Human Powered Responsive Performance Wear
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HUMAN POWERED RESPONSIVE PERFORMANCE WEAR
ARPAN GANGULI, NATIONAL INSTITUTE OF FASHION TECHNOLOGY
NEW DELHI, INDIA
INTRODUCTION
The goal of our knowledge-based society is to integrate intelligence into our everyday environment. Clothing is an important and special part of our environment as it is personal, comfortable, close to the body and used almost anywhere and anytime. The goal of our knowledge-based society is to integrate intelligence into our everyday environment. Clothing is an important and special part of our environment as it is personal, comfortable, close to the body and used almost anywhere and anytime.
To be responsive under strenuous conditions effectively and efficiently, the garment should have the following properties:
Optimum heat and moisture regulations
Good moisture absorption and moisture conveyance capacity
Good air and water vapour permeability
Prevention of long term feeling of dampness
Low water absorption of the layer of clothing facing the skin
Quick drying fabric to prevent catching cold
Pleasant to the skin, soft, non-abrasive and non-chafing
Stable as to shape, even under wet conditions
Durability
Low intrinsic weight
Easy care
OVERVIEW OF TERMS AND EQUATIONS USED IN THE ABSTRACT
Standard conditions used for testing: The fabrics were conditioned for at least 40 hours at 20 б 2 в–‹C and 65 б 2 % r.h.
When a person is involved in strenuous activity under normal ambient conditions or at higher ambient temperatures, additional metabolic heat can be dissipated by evaporation of the sweat, so the heat loss now occurs by both dry and evaporative means.
Therefore:
Total heat loss (H) = Dry heat loss (Hd) + Evaporative heat (He) loss through clothing with its associated layer of air.
Therefore;
Dry heat loss (Hd) = (Ts — Ta)/Rc
Where:
Hd = Rate of dry heat loss per unit area, m2
Ta = Ambient Temperature, в–‹C
Ts = Skin Temperature, в–‹C
Rc = The thermal insulation of clothing plus associated air, m2в–‹CW-1
Evaporative heat loss, He = (ps — pa)/ Re
Where;
Ps = Water vapour pressure at the skin surface, mm Hg
Pa = Water vapour pressure of the ambient air, mm Hg
Re = Resistance to evaporative heat transfer of clothing plus associated air, m2 mm Hg W-1
Therefore, =
H = [(Ts — Ta)/Rc] + [(ps — pa)/Re]
Permeability index: It is a dimensionless ratio of the maximum cooling allowed by clothing and the environment to the maximum cooling obtained by a wet bulb thermometer. It is given by:
Im = [(Re/Rc) x 0.45)]
The range of Im is 0-1, with 0 being for a system with no heat transfer to 1 for a system with optimum evaporative cooling.
Thus, including Permeability Index the equation of total heat loss becomes:
Where, S = 2.2, the slope of the temperature versus relative humidity of the hygrometric chart.
Fig.1: Hygrometric Chart
Carnot Efficiency: is the highest efficiency a heat engine operating between the two thermal energy reservoirs at temperatures T h and T c can have.
Fig.2: Diagram of Carnot Efficiency
PVDF: PVDF stands for Polyvinylidene Difluoride. When poled, PVDF is a ferroelectric polymer, exhibiting efficient piezoelectric and pyroelectric properties. These characteristics make it useful in sensor and battery applications.
HUMAN METABOLISM AND ENERGY EXPENDED BY HUMANS DURING VARIOUS ACTIVITIES
Activity Energy expended in watts/m3/hr
Sleeping 81
Sitting 116
Eating 128
Driving Car 163
Cricket 194-311
Football 194-467
Cycling 291
Swimming 582
Sprinting 1630
Table 1: Metabolic output in various activities
As can be seen from the table above, human body expends energy in the form of heat. The human body is a tremendous storehouse of energy. Now, two things can be done with this heat energy:
Dissipate it to the environment by engineering fabrics such that they facilitate comfort, or
Harness the energy expended and utilise it to aid motion