Stainless Steel Coil in Evaporative Condenser

Stainless Steel Coil in Evaporative Condenser

Evaporative condenser is the key equipment used to condense refrigerant in the refrigeration system, its core principle is “water evaporation heat absorption + air forced convection” composite heat transfer, and stainless steel coil is the refrigerant and the outside world of the heat transfer “bridge”, the specific workflow The specific workflow is as follows:

high-temperature and high-pressure gaseous refrigerant in the refrigeration system into the interior of the stainless steel coil;

outside the coil at the same time “spray water cover” and “fan forced ventilation”: spray water on the surface of the coil to form a film of water, the air flows through the water film to accelerate the evaporation of water, take away the condensation of refrigerant inside the coil The heat of condensation of the refrigerant in the coil;

The gaseous refrigerant in the coil gradually condenses to liquid state due to exothermic heat, and finally flows into the liquid storage tank to complete the condensation cycle.

Evaporative condenser working environment there is water corrosion (spray water may contain impurities, salts), air oxidation, temperature fluctuations and other issues, ordinary metal coils (such as copper, carbon steel) is prone to failure, and stainless steel (especially 304, 316L series) can be a targeted solution to these pain points

304 stainless steel coils: suitable for general working conditions (such as civil refrigeration, food cold storage, spray water for tap water or softened water, no obvious corrosive media), cost-effective, and can be used in a variety of applications. Obviously corrosive media), cost-effective, is the mainstream choice;

316L stainless steel coil: for harsh conditions (such as chemical refrigeration, coastal areas (containing salty air), spray water for groundwater / industrial circulating water (containing impurities, weak acids and alkalis)), corrosion resistance is stronger, but the cost is higher than the 304 (about 30% -50% more expensive)

Pipe diameter: Commonly used φ19mm, φ22mm, φ25mm (outer diameter). The smaller the tube diameter, the larger the heat transfer area per unit volume (the higher the heat transfer efficiency), but the greater the refrigerant flow resistance; need to be combined with the refrigerant flow rate of the refrigeration system, the balance of the condensing load to choose (such as large cooling system (> 100kW) can be prioritized to select φ22-25mm, to reduce resistance).

Wall thickness: usually 0.8-1.5mm, too thin wall thickness is easy to deform due to pressure or collision, too thick to increase thermal resistance (reduce efficiency); 1.0-1.2mm for regular working conditions, 1.2-1.5mm for high-pressure working conditions (e.g., R410A refrigerant).

Coil arrangement: most of them are “serpentine coil” or “U-shaped coil”. “U-shaped coils”, the layout is divided into “smooth rows” and “fork rows”:

Fork rows: staggered spacing of the coils, the air flow through the disturbance is stronger, the heat transfer efficiency is higher than the smooth rows of 10%-15%, but the wind resistance is slightly larger; the smooth rows are more efficient than the smooth rows, but the wind resistance is slightly larger. However, the wind resistance is slightly larger;

Shun row: simple structure, easy to clean, suitable for easy scaling conditions (such as spray water quality is poor).