6 Common Types Of Evaporators Used In Chillers：A Complete Guide

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1 6 Common Types Of Evaporators Used In Chillers：A Complete Guide

1.1 Shell and Tube Evaporator

1.2 Plate Evaporator

1.3 Coil Evaporator

1.4 Finned Tube Evaporator

1.5 Flooded Evaporator

The evaporator is the core component of the industrial chiller, where the refrigerant and coolant exchange the heat. Therefore, the performance of the evaporator will affect the heat exchange efficiency of the chiller.What types of evaporators are commonly used? What are their key features? And how do you choose the right one? This article will tell you the answer.

Type	Main Feature	Pros	Cons	Typical Use
Shell and Tube	Tube bundle in shell	High pressure, durable	Bulky, costly	Large chillers
Plate	Stacked metal plates	Compact, efficient	Leak risk, gasket-limited	HVAC, food, lab
Coil	Spiral coil in tank	Simple, low cost	Large, lower efficiency	Low-temp chillers
Finned Tube	Tubes with aluminum fins	High efficiency, light	Dust-prone	Air cooling
Flooded	Tubes in refrigerant bath	Very efficient	Big, expensive	Industrial chillers
Dry	Refrigerant in tubes	Simple, cheap	Less efficient	Small chillers

Shell and Tube Evaporator

The shell and tube evaporator, as its name suggests, consists of a shell and multiple metal tube bundles inside. Generally, the refrigerant flows in the shell and the coolant flows in the tube bundle. The two can also be reversed, depending on the design of the evaporator. The refrigerant absorbs the heat of the coolant and evaporates in the shell.

The shell and tube heat exchanger has strong pressure resistance and anti-fouling ability, and is suitable for high-pressure and high-temperature scenarios. However, it is large in size, and the purchase and maintenance costs are relatively high. It is commonly used in large chillers for chemical processing, pharmaceutical production, power plants, and similar industries.

Plate Evaporator

Plate evaporators are made of many metal plates stacked together, and resemble a stack of layered wafers or plates..These plates are fixed by frame plates, pressure plates, bolts, gaskets and other parts. An independent cavity is formed between two adjacent metal plates. Different media flow in the two adjacent cavities, so they can exchange heat without mixing.

The metal plates are usually made of stainless steel or titanium, with specially designed patterns on the surface. The most common is the corrugated plate with a corrugated shape. The surface patterns help increase turbulence and promote even flow distribution, improving heat transfer efficiency.

The plate heat exchanger increases the heat exchange area between different media. The number of metal plates can be flexibly increased or decreased. Its purchase, installation and maintenance costs are lower than other types of evaporators. However, its operating temperature is limited by the temperature resistance of the gasket, and it is easy to leak when the seal is not good.

Coil Evaporator

The coil evaporator consists of a spiral coil structure, copper or stainless steel pipes, brackets, coolant boxes and other components. The pipe is the channel for the refrigerant. The spiral coil is used to increase the heat exchange area and evenly distribute the fluid. The coolant box is filled with chilled water or heat transfer oil, and the coil is immersed in it.

The evaporator coil has a simple structure, and the material and manufacturing costs are relatively low. It can be installed in an existing liquid tank, which is very suitable for low-temperature systems. However, it is relatively large in size, and the tube wall introduces thermal resistance.

The heat exchange efficiency is not as good as that of plate heat exchangers and full liquid heat exchangers. Coil evaporators are generally used in temperature control systems such as small chillers, glycol chillers, and oil chillers.

Finned Tube Evaporator

Finned evaporators are usually used for heat exchange between air and refrigerant. The main parts are composed of heat exchange tubes and fins. The heat exchange tubes are generally made of copper, which has good thermal conductivity and strong corrosion resistance. The shape is generally serpentine or straight tube arrangement, and the former is more commonly used.

The fin material is generally aluminum, which will be treated with hydrophilic-coated. They come in various shapes, including flat, corrugated, and perforated types. The fins and copper tubes are combined by mechanical expansion. The closer the fit between the two, the better the heat exchange efficiency. The refrigerant will flow in the heat exchange tube, and the air will be pushed by the fan outside the fins to exchange heat through convection

The fin design of the finned evaporator increases the heat exchange area and has a high heat exchange efficiency. Moreover, the structure is simple and the weight is relatively light. However, its fins are prone to dust accumulation and need to be cleaned frequently.

Flooded Evaporator

The flooded evaporator consists of a shell, heat exchange tubes, and a liquid separator. Its shell is filled with refrigerant, and the coolant flows in the heat exchange tubes. The heat exchange tubes are generally made of copper or stainless steel, and the arrangement varies according to the design.

After the refrigerant liquid enters the flooded evaporator, it will be evenly distributed at the bottom of the shell by the liquid separator. The chiller fluid in the heat exchange tube and the refrigerant outside the tube are indirectly contacted for heat exchange.

Since the heat exchange tube is completely immersed in the refrigerant, the heat exchange efficiency is very high. The refrigerant liquid that has not been completely evaporated will be intercepted by the gas-liquid separator and returned to the shell.

The flooded evaporator occupies a relatively large area and has a high initial cost. It is generally used in medium and large industrial chillers.

Dry Evaporator

In a dry evaporator, the refrigerant flows inside the heat exchange tubes, while the coolant circulates around them in the shell. The coolant surrounds the refrigerant in the heat exchange tubes. Its heat exchange tubes are generally copper tubes, internally threaded tubes or enhanced heat transfer tubes. The refrigerant absorbs the heat of the coolant in the shell and evaporates, entering the compressor through the steam outlet.

The advantage of the dry evaporator is that it has a simple structure and low manufacturing cost. However, it has a limited heat transfer area and a lower heat transfer efficiency than the flooded evaporator. Therefore, it is suitable for small chillers and modular chillers.

Conclusion

Common evaporators used in chillers include shell and tube evaporators, plate evaporators, fin evaporators, coil evaporators, flooded evaporators, dry evaporators, etc. You need to choose according to the heat exchange area, budget, cooling method, space, etc.

LNEYA offers a variety of standard and customized chillers. If you don’t know which evaporator is suitable for your industrial application, our experienced technicians are here to help you choose the most suitable evaporator based on your specific requirements.Just ask!