Capillary tubes, which are used extensively in mechanical refrigeration systems, have been standardised in terms of their parameters through analytical and experimental work. This work is confined mainly to straight capillaries. Since the length required is usually large, other shapes should also be considered for accommodation in available space. This work deals with computer-aided design of straight, helical, and combustion capillaries. A new expression for the friction factor has been proposed, and better property, correlations have been developed. The results obtained are in good agreement with experimental works. For any entry parameters to capillary tubes, this work may prove to be a useful guideline in evaluating the tube length required. Adiabatic slug flow of Refrigerant-12 with no heat exchanger has been considered.

KEYWORDS: computers, computer aided design, capillary tubes, length, helical, combustion, friction factor, calculating, adiabatic, R12, refrigeration, refrigerants, tubes