Food Freezer Evaporator Coils for IQF Sliced Peaches

The evaporator coil provides the cold heat transfer surface that removes latent heat from peaches as they pass through the IQF freezer (fluidized bed or belt type).

Primary functions include:

• Rapidly reducing product temperature from +5~10 °C to ≤ −18 °C core temperature

• Maintaining stable airflow temperature (−30 to −40 °C air)

• Preventing product clumping and surface dehydration

• Supporting uniform freezing of thin, irregular peach slices

Freezing Characteristics of Sliced Peaches

Sliced peaches present unique challenges:

• High water activity → high latent heat load

• Sugar content lowers freezing point (≈ −1.5 to −2.5 °C)

• Soft flesh easily damaged by slow freezing

• Sticky surface increases risk of icing and coil fouling

Therefore, evaporator coils must deliver high heat flux with minimal frost buildup.

Evaporator Coil Design for IQF Sliced Peaches

1. Tube-and-Fin Configuration

• Type: Forced-air finned evaporator coil

• Tube layout: Staggered for maximum air turbulence

• Fin spacing: Wide pitch (6–10 mm) to delay frosting

• Rows: Typically 3–6 rows depending on capacity

Wide fin spacing is essential to maintain airflow stability in high-humidity fruit freezing environments.

2. Tube Material Options

For peaches, aluminum tube + aluminum fin coils are widely used due to balanced cost and performance.

3. Fin Design

• Hydrophilic or epoxy-coated aluminum fins

• Corrugated or louvered fin profile

• Optimized for low air-side pressure drop

Fin coatings help reduce ice adhesion and improve defrost efficiency.

Refrigerant and Operating Conditions

Typical Operating Parameters

• Evaporating temperature: −35 to −45 °C

• Air temperature leaving coil: −30 to −38 °C

• Refrigerants:

• NH₃ (R717) – industrial IQF plants

• CO₂ (R744) – cascade or transcritical systems

• R404A / R507 – legacy systems (being phased out)

Ammonia and CO₂ are preferred for modern fruit IQF lines due to high efficiency and sustainability.

Frost Control and Defrost Strategy

Because peaches release significant moisture during freezing, frost management is critical.

Common defrost methods:

• Hot gas defrost (NH₃ systems)

• Electric defrost (smaller units)

• Warm glycol defrost (CO₂ systems)

Design features supporting frost control:

• Wide fin spacing

• Uniform refrigerant distribution

• Proper air velocity (2–4 m/s across coil face)

• Sloped drain pans for meltwater removal

Hygiene and Food Safety Considerations

Evaporator coils for IQF peaches must comply with food-processing standards:

• Smooth fin edges to prevent fruit damage

• Corrosion-resistant materials

• Easy access for sanitation

• Compatibility with CIP and high-pressure washdown

• FDA / EU food-contact environment compliance

Stainless steel casings and drain pans are strongly recommended.

Impact on IQF Peach Quality

Properly designed evaporator coils contribute to:

• Fast crust-freezing → minimal cell rupture

• Reduced drip loss after thawing

• Bright color retention

• Improved texture and firmness

• True individual freezing without clumping

Poor coil performance results in slow freezing, mushy texture, and excessive dehydration.

Summary

Food freezer evaporator coils for IQF sliced peaches must deliver high-capacity, low-temperature heat transfer while managing heavy moisture loads and strict hygiene requirements. Optimized tube-fin geometry, wide fin spacing, appropriate refrigerant selection, and robust defrost design are essential to achieving fast freezing, superior product quality, and stable long-term operation.