液氮冻结帷幕水热耦合温度场数值分析及应用

Numerical Analysis on Water-Thermal Coupling Temperature Field of Liquid Nitrogen Freezing Wall and Its Application

液氮冻结温度场是具有相变、水分迁移的瞬态热传导问题。基于水热耦合理论建立了液氮冻结的温度场数学模型,获得了液氮冻结帷幕厚度和平均温度随时间发展均呈对数规律分布;冻结管组内连接方式对冻结效果有较大影响:三管串联形成的冻结帷幕厚度最不均匀、平均温度也最高,单管供回液连接方式冻结效果最好;但从经济效益和冻结效果综合因素考虑,双管串联冻结方式宜优先采用。研究成果完善了盾构进洞液氮冻结温度场理论和工艺。

Temperature field of liquid nitrogen freezing is a problem of thermal conductivity with both phase change and water transfer. Based on water and thermal coupling theory, a mathematical model of temperature field of liquid nitrogen freezing was acquired. The relationship between the depth and average temperature of liquid nitrogen freezing wall and freezing time conforms to logarithmic distribution. The way of connection of freezing group has much effect on freezing quality, with triple tubes in series connection, the depth of freezing wall is the most non-uniform, and the average temperature is the highest. Single connection for freezing tube qives the best effect. However, consid- ering both economic benefits and freezing effect, double tubes in series connection should be adopted at first. There- fore, the procedure and theory of temperature field for liquid nitrogen freezing were developed.