几何因素对微通道脉管制冷性能影响的分子动力学分析

Molecular Dynamics Analysis of Influence of Geometric Factors on Microchannel Pulse Tube Refrigerationn Performance

运用分子动力学模拟方法,研究微通道脉管内部微观的制冷效应,讨论了微通道脉管几何因素对制冷性能的影响。建立了矩形截面微通道脉管模型,模拟微通道脉管内工质He气体的充放气过程,获得通道内部轴向压力、速度、温度的分布。分析了脉管固有尺寸对微通道脉管冷热端温度的影响。研究表明:模型1B-2L中随着过程进行,压力梯度逐步减小,最终达到平衡,同时会出现略微的逆向梯度现象;原子轴向速度在200 ps时最大为434 m/s,随后轴向速度峰值向管内移动并递减。维持模型宽度恒定增加长度或者维持模型长度恒定增加宽度,热端温度均有所上升,冷端温度有所下降。长度宽度的增加对微通道脉管性能都有一定促进作用;保持长径比,同比例放大模型,在一定程度上优化了脉管的工作性能,存在一个最优脉管容积。

The molecular dynamics simulation method is used to study the microscopic refrigeration effect inside microchannel vessels,and the influence of microchannel pulse geometry on refrigeration performance is discussed.A rectangular cross-section microchannel vessel model is established.The Inflation and deflation process of the working fluid He gas in the microchannel is simulated,and the axial pressure,velocity and temperature distribution inside the channel are obtained.The influence of the inherent size of the vessel on the temperature of the cold and hot end of the microchannel vessel is analyzed.The study shows that the pressure gradient is gradually reduced in the model 1B-2L,as the process progresses and finally reaches equilibrium in the model 1B-2L,as the process progresses.At the same time,a slight reverse gradient phenomenon occurs.The axial velocity is 434 m/s at 200 ps,followed by the axial velocity peak moves toward the inside of the tube and decreases.Maintaining a constant width of the model to increase the length or maintaining a constant length of the model increases the width of the hot end and the temperature of the cold end decreases.The increase of length and width has a certain effect on the performance of microchannel vessels.Maintaining the aspect ratio and scaling the model can optimize the performance of the vessel to some extent,and there is an optimal vessel volume.