Straight-tube heat exchangers have tubes running through their length from one end to the other, providing minimal resistance to flow and making them easier to clean and maintain than U-tube heat exchangers. Built with tube sheets permanently fixed in place, they are best suited for continuous-duty applications where the difference in temperature between fluids is relatively consistent, reducing the chance of thermal cycling and stress fractures.

U-tube heat exchangers feature tubes that run from one end to the other, turn around, and exit at the same end they came in. Their tube bundle is designed to be a dual-pass heat exchanger where one of the fluids runs the length of the exchanger twice. This design is suited for higher temperature differentials as it gives more dwell time and allows for thermal expansion of the tubes as they are only connected to the shell at one end. Their tube bundles are easily removed for cleaning, inspection, and maintenance.