EXPERIMENTAL AND NUMERICAL INVESTIGATION OF METASTABLE FLOW OF REFRIGERANT R-22 THROUGH CAPILLARY TUBE

This study presents an experimental investigation of metastable region take place forrefrigerant flow through adiabatic and non-adiabatic capillary tube of window type airconditioner. Large numbers of experiments are carried out to explain the effect of length ofstraight and helical capillary tube on metastable region under adiabatic and non-adiabaticconditions. for the case of adiabatic capillary tube, three different length are selected(70,100 and 150) cm and two helical capillary tube, the length of each tube is 100 cm withtwo coil diameters (2 and 6) cm. For the non-adiabatic capillary tube, the straight capillarytube suction line is 150 cm while the length of non-adiabatic helical capillary tube is 200 cmwith 8 cm coil diameter. The results show that the length is the most influence parameterson beginning of metastable region. In addition the helical coil tube effect on the beginningof metastable region. As well as for the adiabatic and non-adiabatic capillary tube it isconcluded that mass flow rate is the main parameters on beginning of metastable region.Also effect of length and coiling on both pressure drop and mass flow rate are discussed.The CFD commercial code, ANSYS CFX 16.1 based on finite volume method using Kturbulencemodel considering the homogeneous flow between phases applied to straightcapillary tube. The present numerical data has been validated with the present workexperimental data and with other researchers. A good agreement is obtained which can belead to use ANSYS CFX 16.1 in the design and optimization of capillary tube in airconditioner.

Exploration of the phase diagram of liquid water in the low-temperature metastable region using synthetic fluid inclusions

The paper presents experimental data of the low-temperature metastable region of liquid water to evaluate and improve theoretical models describing the p–V–T properties of water.

ON THE SPEED OF SOUND IN STEAM

A study of the speed of sound in a pure water substance is presented here. The IAPWS data on the state of water and steam are applied only for investigating the speed of sound for a one-phase medium. A special numerical model for investigating the parameters of shock waves in steam is presented here and is applied for investigating extremely weak waves to obtain velocities representing the speed of sound in both one-phase and two-phase steam. Problems with the speed of sound in two-phase steam are discussed, and three types of speed of sound are derived for the metastable region of wet steam.