DR-FD120A thermal conductivity measuring instrument

I. Introduction:

DR-FD120A thermal conductivity measuring instrument is a new single test piece testing device developed by the company based on the original double test piece thermal conductivity testing device by taking advantage of the structure and principle of the most advanced thermal conductivity testing instrument in the world. It is used to measure the thermal conductivity of various kinds of homogenous plate shaped thermal insulating materials and non-good heat conduction materials. 

This device is for measurement of a single test piece. The test piece is placed on the cold plate surface horizontally and the hot plate is suspended above the test piece exerting a pressure on the test piece with its self weight to ensure reliable contact between the test piece, hot plate and cold plate. 

The cold plate fluid circulation channel adopts a double helix structure to ensure the cold plate surface temperature is uniform. The temperature control system of the cold plate fluid supply tank adopts the double-pump separate flow external circulation heating method to ensure uniform temperatures of the liquid in the tank and small fluctuation of temperature of the liquid flowing across the cold plate. 

The temperature measuring element adopts the high precision platinum resistor PT100 and high precision temperature acquisition module to realize higher accuracy in the control of the hot and cold plate temperature. 

This device adopts a microcomputer automatic control system, characterized by automatic control of the test process, automatic acquisition of data and generation of reports, high level of intelligentization and high test accuracy. It has the highest accuracy in all similar testing products in the country. 

II. Specification & Model: 

DR-FD120A

III. Reference standards:

GB/T 10294-2008 Thermal insulation-Determination of steady-state thermal resistance and related properties-Guarded hot plate instrument

IV. Technical indexes

1,Overall dimensions (L*W*H): 1060x730x1820(mm)

2,Gross weight: 300 (kg)

3,Test piece specification (overall dimensions): φ300(mm) or 300×300 (mm)

4,Test piece thickness: 10~75(mm)

5,Thermal conductivity measurement range: 0.01~1W/(m.K)

6,Cold plate temperature: -5℃~90℃

7,Hot plate temperature: ≤120℃

8,Cold plate temperature control stability: 0.01℃

9,Hot plate temperature control stability: 0.002℃

10,Hot plate measurement unit heating power control stability: 0.001W

11,Test repeatability: ≤1%                                                                                                                                                                                                                                                                                                     12,Supporting power: 4kW  220V

 V. Structure and principle                                                                                                                                                                                                                                      Instrument principle: Under the stable state, in the uniform plate shaped test piece with parallel surfaces within the central measuring area of the protective hot plate, a one dimension constant heat flow is established in an infinite plate with two parallel plates with uniform temperatures as the boundary. 

It consists of the microcomputer automatic control system, measuring heating unit, protective heating unit, back protection unit, cold plate unit, external protection unit (thermal insulation system), measuring system, lifting system, displacement detection system, refrigeration system and case.

1,           Microcomputer automatic control system:

The computer output signals are converted via I/O and D/A to control relevant actuators to realize functions such as temperature control, calculation, temperature acquisition, printing test reports, displaying process curve. The man-machine interface displays the temperatures of various faces and it is capable of self-diagnosis. 

2,           Measuring heating unit

Quality heat conduction materials are adopted as the heating panel. Owing to its good heat conducting property, the heating plate surface temperature is more even with small thermal inertia, making the measuring result more accurate. 

3,Protective heating unit:

It adopts the same panel material as the measuring heating unit. The protective heating unit and the measuring heating unit adopt a connection method that combines mechanical and chemical connection to obtain equal gap width, so as to control the temperature difference at the two sides of the gap more accurately and ensure test accuracy. 

4,Back protection unit:

It adopts the same thermal conduction material as the measuring heating unit and quality thermal insulating material to realize zero temperature difference between the two surfaces of the thermal insulation materials between the measuring heating unit, protective heating unit and back protection unit, thus ensuring test accuracy. 

5,Cold plate unit: 

It adopts quality heat conduction material as the heat conduction panel and the base plate channel adopts the double helix channel to ensure the cold plate temperature is uniform. A single water tank (with anti-freezing solution added) is used to control the cold plate temperature. The cold plate temperature can be set and automatic control is realized via the microcomputer. 

6,External protection unit (thermal insulation system)

  It adopts quality and environmental friendly thermal insulation material. It has good thermal insulation performance and is non-toxic, non-irritating and free from parasites. This thermal insulation system makes the test environment more stable so as to ensure the test accuracy. 

7,Measuring system:

It adopts the high-stability, high-precision platinum resistor temperature sensor and high-precision DC power sensor to make the data acquisition result more accurate. 

The measuring heating unit and measuring protection unit adopt the heat flow meter to measure and control the heating temperature so as to ensure the test result is accurate.

8,Hot plate lifting system: 

  At present, most similar domestic products adopt the pneumatic technology to firmly press the test piece using the pneumatic cylinder or manually; and the test piece is paced on the operation platform in a vertical manner (so particle thermal insulation materials cannot be tested in this way). With the DR-FD120A thermal conductivity measuring instrument, the test piece is placed on the platform in a horizontal manner (so particle thermal insulation materials can be tested), the heating unit and back protection unit, etc. in the hot plate component are moved by the lifting system and the test piece clamping force is applied by the self weight of the hot plate. In addition, the pressing force can be adjusted depending on the specific test piece to make the test more convenient and accurate. The electric hoist is used for lifting and lowering, which is characterized by compactness, stable transmission and no noise. 

9,Displacement detection system: 

The national standard requires that the test piece thickness measuring accuracy should be less than ±0.5% and it recommends that the thickness should be measured in the device under the actual testing temperature and pressure. Due to thermal expansion and pressure of the hot plate, the thickness may vary, thus reducing the test accuracy. For this reason, this device integrates a guiding and displacement detection system in which the displacement sensor outputs digital signals with accuracy ±0.1%FS, so as to completely ensure the test accuracy. 

10,Refrigeration system:

  This system can rapidly reduce the cold plate temperature and realize measurement of the test piece at an average test piece temperature lower than room temperature. The minimum temperature of the cold plate is -5 ℃ (lower temperatures can be customized) to realize larger testing range without being influenced by ambient temperatures. The refrigerating unit adopts the most advanced refrigerating compressor set in the world.  

11,Case: 

All the case frames and panels of the instrument adopt quality carbon steel pipes and plates with surface coated so that the case is environmental friendly, neat, attractive and gives a comfortable impression.  

12,To ensure the test accuracy of the instrument, all electrical components adopt German Siemens and Japanese Omron parts and the circulation system water pumps adopt the Danish Grundfos pumps.