As a type of functional material

nanofluids are widely used to enhance heat transfer; however

as a cold storage agent

there are few studies on its initial freezing temperature. In this study

Al2O3 particles with a particle size of 500 nm were used

and three different cooling rates (1

5

and 10 ℃/min) and three different mass fractions (0.01%

0.05%

and 0.1%) were used to study the freezing point of the Al2O3-H2O nanofluid. The relationship between the cooling rate and particle concentration was investigated. The samples were divided into nine groups

and each group was tested 60 times; the initial freezing temperature was recorded to obtain its probability distribution. The results show that the initial freezing temperature value is approximately Gaussian; increasing the cooling rate will reduce the initial freezing temperature of the fluid during freezing; however

at different cooling rates

the initial freezing temperature and nanofluid mass fraction do not show the same trend: with an increase in the cooling rate

the initial freezing temperature gradually changes

first decreasing and then increasing with an increase in the nanofluid concentration. Moreover

the degree of influence of heterogeneous crystallization on the initial freezing temperature is greater than that of the solution viscosity.