Design and performance of two-phase flow heat transfer experiment platform using R134a as working fluid

A two-phase flow heat transfer experiment platform using alternative refrigerant R134a as working fluid was designed and built to investigate the characteristics of two-phase flow heat transfer. It was primarily made up of circle power, heating/cooling sources, parallel test sections, accumulator and data acquisition system. The working loop was designed for performance pressure of 1.6 MPa and temperature of 200°C, preheated section power of 24 V×300 A and test section of 60 V×500 A. The refrigeration chilling unit had a maximum output of 50 kW. The preheated and test section were designed as horizontal helically-coiled tubes, and a visual reservoir made of electric melting-quartz glass was designed to observe flow patterns intuitively. Technology and methods related to fluid and mechanics were discussed in this paper including the aspects of materials and welding, sealing and heat preservation, special machining and accessories installation etc. Pressure testing, heat balance testing, heat transfer characteristics experiments were performed under various conditions to analyze the usability and stability of this platform. Test results showed that the leak ratio was no more than 250 Pa/h at 2.0 MPa and the heat loss of the system wrapped with PEF materials was less than 5%. Under the conditions of pressures of 0.30-0.95 MPa, mass fluxes of 120-620 kg/m²s, inlet qualities of -0.08-0.38 and heated power of 0.45-1.30 kW, R134a two-phase flow boiling heat transfer characteristics were investigated and discussed in detail. This platform can be used for studying the characteristics of two-phase flow pressure drop, boiling heat transfer and fluid-to-fluid modeling technique etc.