Human safety evaluation based on warm environment of warm body fake people

This paper establishes human security evaluation methods combined with theory and experimental simulation in this paper. Place the hemity dummy in a closed high-temperature environmental experimental cabin, measure the environmental parameters around the human body in real time, and use the thermal reaction model to calculate the human body thermophysiological reaction under the environmental parameter, through the heat of the warmer dummy, sweating The function of this time is realized, and the thermal reaction interaction of the human body is achieved. In addition, through the observation of the changes in the thermophysiological parameters of the human body during the experiment, the safety state of the human body is judged according to the research results of medical students.

1 Experimental Design

The construction of the experimental platform

The experimental platform includes a human-machine-environmental simulation subsystem, Parameter Measurement Subsystem and Data Acquisition / Transmission / Processing Subsystem 3. Man-Machine-Environmental Simulation Sub-system Manufactured a specific thermal stress environment by high temperature cabin and hot radiation plate, using the Newton heater dummy to simulate the thermophysical response behavior of the human body, and wear heat protective clothing for the dummy, and then form people - machine-machine-machine- The thermal reactive system of the environment. Basic parameters such as temperature, humidity, and the equivalence of the environment, etc. measure the thermophysiological parameters of the temperature, humidity of the sub-system measured by the parameter. The data acquisition / transmission / processing subsystem consists of data acquisitionr, dummy control software thermogradac, and human body thermal reaction calculation model, and receives real-time measurement results of parameter measurement system, calculates the thermogravure response behavior of the dummy, and transmits the corresponding instruction to NEWTON warm fake people, as a basis for the thermophysis response of human body dummy in the human body. The overall structure and logical relationship of the experiment platform is shown in Figure 1.

Thermor dummy is analog equipment for human physiological behavior, and is used to apply to clothing comfort. This experiment is based on the Newton heater dummy produced by Northwestern China, with the heat response results of thermophysiological simulation calculation, and simulates the physical reactions such as body heat and sweating in the thermal environment. Newton warm fake people include dummy and skin layers, external systems, environment sensors, and control software. Among them, the fake person and the skin layer are the external structure of the human body, and in the skin layer, the internal controller and capillary are in the skin layer, as a micro-action unit of the simulated human body heat, sweating; the external system is physiologically heat, sweating and other physiology The corresponding external control box composition, the role of the organs corresponding to the human physiological function. The overall structure and functional relationship of the NEWTON warmer fake person is shown in Figure 2.

1.2 Experimental Scheme

The main idea of human body safety research experiments in hot environment is: placing a warm environmental and hot radiation plate in a closed thermal environmental laboratory Inside, the specific thermal environment is manufactured by the hot radiation plate, and the relevant parameters are obtained by the thermal fake person parameter measurement system and the environmental parameter measurement system. The thermal response of the dummy to the dummy under the thermal stress is calculated, transmitted to the warm body.The fake person produces the corresponding physical heat, sweating and other responses. By real-time fake people's biological parameters, two indicators of body temperature and sweating rate, judge the safety status of the human body. In order to facilitate the research of safety evaluation methods, there is no hot protective clothing in the experiment, but only sweat the skin, with the thermal resistance of sweating skin, the wet resistance parameters replace the heat and wet performance parameters of the hot protective clothing.

The main process of the experiment is: 1) Turn on the heat radiation plate, the temperature increase in the cabin; 2) The human body increases heat with the ambient temperature, the body temperature increases; 3) heat accumulate to a certain extent, open Exhignation function, by sweating evaporation, heat; The main process of the experiment is shown in Figure 3.

Calculation of physiological indicators

In the data acquisition / transmission / processing system, embedding the human body thermally physiological reaction calculation model, the environment and human body measured in real time Wet gauge is used as input, iterative calculates the thermophysis response of the human body. The calculation model uses the model recommended in ISO 7933, the main calculation formula is 11:

1) Calculate the maximum evaporation heat flow EMAX (W / M2) required for the skin surface EREQ (W / M2) :

EMAX PSK-PARCL, (1) EREQ M-DEQ-W-CRES-RRES-CR. (2)

Where: PSK and PA are skin surface temperatures and The saturated vapor pressure of the ambient temperature, KPa; RCL is the wet resistance of the skin layer and the garment, M2kPa / W; M is a metabolic rate, W / M2; DEQ is stored with new metabolic rates. Rate, W / m2; W is the external power of the human body, W / m2; CRES and RRES are the heat convection rate and thermal evaporation rate of breathing generated, and W / m2; C and R are thermal convection rates of the skin surface, respectively. Heat evaporation rate, W / m2. In the above parameters: PSK, PA, RCL is worthy of measurement; M, W is set according to the actual situation; other parameters are:

DEQ CSPTCR, EQ, I-TCR, EQ, I-1 Middle; 1- alpha; I-1, (3) CRES 0.01516 mTex-Ta, (4) ERES 0.00127M59.34 + 0.53TA-11.63Pa, (5) C + R TSK-Taicl. (6)

Where: i is the i-th time, each time is 1 min; CSP is human body heat capacity, w / (m2 midd 2; k); TCR, EQ, i is the human core temperature, ° C; alpha; i is the skin-core quality parameters; TEX, TA, TSK is exhaled at the end of the skin - core quality parameters; TEX, TA, TSK, respectively, the ambient temperature and skin temperature, ℃.

2) compute the expected sweat rate si (W / m2),

si si-1 middot; e-110 + sreq1-e-110 (7)

. wherein, sreq sweat rate is desired, W / m2, which is determined by the values of Emax and Ereq.

