DESIGN AND SIZING OF A DIGESTER COUPLED TO AN AIR SOLAR COLLECTOR - Energy Research Developments: Tidal Energy, Energy Efficiency and Solar Energy - page 147

Chapter 6

D ESIGN AND S IZING OF A D IGESTER
C OUPLED TO AN A IR S OLAR C OLLECTOR

S. Igoud 1 , N. Said 1 and R. Benelmir 2
1 Centre de Développement des Energies Renouvelables, Bouzaréah, Alger
2 LEMTA (umr 7563 CNRS-UHP-INPL), ESSTIN 2 Rue Jean Lamour,
Vandoeuvre, France

Abstract

The bio-mechanization of organic waste offers energetic, economic, environmental and social
advantages which harmoniously integrate it in the concept of continuous development.
Among the principal recovered products, we are interested in agricultural biogas whose
production was carried out successfully through the mechanization of cows dungs in an
experimental digester of 800 liters. Following these first experiments, we present a feasibility
study for the realization of a family digester of 15 m³ which can produce between 68.4 and
185.4 m³ of biogas according to the digestion temperature. In order to improve the efficiency
of biogas production, we heat the digestion substrate up to a temperature of 40°C by means of
an air low temperature heating system using 20 m² of solar collectors. The proposed digester
will produce monthly the energy equivalent of three standard cans of butane gas (13 kg/can)
and avoid the use of an equivalent of 927 kg of heating wood.

Nomenclature

I :

solar heat flux (W/m 2 )

()

τα : transmission-adsorption coefficient

U :

heat losses coefficient (W/m2 K)

T :

ambient air temperature (K)

F R , F': correction coefficients

T :

fluid temperature (K)

T :

stone temperature (K)