- Author
-
Aaron, D. A.
|
Domanski, P. A.
- Title
- Experimentation, Analysis, and Correlation of Refrigerant-22 Flow Through Short Tube Restrictors.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Journal
-
ASHRAE Transactions,
Vol. 96,
No. 1,
1990
- Report
-
AT-90-1-2,
- Keywords
-
refrigerants
|
short tube restrictors
|
tests
|
short tubes
|
flow dependency
|
flow model
|
mass flow
|
flow charts
- Abstract
- Refrigerant-22 flow through short tube restrictors was investigated. The analysis pertained to initally sub-cooled refrigerant flowing through short tubes with 5< L/D<20. The flow conditions studies were those typically found in heat pumps. Flow dependencies upon upstream subcooling, upstream pressure, downstream pressure, tube length, tube diameter, entrance chamfering, and exit chamfering were examined. A correlation and flow charts for mass flow rate prediction were developed from a large experimental data base. For a given inlet pressure and subcooling, the flow behaved differently depending upon the downstream pressure level. For downstream pressures greater than the approximate liquid saturation pressure of the entering refrigerant, the flow was strongly dependent upon the downstream pressure, as is typically found for single-phase fluid flow through a duct. However, for downstream pressures below the saturation pressure, as is typically found during heat pump operation, the flow demonstrated a very weak dependence upon the downstream pressure and could be termed as non-ideal choked flow. For the latter case, the mass flow rate was directly proportional to upstream subcooling, upstream pressure, and cross-sectional area, and was inversely proportional to the restrictor length. The mass flow rate was highly sensitive to inlet chamfering and insensitive to exit chamfering.