Simulation and Optimization Study on a Solar Heating for Underground Biogas Digester System
Abstract
A solar heating household biogas digester system (System C) coupled with auxiliary heating source and operational control system is proposed in this paper. The mathematical model and TRNSYS simulation model of the system were established. Firstly, the heating effect of System C was compared with that of System A (without auxiliary heating and temperature control system) and System B (with auxiliary heating system and without temperature control system). Secondly, the influence of the insulation thickness and the collector area on solar fraction was analyzed. The results show that System C could keep the temperature fluctuation range of manure at ±1°C under the setting condition. Besides, the solar fraction of the system C is higher than the system B, the daily energy net production of System C is higher than that of the system A and B with the value of 19.2 kWh. The solar fraction increased with the insulation thickness increased as logarithmic function, which has the most significant growth rate when the collector area is 14 m2. In addition the solar fraction increases with the increase of the collector area in the form of sigmoid function. The research results provide a basis for the optimization design of solar heating household biogas digester system.