In order to improve the effect of cold storage in box with nano fluid

the low density sponge is used to adsorb nano particles and the thermophysical properties of the coolant is changed. The carrots are used as the experimental object in the experiments by orthogonal method. And the integral value of average temperature of the air in the box is taken as the index to compare the effect of cool storage. The influence of thickness of porous sponge (8 mm

16 mm

20 mm)

mass fraction of nanofluids (0.1%

0.15%

0.2%)

quality of cold storage materials for per kilogram of vegetables (0.429 kg

0.5 kg

0.571 kg)

and pre-cooling temperature of vegetables (-1 ℃

4 ℃

12 ℃) on the refrigeration effect in the incubator were explored. The results of the study are as follows: (1) the importance sequences of factors are pre-cooling temperature of vegetables

mass fraction of nanofluids

the quality of cold storage materials for per kilogram of vegetables

and the thickness of porous sponge; (2) with the increasing of the thickness of porous sponge

the mass fraction of nanofluids

and the quality of cold storage materials for per kilogram of vegetable

the effect of cooling storage will be better. The optimal pre-cooling temperature is 4 ℃ out of 12 ℃

4 ℃

- 1 ℃; (3) the optimal combination of all the factors for the effect of cool storage is as following: the thickness of porous sponge of 20 mm

the mass fraction of 0.2%

the quality of cold storage materials for per kilogram of vegetable of 0.571 kg

and vegetables pre-cooling temperature of 4 ℃. But the porous sponge of 16 mm instead of 20 mm

and the mass fraction of nanofluids of 0.15% instead of 0.2% are suggested for economical reason. This experiment method and results provide a theoretical basis for further experiments and analysis.