Boiling heat transfer of water on smooth tubes in a compact staggered tube bundle

In desalinization devices and some heat exchangers making use of low-quality heat energy, both wall temperatures and wall heat fluxes of the heated tubes are generally quite low, hence they cannot cause boiling in flooded tube bundle evaporators with common large tube spacing. However, when the tube spacing is very small, the incipient boiling in restricted spaces can occur and results in higher heat transfer than that of pool boiling at the same heat flux. This study investigated experimentally the effects of tube spacing, positions of tubes and test pressures on the boiling heat transfer of water in restricted spaces of the compact staggered bundles consisting of smooth horizontal tubes. The experimental results show that the tube spacing has a very significant effect on the boiling heat transfer in a compact tube bundle. There is an optimum tube spacing, which provides the largest heat transfer coefficient at the same heat flux.