**Nomenclature**

*A*: Area (m2 )

*AD*: Average deviation, AD=( <sup>1</sup> *<sup>n</sup>* )∑ 1 *n* ((d*p*pred −d*p*exp) ×100 / d*p*exp)


*MD*: Mean deviation, MD=( <sup>1</sup> *<sup>n</sup>* )∑ 1 *n* |((d*p*pred −d*p*exp) ×100 / d*p*exp) |


Pressure Drop and Heat Transfer during a Two-phase Flow Vaporization of Propane… http://dx.doi.org/10.5772/60813 123

Re: Reynolds number, Re= *GD μ*

*T*: Temperature (K)

**5.** The heat transfer coefficient correlations proposed by Shah [37] and Tran et al. [35] show an accurate prediction with the current heat transfer coefficient experimental data. **6.** The geometric effect of the small tube and flow condition must be considered to develop a new heat transfer coefficient correlation. The development of the enhanced factor F for the convective boiling contribution, and the suppression of factor S for nucleate boiling suppression factor have been also clearly evaluated with the consideration of laminar and turbulent flows. A new boiling heat transfer coefficient correlation that is based on a superposition model for propane in minichannels was demonstrated with 9.93% mean

((d*p*pred −d*p*exp) ×100 / d*p*exp)


deviation and -2.42% average deviation.

*<sup>n</sup>* )∑ 1 *n*

*<sup>n</sup>* )∑ 1 *n*

*Gi*fg

**Nomenclature**

)

122 Heat Transfer Studies and Applications

*AD*: Average deviation, AD=( <sup>1</sup>

*Bo*: Boiling number, Bo= *<sup>q</sup>*

*cp* : Specific heat (kJ kg−1 K−1)

*C*: Chisholm parameter

*G*: Mass flux (kg m-2 s-1)

*i*: Enthalpy (kJ kg-1) *L*: Tube Length (m)

*n*: Number of data

*p*: Pressure (kPa)

*Q*: Electric power (kW)

*q*: Heat flux (kW m-2)

*MD*: Mean deviation, MD=( <sup>1</sup>

*M: Molecular weight (*kg kmol-1)

*g*: Acceleration due to gravity (m s-2)

*h*: Heat transfer coefficient (kW m-2K-1)

*D*: Diameter (m) *f*: Friction factor

*A*: Area (m2


#### **Greek letters**

*α*: Void fraction

Δ*i*: The enthalpy rise across the tube (kJ kg-1)

*μ*: Dynamic viscosity (N s m-2)


Δ*T*: Wall super heat (K)

#### **Gradients and differences**

(d*p*/d*z*): Pressure gradient (N m-2 m-1)

(d*p*/d*z F*) : Pressure gradient due to friction (N m-2m−1)

#### **Subscripts**

crit : Critical point

exp: Experimental value

f: Saturated liquid

fi: Inlet liquid

g: Saturated vapor

i: Inner tube

lo: Liquid only

o: Outlet tube

pb: Pool boiling

pred: Prediction value

r: Reduced

sat: Saturation sc: Subcooled t: Turbulent tp: Two-phase v: Laminar w: Wall wi: Inside tube wall
