Table 3.

Experimental conditions and their results

Test	Coded value			Actual value			Porosity (%)
	P	S	A	P	S	A
1	−1	−1	−1	30	75	36	4.51
2	1	−1	−1	35	75	36	2.25
3	−1	1	−1	30	125	36	7.23
4	1	1	−1	35	125	36	2.21
5	−1	−1	1	30	75	48	4.00
6	1	−1	1	35	75	48	2.76
7	−1	1	1	30	125	48	5.13
8	1	1	1	35	125	48	2.38
9	−1.682	0	0	28	100	42	6.47
10	1.682	0	0	37	100	42	1.54
11	0	−1.682	0	33	58	42	3.40
12	0	1.682	0	33	142	42	4.50
13	0	0	−1.682	33	100	32	3.32
14	0	0	1.682	33	100	52	2.21
15	0	0	0	33	100	42	1.70
16	0	0	0	33	100	42	1.82
17	0	0	0	33	100	42	2.10
18	0	0	0	33	100	42	1.70
19	0	0	0	33	100	42	1.70
20	0	0	0	33	100	42	2.41

Abbreviations: A, primary gas flow rate (L/min); P, input power (Kw); S, spraying distance (mm).