Processes 2021 , 9 , 1117
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Step5: It was sent to the moisture rapid analyzer (MB120, Aohaus Changzhou Co., Ltd., Jiangsu, China) to determine the drying curve (Figure 3), obtain and record the test data of paper moisture ( u ) changing with time( t ).
Figure3. Measurement and analysis of drying curve in laboratory.
The experimental model, Gaussian model and Fourier model were used to fit the test data. The fitting curves were shown in Figure 3, and the model structure and model parameter results are shown in Table 2. The Gaussian model has the best simulation effect andR 2 value is 0.996. Therefore, the Gaussin model is used to estimate the subsequent evaporation heat. u = 2.563 · exp − t + 78.25 445.6 2 (11)
Table2. Fitting results of drying curve data in laboratory.
R 2
Models
Model Structure
Model Parameter
a=2.87; b= − 0.00322 a=2.563; b= − 78.25; c=445.6 a=1.59; b=0.953; c= − 0.00282; d= − 1.27
Experimental Model
u = a · exp ( b · t )
0.953
u = a · exp − t − b c 2
Gaussian Model
0.996
Fourier Model
u = a + b · cos ( c · t )+ d · sin ( c · t )
0.995
Figure 4 shows a comparison of calculation results of the evaporation heat between the new and old methods in laboratory. The results calculated by the new method based on the test of drying curve are similar to the old method based on the measurement of the sorption isotherm. The MRE (average relative error) was calculated as 0.81% by Equation (12).
N ∑ i = 1
Δ H 1, i − Δ H 2, i
1 N
Δ H 2, i
× 100%
(12)
MRE =
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