Flow boiling heat transfer of R1234yf on a microparticle coated copper surface.

This paper presents some preliminary experimental measurements collected during flow boiling heat transfer of low-GWP refrigerant R1234yf on a microparticle coated surface obtained via cold spray, a simple and non-expensive technique. The specific surface engineering was obtained by depositing a 100 µm thick pure copper coating on a smooth copper plate 200 mm long and 10 mm wide. The coating was deposited via High Pressure Cold Spray (HPCS) starting from a feedstock of pure copper particles with average size of 20 μm. The experimental measurements, carried out at the department of Industrial Engineering of the University of Padova, refer to a heat flux equal to 50 kW m-2, at a constant saturation temperature of 30°C; the refrigerant mass velocity was varied between 30 and 200 kg m-2 s-1, while the vapour quality varied from 0.2 to 0.95.