What Is The Heat Transfer Coefficient of The All Aluminum Fin Tube Evaporator?

For all-aluminum fin‑tube evaporators (air‑cooled, household/commercial fridge/freezer), the overall heat transfer coefficient (K) typically ranges:

1. Typical K‑value (air side, finned surface)

Standard no‑frost fridge/freezer: 18–35 W/(m²·K)

Low‑temperature freezer (−18 °C): 15–25 W/(m²·K)

High‑humidity / heavy frost: 8–15 W/(m²·K) (frost adds thermal resistance)

2. Air‑side convection coefficient (hₒ)

hₒ ≈ 25–60 W/(m²·K) (at airflow 1.0–2.5 m/s, fin pitch 4–6 mm)

3. Refrigerant‑side boiling coefficient (hᵢ)

hᵢ ≈ 1,500–3,000 W/(m²·K) (R600a/R134a, DX evaporation)

4. Aluminum material thermal conductivity

k_Al ≈ 205–237 W/(m·K) (alloy 3003/1100)

5. Comparison (vs copper‑aluminum)

All‑aluminum K is 7–9% lower than identical copper‑tube/aluminum‑fin coils.

6. Key factors affecting K

Fin pitch/density: Closer fins → higher area but higher air resistance.

Airflow velocity: Higher speed → higher hₒ (but more fan power).

Frost accumulation: Can drop K by 50%+ in freezers.