To express the looseness of cotton on the basis of the porosity of sample, theoretical formula were developed as formula (2) from D'Arcy's law and Kozeny's equation on laminar air flow through the sample of cotton. In the formula (2)
c; Kozeny's constant, λ; porosity of sample,
s; specific surface of material,
w; weight of sample,
q; air flow rate passed through sample and
p; pressure difference between front and back of the sample.
By using the apparatus showed in Fig. I and varying the weights and porosities of samples from three diffrent kinds of cotton, some characteristic results were obtained as follows:
(1) If the weight and porosity of one kind of sample are eqaul, values of
q/
p are constant.
(2) If the weights of the same sample are equal, values of
q/
p are related to λ
x.
(3) In the same kind of material, values of
wq/
p are correlated to λ
x.
(4) When the porosity of one sample is equal to that of another of different kinds of materials, values of
wq/
p are proportional to 1/
s2.
(5) Irrespective of the kinds of materials, values of
s2wq/
p in each sample are related to λ
x only.
(6) The curve between λ
x and 1/
c plotted from experimental results and by the formula (1) is nearly equal to E. Lord's curve.
(7)
C is expressed as the function of
s2wq/
p.
Then, the experimental result betweee
C and
s2wq/
p is shown by formula (10). From (2) and (10), λ
x and the looseness of cotton
Ox are shown by formula (12), (13).
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