Investigation of a device for air cooling of concrete aggregates

Conclusions

• 1. The device for cooling coarse aggregate in hoppers, designed by the Leningrad branch of Orgénergostroi, cools gravel of all fractions to an average temperature of 4–5°C at a temperature of the cooling air of −3°C. At a temperature of the cooling air from −6 to −8°C, the gravel is cooled to 0 to −2°C.

• 2. The degree of cooling of the material is easily regulated by changing the rate of air flow. The gravel is cooled uniformly, and freezing together of the pure material is not observed during continuous plant operation. To prevent freezing then the plant is shut down for more than 20–30 min, and the delivery of cooling air must be discontinued.

• 3. Cooling of sand was ineffective for a number of reasons, the main ones being the large aerodynamic resistance and improper design of the hoppers, which determined the character of sand discharge.

• 4. To calculate the heat-transfer coefficient when designing such devices, it is recommended that B. I. Kitaev’s formula be used with the introduction of our correction factors.