expansion device, flow-induced noise, flow regimes, psychoacoustic annoyance
The flow-induced noise can be very disturbing to the users in the HVAC&R system. The flow-induced noise varies with the flow regimes near the expansion device, especially related to the flow regimes before entering the expansion device. The flow regimes are not only related to the mass flow rate of the flow and the quality of the flow but also related to the gravity orientation of the flow. Therefore, the flow regimes in the tube with different orientations can be different. In this paper, the comparison of the psychoacoustic annoyance of flow-induced noise with different needle valve installations is studied. A needle valve is connected to the system, and the microphone is used as the noise measuring technique. The installation includes the horizontal tube directions, the vertical upward tube directions, the 45o inclined upward tube directions, the 45o inclined downward tube directions, and the vertical downward tube directions. Also, the flow-induced noise generated by an angle valve is used to compare with the straight valve. The results show that the annoyance of flow-induced noise increases as the flow quality increases. Also, it shows that it is the void fraction of the flow other than the quality of the flow that influences the intensity of flow-induced noise. The vertical upward tube installation is the best installation of all five options. The possible explanation is that the flow's void fraction is the lowest as the flow goes vertical upwards. In this case, the intensity of the noise of the case should be the lowest as well. An angle valve is installed as a comparison. It shows that the inlet flow regimes are the primary influence of flow-induced noise for flow-induced noise. The annoyance of which is close to the flow-induced noise of straight valve with horizontal direction.