Great Wall DL30-2500 Closed-Circuit Recirculating Chiller

Overview

The Great Wall DL30-2500 is a high-capacity, microprocessor-controlled closed-circuit recirculating chiller engineered for continuous, stable thermal management in demanding laboratory and pilot-scale applications. It operates on the vapor-compression refrigeration cycle, utilizing R404A — a zero-ozone-depletion-potential (ODP), non-chlorofluorocarbon (CFC)-free refrigerant compliant with international environmental standards including the Montreal Protocol and China’s GB/T 7778–2017 refrigerant classification guidelines. Designed for precise temperature maintenance between −30°C and +5°C, the unit delivers up to 6000 W of cooling capacity at 0°C, scaling dynamically with setpoint (4000 W at −10°C; 2500 W at −20°C; 1100 W at −30°C). Its thermally optimized architecture ensures ±2°C temperature stability under steady-state conditions, making it suitable for coupling with analytical instruments requiring consistent thermal sink performance — including rotary evaporators, spectrophotometers, laser systems, and vacuum jacketed reactors.

Key Features

• Hermetically sealed closed-loop circulation system minimizes evaporation loss and contamination of heat transfer fluid (HTF), supporting long-term use of water-glycol mixtures or specialized organic coolants.
• Tecumseh original imported hermetic piston compressor — rated for >20,000 hours MTBF — provides reliable, low-vibration operation with IP44-rated terminal protection against dust and splashing water.
• Air-cooled finned-tube condenser with oxygen-free copper spiral tubing and proprietary tube-expansion bonding technology enhances heat transfer coefficient while reducing footprint and simplifying maintenance.
• Fully brazed plate-type evaporator fabricated from AISI 316 stainless steel plates enables wide operational temperature range (−160°C to +200°C), low fouling resistance, and weight reduction to 20–30% of equivalent shell-and-tube units.
• Danfoss DML-series dryer-filter with 3A molecular sieve core eliminates moisture and acid-forming contaminants, preventing corrosion and capillary blockage in the refrigeration circuit.
• Serviceable Danfoss thermostatic expansion valve allows in-situ superheat adjustment without refrigerant recovery or line cutting — critical for maintaining long-term system efficiency and refrigerant charge integrity.
• Stainless steel centrifugal circulation pump rated for continuous low-temperature operation with zero leakage risk, integrated with a 50-μm inline particulate filter to protect downstream instrumentation.
• Digital microcontroller interface features real-time display of setpoint, actual bath temperature, system pressure, reservoir level, and fault codes — all accessible via intuitive Chinese-language menu navigation.

Sample Compatibility & Compliance

The DL30-2500 is compatible with a broad spectrum of heat transfer fluids, including deionized water, 30–50% aqueous ethylene glycol solutions, and select synthetic hydrocarbon-based coolants. Its SUS304 reservoir and AISI 316 heat exchanger surfaces resist corrosion from common HTFs across its full operating range. The unit meets CE marking requirements for electromagnetic compatibility (EN 61326-1) and low-voltage safety (EN 61000-6-2/6-3). While not certified to UL or CSA standards out-of-the-box, its electrical architecture complies with IEC 61000-4 immunity testing levels and incorporates dual redundant thermal cutoffs aligned with IEC 60335-1 general safety principles. All safety interlocks — including phase-sequence monitoring, delayed compressor startup, and high-pressure shutdown — are hardwired and independently verified during factory acceptance testing.

Software & Data Management

The embedded controller supports manual setpoint programming, ramp/soak profiles, and real-time parameter logging to internal non-volatile memory (retains ≥72 h of 1-minute interval data). Optional RS485 Modbus RTU communication enables integration into centralized lab monitoring platforms (e.g., LabVIEW, Ignition SCADA, or custom BMS). Though lacking native FDA 21 CFR Part 11 compliance (no electronic signature or audit trail functionality), the system supports GLP/GMP-aligned operation when used with external validation protocols — including IQ/OQ documentation templates available upon request. Data export is supported via USB flash drive (CSV format), facilitating traceability for QC records and instrument qualification reports.

Applications

This chiller serves as a primary thermal regulation source in pharmaceutical R&D labs (e.g., controlled crystallization studies per USP ), chemical synthesis workflows requiring cryogenic reflux control, materials science testing (DSC calibration baths, rheometer cooling jackets), and semiconductor metrology where ambient drift must be suppressed below ±0.5°C/hour. Its 30 L/min flow rate and 1 bar pressure rating support multi-instrument daisy-chaining via manifold distribution systems — provided total pressure drop remains within specified limits. The unit is routinely deployed alongside Buchi R-300 rotovaps, Anton Paar MCR series rheometers, and PerkinElmer Spectrum Two FTIR systems requiring stable sub-zero coolant supply.

FAQ

What is the minimum ambient temperature required for safe operation?
The unit requires an ambient temperature of ≥5°C and ≤35°C, with relative humidity ≤70% non-condensing. Operation below 5°C may impair oil return and cause compressor lubrication issues.
Can the chiller be used with flammable heat transfer fluids?
No. The DL30-2500 is designed exclusively for non-flammable, non-toxic HTFs such as water-glycol blends. Use of hydrocarbon-based or silicone oils is prohibited due to refrigerant compatibility and fire safety constraints.
Is remote monitoring possible without third-party hardware?
Basic remote status readout (temperature, error codes) is achievable via optional RS485-to-Ethernet gateway; however, full supervisory control requires integration with external SCADA or PLC infrastructure.
How often should the dryer-filter be replaced?
Under normal operating conditions using pre-dehydrated HTF, replacement is recommended every 18–24 months or after any refrigerant service event — verified by moisture indicator card color change or dew point analysis.
Does the unit support external temperature feedback control?
Yes. A dedicated PT100 input port allows connection to an external process sensor, enabling cascade control mode where the chiller regulates based on actual sample or jacket temperature rather than internal bath reading.