🔍 Key Concepts

• Thermal expansion differences between tubes and shell in heat exchangers • How U-tube, floating head, and packed tube sheet designs accommodate expansion • What it means mechanically when there is only one tube sheet at one end

💭 Think About

• Visualize the tube bundle layout: in which design do the tubes bend or curve so that they are fixed at only one end? • Ask yourself: which option clearly needs two tube sheets (one at each end of straight tubes) to seal tube-side fluid from shell-side fluid? • Consider which designs are specifically created to let one end move freely to absorb differential expansion without stressing the tubes.

✅ Before You Answer

• Identify which design uses straight tubes and therefore normally needs two tube sheets (one at each end). • Identify which design uses curved or bent tubes that return to the same end, allowing all tubes to be fixed into a single tube sheet. • Confirm which designs (like floating heads or special packed joints) still require a second structural sealing element at the opposite end, even if it can move.