GB/T 34482-2017Determination of thermal transmittance for architecture aluminium alloy thermal barrier profiles (English PDF)

3.1 Areal Density of Heat Flow Rate

q

Areal density of heat flow rate refers to per unit area heat flow, which is vertical to the

0.04 W/(m-K). The actual value of thermal transmittance shall be provided by manufacturers, or, be determined in accordance with the methods stipulated in GB/T

10294. The parallelism of both sides of the thermal insulation board shall be not more than ± 0.5°. Thermal insulation board for calibration, which is known as calibration board for short, has the thickness of 20 mm or 60 mm.

5.4 Test Piece Frame

The texture of test piece frame shall comply with the stipulations in GB/T 13475. The thermal transmittance shall be not more than 0.04 W/(m-K). The thickness of test piece frame shall be not less than 300 mm.

5.5 Hot Box External Wall

The texture of hot box external wall shall comply with the stipulations in GB/T 13475.

The thermal transmittance shall be not more than 0.04 W/(m-K). The thickness of hot box external wall shall be not less than 200 mm.

5.6 Hot Box Calibration

5.6.1 Parameters that the hot box needs to calibrate include: hot chamber external wall heat flow coefficient M1 and test piece frame heat flow coefficient M 2.

5.6.2 When the cold chamber draught fan of the hot box is constant-speed fan, the wind speed of the cold chamber draught fan shall be 3 m/s. In accordance with the methods in Appendix A, calibrate hot chamber external wall heat flow coefficient M 1 and test piece frame heat flow coefficient M 2.

5.6.3 When the cold chamber draught fan of the hot box is adjustable-speed fan, in accordance with the methods in Appendix B, set up the wind speed. Then, in accordance with the methods in Appendix A, calibrate hot chamber external wall heat flow coefficient M1 and test piece frame heat flow coefficient M 2.

5.6.4 Hot box calibration shall be conducted at least once a year. If the location, structure or accessory of hot box changes, re-calibration will be needed.

7.6 Result Calculation

7.6.1 In accordance with Formula (1), calculate the thermal conductivity of

thermal insulation board. The numerical value rounding-off rule shall comply with relevant stipulations in GB/T 8170. The result shall retain 2 decimal places.

Where,

---thermal conductivity of thermal insulation board (reciprocal of thermal insulation board’s thermal resistance), expressed in [W/(m

2

-K)];

lambda---thermal conductivity coefficient of thermal insulation board, expressed in [W/(m-K)];

d---thickness of thermal insulation board, expressed in (m).

7.6.2

In accordance with Formula (2), calculate thermal transmittance coefficient K.

The numerical value rounding-off rule shall comply with relevant stipulations in GB/T

8170. The result shall retain 2 decimal places.

Where,

K---thermal transmittance coefficient, expressed in [W/(m

2

-K)];

Phiin ---energy consumption of maintaining constant hot chamber temperature, expressed in (W);

Deltathetaek ---average temperature difference between internal and external surface of hot chamber external wall, expressed in (K);

Deltathetasur ---average temperature difference between test piece frame hot side surface and cold side surface, expressed in (K);

Deltathetan ---during test, air temperature difference between hot chamber and cold chamber,

Appendix A (Normative)

Heat Flow Coefficient Calibration Method

A.1 An Overview of Method

Adopt a calibration board, whose thickness is around 60 mm. Transform the temperature difference between the hot chamber and the external environment; the temperature difference between the cold chamber and the hot chamber. Calculate hot chamber external wall heat flow coefficient M 1 and test piece frame heat flow coefficient

M 2.

A.2 Calibration of Heat Flow Coefficient

A.2.1 In accordance with B.2.1, install a calibration board, whose thickness is around

60 mm.

A.2.2 In accordance with B.2.2, install a thermocouple.

A.2.3 Set up the test ambient temperature of the hot box to be 25 °C; relative ambient humidity shall be not more than 60%. In accordance with 7.4, set up hot box test conditions. In accordance with 7.5, record the first piece of data.

A.2.4 Set up the test ambient temperature of the hot box to be 20 °C. Maintain the ambient humidity and the hot box test conditions unchanged, comply with 7.5 to record the second piece of data.

A.2.5 In accordance with (A.1) and (A.2) simultaneous equations, calculate hot

chamber external wall heat flow coefficient M 1 and test piece frame heat flow coefficient

M 2. The numerical value rounding-off rule shall comply with relevant stipulations in

GB/T 8170. The result shall retain 3 decimal places.

Where,

Phiin,1, Phiin,2---hot chamber heating power in the first and the second record, expressed in (W);

Deltathetaek,1 , Deltathetaek,2 ---average temperature difference between internal and external surface of hot chamber external wall in the first and the second record, expressed in (K);

Appendix B (Normative)

Cold Chamber Draught Fan Speed Setting Method

B.1 An Overview of Method

Adopt a calibration board, whose thickness is around 20 mm. Operate the equipment, calculate the total surface thermal resistance of the calibration board. Through adjustment of the wind speed of the cold chamber draught fan, make the total surface thermal resistance of the calibration board reach the stipulated value. Then, adopt the wind speed of the cold chamber draught fan at that moment as the set value of the cold chamber draught fan speed in the subsequent calibration and determination.

B.2 Cold Chamber Draught Fan Speed Setting

B.2.1 In the test piece frame, near the hot chamber, place a calibration board, whose thickness is around 20 mm. The end face of the calibration board shall tightly cling to the test piece frame. Both sides of the calibration board shall not exceed the surface of the test piece frame, as it is shown in Figure 1. Use sealing gum to seal up the installation clearance.

B.2.2 In accordance with GB/T 13475, or, hot box instruction, install thermocouple in

hot box space, and on hot chamber external wall and test piece frame. On the calibration board, comply with area to uniformly distribute thermocouple, as it is shown in Figure B.1.