高压氢充放过程中的热物理学机制与热转换规律研究

For increasing the driving range of fuel cell vehicle (FCV), compressed hydrogen with 70 MPa is widely accept as main form of on-board hydrogen storage system. If the filling conditions for 70MPa cylinder are not selected well, temperature rise of hydrogen gas (due to compress effects and etc.) will rise significantly. If inner gas temperature exceeds 85oC, it may cause the degradation of carbon fiber reinforce polymer (CFRP), which may cause risk of hydrogen storage system. Usually extra procedures are required for pre-cooling the filling gas, and adopting cryogenic refrigerating system is one of the most common ways. But that needs large amount of equipment investment and extra energy cost, which greatly reduces the economical efficiency of on-board hydrogen storage system. In this project, filling process of hydrogen refueling station is investigated. Through theoretical, numerical and experimental methods, mechanisms of heat production and transfer during the filling process are explored. The main reason of temperature rise is obtained through analyzing the effects of compression, throttling and kinetic energy - heat transfer phenomenon. Based on it, optimal filling procedures and control methods for different conditions are obtained. The obtained process provides a new energy-efficient filling method for hydrogen refueling station, which can reduce extra energy cost and increase the efficiency of hydrogen energy by decreasing refrigerating level or even removing refrigerating devices.

为提高燃料电池车的续驶里程，采用70MPa压力的车载储氢成为一种趋势。但对70MPa气瓶，在一定充装时间要求下如不选择合理的充装条件，由于气体压缩效应等因素会造成气瓶内氢气温度的快速上升，如温度超过85oC便很可能导致车载气瓶壁面复合材料间的剥离失效，进而影响到车载储氢系统的安全。因此往往需要通过其它方式降低氢气的温度，其中最直接的方法就是安装低温冷却装置对氢气进行预冷。但预冷系统需要大量的固定设备投资及额外的能量消耗，这很大程度上降低了车载高压储氢的经济性。本项目以加氢站加氢系统为研究对象，以理论研究、数值仿真和实验研究为手段，探讨高压氢气充放过程中的热物理学机制与热转换规律，针对压缩效应、节流效应、动能-热能转换等产热机制，发现造成温升的主要因素，并据此制定通过优化换热控制温升的策略，以期建立可减少预冷乃至免除预冷的充氢工艺理论，以达到降低加注过程能耗、提高氢能利用效率的目的。

相对于纯电动汽车，氢燃料电池汽车具有续航里程大、加注燃料快捷、能源转换效率高等优点。为提高燃料电池车的续驶里程，采用70MPa压力的车载储氢成为一种趋势。但对70MPa气瓶，在一定充装时间要求下如不选择合理的充装条件，由于气体压缩效应等因素会造成气瓶内氢气温度的快速上升，如温度超过85ºC便很可能导致车载气瓶壁面复合材料间的剥离失效，进而影响到车载储氢系统的安全。因此往往需要通过其它方式降低氢气的温度，其中最直接的方法就是安装低温冷却装置对氢气进行预冷。但传统的预冷方式需要大量的固定设备投资及额外的能量消耗，这很大程度上降低了车载高压储氢的经济性。本项目以加氢站加氢系统为研究对象，以理论研究、数值仿真和实验研究为手段，探讨了高压氢气充放过程中的热物理学机制与热转换规律，针对压缩效应、节流效应、动能-热能转换等产热机制，发现造成温升的主要因素，并据此提出了通过优化换热控制温升的方法以及制定了以减少预冷能耗为目的的优化加注控制策略，建立了可减少预冷量乃至免除预冷的充氢工艺理论，为降低加注过程能耗、提高氢能利用效率技术的开发奠定了理论基础。