Great Wall ZT-50-200-30H Closed-Loop Refrigerated & Heated Circulator

Overview

The Great Wall ZT-50-200-30H is a high-performance closed-loop refrigerated and heated circulator engineered for precise thermal control in demanding laboratory and pilot-scale applications. It operates on a dual-mode thermodynamic principle—integrating vapor-compression refrigeration with resistive electric heating—to deliver stable, bidirectional temperature regulation across a wide operational envelope of −30 °C to +200 °C. Unlike open-bath chillers or standalone heaters, this system maintains full fluid containment throughout the entire thermal cycle, eliminating evaporation loss, oxidation risk, and ambient contamination. Its sealed architecture ensures consistent heat transfer performance when coupled to external devices such as jacketed reactors, calorimeters, distillation columns, or material testing fixtures. Designed for continuous duty under GLP-compliant environments, the unit meets mechanical and electrical safety requirements per IEC 61010-1 and incorporates redundant thermal and pressure monitoring to support unattended operation.

Key Features

• Integrated dual-stage thermal management: Panasonic/Wanbao hermetic rotary compressor with high volumetric efficiency and low acoustic emission (<62 dB(A))
• High-efficiency plate-type evaporator fabricated from AISI 316 stainless steel, rated for −160 °C to +200 °C service and optimized for low fouling coefficient and minimal thermal mass
• Dedicated pre-cooling module using high-speed external-rotor fans and finned-tube heat exchangers to accelerate ramp-down from elevated temperatures—reducing energy consumption by up to 35% compared to direct compression cooling alone
• Flanged immersion-style electric heater compliant with JB/T 2379, specifically designed for synthetic heat transfer oils and glycol-water mixtures
• Corrosion-resistant circulation loop: All wetted parts—including reservoir, piping, valves, and pump housing—constructed from AISI 304 stainless steel; compatible with non-aggressive heat transfer media (e.g., silicone oils, polyalkylene glycols, aqueous glycols)
• Intelligent control system featuring a 5.7″ TFT color touchscreen with real-time graphical display of temperature vs. time curves, programmable ramp/soak profiles (120 programs × 100 segments), and user-accessible data logging
• Comprehensive safety architecture including high/low refrigerant pressure cutouts, overtemperature shutdown (dual-sensor redundancy), motor overload protection, phase-sequence monitoring, and dry-run prevention

Sample Compatibility & Compliance

This circulator is intended for use with thermally stable, non-corrosive heat transfer fluids operating at atmospheric pressure. Compatible media include silicone oils (e.g., DC200 series), polyalphaolefins (PAOs), and inhibited glycol–water blends (≤60% glycol). It is not suitable for halogenated solvents, strong acids/bases, or fluids exhibiting viscosity >1000 cSt at minimum operating temperature. The system complies with electromagnetic compatibility standards EN 61326-1 and safety standard IEC 61010-1 for laboratory equipment. While not certified to UL or CSA marks, its design principles align with FDA 21 CFR Part 11 data integrity expectations when used with validated software interfaces. Documentation packages support IQ/OQ protocols for GMP-regulated facilities.

Software & Data Management

The embedded controller supports MODBUS RTU protocol via RS-485 interface, enabling integration into centralized SCADA or LIMS platforms for remote monitoring and automated batch reporting. Temperature setpoints, actual readings, alarm status, and pump speed are accessible as discrete registers. On-device data logging records timestamped values at user-defined intervals (1 s to 60 min); logs export via USB to CSV format for traceability. The touchscreen interface includes audit-trail-capable user authentication (admin/operator roles), password-protected parameter modification, and configurable event notifications (e.g., low-level alert, deviation alarm). Firmware updates are performed via secure USB key with SHA-256 signature verification.

Applications

• Temperature control of jacketed glass reactors (1–50 L) during exothermic/endothermic synthesis
• Calibration and stability testing of differential scanning calorimeters (DSC) and thermogravimetric analyzers (TGA)
• Thermal cycling of polymer samples in dynamic mechanical analysis (DMA)
• Conditioning of optical components and laser diodes requiring sub-ambient stabilization
• Process simulation in pharmaceutical freeze-drying development (pre-cooling stage)
• Environmental stress screening of electronic assemblies per MIL-STD-810G Method 502.6

FAQ

What types of heat transfer fluids are approved for use with the ZT-50-200-30H?
Only non-corrosive, thermally stable fluids with flash points above 150 °C and viscosity below 1000 cSt at −30 °C are permitted—such as Dow Corning PM-200, Wacker KF-96, or Shell Heat Transfer Oil S2. Halogenated, acidic, or highly viscous media will void warranty.
Can the unit operate continuously at −30 °C with full load?
Yes—the system delivers 1.0 kW of cooling capacity at −30 °C with a minimum flow rate of 20 L/min and backpressure ≤0.8 bar. Continuous operation requires adequate ventilation (≥0.5 m² free area around condenser) and ambient temperature ≤30 °C.
Is the controller compliant with FDA 21 CFR Part 11 for electronic records?
The device itself does not provide full Part 11 compliance (e.g., electronic signatures, biometric authentication), but its MODBUS interface and audit-ready log structure enable validation within a compliant ecosystem when paired with qualified third-party software.
Does the expansion tank include level sensing and automatic top-up capability?
The integrated expansion vessel features visual level indication and a calibrated float switch for low-level alarm output; however, it does not support automatic fluid replenishment—manual refilling is required per maintenance schedule.
What is the maximum allowable external system pressure drop?
To maintain rated flow (30 L/min) and stability (±0.5 °C), total system pressure loss—including reactor jacket, tubing, and fittings—must remain ≤0.6 bar at 20 °C equivalent. Higher resistance necessitates flow reduction or auxiliary pumping.