Ammonia Cold‑Store Evaporator | Industrial Floor‑Standing, Steel‑Tube Aluminium‑Fin, Hot‑Gas (Hot‑Ammonia) Defrost

VRCOOLER manufactures heavy‑duty floor‑standing ammonia(R717) unit coolers for large‑scale industrial cold‑storage warehouses. Ammonia systems strictly forbid copper tubes. This floor‑mounted layout is widely used for high‑bay warehouses, bulk‑product cold stores, freezing rooms and large‑capacity blast‑chambers. Hot‑ammonia hot‑gas defrost is the standard defrost solution for industrial ammonia installations, fast defrosting plus oil‑blow‑out function for coil internal oil sludge removal.

Installation note: Floor‑standing evaporators sit on cold‑room floor base frame; cold‑air blows upwards / horizontally. No ceiling‑hanging load requirement, suitable for buildings with weak ceiling structure or extra‑large cooling‑capacity demands.

Typical operating conditions

• Application: bulk‑goods cold storage, meat‑block freezer, blast‑freezing room, high‑bay industrial cold‑warehouse

• Room temperature range: 0℃ ~ ‑35℃

• Refrigerant: Ammonia R717, pump‑liquid‑supply flooded circuit (mainstream for industrial ammonia plants)

• Defrost mode: Hot‑ammonia hot‑gas defrost (primary), electric defrost as backup option.

Core construction specifications

1. Heat‑exchange coil (critical ammonia‑compatible design)

• Tube material: Carbon‑steel / hot‑dip galvanized steel tube or stainless‑steel tube. Copper tube is strictly prohibited for ammonia systems.

• Fin material: Aluminium fins; optional epoxy‑hydrophilic coating for high‑humidity / light‑corrosion environment.

• Fin‑spacing selection (industrial ammonia cold‑store):

  • Chilling room (0 ~‑5℃): 6‑8 mm

  • Frozen‑goods storage (‑18~‑25℃): 8‑10 mm

  • Blast‑freezing room (‑28~‑35℃):10‑12 mm wide fin pitch, resist heavy frost‑bridging

• Coil circuiting: Optimised for ammonia pump recirculation flooded feed; low pressure drop, uniform refrigerant distribution, reliable oil discharge during hot‑gas defrost.

• Factory test: Air‑tight & pressure test under ammonia‑design pressure, dry‑nitrogen sealed before shipment.

2. Floor‑standing mechanical structure

• Casing, base support frame, drain pan: Hot‑dip galvanized carbon‑steel; 304 stainless‑steel optional for food‑hygiene wash‑down zones.

• Heavy‑duty base frame, anti‑vibration structure; whole unit sits on floor, no ceiling load.

• Large‑size sloped drain‑pan, big‑calibre defrost‑water outlet. Hot‑gas defrost produces large‑volume melted water; drain‑pan must avoid any water‑stagnant dead corners.

• All bolts & fasteners: Hot‑dip galvanized or stainless‑steel.

3. Fan configuration

• Large‑diameter axial fans, high‑air‑volume for large‑warehouse air circulation; IP55‑protected low‑temperature fan motors.

• Blow‑out direction: upward‑blow or horizontal‑blow according to warehouse layout; multi‑fan modular design for big‑capacity units.

• Fans stop forcibly during hot‑gas defrost cycle, prevent hot‑gas leaking into cold‑room space.

4. Hot‑ammonia hot‑gas defrost system matching

Working principle: High‑pressure hot ammonia vapour from compressor discharge enters coil. Coil temporarily acts as condenser; heat released inside tube melts external frost. Meanwhile lubricating oil accumulated inside coil is flushed out together with liquid ammonia condensate toward low‑pressure recirculating receiver / liquid drain vessel.

1. Unit reserves dedicated hot‑gas inlet, liquid‑condensate drain connections for site ammonia‑piping station.

2. All defrost‑related nozzles & connection stubs comply with ammonia‑pressure rating; safety pressure‑relief protection is required on system side to avoid liquid‑hammer & over‑pressure risk.

3. Control sequence requirement: Stop fans → cut‑off liquid supply → pump‑out residual ammonia inside coil → open hot‑gas valve for defrost → complete defrost & drip‑time → switch back to cooling mode.

4. Important: Hot‑gas defrost is system‑level function; evaporator is structurally prepared, hot‑gas valves, back‑pressure regulator, drain‑vessel belong to site ammonia‑regulating‑station scope.

Common engineering pitfalls for ammonia floor‑standing evaporators

1. Wrong tube material: Copper‑tube coil used for ammonia system → rapid chemical corrosion, coil leakage failure.

2. Too‑narrow fin spacing for low‑temperature freezer: Fast frost‑bridge, short runtime between hot‑gas defrost cycles.

3. Ignoring drain‑pan capacity: Hot‑gas defrost generates large‑quantity melt‑water; undersized drain causes refreezing‑ice on unit base.

4. Fans keep running during hot‑gas defrost: Hot ammonia gas leaks into cold‑room, sharp temperature rise & safety hazard.

5. Poor coil circuiting for pump‑supply ammonia: Uneven flow, bad oil‑removal effect during hot‑gas defrost.

VRCOOLER supplies custom floor‑standing ammonia R717 evaporators, suitable for pump‑liquid‑supply industrial ammonia cold‑stores. Support 1:1 drop‑in replacement based on old‑unit dimensions or customer drawings.