Tetsumi Horikoshi

Experimental study on convective heat transfer coefficient of the human body

Abstract 1. 1. The convective heat transfer coefficient of the human body is essential to predict convective heat loss from the body. 2. 2. The object of this paper is to calculate the convective heat transfer coefficient of the human body using heat flow meters and to estimate the thermally equivalent sphere and cylinder to the human body. 3. 3. The experimental formulae of the convective heat transfer coefficient for the whole body were obtained by regression analysis for natural, forced and mixed convection. 4. 4. Diameters of the thermally equivalent sphere and cylinder of the human body were calculated as 12.9 and 12.2 cm, respectively.

Development of outdoor thermal index indicating universal and separate effects on human thermal comfort.

The purpose of this study is to propose a new outdoor thermal index that simultaneously indicates universal and separate effects. The value indicating universal effect in this index consists of the summation of air temperature and the effective temperature differences by air velocity, longwave radiation, solar radiation, and humidity. This paper describes the theoretical construction of this newly derived index to compare with previous indices. The calculations of the new index are demonstrated using the observed data in order to explicitly indicate the specific features of the new index.

Convective heat transfer area of the human body.

In order to clarify the heat transfer area involved in convective heat exchange for the human body, the total body surface area of six healthy subjects was measured, and the non-convective heat transfer area and floor and chair contact areas for the following nine common body positions were measured: standing, sitting on a chair, sitting in the seiza position, sitting cross-legged, sitting sideways, sitting with both knees erect, sitting with a leg out, and the lateral and supine positions. The main non-convective heat transfer areas were: the armpits (contact between the upper arm and trunk regions), contact between the two legs, contacts between the fingers and toes, and contact between the hands and the body surface. Also, when sitting on the floor with some degree of leg contact (sitting in the seiza position, cross-legged, or sideways), there was a large non-convective heat transfer area on the thighs and legs. Even when standing or sitting in a chair, about 6–8% of the body surface did not transfer heat by convection. The results showed that the effective thermal convective area factor for the naked whole body in the standing position was 0.942. While sitting in a chair this factor was 0.860, while sitting in a chair but excluding the chair contact area it was 0.918, when sitting in the seiza position 0.818, when sitting cross-legged 0.843, in the sideways sitting position 0.855, when sitting with both knees erect 0.887, in the leg-out sitting position 0.906, while in the lateral position it was 0.877 and the supine position 0.844. For all body positions, the effective thermal convective area factor was greater than the effective thermal radiation area factor, but smaller than the total body surface area.

Responses of human skin temperature and thermal sensation to step change of air temperature

Abstract 1. 1. The purpose of this paper is to clarify the non-linearity of the human physiological and psychological responses to step change of air temperature by impulse response analysis using Discrete Fourier Transformation. 2. 2. Experiments were conducted to investigate the effect of thermal transients on human responses. 3. 3. Experimental conditions were as follows: lowering air temperature from 30 to 20°C and raising air temperature from 20 to 30°C. 4. 4. The responses of local skin temperature on lowering air temperature from 30 to 20°C are not necessarily opposite to the responses found on raising air temperature from 20 to 30°C. 5. 5. From impulse response analysis using Discrete Fourier Transformation, skin temperature responses to the opposite air temperature change do not necessarily coincide with each other whenever the same temperature stimulus is occurred.

Effect of the Environmental Stimuli upon the Human Body in Winter Outdoor Thermal Environment

In order to manage the outdoor thermal environment with regard to human health and the environmental impact of waste heat, quantitative evaluations are indispensable. It is necessary to use a thermal environment evaluation index. The purpose of this paper is to clarify the relationship between the psychological thermal responses of the human body and winter outdoor thermal environment variables. Subjective experiments were conducted in the winter outdoor environment. Environmental factors and human psychological responses were measured. The relationship between the psychological thermal responses of the human body and the outdoor thermal environment index ETFe (enhanced conduction-corrected modified effective temperature) in winter was shown. The variables which influence the thermal sensation vote of the human body are air temperature, long-wave thermal radiation and short-wave solar radiation. The variables that influence the thermal comfort vote of the human body are air temperature, humidity, short-wave solar radiation, long-wave thermal radiation, and heat conduction. Short-wave solar radiation, and heat conduction are among the winter outdoor thermal environment variables that affect psychological responses to heat. The use of thermal environment evaluation indices that comprise short-wave solar radiation and heat conduction in winter outdoor spaces is a valid approach.

Behavioral Thermoregulation Model for Evaluation of Outdoor Thermal Environment

In the outdoor environment, the effect of the physical environmental factors that compose the sensational and physiological temperature is remarkably large in comparison to the indoor environment. The purpose of this paper is to propose and develop a behavioral thermoregulation model in the outdoor environment, in order to predict the mean skin temperature for the evaluation of outdoor environment. This model is based on a Two-Node Model, and has three components: direct solar radiation, indirect solar radiation, and heat conduction. Each body part consists of core and skin layers. The model formula, by ratio of body weight of skin layer of heat conductance between skin and core layer, was included in this model. To verify this model, experiments were conducted. It was shown from the relation between ETFe (Enhanced conduction-corrected modified effective temperature) and mean skin temperature that it is possible to quantity explicitly the effects owing to outdoor environmental factors, short-wave solar radiation, heat conduction etc. It was made clear that the current model is valid for simulated mean skin temperature in the outdoor environment.

The influence of ethnic differences upon human responses due to thermal environment

Abstract 1. 1. The influence of ethnic differences is discussed with reference to the following issues. 2. 2. It has been found that total numbers of active sweat glands increase in tropical populations compared with people from northern latitudes. 3. 3. It has also been observed that the active sweat glands of Eskimos are fewer than those of Caucasians. 4. 4. The rate of the evaporated sweat loss was calculated by measuring body weight loss and it was found that the evaporated sweat loss of Caucasians is larger than that of Japanese in the same climate. 5. 5. Meteorological factors might have been responsible for the smaller loss in Japanese compared with that of Japanese-Americans. 6. 6. Under the same experimental conditions, it was observed that there were little or no differences between the Caucasians and Negros.

Detection for Pickup Errors by Artificial Neural Networks

Taping machines, chip mounters and surface mount device (SMD) inspection systems use image processing techniques for the positioning of SMDs. The improvement of the production quality as well as the productivity is strongly requested in these systems. The image processing system in these systems have inspection functions to improve production quality. Generally, images of the part being picked up by the nozzle are acquired in a horizontal direction, and pickup errors are detected by processing these images. The aim of this paper is to develop a system for detecting pickup errors by processing images of parts acquired from the bottom. By using our proposed method, the detection rate of pickup errors is 99.3%.

A Review of Thermal Comfort Studies in Japan

More than 50 papers on thermal comfort are presented in various meetings and symposia every year in Japan. Topics covered by these papers include comfort zone, the effect of fluctuating air movement and asymmetric thermal radiation on human responses, the dynamic analysis of human responses, psy chological and behavioral aspects of thermal comfort, and the development of environmental indices, to name a few. This paper briefly reviews these investi gations.