新型两级开式吸收式热泵系统性能

A novel double-stage open absorption heat pump system

烘干过程广泛应用于造纸、木材、食品加工、化工等行业,并排放大量湿空气,造成能量极大浪费、能源利用效率极低等问题。提出了一种新型两级开式吸收热泵系统,用于回收烘干排气的潜热,并输出高温蒸汽;高温蒸汽直接回用于烘干过程,大大节约了能源并提高了能源利用效率。新系统也可用于回收其他来源的湿空气的潜热。结合造纸烘干过程,对新系统建立了热力学模型以分析其性能,并与传统闭式吸收式热泵系统性能进行了比较。结果表明新系统可产生满足烘干需求的高温蒸汽,回收烘干排气约50%的废热,降低造纸烘干过程能耗达60%以上。在给定工况下新系统的COP根据发生热源温度的不同可达1.204~1.995,而闭式热泵系统的COP最高仅可达1.409。

Considerable amount of energy provided for drying processes is rejected to the environment with the moisture in the discharged moist gas,which results in a significant energy inefficiency of the drying processes.In this paper,a new double-stage open absorption heat pump system has been proposed to recover the latent heat of the moist gas and produce high-temperature output,especially in the forms of steam,which is more practical for industrial application and more easier to store.A mathematical model was constructed to analyze the performance of the system.It was demonstrated that the secondary generator pressure pg2 had to be optimized to get a high energy-saving rate(RES),but heat recovery rate(η)of moist gas decreased with the increase of pg2.The optimized pg2 was 81.78 kPa when pressure of driven steam supplied to generators(pdsg)supplied to generators was above 750 kPa.Theηincreased with the increase of pdsg,and the highestηcould achieve 49.5%.It was also found that the RES achieved from16.47%to 60.3% when pdsg was from 550 to 850kPa,which means that when 1kg paper product was produced 60% of energy consumption could be saved.