Abstract:

With initial water at 26℃ and 15℃ and charge pressure at 3.6-4.2 MPa in the reaction kettle, the hydrates growth and cool storage characteristics of CO₂ hydrates produced in direct-contact way were studied. When initial water was at 15℃ and charge pressure was at 3.6 MPa, precooling time was short, about 11min, and sub-cooled temperature was about 1.3℃ but temperature increment was not obvious at the beginning of growth, and total cool storage average rate and efficiency were about 82.4 kJ·min^-1 and 4.34 respectively. At other temperatures and pressures, there were longer precooling time (between 20-55 min, but decreasing with the increase of charge pressure), higher sub-cooled temperature (at 5.5-9.7℃), rapid growth rate and dense hydrates. Temperature increment was obvious and the largest was at 4.0 MPa; hydrates average growth rate, total storage amount, total cool storage average rate and efficiency increased with the increase of charge pressure, and their maximum values at the experimental initial water temperatures were 77 and 154 g·min^-1, 3.725 and 3.791 MJ, 64.1 and 99.5 kJ·min^-1, 3.14 and 4.91 respectively. The hydrates decomposition releasing cool was a phase change process, and phase transition temperature was generally 10-14℃.

Key words: carbon dioxide, hydrates, compressor, cool storage, direct-contact

摘要：

采用直接接触式水合物反应釜,并在釜内初始水温为26℃和15℃以及充注压力为3.6～4.2 MPa的条件下制备CO₂水合物,研究其生长和蓄冷特性。实验结果表明:在初始水温为15℃、充注压力为3.6 MPa时,预冷时间较短(11 min),水合物开始生长时过冷度约为1.3℃,温升不明显,平均蓄冷速率和平均蓄冷效率分别为82.4 kJ·min^-1和4.34;在其他温压条件下,预冷时间较长(20～55 min),但随充注压力的升高而减小,过冷度较大(5.5～9.7℃),水合物生长迅速且密集,温升明显,并在充注压力为4.0 MPa时温升幅度最大,水合物平均生长速率、总蓄冷量、平均总蓄冷速率和效率随充注压力的升高而变大,其最大值分别为77和154 g·min^-1,3.725和3.791 MJ,64.1和99.5 kJ·min^-1,3.14和 4.91。水合物释冷分解是一个相变过程,相变温度一般在10～14℃。

关键词: 二氧化碳, 水合物, 压缩机, 蓄冷, 直接接触式