Surface tensions and thermal conductivities of aqueous LiBr-based solutions containing n-octanol and 2-ethyl-1-hexanol: Application to an absorption heat pump

Surface tensions and thermal conductivities were measured for LiBr + 1,3-pr opanediol + water and LiBr + LiI + 1,3-propanediol + water. These two mixtu res were chosen as one of the potential candidates for working fluids for a bsorption heat pumps. Surface tensions and thermal conductivities were meas ured by the capillary rise method equipped with a cathetometer and the tran sient hot wire method with a coated tantalum wire, respectively. The measur ed surface tension and thermal conductivity data were well correlated with a simple polynomial function of temperature and absorbent concentration. In addition, the surface tensions of LiBr + 1,3-propanediol + water containin g a small amount of alcohol-based surfactants, n-octanol and 2-ethyl-1-hexa nol, were also measured at 298.15 K by the ring method. An increase in the surfactant concentration up to about 500 ppm leads to a gradual decrease in the mixture surface tensions.