矿井降温系统压力交换装置热混合过程研究

Thermal Mixing Process of a Pressure Exchange Device in a Mine Cooling System

矿井地面集中降温系统中使用压力交换装置对高压冷水进行降压,可以达到节能减耗的目的.该装置采用冷热水直接接触的方式进行压力能交换,冷热水的混合会导致冷水出口温度增加,进而增大末端空冷器的热负荷,影响其降温效率.针对这一问题,建立了适用于矿井降温系统的三缸阀控式压力交换装置(TC-ERD)水压缸内冷热水混合的三维计算流体力学(CFD)模型,研究了二次低压回路中温度混合段的形成和演变规律,分析了热水进流流量、冷热水温差操作参数以及水压缸的长度、直径结构参数对冷水出口温升的影响.结果表明:结合径向速度分布规律,水压缸内速度场和热混合场表现出随时间同步发展的特性,入口效应会造成热混合段初始阶段快速发展.出口温升一定时,热水流量的增加和冷热水温差的减小均会增加水压缸的容积利用率.装置处理量固定为30 m^(3)/h时,增大水压缸的长度可在提高其容积利用率的同时降低电磁阀的切换频率.当水压缸的长度为18 m、出口温升为1℃时,容积利用率能达到93.88%,电磁阀切换频率仅为1.5 min^(-1);内径在100~150 mm范围内,水压缸的容积利用率能达到90%以上.

In ground concentrated mine cooling systems,a pressure exchange device is used to reduce cold water pressure,which can save energy and reduce consumption.Direct contact between hot and cold water is used to perform pressure energy exchange in the device.In this process,mixing of hot and cold water leads to temperature rise at the cold water outlet,thus increasing the heat load of the terminal air cooler,finally affecting the cooling efficiency.In view of this problem,a three-dimensional computational fluid dynamics(CFD)model of hot and cold water mix-ing in a three-cylinder energy recovery device(TC-ERD)was established.Meanwhile,the formation and evolution of a temperature mixing section in the secondary low-pressure loop were studied,and the effects of hot waterinlet flow,temperature difference between hot and cold water,and the length and diameter of the cylinder on the outlet temperature rise were analyzed.The results show that the velocity field and thermal mixing field in the cylinder,combined with the radial velocity distribution,show the characteristics of synergistic development with time,and the inlet effect can result in the rapid development of the initial stage of thermal mixing.In a certain outlet temperature rise,both increase in the hot water inlet flow and decrease in the temperature difference between hot and cold water increases the volume utilization ratio of the cylinder.When the handling capacity of the device is 30 m^(3)/h,increasing the length of the cylinder not only improves the volume utilization ratio but also reduces the switching frequency of the electromagnetic valve.If the cylinder length reaches 18 m and the outlet temperature rises 1℃,the volume utili-zation ratio can reach 93.88%,although the switching frequency of the electromagnetic valve is only 1.5 min^(-1).The volume utilization rate can reach above 90% when the diameter is in the range of 100-150 mm.