500 m² Constant-Temperature Warehouse Renovation Project for Automotive Glass Raw Materials, Saint-Gobain Shanghai

Design Scheme

The original glass enclosure is treated as the outer shell, and an independent insulated warehouse structure is built inside to form a "warehouse within warehouse" layout. A 50 mm air gap is reserved between the outer surface of the insulated panels and the glass wall. This air layer blocks direct structural heat transfer and prevents condensation on the glass surface caused by direct contact with internal thermal insulation.

Ceiling-mounted air coolers are arranged symmetrically on the warehouse roof with a top-air-supply and bottom-air-return airflow pattern to guarantee uniform temperature distribution across all zones. A single continuously operating variable-frequency unit is adopted for the refrigeration system without a standby main unit. However, power supply for key sensors and controllers is backed by UPS to sustain monitoring and retain safe shutdown records during power outages.

A cascade PID control logic combining supply air temperature and return air temperature is deployed for temperature regulation. The outer loop calculates the target supply air temperature based on the deviation between the set warehouse temperature and the average return air temperature measured at multiple points. The inner loop adjusts the compressor speed and electronic expansion valve opening to maintain a narrow temperature band around 9°C for supply air, preventing localized overcooling of materials from direct cold air blow.

When heat load is extremely low, a hot gas bypass valve diverts part of the discharge gas back to the suction side to keep the compressor running continuously and eliminate temperature fluctuations induced by startup shocks.

Equipment List

Construction Process

Insulated panels are fixed to the floor inside the glass wall via anchored floor grooves; the top of the structure does not touch the original ceiling joists to ensure full independence. Polyurethane foam filler is injected into panel joints, which are then covered with self-adhesive aluminum foil sealing tape on the exterior to block water vapor penetration.

Air cooler hangers are secured to the original building beams and columns without applying any load to the glass walls. The refrigeration unit is installed on an equipment platform outside the material room. Flexible sealing sleeves are used at copper pipe wall penetrations to isolate vibration and cold conduction to the glass curtain wall.

Electrical cable trays are routed along the outer wall of the insulated warehouse, with clean sealing fittings installed at all cable entry and exit points. The control cabinet is mounted outside the warehouse for easy access.

During construction, a temporary negative-pressure enclosed working zone is set up with real-time particle counter monitoring. Cleanliness restoration procedures are implemented after each work shift clearance.

Commissioning & Acceptance

For no-load commissioning, air tightness and pressure holding tests are carried out first. After confirming zero leakage of the refrigeration system, the unit is started to cool the warehouse from the workshop ambient temperature of 32°C down to 9°C, to test cooling rate and initial temperature overshoot.

Nine temperature measuring points arranged in a 3-layer × 3-column grid are used to verify no-load temperature distribution. After 8 hours of stable operation, the maximum temperature deviation is controlled within ±0.7°C.

Simulated loads (pallets filled with thermal mass media) are then placed inside, and daily door-opening operations are simulated for 48 consecutive hours of running. The final full-load temperature records show all measuring points fall within 8.3~9.6°C, complying with the 9℃±1°C specification.

Acceptance is jointly verified by Saint-Gobain’s process, equipment and quality departments. Continuous temperature monitoring as well as SMS and email alarm functions are formally handed over upon completion.

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