This paper decribes a study of the heat, mass and momentum transp associated with vapor release in a horizontal stage of a flash evaporat A scaled-down, well-controlled flash evaporator, which also allows gc visual observation, has been designed, constructed and used in the expl ments. In particular, temperature profiles in the stage have been measured an accuracy of ±O.02°C and better. It has ...

Modifications to an automated thermal evaporator were made: A device for angular evaporation was fabricated and a protocol for in vacuum oxidation was developed. The new features allow for versatile fabrication of metaltunnel junction-metal thin film samples. A discussion of the usefulness of tunnel junctions is provided.

Concerns about the impact on the environment of the refrigerants used in HVAC&R equipment are driving the development of alternative refrigerants with lower global warming potentials (GWPs). This paper reports the performance of DR-55 (now designated as R452B), DR-5A (now designated as R454B), and R32 in comparison to R410A at the component level from tests run on a 4 RT (14 kW) commercial unit...

Evaporation of HFC134a inside smooth, horizontal tubes is studied. Te,;ts are made with pure refngerant and with oil-refrigerant mixtures. Heat flux has varied from 2 kW/n? to 10 kW/m . The inner diameter of the tubes are 12 mm. T1.1o evaporators are used, 4 and 10 m long. Oil content is varied from 0 to 2.5 mass percentage (synthetic oil, EXP-0275). Oil free HFC134a is found to have higher hea...

Models for unitary air conditioners and heat pumps typically have difficulties in providing accurate predictions for the following situations: 1) charge modeling over a large range of charge levels, 2) two-phase refrigerant entering fixed-orifice expansion devices, 3) two-phase refrigerant entering compressors, and 4) non-uniform refrigerant mass flow allocation among evaporator circuits at low...