Design Solution

Temperature Design Logic

The design strictly complies with GSP specifications for refrigerated drug storage. The rated warehouse temperature is set at 5°C, with early warning thresholds of 3°C and 7°C; audible, visual and SMS alarms trigger immediately once readings go out of bounds. The design requires temperature uniformity ≤1°C across all measuring points with no cold spots, meeting storage standards for pharmaceuticals stacked at varying heights.

To adapt to the limited 3.0 m clear height, the airflow layout is optimized. Ultra-thin air coolers deliver air sideways and downward, with natural air return at the floor. Cold air flows down both side walls toward the center floor, avoiding direct cold blast on goods that causes localized overcooling, while minimizing vertical space occupied by equipment.

Refrigeration System Design

A direct-expansion air-cooled refrigeration system is adopted, with outdoor units mounted on the factory roof to save indoor storage space.

Cooling load calculation takes full account of Shanghai’s extreme summer outdoor conditions, heat transfer through building envelopes, cooling load from incoming goods, air exchange load from frequent door openings and equipment heat dissipation. The total designed cooling load is 31.8 kW.

A primary-standby dual-unit setup is deployed; a single unit’s 35 kW cooling capacity suffices for full-load warehouse operation. The two units alternate startup and shutdown during daily operation to balance wear. If one unit fails, the control system switches to the standby unit automatically within 60 seconds to avoid drastic temperature swings.

Backup System Design

Beyond redundant refrigeration units, the electrical system is equipped with a UPS. After mains power failure, the UPS sustains operation of the temperature & humidity monitoring system, alarm devices and controllers for over 4 hours to secure complete data recording and functional alarms.

Independent on-site audible-visual alarms are installed inside the warehouse, linked to the duty room monitoring terminal and SMS alerts to management staff for multi-layered notification.

Equipment List

Construction Process

Insulated Panel Installation

The original floor was levelled first, covered with a 0.5 mm PE moisture-proof film, then laid with 100 mm floor insulation panels, topped by a 2 mm epoxy wear-resistant floor coating to resist abrasion from cargo handling.

Wall and ceiling panels are joined via eccentric hooks, with polyurethane foam injected into all seams for airtightness. Ceiling panels are mounted flush against the bottom of factory beams to maximize vertical space, delivering a finished clear height of exactly 3.0 m as designed.

All internal corners are finished with aluminum alloy profiles, and neutral silicone sealant is applied externally on panel joints to block moisture penetration.

Refrigeration Equipment Installation

Outdoor units sit on 200 mm high concrete bases fitted with rubber vibration pads, with 1.2 m ventilation clearance reserved between units for effective heat dissipation.

Indoor air coolers are suspended by short 120 mm hangers, mounted as close to the ceiling as possible to save storage space. Two coolers are symmetrically installed above the two long side walls to ensure full air coverage without dead zones.

Piping Construction

TP2 copper tubes are used for refrigerant piping with brazed joints. After welding, the system undergoes a 2.5 MPa dry nitrogen pressure hold test; a pressure drop ≤0.02 MPa over 24 hours is deemed acceptable.

All pipes are wrapped with 20 mm rubber-plastic thermal insulation and covered with aluminum foil to stop condensation. Condensate drain pipes feature U-shaped water seals and slope outward to prevent cold air leakage.

Electrical System Installation

Power cables are concealed inside galvanized steel conduits, separated from control wiring to avoid electromagnetic interference.

Temperature & humidity sensors are positioned strictly per GSP codes. Six sensors are deployed across the 530 ㎡ warehouse: four at corners, one at the center and one at the air cooler return air outlet. All sensors come with official calibration certificates.

Commissioning & Acceptance

After full installation, sequential tests are carried out: no-load cooling test, full-load stability test, unit switchover test, power failure test and frequent door opening simulation test.

No-load test: Starting at an ambient temperature of 25°C, the warehouse cools down to 5°C within 8 hours. After 24-hour stable operation, all measuring points range from 4.2°C to 5.0°C with a maximum temperature difference of 0.8°C, satisfying uniformity requirements.

Full-load test: Simulated goods are stacked to 80% of total capacity and run continuously for 72 hours with data logged every 30 seconds. Temperature fluctuation is limited within ±0.7°C with no out-of-limit records.

Unit switchover test: After manually shutting down the primary unit, the standby unit starts automatically within 52 seconds; peak temperature rise during switchover is only 0.4°C, staying below warning thresholds.

Power failure test: The UPS takes over seamlessly after mains cut-off, supporting 4.5 hours of uninterrupted monitoring with intact data and fully functional alarms.

Door opening test: After the door stays fully open for 10 minutes then closes, temperature rises by 1.2°C and recovers to setpoint within 14 minutes of unit operation.

Acceptance Procedure

The contractor completes self-inspection and issues a self-check report first. A metrology-certified third-party institute is then commissioned to conduct official GSP temperature mapping validation and release a formal report.

Finally, the client organizes a joint acceptance team from engineering, warehousing and quality departments to verify equipment documents, construction records and validation reports, and test all functions on site. Confirming full compliance with design and regulatory standards, the project passed final acceptance officially on December 26, 2025.

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