Biomass Gasification/Solar Heat Collection Hybrid Energy System Simulation Modeling And Thermoeconomic Analysis

In recent years,with the rapid growth of fossil fuel consumption and the deteriorating environmental problems,green and environmentally friendly and abundant renewable energy resources have attracted widespread attention.Hybrid energy systems based on renewable resources such as biomass and solar energy have a high Potential application value.According to the daily energy demand of a small residential building in Qingzhou City,Shandong Province,as well as the local climate and renewable resources,this study developed a biomass gasification/solar heat collection hybrid energy supply system to increase the Renewable energy ratio of daily energy supply of the small residential building.This solution couid effectively solves the energy supply problems of residents’refrigeration,heating,domestic gas and domestic hot water,and couid adjust the energy structure,reduce environmental pollution,and is more in line with my country’s current strategic requirements for building a resource-saving,environment-friendly socialist harmonious society.This research first introduced the various subsystems of the biomass gasification/solar heat collection hybrid energy system in detail,Subsystems included solar heat collection system,biomass gasification system,biomass gasification system,absorption refrigeration system.The mathematical model of each subsystem was established,the system control function was determined,and the heat balance and energy balance equation of the overall system were obtained.The thermodynamic indicators required for the evaluation of the system’s technical performance were put forward,and the feasibility of the system’s operation was verified by selecting the operating conditions from 8:00 to 17:00 on a typical day.Then,the Aspen Plus process simulation software was used to conduct a steady-state simulation of the hybrid system,which verified the rationality of the model simulation results.The model was used to study the effects of roasting temperature,water vapor/biomass mass ratio（S/B）on gasification products,and the effects of heat source water temperature,condensation temperature,evaporation temperature and dilute solution flow rate on the performance of absorption refrigeration units.The results showed that as the torrefaction temperature increases,the volume fractions of CO and CH₄increase,and the volume fractions of H₂and CO₂decrease.The calorific value of biomass raw materials increases from 12.8 MJ/m³to 20.1 MJ/m³,and the tar content decreases from 40.2 g/Nm³to 27.2 g/Nm³.As S/B increases,the volume fractions of H₂and CO₂increase,and the volume fractions of CO and CH₄decrease.The calorific value of biomass gasification gas decreases from 11.6 MJ·m³to 9.5 MJ·m³,and the tar content does not change significantly;The best heat source water temperature range was 88-90℃,the evaporation temperature was 5-11℃,and the condensation temperature was 30℃;the flow rate of the dilute lithium bromide solution should be in the range of 2000 kg/h-2200 kg/h.The thermodynamic parameters of each stream in the system were obtained by running the simulation model.Based on the exergy economy theory,the system was analyzed with thermoeconomics,and the equipment utilization efficiency and exergy loss of the hybrid energy system were analyzed more clearly.In the biomass gasification system,biomass gasifiers accounted for 46.67%of the total exergy loss,and gas boilers accounted for23.39%of the total exergy loss,both of which were caused by excessive irreversible losses during the chemical combustion process;In the absorption refrigeration system,the generator’s largest exergy loss was not only related to the properties of the lithium bromide solution,but also related to the heat transfer temperature difference between the heat source water and the lithium bromide solution.Through the sensitivity analysis of changing parameters,which explained the impact of biomass prices and different baking temperatures on the unit exergy cost of system products,and provided guidance for further optimization and transformation.Finally,the economic benefits,energy-saving benefits and environmental protection benefits of the hybrid energy system were analyzed.The estimated annual income was518275.2 yuan,and the payback period was 2.89 years.The annual system can save 1.05×10⁶MJ of heat,and the carbon dioxide emission reduction within the life span was 550,595.13 tons.