Self-heating and drying in two-dimensional bagasse piles. (English) Zbl 0998.80003
Summary: This paper describes a two-dimensional model for self-heating and changes in water levels in bagasse piles of constant rectangular or triangular cross section. (Bagasse is the residue, mainly cellulose, that remains after sugar has been extracted from sugar-cane.) After milling, the bagasse has almost \(50\%\) water by weight, as hot water is used to remove the last of the sugar. The bagasse can be used as fuel in electrical power stations, but needs to be dried out before use.
This paper discusses the way in which the drying out of a pile depends on the ambient conditions, and the shape and size of the pile. Accordingly, the energy equation, and equations for liquid water, water vapour and oxygen are solved numerically using the method of lines. The equations include terms describing heat conduction, diffusion of water vapour and oxygen, condensation and evaporation and an Arrhenius self-heating term. In addition, recent measurements show that there is also self-heating due to the presence of water in the bagasse, with a maximum effect near \(60^\circ\) C, which is modelled by a modified Arrhenius expression.
The local maximum in the heat release curve for the problem leads to approximate steady-state behaviour on short time scales that eventually is lost as the pile dries out. This interesting physical behaviour motivates an approximate analytical model for the rate at which liquid water is reduced in the pile. Analytical and numerical results are presented for a variety of pile configurations and some fairly general conclusions are drawn.
This paper discusses the way in which the drying out of a pile depends on the ambient conditions, and the shape and size of the pile. Accordingly, the energy equation, and equations for liquid water, water vapour and oxygen are solved numerically using the method of lines. The equations include terms describing heat conduction, diffusion of water vapour and oxygen, condensation and evaporation and an Arrhenius self-heating term. In addition, recent measurements show that there is also self-heating due to the presence of water in the bagasse, with a maximum effect near \(60^\circ\) C, which is modelled by a modified Arrhenius expression.
The local maximum in the heat release curve for the problem leads to approximate steady-state behaviour on short time scales that eventually is lost as the pile dries out. This interesting physical behaviour motivates an approximate analytical model for the rate at which liquid water is reduced in the pile. Analytical and numerical results are presented for a variety of pile configurations and some fairly general conclusions are drawn.
MSC:
| 80A20 | Heat and mass transfer, heat flow (MSC2010) |
| 80A99 | Thermodynamics and heat transfer |
| 80M25 | Other numerical methods (thermodynamics) (MSC2010) |
References:
| [1] | Bowes P C, Self heating: Evaluating and Controlling the Hazards (1984) |
| [2] | Dixon T, Proc. Aust. Sugar Cane Tech. 10 pp 53– (1988) |
| [3] | Forbes L K, Proc. R. Soc. 454 pp 2667– (1998) · Zbl 0915.65129 · doi:10.1098/rspa.1998.0275 |
| [4] | Graham-Eagle J, IMA J. Appl. Math. 54 pp 1– (1995) · Zbl 0836.35073 · doi:10.1093/imamat/54.1.1 |
| [5] | Gray B F, J. Chem. Tech. Biotechnol. 34 pp 453– (1984) · doi:10.1002/jctb.5040340808 |
| [6] | Gray, B F, Sexton, M J, Halliburton, B and Macaskill, C. 2001. ”Wetting induced ignition in cellulosic materials”. submitted |
| [7] | Gray B F, Combust. Flame 79 pp 2– (1990) · doi:10.1016/0010-2180(90)90084-5 |
| [8] | Halliburton, B.PhD ThesisSchool of Chemistry, Macquarie University, in preparation |
| [9] | Macaskill C, ANZIAM J. 43 pp 13– (2001) |
| [10] | Sexton M J, Proc. CTAC99, ANZIAM J. 42 pp C1283– (2000) · doi:10.21914/anziamj.v42i0.646 |
| [11] | Sisson R A, IMA J. Appl. Math. 49 pp 273– (1992) · Zbl 0773.35032 · doi:10.1093/imamat/49.3.273 |
| [12] | Sisson R A, IMA J. Appl. Math. 50 pp 285– (1993) · Zbl 0781.35032 · doi:10.1093/imamat/50.3.285 |
This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. In some cases that data have been complemented/enhanced by data from zbMATH Open. This attempts to reflect the references listed in the original paper as accurately as possible without claiming completeness or a perfect matching.
