Investigation on the viability of using Biocomposite materials for the construction of cost-effective Biogas plant
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Date
2023-02
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G. B. Pant University of Agriculture & Technology, Pantnagar-263145
Abstract
Utilizing natural fiber-reinforced composite materials in the construction of biogas plants was
the primary focus of the current investigation. This was accomplished with the objective of enhancing
the thermal stability of biogas plants and allowing them to operate continuously throughout the year.
Additionally, the investigation aimed to reduce the environmental dumping problems that are caused by
synthetic fiber-reinforced biogas digesters and plastic digesters over the course of their lifetimes.
The surface roughness of selected natural fibers improved by the alkaline treatment. According
to an ultimate analysis, physically activated biochar (PAC) at 600 °C and chemically activated biochar
(CAC) at H2SO4 impregnated 450 °C both have high carbon contents, but PAC has 82.16 percent and
CAC 57.40 percent. As the fiber content increases by 3 to 9 percent in the loose fiber-reinforced
biocomposites, the density, compressive strength, thermal conductivity, and diffusivity decrease with
fiber content whereas the percentage of water absorption, tensile strength, and flexural strength increase
with the increased fiber content (3 to 9 percent). In contrast to the loose fiber reinforced composites, the
weaved bamboo fiber sheet laminated composites’ density and thermal properties increase with the
increase of the number of layers of sheets whereas the tensile strength and flexural strength decreased
by increasing the number of layers (2, 4 and 6 layers). A significant difference was observed in each
treatment for strength parameters and thermal parameters at 5 percent level significance and a p-value
less than 0.05 was achieved in all cases of pair-wise comparison, suggesting that at a 95 percent
confidence level, the reinforced fiber and reinforced charcoal composites exhibited good mechanical
and thermal properties. Composite resistance test at 3600 h for biocomposites shows a beneficial
impact by ecological zones (digested slurry, water, and soil) and no surface degradation for all selected
biocomposites. The resistance test (3600 h) increased biocomposites' compressive strength. Thermal
degradation tests show that polyester fiber-reinforced biocomposites are more stable than epoxy ones.
PR/Bm/9 (374 °C) was the most stable. At finite element analysis, the 5mm thickness digester exhibits
good thermal and stress distribution. The polyester resin reinforced with 4 layers of weaved bamboo
fiber sheet laminated composite was optimized for biogas digester construction and with the following
optimal properties: 5 mm thickness, 1.22 g/cc density, 48.54 MPa tensile strength, 10.98 MPa flexural
strength, 0.11 w/mk thermal conductivity, and 646 j/kg.k specific heat.
Biocomposite cylindrical biogas digester designed for 0.1 m3 capacity with a total volume of
the digester was 0.372 m3, height: diameter ratio of 714 mm, and 5 mm thickness. The inlet and outlet
angles were 45 and 60 degrees. The hydrostatic pressure inside the digester was 0.0147 MPa and the
earth pressure on the digester was 0.001152 MPa at saturated clay soil conditions. The biogas digester
was evaluated in the winter season at the psychrophilic range (10 to 29 °C) by dairy cattle manure, and
the findings showed that the internal temperature was steady compared to the ambient temperatures,
producing an average of 0.00223 m3 of biogas per day at a gas pressure of 12 cm of the water column.
During the 55-day digestion period, a total of 0.12 m3 of biogas was produced. The optimized
biocomposite material act as an insulation material for the biogas digester. The total cost of metal mold
was Rs.5767.68 /- and the total cost of biocomposite biogas digester was Rs.16465.89 /-. However,
before being recommended, the long-term performance of the proposed biocomposite biogas plant must
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Theses of Ph.D