Boiling heat transfer coefficients inside a vertical smooth tube for water/ammonia and ammonia/lithium nitrate mixtures

This paper describes the experimental results obtained on the heat transfer in forced convective boiling for the water/ammonia and ammonia/lithium nit rate mixtures flowing upward in a vertical tube uniformly heated. The conce ntration range for both mixtures was 38-48 wt%. Correlations were proposed to correlate the experimental local heat transfer coefficients with a mean deviation of +/-16% for the ammonia/lithium nitrate mixture and +/-25% for the ammonia/water mixture. The results showed that the local heat transfer coefficients are strongly dependent on Bo for the ammonia/lithium nitrate m ixture and more dependent on quality and 1/X-u for the ammonia/water mixtur e at the analysed conditions. Comparing the heat transfer coefficient value s for both mixtures, it was observed that the lowest values were obtained w ith the ammonia/lithium nitrate mixture. (C) 1998 Elsevier Science Ltd. All rights reserved.