Comparison of shell-and-tube and air-cooled heat exchangers

1. Structure and Principle of Shell-and-Tube Heat Exchangers

Shell-and-tube heat exchangers are water-cooled heat exchange devices. Their core structure consists of a steel shell, internal tube bundles, tube sheets, and end caps, resulting in a robust and well-organized structure. The working principle involves heat exchange between two fluids: one flows inside the tube bundle, while the other flows in the gap between the shell and the tube bundle. Water is the core cooling medium, and heat exchange is achieved through the tube walls. Common structural types include fixed tube sheet type, floating head type, and U-tube type.

2. Structure and Principle of Air-Cooled Heat Exchangers

Air-cooled heat exchangers are mostly finned tube structures, mainly composed of metal tube bundles, aluminum fins, axial flow fans, and frames. They do not require cooling water; instead, the fan drives ambient air to sweep across the finned tube bundles, and the heat exchange cycle is completed by air convection carrying away the heat from the fluid. The overall structure is lightweight and has no water circuit components.

1. Efficiency and stability of shell-and-tube heat exchangers

It boasts higher and more stable heat exchange efficiency. Water's thermal conductivity is far higher than air's, resulting in a smaller temperature difference, more efficient heat exchange, and high temperature control accuracy. The equipment is adaptable to constant temperature and stable operation, unaffected by minor fluctuations in ambient temperature. Even during long-term continuous operation, its heat exchange efficiency decays slowly, making it suitable for high-precision, high-load continuous production conditions. It can also accommodate phase change heat transfer (condensation, vaporization) to meet complex heat exchange requirements.

2. Efficiency and stability of air-cooled heat exchangers

The heat exchange efficiency is relatively low, and the air has poor thermal conductivity. Under the same operating conditions, the heat exchange efficiency is 15%-20% lower than that of shell and tube type. The operational stability is greatly affected by the ambient temperature. High temperatures in summer will cause the condensing temperature to rise and the heat exchange effect to decrease, forcing an increase in equipment load. Low temperatures in winter, rain, snow, and dusty weather will also slightly affect the heat exchange stability. The temperature control accuracy is relatively wide.

1. Adaptability of shell-and-tube heat exchangers to various operating conditions

Suitable for harsh industrial conditions, it boasts outstanding pressure and high temperature resistance, capable of withstanding temperatures up to 400℃ and pressures up to 10MPa, making it perfectly suited for high-pressure and high-temperature production scenarios in petroleum, chemical, and heavy industries. The tube bundle has a large flow cross-section, making it less prone to clogging. It can be adapted to corrosive and viscous fluids by replacing materials such as stainless steel and titanium, exhibiting strong durability and meeting the heat exchange needs of various complex industrial media.

2. Adaptability of air-cooled heat exchangers to various operating conditions

It is suitable for normal temperature and low pressure operating conditions, but cannot withstand high pressure and high temperature operations; it is only suitable for low-pressure fluid heat exchange. It requires high cleanliness of the medium; viscous, impurity-rich, or highly corrosive media can easily cause fin blockage and corrosion damage. Its core advantage is its adaptability to water-scarce, remote, and unsupported water supply sites, making it unrestricted by water resources and offering greater flexibility in environmental adaptation.

1. Installation and floor space requirements of shell-and-tube heat exchangers

It occupies a small area and has a compact overall design. It can be installed in both vertical and horizontal configurations to suit small workshop spaces. However, it has high installation requirements. A complete cooling water system must be built, including a cooling tower, circulating water pump, water pipes, valves, water treatment equipment, etc. The installation process is complex and has strict requirements on the site's water supply and drainage infrastructure.

2. Installation and floor space requirements of air-cooled heat exchangers

No water system is required; it only needs a power supply to operate. The installation process is simple and the construction period is short, making it suitable for outdoor, open-air, and remote construction sites. The disadvantages are that the equipment is large in size and occupies a large area, requiring sufficient ventilation space to ensure air convection. It cannot be installed or used in enclosed indoor spaces.