Characterization and modelling of the heat transfers in a pilot-scale reactor during composting under forced aeration

Journal Article · Fri Jun 15 00:00:00 EDT 2012 · Waste Management

DOI:https://doi.org/10.1016/j.wasman.2011.12.028· OSTI ID:21612981

Petiot, C; Benoist, J C; Druilhe, C ^[1]

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1. Irstea/Cemagref, UR GERE, 17 Avenue de Cucille, CS 64427, F-35044 Rennes (France)

The paper focused on the modelling of the heat transfers during composting in a pilot-scale reactor under forced aeration. The model took into account the heat production and the transfers by evaporation, convection between material and gas crossing the material, conduction and surface convection between gas and material in bottom and upper parts of the reactor. The model was adjusted thanks to the measurements practised during fifteen composting experiments in which five organic wastes were, each, composted under three constant aeration rates. Heat production was considered proportional to oxygen consumption rate and the enthalpy per mole oxygen consumed was assumed constant. The convective heat transfer coefficients were determined on basis of the continuous measurements of the temperatures of both the lid and the bottom part of the reactor. The model allowed a satisfying prediction of the temperature of the composting material. In most cases, the mean absolute discard between the experimental and the simulated temperatures was inferior to 2.5 Degree-Sign C and the peaks of temperature occurred with less than 8 h delay. For the half of the experiments the temperature discard between the simulated peak and the experimental one was inferior to 5 Degree-Sign C. On basis of the calculation of a stoichiometric production of water through oxidation of the biodegradable organic matter, the simulation of water going out from material as vapour also allowed a rather satisfying prediction of the mass of water in final mixture. The influence of the aeration rate on every type of heat loss was characterized. Finally, the model was used to evaluate the impacts on material temperature caused by the change of the insulation thickness, the ambient temperature, take the lid away, the increase or the decrease of the mass of waste to compost.

• OSTI ID: 21612981
• Journal Information: Waste Management, Vol. 32, Issue 6; Other Information: DOI: 10.1016/j.wasman.2011.12.028; PII: S0956-053X(12)00004-9; Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
AERATION
AMBIENT TEMPERATURE
COMPOST
COMPOSTING
CONSUMPTION RATES
CONVECTION
ENTHALPY
EVAPORATION
HEAT LOSSES
HEAT PRODUCTION
ORGANIC MATTER
OXIDATION
OXYGEN
SIMULATION
STOICHIOMETRY
VAPORS
WATER
CHEMICAL REACTIONS
CONVERSION
ELEMENTS
ENERGY CONVERSION
ENERGY LOSSES
ENERGY TRANSFER
FLUIDS
GASES
HEAT TRANSFER
HYDROGEN COMPOUNDS
LOSSES
MANAGEMENT
MASS TRANSFER
MATTER
NONMETALS
ORGANIC WASTES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PROCESSING
THERMODYNAMIC PROPERTIES
WASTE MANAGEMENT
WASTE PROCESSING
WASTES