Ingersoll Rand Air Compressor Tube Coolers

Tube coolers have a long history of use. Through continuous improvements, their size and weight have been reduced, and they remain the most commonly used type in Ingersoll Rand compressor units. There are three types of tube coolers: serpentine, shell-and-tube, and tubular.

1. Serpentine Cooler

A serpentine cooler consists of tubes wound into a spiral shape and placed within a housing. Gas flows inside the tubes, while water flows outside the housing.

Cooling water enters from the bottom of the housing and flows out from the top. As the water gradually rises, its temperature gradually increases, utilizing natural convection.

The characteristics of serpentine coolers are simple structure, ease of manufacturing, and the ability to combine several intercoolers into a compact design.

Ingersoll Rand Air Compressor Oil Coolers

However, the cooling water flows slowly within a large housing, resulting in poor cooling efficiency. Generally, copper is used for the serpentine tubes to improve overall heat transfer.

Ingersoll Rand Air Compressor Oil Coolers

However, the cooling water flow rate is slow within a large housing, resulting in poor cooling performance. Generally, copper is used for the serpentine tubes to improve overall heat transfer.

Furthermore, the tube diameter should not be too large. Large-diameter tubes not only have poor heat transfer but are also more difficult to bend. Therefore, coil coolers are only suitable for compressors with small gas volumes, but the pressure is not limited.

2. Shell-and-Tube Coolers

A coaxial cooler consists of an outer tube surrounding the main tube. Gas flows between the inner and outer tubes, while water flows inside. To increase the heat transfer area, longitudinal fins are welded to the outer side of the inner tube.

Considering the inconsistency in thermal expansion between the inner and outer tubes during operation, compensation measures are taken. Coaxial coolers with gas flowing between the inner and outer tubes are generally suitable for high pressures with a cold medium inlet pressure of 20 MPa.

Because the outer tube diameter is larger than the hot medium outlet diameter, the wall thickness increases at higher pressures, making it uneconomical. Furthermore, sealing the compensation points is difficult.

Therefore, for higher pressure coaxial coolers, the cold medium outlet should allow gas to flow inside the tubes, while water flows between the inner and outer tubes. The tube diameter of coaxial coolers should also not be too large, generally suitable for high-pressure stages, as the structure is not compact, resulting in relatively large dimensions and weight.

3. Deck-and-Tube Coolers

A schematic diagram of a low-pressure shell-and-tube cooler shows a core consisting of a series of parallel, smooth cylindrical tubes expanded onto two end plates. The core is housed within a cylindrical shell with end caps at both ends.

Gas flows outside the heat exchange tubes, guided by specially designed baffles to flow perpendicularly across the tube bundle, meandering forward. Water flows inside the heat exchange tubes.

Gas enters from one end of the shell-side inlet and exits from the other. As the gas is gradually cooled, its density increases, causing it to sink in the direction of flow. To maintain a necessary airflow velocity, the baffle spacing varies, starting larger and gradually decreasing.

Because the compressor’s exhaust is pulsating, the baffles are subjected to pulsating loads, requiring good support and positioning. If the baffles are not securely supported, vibrations during operation and continuous friction between the baffles and the tube walls may cause the tube walls to rub through, leading to air leakage.

In more serious cases, the baffles may detach from the support rods, and several baffles may stack together, blocking the passage and causing a major accident.