Airflow Distribution in the Cooling Chamber

Airflow distribution constitutes a core element within the fields of air environment and refrigeration HVAC, having been recognised by humankind for considerable time. For instance, in regions such as the northwest where sandstorms are prevalent, afforestation has been employed to mitigate sandstorms – this represents a modification of airflow organisation. Consequently, for cold storage spaces with specific temperature requirements, how might one achieve optimal results by strategically arranging air coolers to rationally plan the airflow organisation?

Layout of Evaporator Air Coolers

(1) The evaporator (air cooler) is positioned beside the warehouse door. This arrangement offers the advantage of convenient operation, as warm air infiltrating the warehouse through the door is readily drawn in by the cooler, maintaining relatively stable temperatures near the door. The disadvantage is that it occupies a large area for operational walkways, resulting in lower warehouse utilisation.

(P2:Air cooler is positioned opposite the door)

(2) The air cooler is positioned opposite the door. This arrangement offers the advantage of occupying minimal space in the operational aisle, thereby maximising the utilisation of warehouse floor area. The disadvantage is significant temperature fluctuations on the door side. The positioning of the air cooler must also take into account the relative location of the plant room and the warehouse.

(P2:Air cooler is positioned beside the door)

Uniform Air Distribution Duct Layout and Design Requirements

The cold storage room for chilled goods houses fresh produce, requiring constant temperature and humidity. Temperature variations across different zones within the chamber must not exceed 0.5°C, while humidity differences should remain below 4%. As the foodstuffs continue to respire, significant heat and moisture exchange occurs, necessitating uniform airflow distribution. Consequently, uniform supply ducts are employed. When the cold room width exceeds 12m, supply ducts are positioned above the cold room aisle; For widths below 12m, supply ducts may be positioned above one side of the cold room. Design requirements for uniform supply ducts:

(1) Primary duct design: Initial section velocity 10–12m/s, height 450–630mm (typically 2–3 times the height, depending on air volume and duct diameter variation requirements).

(2) Terminal section dimensions: width shall not be less than height (for side-discharge ducts, if height exceeds width, discharge resistance increases). Employ a tapered design.

(3) Circular diffuser diameter shall be designed for a nozzle outlet velocity of 10–12 m/s. Louvered diffusers shall be designed for approximately 5–8 m/s, and slot diffusers for approximately 3–5 m/s.

(4) Number of outlets per section: Circular diffusers shall be designed with 4 or 6 outlets per section; louvred diffusers with 2 or 4 outlets per section.