P14 Enhanced evaporation heat transfer in narrow channels
smala kanaler  


Project leader Björn Palm
Performer KTH


Efficient heat transfer is necessary to reach high COP. One degree C decrease of the temperature difference between the ambient and the refrigerant decreases the energy use by 2-3%. Lately, channels with small diameter has become more common. Small channels give higher heat transfer coefficients and decrease the amount of refrigerant in the system. In this project, numerical simulations of bubble growth in small channels is performed. With modern CFD-programs, the forces and energy flows for microscopic chunks of fluid can be calculated and the results in the form of macroscopic effects as heat transfer coefficients and transferred power can be determined. In the project, commercial code is used in combination with code developed in the project based on the latest scientific publications to do calculations of the bubble growth in small channels. The work will give basic understanding of the phenomena and the results are important for optimizing the geometry in future evaporators.