充注压力对压缩式制冷循环连续制备CO2水合物的影响

摘要

A novel pilot-scale apparatus was designed to continuously produce CO2 hydrate for cool storage. The pre-chilling time, amount of CO2 hydrate formation, hydration ratio, and cool energy of hydrate were analyzed under different CO2 charge pressures. Results showed that CO2 hydrate formed during the rising process of CO2 bubbles in water and cumulated at the gas-liquid interface. The cool storage performance can be improved greatly as the charge pressure increases. Under charge pressure of 4.2 MPa, the pre-chilling time, amount of hydrate formation, hydration ratio and latent cool energy storage are 8 min, 8.44 kg, 75.1% and 4.22 MJ respectively. When the charge pressure is higher than 3.8 MPa, large temperature differences appear between the middle and low parts of reactor, resulted from low thermal conductivity of formed hydrate. Evaporation of liquid CO2 reduces reactor temperature to 0℃ or even lower at late stage of hydrate formation, which is more evident at higher charge pressures.%研制了一台能够连续制备蓄冷用CO2水合物的压缩式循环实验装置，并在该装置上研究了充注压力对水合物的预冷时间、生成质量、水合比例和潜热蓄冷量的影响。实验结果表明水合物在CO2气泡上升过程中生成，在气液界面处堆积。高的充注压力有着更理想的蓄冷特性，当充注压力为4.2 MPa时，预冷时间为8 min、水合物生成质量为8.44 kg、水合比例为75.1%、水合物潜热蓄冷量为4.22 MJ。充注压力为3.8 MPa及以上时，水合物生成量大，水合物阻碍釜内各部分的传热，使釜内中层、下层的温差较大。水合物生成过程后期，水合放热量减少，液体CO2在反应釜内的蒸发吸热效应使得釜内温度继续降低，一直到低于0℃，充注压力越高，此现象越明显。