Agricultural and Biosystems Engineering Publications

Document Type

Article

Publication Date

2009

Journal or Book Title

Bioresource Technology

Volume

100

Issue

17

First Page

3974

Last Page

3981

Research Focus Area(s)

Land and Water Resources Engineering

DOI

10.1016/j.biortech.2008.11.056

Abstract

Thermal properties of compost bulking materials affect temperature and biodegradation during the composting process. Well determined thermal properties of compost feedstocks will therefore contribute to practical thermodynamic approaches. Thermal conductivity, thermal diffusivity, and volumetric heat capacity of 12 compost bulking materials were determined in this study. Thermal properties were determined at varying bulk densities (1, 1.3, 1.7, 2.5, and 5 times uncompacted bulk density), particle sizes (ground and bulk), and water contents (0, 20, 50, 80% of water holding capacity and saturated condition). For the water content at 80% of water holding capacity, saw dust, soil compost blend, beef manure, and turkey litter showed the highest thermal conductivity (K) and volumetric heat capacity (C) (K: 0.12–0.81 W/m °C and C: 1.36–4.08 MJ/m3 °C). Silage showed medium values at the same water content (K: 0.09–0.47 W/m °C andC: 0.93–3.09 MJ/m3 °C). Wheat straw, oat straw, soybean straw, cornstalks, alfalfa hay, and wood shavings produced the lowest K and C values (K: 0.03–0.30 W/m °C and C: 0.26–3.45 MJ/m3 °C). Thermal conductivity and volumetric heat capacity showed a linear relationship with moisture content and bulk density, while thermal diffusivity showed a nonlinear relationship. Since the water, air, and solid materials have their own specific thermal property values, thermal properties of compost bulking materials vary with the rate of those three components by changing water content, bulk density, and particle size. The degree of saturation was used to represent the interaction between volumes of water, air, and solids under the various combinations of moisture content, bulk density, and particle size. The first order regression models developed in this paper represent the relationship between degree of saturation and volumetric heat capacity (r = 0.95–0.99) and thermal conductivity (r = 0.84–0.99) well. Improved knowledge of the thermal properties of compost bulking materials can contribute to improved thermodynamic modeling and heat management of composting processes.

Comments

This article is from Bioresource Technology 100, no. 17 (September 2009): 3974–3981, doi:10.1016/j.biortech.2008.11.056.

Rights

Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.

Language

en

Date Available

January 17, 2013

File Format

application/pdf

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