Which type of heat exchanger is not usually used with steam because condensate does not easily drain from them?

The plate type heat exchanger is not typically used with steam applications due to its design, which can make it difficult for condensate to drain effectively. Plate heat exchangers have a series of thin plates arranged in a way that creates channels for the fluids to flow. While they are efficient for transferring heat between two fluids, they can trap condensate. This retention can lead to operational issues, such as decreased efficiency or even damage to the heat exchanger if the trapped condensate causes water hammer or corrosion.

In contrast, other types of heat exchangers, such as the tubular, screw, and shell and tube types, generally provide better drainage capabilities for condensate. For example, the shell and tube heat exchanger allows for easier removal of condensate through its larger tubes and shell configuration, making it more suitable for steam applications where proper drainage is crucial for efficient operation.