Experimental investigation for the spiral coiled capillary tube for various spiral pitches for the flow of refrigerant R32

ABSTRACT

The experimental investigation was carried out for the spiral coiled capillary tube having a spiral pitch of 32 mm, 48 mm, and 64 mm to study the mass flow rate of R32. A wooden spiral pattern was used to get the spiral shape of the capillary tube. Three wooden patterns were prepared for three different spiral pitches. The spiral convolutions are calculated for the capillary tube length of 1000 mm, 1500 mm, and 2000 mm. The variation in mass flow rate for all three spiral pitches was studied, and the results were shown on a graph. The effect of variation of capillary inlet pressure and degree of subcooling were observed. From the data comparison, it can be concluded that if the spiral pitch increases from 32 mm to 48 mm, for all the diameters for similar operating conditions, the mass flow rate increases from 3.89% to 5.05%. If the spiral pitch increases from 32 mm to 64 mm, for all the diameters for similar operating conditions, the flow rate increases from 6.49% to 11.64%. The measured mass flow and predicted mass flow rate is well within the accepted range. The percentage deviation of the mass flow rate is compared with the other researchers and found between +30% and −34%. The mass flow rate was higher for the higher spiral pitch, a higher degree of subcooling, higher capillary inlet pressure, and higher capillary diameter.

KEYWORDS:

• Coiled capillary
• mass flow rate
• R-32
• subcooling
• spiral pattern
• spiral pitch

Nomenclature

Table

Acknowledgments

The experimental setup was formed in the laboratory of Refrigeration and air conditioning in IIT Roorkee. The lab assistant and my friends in the research lab helped me in various ways. This research did not receive specific grants from funding agencies in the public, commercial, and not-for-profit sectors.

Disclosure statement

No potential conflict of interest was reported by the author(s).