Speed in evaporator tube

[Aik]

Q=m'*dH - capacity [kW]
m' - mass flowrate [kg/s]
dH - difference of enthalpies of evaporating and suction refrigerant [kJ/kg]
Acording to this formula you can calculate m'. After with help DesA's formula you can calculate velocity. Entalpy you can find using CoolPack.

dP=lamda*(l/d)*(r*v^2)/2 - pressure drop on straight tube [Pa]
lamda - friction coefficient, for copper tubes lamda=0.03
l - tube's length [m]
d - inner diameter of tube [m]
r - density (vapour, or liquid, or 2-phase) [kg/m3]
v - velocity [m/s]

P.S. for more accuracy for 10^5< Re < 10^8
lamda=0.0032+(0.221/(Re^0.237))
Re - Reynolds number