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Research Papers: Energy From Biomass

# Ventilation of Compost Heating System by Permanent Magnets

[+] Author and Article Information
Harumi Toriyama1

Department of Mechanical Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japantoriyama-harumi@ed.tmu.ac.jp

Yutaka Asako

Department of Mechanical Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan

1

Corresponding author.

J. Energy Resour. Technol 132(4), 041802 (Jan 06, 2011) (8 pages) doi:10.1115/1.4003076 History: Received December 01, 2009; Revised November 15, 2010; Published January 06, 2011; Online January 06, 2011

## Abstract

The effect of a permanent magnet on ventilation of an air duct through compost has been investigated numerically. Some composts yield heat over $60°C$ in the fermentation process. This exothermic reaction produces a considerable amount of heat, which could be a potential heating source. Fermentation reaction requires ventilation, sufficient supply of oxygen, and exhaust of metabolized diamagnetic carbon dioxide gas. Continuous and forced air supply is more efficient rather than the conventional manual turn or stirring as ventilation means. In magneto-aero-dynamics, the magnetizing force acting on a paramagnetic oxygen gas is applied to enhance air flow, heat, and mass transfer. In our research, the enhancement of the air flow through air ducts of various sizes has been numerically investigated by applying a permanent magnet on an air duct. Numerical results show that a permanent magnet enhances the air flow, where we obtained a maximum inlet air velocity $(uin)$ of $6.24×10−2 m/s$. The application of a permanent magnet to an air duct is useful for compost heating system, a promising alternative energy system.

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## Figures

Figure 1

Compost Heating System (CHS)

Figure 2

Analytical model

Figure 3

Inlet air velocity uin as a function of L

Figure 4

Vector plots of (a) magnetic flux density b and (b) gradient of b2 (hM=0.01 m and bT=0.818 T) with single magnet-set

Figure 5

(a) Velocity vectors and contour plots of (b) oxygen mass fraction and (c) pressure for the typical case with single magnet-set

Figure 6

(a) Velocity vectors and contour plots of (b) oxygen mass fraction and (c) pressure for the typical case without magnets

Figure 7

Vector plots of (a) magnetic flux density b and (b) gradient of b2 (hM=0.01 m and bT=0.843 T) with double magnet-sets

Figure 8

(a) Velocity vectors and contour plots of (b) mass fraction of oxygen and (c) pressure for the typical case with double magnet-sets

Figure 9

Effect of distance from compost edge to magnet (LM) on inlet air velocity (uin)

Figure 10

Effect of gap between magnets (hM) and gradient of squared magnetic flux density (∂b2/∂x) as a function of hM on inlet air velocity (uin) in the case of gap between composts (hC), 0.01 m

Figure 11

Effect of gap between stacked composts (hC) on inlet air velocity (uin) for varied gaps between magnets (hC)

Figure 12

Effect of both gap between magnets (hM) and gap between stacked composts (hC) on inlet air velocity (uin) in a special case in which the gap between magnets and the gap between stacked composts are equal

Figure 13

Effect of gap between magnets (hM) on inlet air velocity (uin) for varied gaps between stacked composts (hC)

Figure 14

Effect of thickness of composts (hT) on inlet air velocity (uin)

Figure 15

Effect of cross-sectional area ratio at inlet A1 and at gap between stacked composts A2 on inlet air velocity (uin)

Figure 16

Effect of compost length (LC) on inlet air velocity (uin)

## Errata

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