The full name is copper tube string fin surface cooler. The principle is to let the heat medium or cold medium or refrigeration working medium flow through the inner cavity of the metal pipe, and the gas to be processed flows through the outer wall of the metal pipe for heat exchange to achieve the purpose of heating or cooling the gas. The purpose of string fins is to increase the heat exchange area and improve the heat exchange effect. The copper tube has better heat exchange effect than the stainless steel tube, and the copper tube surface cooler is generally used for the working conditions that do not corrode the copper tube.