electronic expansion valve, capillary tube, expansion device
This work focuses on the HC-600a flow through small capacity fixed and variable expansion devices. To this end three electronic expansion valves of the same innovative design but with distinct orifices, were firstly tested in a dry nitrogen flow testing apparatus by varying the opening ratio an the operating conditions. Secondly, equivalent capillary tubes were defined based on the measured nitrogen mass flow rates through an updated version of the well know Kipp Schmidt’s equation. Thirdly, simulations were carried out with an in-house validated capillary tube model to estimate the HC-600a mass flow rate, using the length and inner diameter of the equivalent capillary tubes as input data. A test rig was also designed, constructed and used to measure the valve HC-600a mass flow rates under different operation conditions and opening ratios. Comparative analyses between the valve and capillary tube mass flow rates were then carried out under different conditions. In-depth knowledge about the two-phase capillary tube and valve flows were then used to explain the observed differences.