Forced Draft ACHE Air-Cooled Heat Exchanger, ASME / API Standard, In Various Refining Processes

ACHE Overview

Air cooled heat exchanger (ACHE) is a heat exchange device that uses ambient air as a cooling medium to remove heat. Its core feature is that it does not require the consumption of process cooling water and achieves cooling through indirect heat transfer between air and high-temperature fluids (liquids or gases), belonging to the "dry cooling" technology.

Core principle of Air Cooler

1. Heat transfer method

• High temperature process fluids (such as lubricating oil, hot water, steam, process gases, etc.) flow in a closed tube side; The ambient air is forced to flow over the surface of the outer fins of the tube under the drive of the fan. Heat is transferred from the fluid to the air through the tube walls and fins, and the air is discharged into the atmosphere after heating up. No phase change: only sensible heat exchange occurs (air temperature rises), without involving water evaporation (different from "wet" cooling towers).
• Indirect contact: Air and process fluid are isolated by metal walls to avoid contamination.

2. Core structure "finned tube"

• Aluminum/copper fins are tightly embedded outside the tube to increase the heat transfer area on the air side (due to poor air thermal conductivity, area compensation needs to be expanded).
• Common types: winding finned tube, brazed plate finned tube (compact type, used for gas cooling)

How It Works

1. Hot process fluid flows through the tubes.
2. Air flows over the finned surface of the tubes (forced or pulled by fans).
3. Heat is transferred from the fluid to the fins, then to the air.
4. Cooled fluid exits the exchanger; hot air is expelled to the atmosphere.

Basic Components of an ACHE