Measurements of the contact angle between R134a and both aluminum and copper surfaces

Measurements of quasi-static advancing contact angles of refrigerant R134a on copper and aluminum surfaces are reported over a temperature range from 0 degrees C to 80 degrees C. The metal surfaces tested were aluminum (alloy 3003) and copper (alloy 101) plates. Measurements were done using a direct optical observation technique where the liquid meniscus at the surface of a vertical plate was captured using a high magnification camera system. The contact angle of solid-liquid interface was deduced by enhancing and manipulating the digital image using solid modeling software by drawing a tangent line to the meniscus at the intersection location of the solid, liquid and vapor. Values of the contact angle were found to vary between 8.3 degrees and 5.6 degrees for aluminum and between 5.1 degrees and 6.5 degrees for copper when the temperature rose from 0 degrees C to 80 degrees C. Maximum standard deviation amongst the measured values of contact angles was 1.3 degrees. (c) 2006 Elsevier Inc. All rights reserved.