Table 1: Summary of correlations for friction factor considered for single phase and two-phase flow.

Authors	Correlation		Conditions
Correlations for Friction factor coiled pipes considering single-phase flow
White [11]	fc=0.08∙Re-0.25+0.012∙(d/D)0.5		Smooth pipes, empirical, turbulent flow 15000<Re<100000
Ito [9]	fc=0.076∙Re-0.25+0.00725∙(d/D)0.5		Theoretical ,turbulent flow 0.034<Re(d/D)2<300
Mishra and Gupta [12]	fc=0.079∙Re-0.25+0.0075∙(d/D)0.5		Empirical, turbulent 4500<Re<105
Correlations for Friction factor considering two-phase flow
Lockhart-Martinelli [13]			Gas-liquid
Awwad et al. [14]			Air-water 12.7<d<38.1 mm 330<D<670 mm 0.008<UL<2.2 m s-1 0.2<UG<50 m -1
Xin et al. [15]			Air-water 12.7<d<38.1 mm 305<D<609 mm 0.008<UL<2.2 m-1 0.2<UG<50 m-1