Multi-objective Optimization Design and Operation Analysis of a Small Biomass Biogas Combined Cooling Heating and Power System

As a brand new and effective approach to solve biomass resource wastes in China's rural areas,the multi-kilowatt combined cooling heating and power(CCHP)system has extremely great potential for development.A small CCHP system is designed that is driven by biogas fuelled internal-combustion engine on the transient system simulation program platform considering off-design conditions.Its energy flow and operation mode are described and a model for multi-objective optimization of energy,economic and environmental benefits is developed.The particle swarm optimization algorithm with constraint coefficients is used in calculation to realize the equipment capacity and operation parameter optimization.As an example,a case study is made by simulation using the annual cooling,heating and electrical load of a farmland buildings.The operation performance of the optimized system is analyzed and the difference in performance between the biogas CCHP system and the natural gas CCHP system is shown.The results show that,the optimized CCHP system has effectively achieved energy-saving and carbon dioxide emission reduction compared to conventional separate production system,while the cost of investment can also be recovered within the lifetime of system.On the other hand,comparing to natural gas CCHP system,biogas CCHP system has obvious advantages of resource efficiency and carbon dioxide emission reduction.