|Abstract:||Fixed-area expansion devices are widely used in refrigerators, air-conditioners, and heat
pumps of up to 3.5 kW capacity with variable operating conditions. A fixed-area expansion
device falls into one of the three categories: an orifice, a short tube, and a capillary tube. The
earliest studies on orifices began in 1900s, with the interest in metering fluid flow rate. The
research on capillary tubes began to be active in 1940s. Since then, the study of fixed-area
expansion devices has been one of main activities in refrigerating. With the increasing need to
replace the ozone-depleting CFC and HCFC refrigerants, refrigerators, air-conditioners, and
heat pump systems have to be redesigned to accommodate new replacement refrigerants so
that research activities in fixed-area expansion devices have been intensified since early
1980s. This paper gives a detailed review of the literature on fixed-area expansion devices.
The main topics include the mass flow rate through orifices, the mass flow rate through short
tubes, rating capillary tubes, metastable flow, the friction factor and friction pressure drop,
and mathematical solution of fixed-area expansion device.