Experimental study on effects of particle melting and micro-convection on measurement of thermal conductivity of ice slurry

Ice slurry is a widely used storage medium for latent heat energy. However, as ice slurry is a liquid-solid twophase fluid, it is challenging to measure its thermo-physical parameters. In this study, circuit data acquisition was performed by using the transient hot-wire method and Wheatstone bridge, the test system of thermal conductivity was built. Subsequently, a uniform suspension test device with a multi-interlayer was innovatively designed, which suppresses the micro-convection heat transfer of solid particles caused by the solid-liquid density difference, the total uncertainty of the thermal conductivity measurement system was < 2%, the reliability of the experimental device was verified by testing the thermal conductivity of four standard liquids, at the same time, on the basis of theoretical study, a theoretical model of the thermal conductivity of ice slurry was established considering the influence of latent heat of ice crystal melting, which is more suitable for experimental measurement process. The results show that the thermal conductivity of the device increased gradually with an increase in the IPF, but when two devices were tested with and without an interlayer simultaneously, the thermal conductivity of the suspension device with the interlayer was generally higher than that of the suspension device without the interlayer. By comparing the experimental results, it was found that compared with the conventional models for predicting the thermal conductivity of liquid-solid two-phase fluids, the accuracy of the proposed model for predicting the thermal conductivity of ice slurry based on the influence of latent heat of ice crystal melting was significantly better, the results were in good agreement with the experimental results, the minimum relative error is 0.05%, and the maximum relative error is 8.96%.This study is helpful to obtain the thermal properties of ice slurry accurately.

Automated summary

This study measured and predicted the thermal conductivity of ice slurry using a test system and innovative device. The proposed model considering the influence of latent heat of ice crystal melting showed significantly better accuracy compared to conventional models.