Diseño de un Sistema Solar para Suministrar Energía a un Digestor

Abstract

In this work, the development of the methodology to the design of a Digester-SCA system is shown. The system was designed to raise the efficiency of the biogas generation process. The water heating solar system (SSCA) provides the necessary energy to keep the temperature into the thermophilic range (40 to 60 °C). It begins with a description of the main features of the solar energy and the biogas generation systems (SGB). The factors that have an influence on solar energy, on his availability and in the generating of biogas as well as on solid waste urban availability are determined. Then, the parameters of design and energy required are described. Once obtained the necessary energy to rise and keep the mix in the range of 55°C, the selection of the solar mix heating system is made using the f method. This method was developed by Klein in the University of Wisconsin, US, to determine the energy fraction supplied to the designed solar energy heating system [Klein, 1977]. To determine the f fraction, the SOLAR program [Barbosa, 1999] is used; this program determines the theoricalf fraction of the solar energy, the heating load, the storage capacity of water by collector area and the collector area. Finally the computer program which was used is shown to make easier the design of the SGB. The program determines the digester dimensions, the necessary energy to maintain the temperature, the homogenization system of the mixture as well as the biogas theorical generation in pressure and temperature normal conditions. The program has two options: option 1; entering the quantity of RSU to convert in biogas (kg) and option 2; entering the volume of the digester obtained (m3) when there is one. The program was validates with the reported data from the experimental tests made at Centro Interdisciplinario de Investigaciones y EstudiossobreMedioAmbiente y Desarrollo, CIIEMAD, by A. Castro (2010). The results obtained allow determining the energy requirements of the digester to design the SSCA and the theorical quantity of methane in normal conditions. The results of theorical biogas production are into the values obtained from experimental tests made at CIIEMAD. The heating load calculated with the program was checked with the results obtained analytically with a difference of 0.33%.