Heat Exchanger Sizing Calculation

Heat Exchanger Area Equation:

\[ A = \frac{Q}{U \times \Delta T_{lm}} \]

Heat Transfer Rate (Q):

Overall Heat Transfer Coefficient (U):

W/m²K

Log Mean Temperature Difference (ΔT_lm):

Required Heat Transfer Area (A):

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1. What Is Heat Exchanger Sizing Calculation?

Heat exchanger sizing calculation determines the required heat transfer area for efficient thermal energy exchange between fluids. This calculation is essential for designing effective and economical heat exchange systems in various industrial applications.

2. How Does The Calculator Work?

The calculator uses the fundamental heat exchanger equation:

\[ A = \frac{Q}{U \times \Delta T_{lm}} \]

Where:

\( A \) — Required heat transfer area (m²)
\( Q \) — Heat transfer rate (W)
\( U \) — Overall heat transfer coefficient (W/m²K)
\( \Delta T_{lm} \) — Log mean temperature difference (K)

Explanation: This equation calculates the surface area needed to transfer a specific amount of heat given the temperature driving force and the overall heat transfer characteristics.

3. Importance Of Heat Exchanger Area Calculation

Details: Accurate area calculation ensures optimal heat exchanger performance, prevents under-sizing (insufficient heat transfer) or over-sizing (unnecessary cost), and helps in selecting appropriate heat exchanger types and configurations.

4. Using The Calculator

Tips: Enter heat transfer rate in watts, overall heat transfer coefficient in W/m²K, and log mean temperature difference in Kelvin. All values must be positive and non-zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What Is Log Mean Temperature Difference (LMTD)?
A: LMTD is the logarithmic average temperature difference between the hot and cold fluids at each end of the heat exchanger, representing the effective temperature driving force for heat transfer.

Q2: How Do I Determine The Overall Heat Transfer Coefficient?
A: The U-value depends on fluid properties, flow rates, heat exchanger geometry, and materials. Typical values range from 10-1000 W/m²K for different applications and fluid combinations.

Q3: What Are Common Heat Transfer Rate Calculations?
A: Heat transfer rate can be calculated using Q = m × Cp × ΔT for single-phase fluids, where m is mass flow rate, Cp is specific heat capacity, and ΔT is temperature change.

Q4: When Is LMTD Method Not Applicable?
A: LMTD method assumes constant U-value and specific flow arrangements. For variable U or complex flow patterns, the effectiveness-NTU method may be more appropriate.

Q5: What Safety Factors Should Be Considered?
A: Typical safety factors range from 10-25% to account for fouling, uncertainties in fluid properties, and future operational changes.