制冷系统毛细管节流特性的试验与分析

在一台采用旋转式压缩机的某品牌KC-25窗式空调器上,进行了毛细管节流特性的试验研究,得出了毛细管节流对空调器性能的影响以及气态制冷剂在毛细管中流动时的能量损失规律,经过DPS数据处理,拟合出了毛细管的流量随内径长度的变化曲线及其变化率曲线,推导出了其韦泊分布函数.为空调器的优化设计匹配,提高空调器的性能奠定了基础,为毛细管批量生产的质检提供了一些有益的参考.     

短管节流流量特性实验研究

通过毛细管与短管节流气态流量特性的实验研究,对比分析两者的气态流量特性,得出节流短管气态流量与孔径的函数关系,证明节流短管内制冷剂的流量函数与N2的流量函数类似,短管节流与毛细管节流具有相似的气态流量特性,可以将节流短管当作长度较短的毛细管进行研究。     

变频空调器中毛细管应用的理论计算与研究

在结合毛细管、冷凝器、蒸发器、压缩机的数学模型的基础上,对采用毛细管作为节流元件的变频空调器系统进行整体计算,绘制出相应的计算结果图表,进而分析了不同频率下系统达到稳定时的制冷量、COP、制冷剂流量等随压缩机频率变化而变化的趋势,得出毛细管所能适应的频率范围。     

一种应用于岩石渗透率测试的气体流量计量方法-节流毛细管法

本文介绍了国内外岩石渗透率测试气体流量计量技术的现状,针对低渗透储层油气藏勘探开发过程中岩石气体渗透率测试存在的问题,开发研制了一套节流毛细管气体流量计量自动测定装置,建立了岩石渗透率节流毛细管测试压力P-与测量气体流量Q回归的测试方法。该测试方法计量气体通过岩石的能力速度快,测试精度高,自动化程度高,是岩石气体渗透率测试技术的重大突破。     

岩石渗透率节流毛细管气体流量计量测试方法研究

岩石气体渗透率是油田勘探开发最重要的基础数据之一。文章介绍了国内外岩石渗透率测试气体流量计量技术的现状，针对低渗透储层油气藏勘探开发过程中岩石渗透率测试存在的问题，开发研制了一套节流毛细管气体流量计量自动测定装置，建立了岩石渗透率节流毛细管p-g回归测试方法。该测试方法计量气体通过岩石的能力速度快，测试精度高，自动化程度高，是岩石渗透率测试技术的重大突破。     

一种应用于岩石渗透率测试的气体流量计量方法-节流毛细管法

本文介绍了国内外岩石渗透率测试气体流量计量技术的现状，针对低渗透储层油气藏勘探开发过程中岩石气体渗透率测试存在的问题，开发研制了一套节流毛细管气体流量计量自动测定装置，建立了岩石渗透率节流毛细管测试压力P-与测量气体流量Q回归的测试方法。该测试方法计量气体通过岩石的能力速度快，测试精度高，自动化程度高，是岩石气体渗透率测试技术的重大突破。     

采用R22、R134a两种制冷剂的毛细管特性对比研究

建立单相区和两相区毛细管模型,模型计算的毛细管质量流量与实验测量的质量流量差别小于(10%.研究了R134a代替R22后毛细管的质量流量随冷凝温度、过冷度、毛细管内直径和毛细管长度的变化规律,结果表明,两种制冷剂有相同的变化规律,但是在相同的条件下,R22的质量流量比R134a大,比如冷凝温度为45℃时,R22的质量流量比R134a高31.1%.     

毛细管的进出口状态参数对制冷剂流量的影响

本文建立了绝热毛细管的分布参数仿真模型,分析了毛细管内制冷剂的流动特性,得出了毛细管进口压力、进口过冷度和出口压力对制冷剂流量的影响情况.     

多孔板送风末端流量与管路阻力特性的数值模拟

本文对于圆柱面孔板的阻力特性进行数值模拟,拟合出其阻力特性随开孔率变化的曲线。得出了圆柱面孔板与平面孔板送风末端兼有的管路的流量分配和阻力特性。并提出当管路中存在变阻力系数的阻力件（比如阀门）时的水力计算方法,对于解决此类问题有一定的参考价值。     

小型制冷装置毛细管实验研究

设计并建造了一套小型制冷装置的毛细管实验研究台以及基于Labview的计算机数据采集系统,改变毛细管的组合方式和实验工况,得到了一系列实验数据,并对其进行处理,得出了过冷度、毛细管长度、毛细管进口压力、出口压力等参数与质量流量之间的关系.     

