基于生物质气化的内燃机-吸收式制冷联合冷热电系统分析

Performance analysis of a combined cooling heating and power system with ICE and absorption chiller based on biomass gasification

可再生能源发电技术是解决能源短缺和环境污染问题的有效途径之一,本文提出了基于生物质气化的联合冷热电(combined cooling heating and power,CCHP)系统。该系统以生物质气化气为燃料,通过内燃机(internal combustion engine,ICE)发电。为提高燃料的整体利用水平,对内燃机排气的低温余热由吸收式制冷及热水系统进行回收。气化炉模型考虑了热解、还原及氧化反应,内燃机模型考虑了气缸内压力、温度随转角的变化。对于单效溴化锂–水吸收式制冷单元,研究了发生器和吸收器工作温度对制冷量的影响。研究结果表明:采用气化气为燃料的内燃机热效率可达37%。增大内燃机转速使系统电效率提高2%,整体冷热电效率为47%;压缩比的增大使系统电效率提高1%,冷热电效率几乎不变。降低吸收器工作温度和提高发生器工作温度可增大制冷量并提高制冷性能,效能系数可以达到77%。整个联合冷热电系统的电效率为22%,冷热电联合效率可以达到48%,投资回收期为3~4 a。

Power generation technology by renewable energy is one of the effective ways to solve the problems of energy shortage and environmental pollution.This paper proposes a combined cooling,heating and power(CCHP)system based on biomass gasification.The syngas is used as fuel and the power is generated by internal combustion engine(ICE).In order to improve the level of fuel utilization,the low temperature waste heat of ICE is recovered by absorption refrigeration and heat recovery unit to supply domestic hot water.The gasification furnace model has taken account of pyrolysis,reduction and oxidation reactions,and the internal combustion engine model has taken account of the pressure and temperature in the cylinder changing with the rotation angle.For the single-effect lithium bromide-water absorption refrigeration unit,the influence of the working temperature of the generator and absorber on the refrigeration capacity is studied.The results show that the thermal efficiency of 37%could be achieved by using syngas as fuel in ICE.The electrical efficiency is increased by 2%and total efficiency is 47%as the engine rotation speed increases.The higher compression ratio of engine improves the production of power of the CCHP system by 1%,while the efficiency of cold,heat and electricity is almost constant.Reducing the working temperature of absorber and increasing the working temperature of generator can increase the refrigeration capacity and improve the refrigeration performance,and the efficiency coefficient can reach 77%.Total CCHP can achieve an electrical efficiency of 22%.The combined efficiency of cooling,heating and power can reach 48%.The payback period is 3~4 years.