Shell & Tube Heat Exchanger LMTD Calculator
Calculate counterflow Log Mean Temperature Difference (LMTD), TEMA multipass F-correction factors, thermal duty, and required tube surface area.
Hot & Cold Stream Temperatures
Exchanger Pass & Overall U-Value
LMTD & Surface Area Sizing
Thermal Effectiveness Parameters
TEMA Engineering Advisory
Recommended Tools & Equipment
Tested hardware and components for high reliability
Frequently Asked Questions
What is Log Mean Temperature Difference (LMTD) and why is arithmetic mean wrong?
In a heat exchanger, fluid temperatures change non-linearly along the tube bundle as heat transfers. An arithmetic average temperature difference severely overestimates the true driving force. The logarithmic mean (LMTD) mathematically integrates the exact exponential decay curve across the surface.
What is the TEMA F-correction factor in multipass shell-and-tube exchangers?
In multipass exchangers (e.g. 1 shell pass with 2 or 4 tube passes), fluid flows co-current on some passes and counter-current on others. The F-correction factor adjusts the ideal pure counterflow LMTD: Effective LMTD = F × LMTD_counter. TEMA standards mandate F ≥ 0.75–0.80.
What is a "temperature cross" and why does it break a single-shell design?
A temperature cross occurs when the cold fluid exit temperature is higher than the hot fluid exit temperature (Tc2 > Th2). In a single-shell multipass exchanger, this causes heat to flow backwards from cold fluid into hot fluid during the co-current pass. Overcoming this requires two or more shells in series.
What are typical overall heat transfer coefficients (U-values)?
Typical U-values: Water-to-water: 150 to 300 BTU/(hr·ft²·°F); Organic solvent to water: 50 to 120; Steam condensing to water: 300 to 600; Gas/Air to liquid: 10 to 30.