Preparation and investigation on density and surface tension of quaternary bromides for concentrating solar power

In order to improve the unsteady high temperature heat transfer performance of receivers in solar thermal power stations the receivers should be optimized further. High temperature could help to optimize heat transfer of the receiver. Based the selection of heat pipes and bromides this work prepared six samples of quaternary bromides with different composition ratios of KBr, LiBr, NaBr, and CaBr2 and their density and surface tension were measured and analyzed. Experimental results show that density of quaternary bromides shows very good linearity with salt temperature, and density of quaternary bromides is higher than that of Solar salt at a same temperature. Also, quaternary bromide NO.2 has maximum density, and quaternary bromide NO.3 has minimum thermal expansion coefficient while quaternary bromide NO.6 has the minimum density and maximum thermal expansion coefficient at the same temperature. In addition, quaternary bromide NO.1 has a maximum surface tension and fitting curve slope at a same temperature among the six samples of quaternary bromides. Their density and surface tension were fitted with linear fit with their temperature respectively. Furthermore, that the composition ratio has evident influence on the density and surface tension of quaternary bromides has been concluded.