Why is the energy-saving effect of evaporative condenser more significant

In refrigeration and air conditioning systems, the condenser is a crucial component that cools and liquefies the high-temperature, high-pressure gaseous refrigerant discharged from the compressor. Traditional condensers mainly include air-cooled and water-cooled (with supporting cooling towers), while evaporative condensers cleverly combine the principles of the two and introduce the efficient natural process of water evaporation and heat absorption, thereby achieving significant energy-saving effects. Its energy-saving advantages are mainly reflected in the following aspects:

1. Core principle: Utilizing the latent heat of evaporation of water, the heat transfer efficiency is extremely high

This is the fundamental reason for the energy-saving of evaporative condensers. Its thermodynamic principles determine its unparalleled efficiency.

The difference between sensible heat and latent heat: Traditional air-cooled condensers only use the sensible heat of air (i.e. the heat absorbed by the increase in air temperature) for cooling. The specific heat capacity of air is very small (about 1.005 kJ/kg · K), and the temperature rise is limited, so a huge air flow is required to remove heat, resulting in high energy consumption of the fan.

Water cooling+cooling tower system: Although it utilizes the evaporation of water, the cooling tower is responsible for dissipating the system's heat into the atmosphere, while the condenser itself (shell and tube or plate type) still relies mainly on the sensible heat of water (rising water temperature) to absorb heat. The water pump needs to circulate a large amount of water to the cooling tower, and the energy consumption of the water pump is considerable.

The breakthrough of evaporative condenser: it directly places the heat exchange coil in a water spray system and uses a fan to guide the air flow. Water is sprayed onto the surface of the coil to form a water film, while air is swept over from outside the water film. The heat exchange process combines sensible heat transfer and latent heat transfer:

Sensible heat transfer: The heat of the refrigerant inside the coil is transferred to the water film through the tube wall, causing the temperature of the water film to increase.

Latent heat transfer (dominant): The flowing air promotes the evaporation of water molecules on the surface of the water film. When water evaporates, it needs to absorb a large amount of latent heat of vaporization (about 2257 kJ/kg), which is directly taken from the water film and coil, greatly enhancing the cooling effect.

Due to the fact that the latent heat of evaporation of water is much greater than its sensible heat (only 21 kJ of sensible heat is required to raise 1 kg of water by 5 ° C, while evaporating 1 kg of water requires 2257 kJ of latent heat), a small amount of water evaporation can take away a huge amount of heat, resulting in extremely high efficiency.