An evaporative condenser uses water and air as cooling media and uses the evaporation of water to remove the condensation heat of the vapor refrigerant.

During operation, cooling water is pumped to the upper nozzle of the condensing tube group and evenly sprayed on the outer surface of the condensing tube group, forming a thin water film. High-temperature vapor refrigerant enters from the upper part of the condensing tube group and is condensed into a liquid by the cooling water outside the tube, which flows out from the lower part. Part of the water that absorbs heat evaporates into steam, while the rest falls into the lower water collection tray. The water supply pump is used for circulation, The fan forces the air to pass through the condensing exhaust pipe at a speed of 3-5 m/s, promoting water film evaporation, strengthening the heat release outside the condensing pipe, and cooling the absorbed water droplets by the air during the falling process. The evaporated water vapor is discharged from the air by the fan, and the non-evaporated water droplets are blocked by the dehydrator from falling back into the water tray.

A float valve is installed in the water tray to automatically replenish the cooling water volume.

According to the different heat exchange components, it can be divided into coil evaporative condensers and plate evaporative condensers. This article mainly introduces the plate evaporative condenser.

When the Superheated steam discharged from the refrigeration compressor enters the condensing heat exchange plate, the cooling circulating water is continuously sprayed on the outside of the heat exchange plate, forming a water film on the outer surface of the condensing plate and flowing down. After the water film absorbs the heat of the refrigerant from the condensing plate wall, part of the water is evaporated into steam under the effect of evaporation, Being carried away by rapidly flowing air effectively utilizes the latent heat of water evaporation, achieving the purpose of condensing and cooling the refrigerant gas inside the plate with less water, and enhancing the heat transfer effect. The main function of air is to carry away the evaporated water vapor outside the condensing plate. When the temperature of the air is lower than the water temperature, it can also play a certain cooling role. The air flows from bottom to top or intersects with the spray water to blow away from the surface of the water film. In addition to carrying away the water vapor, it also carries some small water droplets. In order to reduce the loss of water due to blowing, a water baffle is installed between the condensing plate bundle and the fan. Its function is to separate the water droplets carried in the air as much as possible.

Analysis of Heat Transfer Performance of Plate Evaporative Condenser

Liquid flows downward along the wall in a thin layer under the action of gravity, known as liquid thin film flow. It has the advantages of a small flow rate, small temperature difference, high heat transfer, mass transfer coefficient, high heat flux density, simple structure, and low power consumption. Its heat and mass transfer characteristics include high efficiency, high intensity, and small temperature or concentration gradient; Low flow rate and low power consumption; The contact area between liquid-solid and gas-liquid phases is large, the heat and mass transfer are sufficient, and the process time is short.

Using liquid film for heat and mass transfer has become one of the most important Unit operations in power, chemical, food, and other industries. The plate evaporative condenser is an efficient, energy-saving, and water-saving cooling equipment developed based on the heat and mass transfer theory of liquid thin film flow and the mechanism of evaporation and condensation heat transfer. Its working process can be divided into: the process fluid inside the plate condenses and then transfers heat to the outer water film of the plate covered by the thin water film through the plate wall. After evaporation, the heat is transferred to the air, and finally, the air discharges this part of the heat and water vapor. This is a typical process of mass transfer driving heat transfer.

The main factors affecting the heat transfer performance of plate evaporative condensers include spray water flow rate, wind speed, steam liquid flow direction, and the position of process fluid inlet and outlet.