IQF Internal Tube & Fin Evaporator

IQF Internal Tube & Fin Evaporator

The tube and fin evaporator mainly consists of heat exchanger tubes and fins.

The heat exchanger tube is usually made of copper or aluminum tube with good thermal conductivity. The refrigerant circulates inside the tube, and the cooling of the surrounding air or other media is realized through the evaporation of the refrigerant and heat absorption. The diameter and wall thickness of the heat exchanger tubes are selected according to the specific needs of the application to ensure adequate strength and pressure resistance while meeting the heat transfer requirements.

The fins are an important part of the tube and fin evaporator, and their function is to increase the heat transfer area and improve the heat transfer efficiency. The fins are usually made of aluminum or copper foil with good thermal conductivity and corrosion resistance. There are various shapes of fins, such as flat fins, corrugated fins, louvered fins, etc. Different shapes of fins have different heat transfer performance and air flow resistance.

The fins are connected to the heat exchanger tube by mechanical connection and welding. Mechanical connection usually adopts the method of expanding the tube or winding the fins to fix the fins closely on the heat exchanger tube. Welding method is through the brazing or welding will be connected to the fins and heat exchanger tube together, has the advantages of solid connection, good heat transfer performance, but the cost is relatively high.

In addition, the tube-fin evaporator also includes end plates, side plates, collector tubes and other components. The end plate and the side plate are used to fix the heat exchanger tube and the fins to form an integral structure. The collector tube is used to distribute and collect the refrigerant to ensure the uniform flow of refrigerant in the heat exchanger tube.

In the IQF system, the working principle of the tube and fin evaporator is based on the evaporation and heat absorption process of the refrigerant.

Refrigerant cycle

The refrigerant is compressed into a high temperature, high pressure gas under the action of the compressor and then enters the condenser. In the condenser, the refrigerant releases heat through heat exchange with outside air or water and condenses into a high-pressure liquid. The high-pressure liquid becomes a low-temperature, low-pressure liquid after being depressurized by a throttling device (e.g., an expansion valve) and enters a tube-fin evaporator.

Heat exchange process

In the tube-fin evaporator, low-temperature and low-pressure refrigerant liquid flows in the heat exchanger tube, at the same time, need to be cooled by the air or other media in the fins between the flow. The refrigerant exchanges heat with the fins through the wall of the heat exchanger tube, absorbs the heat of the surrounding air or medium, and evaporates into a low-temperature, low-pressure gas. The cooled air or medium is under the action of the fins, and the heat exchanger tube is in full contact with the heat transfer to the refrigerant, so as to realize the purpose of cooling.

Air flow and heat transfer

In an IQF system, a fan is usually used to force air flow through the tube and fin evaporator. As the air flows between the fins, it exchanges heat with the heat exchanger tubes and fins, gradually lowering the temperature. The speed and direction of air flow have a great influence on the heat exchange efficiency. Reasonable air flow design can improve the heat exchange efficiency, reduce the air flow resistance, and reduce the energy consumption of the fan.