Experimental study of flow noise in short tube throttle valve and noise reduction measures

doi:10.11949/0438-1157.20221529

Abstract

Abstract:

Short tube throttle valve as a throttling device is widely used in household air conditioners because of its simple structure. When the refrigerant in two-phase state flows through the short tube throttle valve, serious noise is generated. In this paper, we designed and built a test bench for flow noise of short tube throttle valve, and experimentally studied the effect of refrigerant flow pattern, refrigerant mass flow rate and refrigerant quality on the frequency and sound pressure level of flow noise. The experimental results show that the sound pressure level of the flow noise is the largest when the valve inlet flow pattern is churn flow, and the flow noise is smaller when the valve inlet flow pattern is bubble flow and annular flow. The peak frequency of flow noise increases with the increase of mass flow rate. When the mass flow rate increases from 20 kg/h to 80 kg/h, the peak frequency of flow noise increases by 38.6%; when the refrigerant quality increases from 0.05 to 0.4, the average sound pressure level of flow noise firstly increases by 7 dB and then decreases by 3 dB. The optimized structural solution is proposed to reduce the average sound pressure level of flow noise by 2 dB by replacing the sudden contraction structure at the spool inlet with a flared and tapering structure.

Key words: short tube throttle valve, flow noise, two-phase flow pattern, experimental research

摘要：

短管节流阀作为节流机构，因其结构简单而广泛应用于家用空调器中，当两相状态的制冷剂流经短管节流阀时会产生严重的噪声。设计并搭建了短管节流阀流动噪声测试台，实验研究了制冷剂流型、流量和干度对短管节流阀内流动噪声频率和声压级的影响规律，并在此基础上提出了降噪措施。实验结果表明，阀进口流型为搅浑流时产生的流动噪声声压级最大，阀进口流型为泡状流型和环状流型时产生的流动噪声较小；流动噪声的峰值频率随质量流量的增大而增大，质量流量由20 kg/h增大到80 kg/h时，流动噪声的峰值频率增大38.6%；干度由0.05增大到0.4时，流动噪声的平均声压级先增大7 dB，后减小3 dB。提出了将阀芯入口处的突扩突缩结构改为喇叭口渐缩结构的方式来实现降噪的结构优化方案，优化后的结构方案可将流动噪声的平均声压级降低2 dB。

关键词: 短管节流阀, 流动噪声, 两相流型, 实验研究

CLC Number:

TB 657.2

Shaohua ZHOU, Feilong ZHAN, Guoliang DING, Hao ZHANG, Yanpo SHAO, Yantao LIU, Zheming GAO. Experimental study of flow noise in short tube throttle valve and noise reduction measures[J]. CIESC Journal, 2023, 74(S1): 113-121.

周绍华, 詹飞龙, 丁国良, 张浩, 邵艳坡, 刘艳涛, 郜哲明. 短管节流阀内流动噪声的实验研究及降噪措施[J]. 化工学报, 2023, 74(S1): 113-121.

Figures/Tables 11

Fig.1 Flow noise test schematic diagram of short tube throttle valve

Fig.2 Experimental sample

Fig.3 Visualization section and its installation method

Table 1 Uncertainties of direct measurements and experimental parameters

试验参数	仪器	量程	精度
质量流量	科氏流量计（E+H）	0~250 kg/h	+0.5%
温度	铠装热电偶（OMEGA）	-200~800 ℃	±0.1℃
压力	压力变送器（罗斯蒙特）	0~10 MPa	±0.075%
声压级	传声器（BSWA MPA201）	30~80 dB	±0.5 dB
制冷剂干度	—	0.02~0.4	±2.6%
噪声频率	—	2000~6000 Hz	—

Fig.4 Effect of refrigerant mass flow rate on the peak frequency of flow noise

Fig.5 Effect of refrigerant quality on the peak frequency of flow noise

Table 2 Four typical flow patterns at the valve inlet

项目

Q_m=80 kg/h

x=0.02

Q_m=40 kg/h

x=0.05

Q_m=40 kg/h

x=0.2

Q_m=40 kg/h

x=0.4

实验照片

示意图

Fig.6 Effect of refrigerant quality on the sound pressure level of flow noise

Fig.7 The improvement scheme of short tube throttle valve

Fig.8 Simulation analysis of noise reduction effect of short tube throttle valve structure optimization

Table 3 Comparison of simulation and experimental values of flow noise SPL before and after improvement

项目	仿真值/ dB	实验值/ dB
优化前	54.1	51.8
优化后	52.3	49.5

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