Heat Exchanger Design Calculator

Mass Flow Rate of Hot Fluid (kg/s):

Specific Heat of Hot Fluid (kJ/kg·K):

Hot Fluid Inlet Temp (°C):

Hot Fluid Outlet Temp (°C):

Cold Fluid Inlet Temp (°C):

Cold Fluid Outlet Temp (°C):

Overall Heat Transfer Coefficient U (W/m²·K):

Heat Duty (Q):

LMTD (ΔTlm):

Required Area (A):

About Heat Exchanger Design

Heat exchangers transfer heat between two fluids at different temperatures. The LMTD (Log Mean Temperature Difference) method is a common approach to design.

Formulas used:

Heat Duty: Q = ṁh × Cph × (Th,in − Th,out)
LMTD: ΔTlm = (ΔT1 − ΔT2) / ln(ΔT1/ΔT2)
Area: A = Q / (U × ΔTlm)

Where ΔT1 = Th,in − Tc,out, ΔT2 = Th,out − Tc,in. Results help engineers size exchangers for efficient performance.

FAQs

Q: Why use LMTD instead of average temperature difference?
A: Because temperature difference changes along the length of exchanger.

Q: What are typical U values?
A: From ~100 W/m²·K for gases to ~1000 W/m²·K for liquid-liquid exchangers.

Q: What if ΔT1 = ΔT2?
A: Then LMTD = ΔT1 (limit case).