Experimental sizing and assessment of two-phase pressure drop correlations for a capillary tube with transcritical and subcritical carbon dioxide flow

31st UIT (Italian Union of Thermo-fluid-dynamics) Heat Transfer Conference 2013

Trinchieri, R.^1 ; Boccardi, G.^1 ; Calabrese, N.^1 ; Celata, G.P.^2 ; Zummo, G.^1

ENEA, Laboratory of Thermal Fluid-Dinamics Applied to Energy Systems, Italy^1

ENEA, Division of Advanced Technologies for Energy and Industry, Italy^2

关键词: Alternative refrigerant;    Automotive air conditioning;    Conventional components;    Experimental campaign;    External temperature;    Household refrigerators;    Subcritical carbon dioxide;    Two-phase pressure drops;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/501/1/012018/pdf
DOI  :  10.1088/1742-6596/501/1/012018

来源: IOP

【 摘 要 】

In the last years, CO2was proposed as an alternative refrigerant for different refrigeration applications (automotive air conditioning, heat pumps, refrigerant plants, etc.) In the case of low power refrigeration applications, as a household refrigerator, the use of too expensive components is not economically sustainable; therefore, even if the use of CO2as the refrigerant is desired, it is preferable to use conventional components as much as possible. For these reasons, the capillary tube is frequently proposed as expansion system. Then, it is necessary to characterize the capillary in terms of knowledge of the evolving mass flow rate and the associate pressure drop under all possible operative conditions. For this aim, an experimental campaign has been carried out on the ENEA test loop «CADORE» to measure the performance of three capillary tubes having same inner diameter (0.55 mm) but different lengths (4, 6 and 8 meters). The test range of inlet pressure is between about 60 and 110 bar, whereas external temperatures are between about 20 to 42 °C. The two-phase pressure drop through the capillary tube is detected and experimental values are compared with the predictions obtained with the more widely used correlations available in the literature. Correlations have been tested over a wide range of variation of inlet flow conditions, as a function of different inlet parameters.