复合无机膜管捕集大气中挥发性有机物--气体样品前处理新方法的研究

建立了一套用复合无机膜管捕集大气中挥发性有机物(VOCs)的实验室装置和流程．在此装置上研究了挥发性有机污染物(乙醇)浓度、气体流速对用无机膜管捕集VOCs的截留率的影响．结果表明，截留率随乙醇浓度的增大而增加，与乙醇浓度的关系符合Boltzmann分布；截留率随气体流速的减小而增加，与流速关系符合指数衰减的趋势．从改进膜管性能，使得膜管的毛细管冷凝作用成为截留挥发性有机污染物的主控阶段的角度，讨论了采用复合无机膜管捕集大气中VOCs的这种大气样品前处理新方法中潜在应用的可能性．     

Visualization and void fraction measurement of decompressed boiling flow in a capillary tube

A capillary tube is often used as a throttle for a refrigerating cycle. Subcooled refrigerant usually flows from a condenser into the capillary tube. Then, the refrigerant is decompressed along the capillary tube. When the static pressure falls below the saturation pressure for the liquid temperature, spontaneous boiling occurs. A vapor-liquid two-phase mixture is discharged from the tube. In designing a capillary tube, it is necessary to calculate the flow rate for given boundary conditions on pressure and temperature at the inlet and exit. Since total pressure loss is dominated by frictional and acceleration losses during two-phase flow, it is first necessary to specify the boiling inception point. However, there will be a delay in boiling inception during decompressed flow. This study aimed to clarify the boiling inception point and two-phase flow characteristics of refrigerant in a capillary tube. Refrigerant flows in a coiled copper capillary tube were visualized by neutron radiography. The one-dimensional distribution of volumetric average void fraction was measured from radiographs through image processing. From the void fraction distribution, the boiling inception point was determined. Moreover, a simplified CT method was successfully applied to a radiograph for cross-sectional measurements. The experimental results show the flow pattern transition from intermittent flow to annular flow that occurred at a void fraction of about 0.45.     

针翅换热管对蓄冷用气体水合物生长过程的强化

为了促进蓄冷过程中气体水合物在换热管外的生长，对比研究了冰、THF和HCFC141b气体水合物在光管和针翅管外生长的过冷度、诱导时间和生长速度。研究表明，相对于光管，针翅管对冰、THF气体水合物和HCFC141b气体水合物的生长过程均具有良好的强化作用（减小过冷度、缩短诱导时间和加快生长速率）。对于针翅管本身来说，内外双翅式针翅管比外翅式针翅管可以更大幅度地强化生长过程。     

A study of transcritical carbon dioxide flow through diabatic capillary tubes

An experimental and theoretical study of the diabatic flow of carbon dioxide through lateral capillary tube suction line heat exchangers is outlined. The influence of both operating conditions (capillary tube inlet and outlet pressures, capillary tube inlet temperature and suction line inlet temperature) and tube geometry (heat exchanger length and position, suction line diameter and capillary tube length) on the heat and mass flow rates was experimentally evaluated using a purpose-built testing facility. In total, 75 tests were carried out with heat fluxes spanning from 1 to 11 kW m⁻² and refrigerant mass flow rates ranging from 12 to 26 kg h⁻¹. In addition, the mathematical model of Hermes et al. (2008) was adapted to run with carbon dioxide as working fluid. The model was validated against experimental data, and a good agreement between the experimental and calculated mass flow rates was achieved with 85% and 98% of the data points being within ±5% and ±10% error bounds, respectively.     

液氦温区VM-PT制冷机气量分配特性研究

VM气耦合脉冲管制冷机(VM-PT)是一种新型的液氦温区制冷机,为探索两级气耦合复杂的机理,本文采用Sage软件构建了低温调相VM-PT制冷机的整机模拟程序,研究了运行频率、平均压力、毛细管长度以及Er3Ni填充长度等参数对两级气量分配的影响。数值结果表明运行频率、平均圧力、毛细管长度以及Er3Ni填充长度均会影响两级质量流的分配,进而影响制冷机的最低温度,权衡工质的做工能力以及蓄冷器损失两方面因素,该四个参数均存在一个最佳值。搭建了实验平台并对数值模拟进行了验证。在实验中通过优化毛细管和蓄冷器,在运行频率1.6 Hz、平均压力1.4 MPa、压比1.6的情况下得到了3.86 K的无负荷制冷温度,在4.2 K可提供约10 mW的制冷量。     

以毛细管为节流装置的CO_2小型热泵热水器实验研究

介绍以毛细管为节流装置跨临界CO2热泵热水试验系统。实验研究了不同气冷器进水温度下系统的COP及其变化、气冷器沿管长水温温升梯度变化。分析了不同环境温度下制冷剂充注量对系统高压侧压力的影响。可以得出:以毛细管做节流装置也可以得到较高的COP;气冷器水温在高温CO2进口段温升幅度最大;系统对环境温度的变化很敏感,环境温度较低时要想得到合适的高压侧压力,制冷剂的充注量要比环境温度高时多。     

两级脉冲管制冷机穿梭和泵气热损失计算分析

脉冲管制冷机以空管取代了G-M和斯特林型制冷机中的冷端活塞,分析了由这种特点和交变流动引起的两级脉冲管制冷机的穿梭热损失和泵气热损失,以及损失的来源,并进行了详细的定量计算。     

End corrections for rarefied gas flows through capillaries of finite length

The influence of end effects on rarefied gas flows through moderately long capillaries is investigated by implementing the concept of effective capillary length, representing a sum of the real length of capillary and its increment. To calculate the length increment, a flow field near the inlet cross section of capillary is analyzed on the basis of the linearized kinetic equation. Far from the inlet inside of capillary, the solution is matched at the level of the distribution function with the one-dimensional solution corresponding to the flow in an infinite capillary. Far from the inlet outside of capillary, the gas is assumed to be in equilibrium at a specific pressure and temperature. The capillary length increment has been calculated as a function of the gas rarefaction. Using these results it is possible to estimate a flow rate through a moderately long capillary without hard calculations for the complete geometry.