Thermal Conductance And Resistance Formula

Thermal Conductance and Resistance Formulas:

\[ G = \frac{1}{R} \] \[ R = \frac{L}{k A} \]

Calculate:

Thermal Resistance (R):

K/W

Thickness (L):

Conductivity (k):

W/mK

Area (A):

m²

Result:

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1. What is Thermal Conductance and Resistance?

Thermal conductance (G) and thermal resistance (R) are fundamental concepts in heat transfer that describe how easily heat flows through a material. Thermal resistance is the opposition to heat flow, while thermal conductance is the ease with which heat flows.

2. How Does the Calculator Work?

The calculator uses the fundamental thermal formulas:

\[ G = \frac{1}{R} \] \[ R = \frac{L}{k A} \]

Where:

\( G \) — Thermal conductance (W/K)
\( R \) — Thermal resistance (K/W)
\( L \) — Material thickness (m)
\( k \) — Thermal conductivity (W/mK)
\( A \) — Cross-sectional area (m²)

Explanation: Thermal resistance increases with thickness and decreases with conductivity and area. Conductance is simply the reciprocal of resistance.

3. Importance of Thermal Calculations

Details: Accurate thermal calculations are crucial for building insulation design, electronic cooling systems, HVAC design, and energy efficiency analysis in various engineering applications.

4. Using the Calculator

Tips: Select whether you want to calculate conductance or resistance. For conductance, provide thermal resistance. For resistance, provide thickness, conductivity, and cross-sectional area. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between conductivity and conductance?
A: Conductivity (k) is a material property (W/mK), while conductance (G) depends on both material and geometry (W/K).

Q2: How does area affect thermal resistance?
A: Larger cross-sectional area decreases thermal resistance, allowing more heat to flow through the material.

Q3: What are typical conductivity values?
A: Copper: ~400 W/mK, Aluminum: ~200 W/mK, Steel: ~50 W/mK, Wood: ~0.1 W/mK, Insulation: ~0.04 W/mK.

Q4: When is thermal resistance used in practice?
A: Commonly used in building insulation (R-values), electronic heat sinks, and thermal interface materials.

Q5: Can I calculate conductance for composite materials?
A: For series arrangements, total resistance is sum of individual resistances. For parallel, total conductance is sum of individual conductances.