Abstract
A long - term change of nucleate boiling heat transfer coefficients in water and ammonia have been measured when a surface active agent was added into water and those have been measured on a heated wire that PEEK (Poly Ether Ether Ketone) resin was coated in ammonia. The experiment has been carried out using a thermosyphon with a plain heated surface and a pool boiling vessel with a heated fine wire. The effect of the surface - active agent and PEEK coating on the nucleate boiling heat transfer coefficient and time variation of the nucleate boiling heat transfer coefficient were investigated experimentally for the surfactant concentration, Cs=0 and 1000 ppm. The result shows that the nucleate boiling heat transfer coefficient never changes for a month in pure water and in ammonia with the heated wire coated by PEEK resin. On the other hand, the boiling heat transfer coefficient decreases gradually till the end of operation in water with the surfactant. The surfactant incresed the nucleate boiling heat transfer and PEEK resin decreased one.