3) Calculate the rectal temperature Tre, i, ℃,

Tre, i Tre, i-1 + 2Tcr, i-1.962Tre, i-1-1.319. (8)

Among them, TCR, I is the human core temperature, ° C,

TCR, I 11- alpha; I2DICSP + TCR, I-1-TCR, I-1-TSK, I-12 Alpha ; i-1-Tsk, i alpha;. i2 (9)

in medical physiology, rectal temperature used in place of the core temperature of the body 12. Thus, by setting the body parameters, measuring environmental parameters, calculate the required human sweat rate and rectal temperature in the thermal environment.

Experimental results and analysis

Skin temperature at which thermal comfort Tsk 34 ℃ 12, this value is set to the human skin temperature initial value. The temperature TRAD of the heat radiation plate is set to 30 ° C, 32 ° C, 34 ° C, 36 ° C, 38 ° C, 40 ° C, and investigate the thermophysiological changes in the human body in the experiment 4 H, and judge the human body by body temperature and sweating. the security status.

2.1 rectal temperature change

Tre rectal temperature change during the experiment is shown in Fig.

1) the higher the thermal radiation temperature Trad, Tre rises faster.

2) When Trad is 30 ℃ and 32 ℃, Tre rises after the first decrease, and finally reaches a stable value, this indicates that the body can adapt to the heat radiation environment; when Trad 34 ℃, Tre Finally, there is still fluctuations, indicating that this thermal radiation temperature is a critical condition of the human body to the thermal environment, which is consistent with the TSK stability of 34 ° C; when the TRAD is 36 ° C, 38 ° C, TRE is more rapidly increased, until close to ISO 7933 models haveThe critical value of TRE 40 ° C (corresponding time t1 98 min), at this time, the thermal response law of the human body has not been calculated using ISO 7933 model.

3) When TRE reaches a dangerous value, the human body enters the corresponding dangerous state. The danger limits of rectal temperature are physiological sunsimitations 38.5 ° C, safety upper limit 38.9 ° C, tolerated upper limit 39.4 ° C 13. The hazard time thus judge is shown in Table 1.

As can be seen from Table 1, when the thermal environment intensity exceeds the adjustment capability of the human body, the higher the thermal radiation temperature, the earlier the human body is in a hot dangerous state.

2.2 Sweating Rate Change

Analysis of the change law of sweating rate S in the experiment process, judge the human safety status, as shown in Figure 5.

1) The higher the TRAD, the faster S growth;

2) When the TRAD is 30 ° C and 32 ° C, the S is first increased, then decreases. Finally, a more stable value is reached, indicating that the human body can adapt to this thermal radiation environment; when trad 34 ° C, S is finally fluctuated, indicating that the thermal radiation temperature is a critical condition of the human body to thermal environment; when TRAD is 36 ° C, At 38 ° C, 40 ° C, S is faster to grow, and then stabilize to a pole limit. The control TRE curve can be found that TRE 40 ° C, that is, the experimental time TL 108 min, the thermal response regular of the human body has not been calculated using the ISO 7933 model. At this time, SL 375 ml / (M2 MIDDOT; H) is also calculated. The limit value of the sweating rate is obtained.

3) When S is greater than 0.01% (246.33 ml / (M2 M2 M2 MIDDOT; H)), the human body is in a dangerous state of the sweating rate judgment 13. The dangerous time corresponding to each of the thermal radiation temperatures thus determined is shown in Table 2.

When the human body can adapt to the heat radiation environment, the dangerous time has gradually shortened with the increase in the temperature of the thermal radiation; when the human body cannot adapt to the heat radiation environment, the dangerous time is basically the same. This shows that when the intensity of the thermal environment exceeds the human regulation capability, the sweating ratio of the human body has a corresponding limit value, and the sweat rate changes around the limit.

4) There is a limit value of the total number of people with the human body. When the total amount of loss sigma; s exceeds this limit, the human body is in a dangerous state of lossless. When sigma; s reaches a weight of 2% (1.4 kg), enter the dangerous state; when sigma; s reaches 5% (3.5 kg) of body weight, enter the heat hazard state 14. When there is a dangerous state of different thermal radiation temperaturesAs shown in Table 3.

3 Discussion and Conclusion

When a single theoretical calculation or experimental simulation is in studying human safety problems in high temperature environment Limitations, this paper applies the sweeping warm body dummy as the core equipment, established the human thermal safety evaluation model combined with theory calculation and experimental simulation. The model can react to the thermal environment, judge the thermal safety state of the human body through the change in body temperature and sweating rate, thereby achieving auxiliary decision function for human safety protection in high temperature environments.

There is still a deficiency of the safety evaluation method, mainly:

1) The body surface temperature value is weighted by the body surface temperature of 20 borders, sweating The amount is adjusted according to the weight of the weighted body surface. More precisely, each of the bosses should be treated, ie, according to the surface temperature of each of the bosses, respectively, and adjust the sweat rate.

2) Experiments in the closed thermal environmental laboratory, the temperature and humidity in the inside of the experiment change, due to this change and the heating rate of the heaters, the sweating rate is directly related, The experimental results are difficult to calculate the

ratio of

. The next step should be carried out in a constant temperature and humidity environment box, and the experimental results are compared with the theoretical model calculation results, thereby improving the safety evaluation method.

3) In this experiment, in order to simplify the method, the warm body is not hot protective clothing, only the thermal resistance of sweating skin attached to the outer layer of the fake, instead of protective clothing Wet performance. Obviously, the hot and humidity value of sweating skin is much smaller than the corresponding parameters of the thermal protective clothing. The next step should carry out the thermal safety experiment of the high temperature environment after protective clothing.