COMPARISON OF THERMAL HAND MODELS AND MEASUREMENT SYSTEMS

Five sets of gloves were tested on 3 hand models with 2 measuring system in order to ensure repeatability of results from the past and for the future. The other aims of the study were to compare the possible differences related to different number of measuring zones, and effect of temperature distribution over hand surface. The hand models had 2 (HF), 9 (H2) and 10 (H3) zones respectively. Models H2 and H3 were tested on the new regulation system and models H2 and HF on the old regulation system. Homogenous vs. inhomogeneous surface temperature was tested on H2 and HF. All hands were tested at low (0.3 m/s) and high (4.0 m/s) air velocity. Non‐uniform temperature did not affect the results if parallel method of EN ISO 15831 was applied. A higher insulation value was acquired with a one zone model vs. multiple zones. The transfer to new system did not affect the results

COOLED PLATE TESTS ON TEXTILE MATERIALS IN SIMULATED COCKPIT UNDER “SOLAR RADIATION”

This study investigated if clothing material with reflective properties has an effect on heat gain in pilot, specifically, under solar radiation. Two materials, conventional pilot suit material (Old) and material coated with coldblack® (New, Schoeller Technologies AG, Switzerland) were tested over variety of underwear layers and in a box simulating cockpit. A hot plate was used to measure textile combinations’ insulation. Under the solar radiation simulation with a Thorn lamp (841 W/m2) a water cooled plate was utilized. The insulation of New was slightly lower than in Old. New showed about 10 % lower heat transmission under solar radiation than Old. Textile surface temperature in New was several degrees lower than in Old. When placed in the box the heat transmission difference reduced to nothing. The new material has ability to reduce the heat load in the open space. In closed space the advantage disappears, i.e. the effect of the outer layer in cockpit scenario is marginal

User friendly bicycle helmet for commuters

The number of adult bicycle helmet users in Sweden has stayed over the years relatively stable around 20 % [1]. In Europe the number of helmet users varies between 1 and 40 % depending on country. Research has shown that the use of helmet considerably diminishes head injuries in the case of traffic accidents [2]. In spite of that it is not fully clear what are the main factors why only a small number of bicyclists use a helmet. In order to raise awareness of helmet use and improve traffic safety COST Action supported a European initiative “Towards safer bicycling through optimization of bicycle helmets and usage”. Why helmet use is not popular? Several reasons could be pointed out: design, destroys the hair style, attitudes against helmet use, nowhere to put, too warm etc. Often the initial complaints are related to heat [3]. In cold additional insulation from the helmet may be a positive factor while compatibility issues may rise. As the professional bicyclists and most training/competing amateurs do wear the helmets then the aim for traffic safety should be increasing helmet use among commuters and bicyclists who do it just for fun. Therefore a project was initiated where main issue was to reduce initial thermal disturbance from a bicycle helmet while keeping in mind visibility, protection aspects, look, issues related to wearing comfort etc. Some relevant factors to be considered are: • The motion speeds of commuters would stay on average around 15 km/h (4.2 m/s) with average high speed not much above 20 km/h. • Aerodynamics and placement of the vents and air channels. • The effect of hair should not be underestimated – these may fill air channels with very effective insulation material

Thermal stress on firefighters in extreme heat exposure

Five students of a rescue training school cycled at 50 W for 20 minutes at 20 °C before walking up to 30 minutes in a climatic chamber at 55 °C and 30 % relative humidity. Four different types of clothing ensembles were used differing in terms of thickness and thermal insulation value were tested on separate days. All subjects completed 28-30 minutes in light clothing, but quitted after 20-27 minutes in three firefighter ensembles due to a rectal temperature of 39.0 °C or subjective fatigue. No difference in the evolution of mean skin or rectal temperature was seen for the three turnout ensembles. Sweat production amounted to about 1000 g in the turnout gears of which less than 20 % evaporated. It was concluded that the small differences between the turnout gears in terms of design, thickness and insulation value had no effect on the resulting physiological strain for the given experimental conditions

Effects of natural solar radiation on manikin heat exchange

The main objective was to compare short wave radiation from Thorn lamp to solar radiation. In sun all manikin front zones get more or less evenly radiated but in the lab the radiated power reaches some zones more than others. Tests were carried out on the thermal manikin Tore under clear sky in a building corner facing the sun. The manikin was turned so that in the end of each trial the sun faced manikin front. Basic tests without radiation were carried out in homogenous conditions in the climatic chamber. 4 sets of clothing were tested: black Nomex (BN), orange Nomex (ON), white cotton (WC) and reflective Nomex (RN). Helly-Hansen underwear (super stretch, polypropylene) was used under all coveralls. Thermocouples were fixed at chest on underwear inner and outer surfaces and outer layer inner and outer surfaces for textile surface temperature measurements. From basic tests there were estimated the heat losses for particular outdoor conditions. The insulation values were corrected for air velocity according to EN 342 (2004). The difference between the calculated heat losses and actual measured heat losses outdoors gave heat gain from sun for those particular conditions. There was a clear difference between BN and the other suits and RN and the other suits, however, ON and WC were quite similar. The highest textile temperatures were recorded for BN and lowest for RN. A difference between ON and WC was present, too. The curves followed the same pattern as observed from the manikin tests with solar lamps in the climatic chambers: underwear had often the highest temperatures

Thermoregulatory manikins are desirable for evaluations of intelligent clothing and smart textiles

Thermal manikins have been used to measure thermal properties of clothing. The use of thermal manikins has made a step forward in terms of quantifying thermal properties of clothing in a 3-D manner compared with the use of hotplates for material testing. The effects of clothing properties measured on the thermal manikins under steady state (constant manikin surface temperature and constant environmental condition) have usually to be validated by human subject tests. The thermal insulation and evaporative resistance values measured in the constant conditions are also used in modeling to calculate heat balance, predict human thermal physiological responses, and thermal comfort. However, in many real life situations, clothing properties (e.g. moisture transfer), in particular the clothing properties with smart materials, e.g. phase change materials (PCMs), environmental conditions, sweating rate, skin temperatures are neither constant nor uniform. These make mathematical modeling complicated to take into account various transient, non-uniform conditions, and changeable properties of smart clothing which is becoming increasingly popular (Tang and Stylios 2006). Moreover, skin and core temperatures rather than heat loss or storage are commonly used to evaluate thermal comfort, define hypothermia and hyperthermia and evaluate heat strain. Therefore, the direct prediction of thermophysiological responses (skin and core temperatures) based on manikin measurements are valid (Psikuta and Rossi 2009), and could be considered another step forward towards direct evaluation of human-clothing-thermal environment interactions. In the case of measuring a personal cooling system, current standard specifies the measurement of the average heat removal rate from a sweating heated manikin (ASTM F2371-10). This heat removal rate is not constant for the PCMs. The objective of this study was to investigate the gap between the measured heat removal rate of smart clothing with PCMs obtained on a thermal manikin in a stable state, and clothing effects on local human skin and on core temperature, to compare the difference of the results obtained from both methods, and to highlight the need for developing intelligent thermoregulatory manikins