低品位热驱动CO_(2)-[emim][Tf_(2)N]吸收-喷射冷热电联供系统性能研究

Performance study on CO_(2)-[emim][Tf_(2)N]absorption-ejector combined cooling,heating and power system driven by the low-grade energy

传统的吸收式冷热电联供系统普遍存在制冷量小、制冷效率低等问题。对此,在能量梯级利用及循环制冷原理的基础上,提出一种使用CO_2结合1-乙基-3-甲基咪唑双三氟甲磺酰亚胺盐(CO_2-[emim][Tf2N])的吸收-喷射式冷热电联供(CCHP)系统。固定系统的稳态性条件,阐述了CCHP系统的工作原理,组建系统的热力学模型,采用热效率ηthm及?效率ηexg评估关键热力学参数对系统性能影响。结果表明:增加系统的蒸发温度及系统高压侧压力均可有效提升系统性能;蒸发温度在3~8℃变化时,ηthm、ηexg均有上升趋势;高压侧压力在9~12 MPa变化时,ηexg由0.37提升至0.44;但系统膨胀机压力增大时系统的性能会出现下降趋势,膨胀机压力在7.4~9.0 MPa变化时,ηthm由0.47降至0.39,ηexg由0.47降至0.43;在给定模拟工况下,喷射-CCHP系统Ccop高于传统CCHP系统的Ccop。

In the view of the defects of the traditional absorption combined cooling,heating and power system(CCHP)system,such as low refrigeration capacity and low refrigeration efficiency,a new absorption-ejector CCHP system is developed using CO2-[emim][Tf2N]based on the energy cascade utilization and principle of recycle refrigeration.The steady-state conditions of the system are fixed,the corresponding working principle of the CCHP system is elaborated,the thermodynamic model of the system is set up and the influence of the key thermodynamic parameters on the system performance is evaluated by using the thermal efficiency hthm and the exergy efficiency hexg.The results show that the increasing the evaporation temperature of the system and the pressure of the high pressure side of the system can effectively improve the system performance.hthm and hexg have the upgrade trend when evaporation temperature ranges from 3℃to 8℃.hexg increases from 0.37 to 0.44 when the pressure of the high pressure side ranges 9 MPa to 12 MPa.However,when the pressure of expander increases,the system performance shows a downward trend.hthm decreases from 0.47 to 0.39 and hexg decreases from 0.47 to 0.43 when the pressure of expander ranges from 7.4 MPa to 9.0 MPa.Besides,under the given simulated conditions,the Ccop of the CCHP with ejector is higher than that of the traditional CCHP with no-ejector.