  Experimental results for condensation in compact heat exchangers show that
the heat transfer due to condensation is significantly better compared to
classical heat exchangers, especially when using R134a instead of water as the
refrigerant. This suggests that surface tension plays a role. Using generalized
dimensional analysis we derive reduced model equations and jump conditions for
condensation in a vertical tube with cylindrical cross section. Based on this
model we derive a single ordinary differential equation for the thickness of
the condensate film as function of the tube axis. Our model agrees well with
commonly used models from existing literature. It is based on the physical
dimensions of the problem and has greater geometrical flexibility.
