Page 69 - AJWEP-22-6

Pine sawdust biofuel: Quality and temperature optimization

the dispersion degree of temperature data relative to 3.3. Experimental steps
the mean value. This parameter provides a measurable This study is divided into three main parts: experimental
characterization of both uniformity and dispersion preparation, biomass densification testing, and data
within the temperature field. analysis, as shown in Figure 1.
(i) Experimental preparation: Raw material moisture
3. Materials and methods content and binder addition ratio were adjusted to
target values, followed by sealed storage.
3.1. Experimental materials (ii) Experimental procedure: The forming mold with
The experimental materials consisted of pine sawdust the temperature controller was mounted on the
(particle size <2.5 mm) containing 34–46% cellulose, universal testing machine. Prepared materials were
20–35% hemicellulose, and 26–34% lignin. Molasses loaded into the die for compression molding under
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served as the binder for biomass densification. 30-s pressure maintenance, after which samples
Prior to experimentation, the moisture content of the were extracted and stored at ambient conditions.
biomass material (pine sawdust) required measurement (iii) Post-experiment processing: The relaxation
and adjustment. The moisture content was determined ratio, relaxed density, and impact resistance of
in accordance with the Chinese National Standard GB/T each test group were calculated and averaged to
1927.4-2021, calculated using the following formula in ensure data reliability. Systematic data processing
Equation VI: was performed to evaluate the effects of various
parameters on densified biofuel quality and
m − m temperature field distribution.
W = 1 0 ×100 % (VI)
m 0
4. Results and discussion
Where W is the moisture content (%), m is the mass
of undried sawdust (g), and m is the mass of oven-dried 4.1. Experimental results of densified biofuel
sawdust (g). quality evaluation indicators
The pine sawdust was heated using a moisture Following the experimental steps outlined in Sections
analyzer until a constant mass was achieved. The 2.1 and 3.3, a total of 25 experimental groups were
initial moisture content of the pine sawdust was conducted in this study. Each group was repeated three
determined to be 8.3%. Fine water mist spraying times, and the average values and standard errors were
was employed to adjust the moisture content to the calculated. The experimental results are shown in
required experimental range, followed by sealed Table 1.
storage under ambient conditions. The experimental Experimental results revealed that the maximum
environment was maintained at 15–25℃ with relative relaxed density of 1.066 g/cm was achieved at 50 MPa
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humidity ≤80%. forming pressure with 10% moisture content, 2% binder
addition ratio, and 160°C heating temperature. The
3.2. Experimental equipment minimum relaxation ratio of 1.009 occurred at 10 MPa
The experimental setup comprised a forming system forming pressure with 14% moisture content, 4% binder
and measurement instruments. The forming system addition ratio, and 190°C heating temperature. Optimal
incorporated a mold with an integrated heating coil and impact resistance (97.939%) was obtained at 40 MPa
temperature controller, while measurement instruments forming pressure with 10% moisture content, 4% binder
included a universal testing machine (REGER Model addition ratio, and 150°C heating temperature.
4050; Shenzhen REGER Instrument Co., Ltd., China) With an impact resistance threshold of ≥95%
and an infrared thermometer (FLUKE Ti95; FLUKE indicating satisfactory densification performance, 92%
Test Instruments Co., Ltd., China) with dedicated of the 25 experimental groups produced good-quality
software. densified biofuel. Two exceptions failed to meet the
The heating coil was precisely fitted to the mold’s requirement: (i) at 20 MPa forming pressure with 16%
outer circumference, with temperature regulation moisture content, 2% binder addition ratio, and 150°C
achieved through the controller. The mold assembly, temperature, and (ii) at 10 MPa forming pressure with
installed on the universal testing machine, featured a 16% moisture content, 3% binder addition ratio, and
polytetrafluoroethylene insulation plate. 160°C temperature.

Volume 22 Issue 6 (2025) 63 doi: 10.36922/AJWEP025240195