Keep in mind that heat moves from a hotter to a colder substance. As a result, the temperature of the evaporator must be lower than the ambient temperature. When utilizing refrigerant-22, the evaporator coil temperature of a residential air conditioner would be 40°F, which is the boiling temperature at 68.5 PSIG (R-22). The refrigerant in the evaporator will boil as long as the air passing over it stays above 40°F, collecting heat from the room air and transmitting it to the refrigerant. Alaqua is an evaporators supplier that also supplies other processing equipment like crystallizers, solvent recovery systems, distillation, and heat exchangers.
Evaporators are utilized in a variety of refrigeration applications and hence have a variety of designs. The architecture of the evaporator, the technique of feeding the refrigerant, the direction of air circulation around the evaporator, and other factors may all be used to classify evaporators. The evaporators have been categorized depending on their construction.
Evaporators Classification Based On Their Construction
Depending on the application, several styles of construction are employed in evaporators for refrigeration and air conditioning. The different types of evaporators are classified according to their construction:
Bare Tube Evaporators
Copper tubing or steel pipes comprise the bare tube evaporators. Small evaporators with a refrigerant other than ammonia utilize copper tubing, whereas big evaporators with ammonia as the refrigerant use steel pipes. The bare tube evaporator is made up of multiple rounds of tubing, the most frequent forms being flat, zigzag, and oval trombone. Liquid cooling is commonly done with bare tube evaporators. The ambient air passes over the bare tube evaporator during the blast cooling and freezing processes, and the chilled air leaves it to be used for cooling. Bare tube evaporators services are employed in a limited number of applications, while finned evaporators, which are bare tube evaporators with fins, are widely utilized.
Plate Type Evaporators
The coil, which is generally composed of copper or aluminum, is inserted into the plate to provide a smooth appearing surface in plate evaporators. The plate evaporator seems to be a single plate from the outside, but inside it has multiple turns of metal tubing through which the refrigerant flows. Plate evaporators have the benefit of being more robust due to the exterior plate providing a lot of safety. Additionally, the exterior plate aids in boosting heat transmission from the metal tube to the chilled material. In addition, plate evaporators are simple to clean and can be produced inexpensively.
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Plate type heat exchangers may be readily shaped into a variety of forms to meet the needs of the application. Thus, in most domestic refrigerators and deep freezers, they may be transformed into a box shape to provide a closed enclosure where various foods can be stored frozen. The plates can also be welded together to form a bank of plate evaporators, which are suitable for bigger, higher-capacity evaporators.
Plate Evaporators make great freezer shelves and other uses. They are great for freezer dividers, frozen food display cases, ice cream cabinets, and soda fountains, among other things. The plate type of evaporator is widely utilized due to the numerous advantages and flexibility it provides.
Finned Evaporators
Finned evaporators are bare tube evaporators that have been coated with fins. When the chilled fluid (air or water) passes through a bare tube evaporator, most of the refrigerant’s chilling action is lost since there is less surface area for heat transfer from the fluid to the refrigerant. Because the fluid tends to travel through the tubing’s open gaps and does not come into contact with the coil’s surface, bare tube evaporators are less effective. Fins on the outside of bare tube evaporators enhance the contact surface of the metallic tubing with the fluid and therefore improve the heat transfer rate, making finned evaporators more effective than bare tube evaporators.
Fins are protrusions from the coil’s surface that extend into space. They aid in the removal of heat from the fluid that would not have otherwise come into touch with the coil.
It is critical that the coil and the fins make excellent contact in order for the fins to work well. In some situations, the fins are soldered directly to the coil’s surface, while in others, the fins are simply slipped over the surface of the fins and then expanded, resulting in tight thermal contact. Though fins aid in heat transmission, adding them in excess of a specific number will provide no extra benefits; thus, only a certain number of fins should be placed to the tube’s exterior surface.
Window, split, packaged, and central air conditioning systems all employ finned evaporators. The cooling coil is commonly referred to as the finned evaporator in these systems. The heated room air passes through the finned evaporator or cooling coil, becomes cooled, and then returns to the room to cool it. Finned evaporators are hidden behind the attractive grill in window air conditioning. It’s hidden below the front grill of the indoor unit in the wall-mounted split system.
Internal fins are added to the tubing to further improve the efficiency of heat transmission from the evaporators. These fins are created by creating various internal cross-section forms while the tube is being produced.
Tube or Shell Type Evaporators
In large refrigeration and central air conditioning systems, evaporators of the shell and tube types are utilized. Chillers are the usual name for the evaporators in these systems. A huge number of tubes are placed within the drum or shell to make up the chillers. Dry expansion type and flooded type chillers are categorized based on the refrigerant flow direction in shell and tube chillers. The refrigerant runs along the tube side of a dry expansion chiller, while the fluid to be cooled flows along the shell side. The expansion valve regulates the refrigerant flow to these chillers. The refrigerant runs along the shell side of flooded evaporators, while the fluid to be cooled flows down the tube. The float valve, which also serves as an expansion valve in these chillers, keeps the refrigerant level constant.
Alaqua supplies processing equipment such as crystallizers, distillation equipment, solvent recovery systems, spray dryers, heat exchangers, and evaporators made in USA for food and beverages, pharmaceutical, and other industries along with equipment fabrication, installing and commissioning, personnel training, retrofitting, field and troubleshooting services. Contact them today to know more!
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