Core Structure of a Thermal Conductivity Meter

A thermal conductivity meter typically uses a dual-specimen measurement configuration. The test specimens are placed vertically between two parallel plates maintained at constant temperatures. Once the system reaches thermal steady state, the metering zone at the specimen center experiences a constant heat flux. By measuring the thermoelectric potential from the hot and cold plate thermocouples and the surface temperatures, the thermal resistance R at any given mean temperature is calculated. With the specimen thickness known, the thermal conductivity can then be accurately determined. Key design features include: (1) a modular main chassis that simplifies installation and commissioning while offering a clean, modern appearance; (2) hot and cold plate surfaces made from high-quality polymer materials that provide good thermal conductivity, flexibility, and wear resistance to ensure tight contact with the specimen and improve measurement accuracy; (3) a pneumatic cylinder clamping system on the cold-side unit that allows adjustment of air pressure in the pneumatic circuit, strictly meeting the requirement of not greater than 2.5 kPa; (4) a directly cooled side plate in the cold unit with built-in temperature regulation to quickly reach steady-state conditions; (5) a fully enclosed, air-cooled imported compressor assembly offering low noise, strong refrigeration performance, and long service life; (6) an industrially engineered cold unit and refrigeration system that deliver fast cooling, uniform cooling capacity, and superior performance compared with water-cooling approaches; and (7) computer-automated measurement, calculation, and reporting for end-to-end test execution. The instrument is primarily composed of the following modules: 1) Control cabinet: The cabinet has two sections. The upper section includes manual control buttons and houses the dual-specimen measurement assembly. The lower section contains the refrigeration system and the pneumatic transmission/control system. 2) Microcomputer control system: Comprising a high-performance computer and printer, it handles signal acquisition and processing, temperature control, time-based control and calculation, and automatic report printing. 3) Dual-specimen measurement assembly: Built from a heating unit and two cooling units. The cooling units can automatically adjust their position via the drive system to accommodate different specimen thicknesses. 4) Refrigeration system: Uses a direct-cooling method with cooled side plates to enhance heat extraction and stability.

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