金属氢化物及其热驱动型制冷系统的设计与实验研究

DESIGN AND EXPERIMENTAL RESEARCH ON MEATL HYDRIDES AND ITS HEAT DRIVEN REFRIGERATION SYSTEMS

制备了设计工作温度为150-200℃/20-50℃/0℃的金属氢化物合金工质对LaNi4.61Mn0.26Al0.13/La0.6Y0.4Ni4.8Mn0.2,测定了合金对在各温度下的吸氢性能,作出了Van’t-Hoff图,并推导了合金反应焓、反应熵和理论循环特性;设计了反应床,实测高温反应床的导热系数;搭建了间歇制冷的热驱动金属氢化物循环系统,在150℃/30℃/0℃工况下测定了系统的循环特性和制冷性能。实验结果表明,合金工质的平台斜率和滞后系数小、吸氢动力性能较好,低温合金的吸氢反应焓值达-27.1kJ/molH2;设计反应床的导热系数约为1.3W/(m.K),较合金粉末的导热系数有了很大提高,但仍未达到实用要求;制冷系统在设定工况下完成了循环,获得了84.6W的平均制冷功率、COP达0.26,从而验证了金属氢化物制冷系统的可行性。

Adopting hydrogen as refrigerant, driven by low grade energy such as solar energy, heat driven metal hydride （MH） refrigeration systems have their potentials in energy conservation and environmental protection. The MH pair LaNi4.61Mn0.26Al0.13/La0.6Y0.4Ni4.8Mn0.2 working at 150-200℃,20-50℃/0℃ were prepared, their hydrogen absorption characteristics were measured, the Van＇ t-Hoff diagram was drawn, and their reaction enthalpy, reaction entropy as well as theoretical cycling performance were deducted. Reaction beds were designed and tested for heat conduction coefficient. A heat driven MH intermittent refrigeration system was set up, then cycle characteristics as well as refrigeration performance were measured at 150℃/30℃/0℃. The test results show that the MH working pair has flat plateau slope, small hysteresis and better reaction dynamics; the low temperature MH reaction enthalpy reaches -27. lkJ/molH2. The heat conduction coefficient of the reaction beds is merely 1.3W/（m· K）, which is greatly improved compared with MH powder yet hasn＇t met practical requirement. Several refrigeration cycles were finished under designed work conditions, an average cooling power of 84.6W was achieved with COP being 0.26, which confirms the feasibility of MH refrigeration systems.