), as shown in equation (3).

In formula (4), VAIR is the air volume between the underwear and the dummy, VCL is The volume of the dress, vbody is the volume of the bare dummy.

1. Measurement of thermal resistance and wet resistance

(1) measurement, ambient temperature in a constant temperature and humidity artificial climet The humidity is (25 plusmn; 2) ° C, 65% PLUSMN; 5%; (2) The average skin temperature of the entire measurement process is maintained at 35 ° C; (3) All underwear is placed 24 h before the measurement is measured. (4) All underwear measurements 3 times, and then take off and then put it on the next measurement;

(5) at least at least when the thermal resistance is measured at least After 8 h, the water is accumulated and the accumulation speed is stable.

2 results and discussion

2.1 thermal resistance and wet resistance measurement Table 3 shows the overall thermal resistance and wet resistance of the thermal resistance of different types of thermal underwear in different air layers.

As can be seen from Table 3, in the range of thermal underwear, it is generally hot The increasing increase in the number is reduced and decreased. 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, thermal resistance and wet resistance Value and equation (3) can calculate its moisture permeability index. 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. It is illustrated that the thermal comfort of the thermal underwear is preferably hot and comfortable. At this time, the air layer volume is 3 283 cm3; the XXL number is the worst, the corresponding air layer volume is 11 068 cm3. The air layer volume is an important factor affecting the thermal comfortability of underwear.

As shown in FIG. 2, the influence of the air layer volume on thermal resistance of thermal underwear is further analyzed. The polynomial regression model (R2 0.99, P u003c0.05) between the air layer between the underwear and the dummy is established (R2 0.99, P u003c0.05), and its regression model is shown in equation (5).

Where 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, the air layer is volume Increase and gradually decrease.

2. The relationship between air layer volume and wet resistance Fig. 3 is in maintenanceThe wet resistance of the coat with changes in the volume of the air layer. 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 0.91, P u003c0.05), and its regression model is shown in formula (6).

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

From the regression model, the wet bar of the thermal underwear is within a certain air layer volume range. Gradually increase, when the wet resistance reaches a certain value, gradually decreases as the volume of the air layer is increased.

3 conclusions

In the measured range, thermal underwear The thermal resistance decreases as the volume of the air layer is increased, and its wetbed 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.