THERMOREGULATORY SYSTEM’S INTEGRATED IN THE CLOTHES EFFECT ON

THE HUMAN MICROCLIMATE

Ingrida Shahta1, Juris Blums2, Ilze Baltina1, Vilnis Jurkans3

1Institute of Textile Materials Technologies and Design2Institute of Technical Physics3Faculty of Electronics TelecommunicationsRiga Technical University

ACKNOWLEDGMENT This work has been supported by the European Social Fund within the project «Support for the implementation of doctoral studies at Riga Technical University» and “Establishment of interdisciplinary research groups for new functional properties of smart textiles development and integrating in innovative products".

Measurements with the switched on cooling system and physical activities

Thermal comfort of a clothing system is associated with the thermal balance of the body and its thermoregulatory responses to the dynamic interactions with the clothing and the environment. [2]

Thermal comfort of a clothing system is associated with the thermal balance of the body and its thermoregulatory responses to the dynamic interactions with the clothing and the environment. [2]

Thermal comfort of a clothing system is associated with the thermal balance of the body and its thermoregulatory responses to the dynamic interactions with the clothing and the environment. The clothes create a certain microclimate around the human body, which affects human feeling of comfort. One of the most important using parameter of garment should be mentioned the air temperature between the body and the first layer of clothing - underwear. The optimum level of this temperature is determined by human physical activities.

The research concerns to the microclimate control system containing thermoelectric converters – Peltier coolers - integration in the clothes prototype. The temperature measurements modelling experiments are planned to optimize microclimate regulatory garment functionality and to verify microclimate temperature regulatory system efficiency.

Research aim: to create a microclimate control system, which would not contain a liquid, or gaseous fluids, but the heat draining function is based on heat conduction processes in solid states, as well as the source of power should be mobile, environmentally friendly form of energy.

Thermal comfort of a clothing system is associated with the thermal balance of the body and its thermoregulatory responses to the dynamic interactions with the clothing and the environment. [2]

GARMENT CONCEPT CONCLUSIONS

EXPERIMENTAL

First experiments by the switched on cooling system and one Peltier cooler demonstrated the system's efficiency: already in 120 seconds temperature parameters began to decline, continuing even after physical activities.

The most changes were observed under the Peltier cooler and a copper radiator coolant (sensors 3, 4 and 5).

Apparently the system does not work just locally, but affects the entire body microclimate regulation. It was observed tendency of temperature to decline quite sharply again after the switching off of the cooling system. It should be noted that such a sharp decline in temperature is explainable by heating radiator surface inability to enough quickly transfer heat away.

RESULTS AND DISCUSSION

Generally the microclimate regulatory garment contains: Peltier coolers, which provide cooling effect,electronic control system - controls the optimal operating parameters,solar cells are used as energy source,batteries charged by solar cells are used for cooling system’s stable operation.

Preliminary experiments with solar cells have shown that it is possible to operate the micro-climate regulation system with such an environmentally friendly energy source,

currently experiments are going on the optimization of cooling system.

The analysis of human microclimate temperature modeling experimental results makes possible to carry out common conclusions: the cooling system is able to lower the temperature of the microclimate, Peltier element and its attached copper foil has a negative impact on the possibility of removal of vapour through the garment surface, which causes additional temperature rise of the microclimate in the area under the copper foil,the microclimate control system with two thermobatteries works more effectively as with four,measurement results are also affected by external environmental circumstances, for example air circulation when body moves.

Thermobattery (Peltier element) by the current flowing through it creates a temperature difference or, by the temperature difference, causes a current flow.

The heat created by the current is absorbed by the copper foil, attached to the hot surface of the element, and by thermal transfer removed and radiated into the environment.

Another copper foil is used to increase cooling surface and for the smooth the temperature conduction.

The aim of experiments - to verify, how the cooling system integrated in the clothes influences indicators of the human microclimate.

The plan of experiments is scheduled in accordance with the following points: measurements without the garment with integrated cooling system, measurements with switched off cooling system, measurements with switched on cooling system, to establish parameters of the body microclimate. During the experiments are performed physical exercises (15 min running).

Environmental conditions: 60% humidity and 24 degrees air temperature.

Sensors placement. Measurements are performed in the space between the garment first layer and cotton T-shirt to determine changes of the body microclimate at rest and during the time of physical activities.

1 - the neck area, 2 - shoulder, 3 and 11 - under the Peltier cooler, 4 - 6 cm away from the Peltier element, 5 - 6 cm away downwards from the element, 9 and 10 - the moisture sensors 15 and 14 are located on the skin under the system of thermobattery with added copper foils, 19 - moisture sensor and it is placed on the skin,18 – thermistor between the undershirt and T-shirt in the neck area.

Sensors location in lateral section

Experiments with 4 and 2 Peltier coolers (in the Figure Peltier elements are lettered by PE). Comparing system of two Peltier coolers, four elements cause faster overheating of the copper foil that could be explained not only by material not enough transfer of heat during the necessary period, but also draws attention to the influence of water vapour to increase the heat under the non-porous metal material, which for four elements is considerably larger.

The system and microclimate cooling process after the system’s switching off is faster also in the case with two thermobatteries.

Further are carried out experiments with 2 and 4 Peltier coolers, searching for the most suitable amount of microclimate cooling elements after the optimization of the control system.

Experiment with 4 elements demonstrates the effective operation of the longer term after the physical activity (without system's overheating and switching off).

In the Figure shown curves, representing the 6th, 7th, 8th and 16th sensors measurement results (sensors placed on the hot surface and on it attached copper foil), continuing increase indicates to insufficient quickly heat transferring of the material to the environment. The taken off jacket solves the problem of thermobattery overheating which leads to the conclusion of the free flow of air role in this process.