相变储热型太阳能甲醇重整反应器稳态及动态制氢特性的实验研究

Experimental study of the steady and dynamic efficiencies of a solar methanol steam reforming reactor filled with a phase change material for hydrogen production

太阳能热化学制氢是生产清洁能源的重要途径。针对太阳辐射波动性大,易造成太阳能甲醇重整制氢反应器温度剧烈变化,不利于反应器稳定运行等问题,该文利用相变材料对太阳能甲醇重整制氢反应器进行热管理,以提高反应器的制氢效率和运行平稳性。首先,提出了2种相变储热型热化学反应器结构;其次,实验探究了甲醇重整制氢反应器内部的传热特性及制氢特性,分析了反应器表面热流密度大小对反应器反应产物成分及甲醇转化率的影响规律;然后,研究了相变材料的添加位置对化学反应器稳态制氢效率的影响机制;最后,分析了在非稳态工况下,不同结构的相变储能型热化学反应器甲醇转化率的动态变化情况。结果表明,在反应器制氢特性方面,当反应器表面热流密度达到7 kW·m;时,反应产物中H;占比为0.713,甲醇转化率为0.956,且随着热流密度的增大,热化学反应器的甲醇转化率不断增加。将相变材料分别填充在反应器壳侧和管侧后,稳态工况下,催化剂用量分别减少了66.0%和13.5%,反应器的甲醇转化率仍较高,单位体积催化剂的反应速率更高;动态工况下,热化学反应器的甲醇转化率变化幅度分别缩小了23.4%和13.7%,有效提高了反应器的热惯性,使反应器运行更加平稳。

Solar thermochemical reactors are a promising way to produce clean hydrogen energy. However, the operation of a reactor driven by solar irradiation will fluctuate as the solar irradiation changes. This study analyzed the thermal management of a solar methanol steam reforming reactor for hydrogen production with phase change material(PCM) in the reactor. The analyses considered two latent heat type thermochemical reactors. The thermal and hydrogen production characteristics of these thermochemical reactors were investigated experimentally to show the influence of the heat flux variations. Then, the models were used to study the effect of the phase change material position on the reactor hydrogen production. Finally, the dynamic efficiencies of the latent heat type reactors were compared with that of the original design to show that when the reactor surface heat flux reaches 7 kW/m;, the H;proportion of the production rate is 0.713 and the methanol conversion efficiency is 0.956. Increasing the heat flux increases the methanol conversion efficiency. Adding the PCM in the shell reduces the required catalyst mass by 66.0% while adding the PCM in the tube side reduces the required catalyst mass by 13.5% for steady-state operation while the reactor continues to operate efficiently. For dynamic operation, the methanol conversion efficiency is reduced by 23.4% when the PCM is added to the shell side and by 13.7% when the PCM is added to the tube side while the reactor thermal inertia is improved to cope with sudden heat flux changes.