Parameter Optimization and Prediction Model of Induction Heating for Large-Diameter Pipe

Table 5

Variance analysis results of orthogonal test of temperatures for pipe’s inner wall.

Sources of Variance	Degree of Freedom	Sum of Squares	Mean Square	F	Contribution Rate (%)	Significance
Current Frequency	4	0.478	0.12	37.77	25.78
Current Density	4	0.589	0.147	46.47	31.72
Air Gap	4	0.751	0.188	59.26	40.45
Error	12	0.038	0.003	--	2.05
Total	24	1.856	0.458	--	100

Note: indicates that the difference is significant; indicates that the difference is extremely significant.