Pressure vessel design for use in miscibility testing
Abstract
Knowledge of lubricant and refrigerant miscibility is necessary for the optimaldesign and function of compressors in refrigeration systems. Without adequate knowledge of mixture miscibility, compressor lubricants can drift into refrigerant systems, fail to return to the compressor and cause build-up in the pipes. This entrapped lubricant will reduce the systems efficiency by lowering the heat transfer coefficient of the system and introducing flow irregularities. To obtain data on refrigerant and lubricant miscibility a pressure vessel needed to be designed and manufactured. This pressure vessel needed to withstand a working pressure of 150 bar, a temperature range of -40 C to 160 C, and have an integrated mixer. ASME, ISO, and ASHRAE standards were referenced in the design of this vessel to ensure proper function and safety. Stress and displacement simulations were conducted using SolidWorks to help inform the final design. Additionally, ANSYS and COMSOL were leveraged for fluid mixing simulations to determine optimal mixing impeller design for our system. The rushton and hydrofoil impellers showed the greatest eddy diffusivity and mixing potential. Overall, this work has produced a functioning pressure vessel, a system for temperature regulation of the pressure vessel, and a proposed method to obtain lubricant and refrigerant miscibility data.