Experimental Study On Nucleate Pool Boiling Heat Transfer Characteristics Of Lithium Bromide Solution With Surfactant

The LiBr absorption chiller has been gradually widespread attention worldwide because of its great advantages in energy saving and environmental protection which takes water as working fluid, non-toxic and odorless LiBr as absorbing substance and low temperature heat source as driving force. But the boiling heat transfer characteristics of LiBr solution is poor and the heat exchange efficiency of the generator is low. So improving the heat transfer characteristics of LiBr solution is necessary and currently research on heat transfer characteristics of the solution and heat transfer enhancement are still lacking. Therefore this article is significant both in theory and practical.In this paper, 10%, 20% and 30%( mass fraction) LiBr solution were chosen as base fluid,Triton X-100,Triton X-114 and 2EH as additives which were stable in the acid and salt environment. The effect of LiBr concentration, static surface tension, and CP of NS and other factors on boiling heat transfer characteristics were studied.Static surface tension measurements showed that the concentration of LiBr salt solution had a significant effect on surface tension. Three types of surfactants could effectively reduce the surface tension of lithium bromide salt solution, wherein the ability to reduce the surface tension of 2EH was the best, reduced about 35%. But 2EH needed higher concentration which was about six times around the other two. Further more concentration of LiBr salt could also impact the CMC of additives. Detailed analyses of the relevant phenomena were maded mainly based on the formation mechanism of surface tension and the salting out effect of LiBr.The observation apparatus was built to study the CP of NS. The effect of NS concentration and LiBr concentration on CP were studied. A detailed analysis of experiments phenomenon and discussion of CP on the impact of pool nucleate boiling heat transfer characteristics were made based on the CP formation mechanism.The reletive experimental apparatus was built to study the pool nucleate boiling heat transfer of LiBr. The result showed that, Triton X-100 and Triton X-114 could be used to improve nucleate pool boiling heat transfer characteristics of LiBr solution. Its optimal concentration is about CMC and the maximum enhancement effect is about 40%. But 2EH has no corresponding effect. From the boiling heat transfer mechanism, a detailed analysis of the relevant experimental phenomena was maded in the paper combined with surface tension, LiBrconcentration influence(CIF) and surface tension influence(SIF) and other parameters.