Heat Exchanger LMTD & Temperature Efficiency (TEMA)

Calculate Logarithmic Mean Temperature Difference (LMTD) for counter-flow and parallel-flow shell & tube heat exchangers.

💡 Engineering Knowledge PrimerLog Mean Temperature Difference (LMTD) quantifies the effective thermal driving force for heat transfer across heat exchanger tube bundles. Counter-flow orientation maximizes LMTD compared to co-current flow.

CALCULATION SCOPE — Deterministic calculation within the published assumptions. Independently verify all design decisions and project-specific code requirements.

INPUT DESIGN PARAMETERS (SI)

Hot Stream Inlet Temp (Th,in)[°C]

°C

Hot Stream Outlet Temp (Th,out)[°C]

°C

Cold Stream Inlet Temp (Tc,in)[°C]

°C

Cold Stream Outlet Temp (Tc,out)[°C]

°C

CALCULATED SPECIFICATION OUTPUT

Log Mean Temperature Difference (LMTD)

42.06 °C

Terminal Temperature Ratio (ΔT1/ΔT2)

1.43 1

Related planning checklists

This calculator appears in the following engineering planning checklists:

HVAC Controls & Automation

Controls Engineer

1. 4-20mA Analog Sensor Signal Scaling2. PID Controller Loop Tuning (Ziegler-Nichols)3. Heat Exchanger LMTD & Temperature Efficiency (TEMA)4. Industrial Chilled Water Cooling Capacity (HVAC)

Technical Methodology & Engineering Principles

GOVERNING EQUATION

ΔT1 = Th,in - Tc,out ΔT2 = Th,out - Tc,in LMTD = (ΔT1 - ΔT2) / ln(ΔT1 / ΔT2)

Assumptions & Scope

True counter-current flow orientation without phase change.

Operating Range & Boundary

Use finite, physically meaningful inputs within the stated operating assumptions.

Peer Reference: Standards of the Tubular Exchanger Manufacturers Association (TEMA 10th ed.).