ISSN:
1572-9567
Schlagwort(e):
ammonia
;
alternative refrigerants
;
capillary viscometer
;
R32
;
R134a
;
saturated liquid
;
radial acceleration correction
;
vapor buoyancy
;
viscosity
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Physik
Notizen:
Abstract The saturated liquid viscosity of ammonia (NH3) and of the hydrofluorocarbons, difluoromethane (CH2F2, R32) and 1,1,1,2-tetrafluoroethane (CF3–CH2F, R134a), was measured in a sealed gravitational viscometer with a straight vertical capillary. The combined temperature range was from 250 to 350 K. The estimated uncertainty of the ammonia measurements is ±3.3 and ±2 to 2.4% for the hydrofluorocarbons with a coverage factor of two. The results are compared with literature data which have been measured with capillary viscometers of different design. Agreement within the combined experimental uncertainty is achieved when some of the literature data sets are corrected for the vapor buoyancy effect and when a revised radial acceleration correction is applied to data which were obtained in viscometers with coiled capillaries. An improved correction for the radial acceleration is proposed. It is necessary to extend inter-national viscometry standards to sealed gravitational capillary instruments because the apparent inconsistencies between refrigerant viscosity data from different laboratories cannot be explained by contaminated samples.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1023/A:1022644718603
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