How to improve heat transfer efficiency of evaporative condenser

Evaporative condenser, as an efficient and water-saving heat exchange device, has been widely used in refrigeration, chemical, power and other fields. The core principle is to simultaneously utilize the latent heat of evaporation of water and the sensible heat exchange of air to remove system heat, so its heat exchange efficiency is much higher than that of simple air-cooled or water-cooled condensers. However, in actual operation, various factors can affect its efficiency. To comprehensively improve the heat transfer efficiency of evaporative condensers, systematic optimization is needed from multiple dimensions such as design, operation, maintenance, and management.

1、 Review of Core Mechanisms and Efficiency Influencing Factors

Before exploring how to improve efficiency, it is necessary to first understand its heat transfer mechanism. The heat exchange process is mainly divided into two stages:

Sensible heat exchange: The high-temperature refrigerant inside the tube undergoes convective heat exchange with the water film outside the tube, transferring heat to the water film and raising the water temperature.

Latent heat exchange: When a water film comes into contact with flowing air, a portion of the water evaporates, absorbing a large amount of latent heat of vaporization, thereby efficiently carrying heat into the atmosphere.

The total heat transfer is the sum of sensible heat transfer and latent heat transfer. Therefore, all measures to increase the evaporation rate of water film and enhance heat conduction can effectively improve efficiency. The main influencing factors include: spray water distribution, air flow rate, water to air ratio, heat exchange tube bundle characteristics, water quality, etc.

2、 Key strategies for improving heat transfer efficiency

1. Optimize the spray water system to ensure a uniform and complete water film

Water film is a key medium for heat transfer from the pipe wall to the air. A thin, uniform, and complete water film covering all surfaces of the heat exchange tubes is crucial.

Selection and layout of nozzles: Choose nozzles that are not easily clogged, have good atomization effect, and are evenly distributed. Regularly check whether the nozzle is blocked or damaged, and replace it in a timely manner. The arrangement of nozzles should ensure that there are no "dry spots" (pipe surfaces without water film coverage), as dry spots can cause a sharp increase in heat transfer resistance in the area and a sudden drop in overall efficiency.

Maintain spray water volume: The water volume is too small to form a complete water film, and some pipe walls are dry; Excessive water volume not only increases the power consumption of the water pump, but also leads to a thick water film, which in turn increases the thermal resistance and may cause water loss. There exists a water to air ratio (the ratio of spray water volume to air flow rate) that needs to be determined through calculation and debugging to achieve high evaporation efficiency.