Heat Exchanger Configuration
Select the heat exchanger type and flow arrangement. Geometry inputs will update automatically based on your selection.
Geometry
Enter the physical dimensions of the heat exchanger. These drive heat transfer area, velocity, and resistance calculations.
Process Conditions — Hot Side
Enter the inlet and outlet conditions for the hot-side fluid. Fouling factors default to TEMA standards based on fluid type.
Process Conditions — Cold Side
Enter the cold-side fluid conditions. At least inlet temperature is required for LMTD calculations.
Metallurgy
Select tube and shell materials. Thermal conductivity auto-fills from selection and is editable. Wall resistance is calculated from geometry and conductivity.
Known Performance optional
Enter the design U coefficient from the original datasheet. Cleanliness factor and fouling margin are calculated by comparing the design U against the U calculated from your process inputs. Heat duty Q override is optional.
Calculate & Results
Click Calculate to run all available computations based on provided inputs. Blank inputs are allowed — the calculator computes what it can.
Formulas & References
LMTD = (ΔT₁ − ΔT₂) / ln(ΔT₁/ΔT₂)For countercurrent: ΔT₁ = Th,in − Tc,out ; ΔT₂ = Th,out − Tc,in
For cocurrent: ΔT₁ = Th,in − Tc,in ; ΔT₂ = Th,out − Tc,out
Q = U × A × F × LMTDF = correction factor for multi-pass or crossflow arrangements (F=1 for ideal countercurrent). Calculated via P-R method per TEMA standards. Values of F < 0.75 indicate a thermodynamically unfavorable design.
1/U = 1/hs + Rf,s + (tw/kw)(Ao/Alm) + Rf,t(Ao/Ai) + (Ao/Ai)(1/ht)Where hs = shell-side HTC, ht = tube-side HTC, Rf = fouling resistance, tw = wall thickness, kw = wall conductivity, Ao/Ai = OD/ID area ratio, Alm = log-mean area.
Nu = 0.023 × Re0.8 × Prnn = 0.4 for heating, 0.3 for cooling. Valid for Re > 10,000 and 0.7 < Pr < 160. For 2,300 < Re < 10,000 (transitional), the Gnielinski correlation is used: Nu = (f/8)(Re−1000)Pr / [1 + 12.7(f/8)0.5(Pr2/3−1)].
Shell-side HTC estimated via simplified Bell-Delaware approach accounting for baffle geometry, bundle bypass, and leakage effects. Reference: Kern (1950) and Bell & Delaware (1963).
hs = hideal × Jc × Jl × JbJc = baffle cut correction, Jl = leakage factor, Jb = bundle bypass factor (simplified to 1.0 in this calculator).
CF (%) = Uoperating / Uclean × 100%CF < 85% typically indicates cleaning is warranted. CF < 75% indicates significant fouling reducing heat transfer capacity. Reference: HEI Standards for Steam Surface Condensers.
Rf = 1/Udirty − 1/UcleanNTU = U × A / CminCmin = min(ṁh·Cp,h, ṁc·Cp,c)ε = Q / Qmax = Q / [Cmin(Th,in − Tc,in)]For countercurrent flow: ε = [1 − exp(−NTU(1−C*))] / [1 − C*·exp(−NTU(1−C*))] where C* = Cmin/Cmax.
Cooling water — treated: 0.001Cooling water — untreated: 0.002Steam — clean: 0.0005Process water: 0.002Oil / lube: 0.002Process gas: 0.001FTSI = (q″ × RT) / 50,000q″ = heat flux density (BTU/h·ft²) = Q / Ainner | RT = residence time in heat transfer zone (seconds) = Vtube / Q̇vol
Surface temperature: Tsurf = Tbulk,cold + q″ / htube
FTSI quantifies the combined driving force for fouling from heat flux, residence time, and surface temperature. Values below 2 indicate low fouling stress; 2–3 are manageable with chemical treatment; above 3.5 indicates conditions requiring operational or design review. For plate & frame exchangers, a corrugation-angle correction factor is applied to account for enhanced turbulence. Reference: Epstein (1981); Beardwood et al. (2009–2021); IWA methodology.
References: TEMA Standards (9th ed.); Kern, D.Q. — Process Heat Transfer; Bell & Delaware method; HEI Standards for Steam Surface Condensers; Incropera & DeWitt — Fundamentals of Heat and Mass Transfer; Epstein, N. (1981) Fouling in Heat Exchangers, in Multiphase Science and Technology; Beardwood, E.S. et al. (2009–2021) Heat Exchanger Fouling and Cleaning Conference Proceedings.