GB/T 27698.3-2023Test methods for the performance of heat exchangers and heat exchange elements - Part 3: Heat exchanger elements (English PDF)

3.1 Test sample

Heat transfer elements for testing heat transfer performance and flow properties.

5.3 Heat transfer plate bundles

When testing the heat transfer plate bundles, the product model and the following parameters shall be clearly stated:

a) Plate corrugation form (corrugation angle, corrugation depth, corrugation spacing, mixing angle);

b) Plate geometric dimensions (length, width, corner hole diameter, longitudinal and transverse center distance);

c) Heat transfer area of a single plate;

d) Spacing between plates;

e) Flow channel cross-sectional area;

f) Plate thickness;

g) Plate material;

h) Number of plates.

7.1 Test system

The test device consists of two parts: the air system and the stream system. The air system shall have a pretreatment section and a measuring section. The pretreatment section shall ensure that the air reaches a stable state suitable for testing. The wind speed measuring section of the air system shall ensure a certain length of straight tube section to meet the requirements for the use of the measuring instrument. To ensure stable air flow through the test sample, the length of the working section of the air duct shall not be less than 1.5 m. There is no uniform regulation for the cross-sectional width within the working section of the air duct, but the air mass flow rate at the effective venting area shall meet the test requirements. The test system is shown in Figure 1.

7.3 Measurement method

7.3.1.2 The air flow rate can be measured by an anemometer, whose installation and operation procedures shall be carried out according to the instruction manual; it can also be measured by an orifice plate or a Pitot static pressure tube, where the measurement method shall comply with the provisions of GB/T 1236.

7.3.2 Temperature measurement

7.3.2.1 The working end of the temperature measuring element shall be located at the center of the pipeline or working section cross section, and its insertion depth shall not be less than the pipeline radius or the center of the working section cross section. When measuring in a narrow pipeline, a measuring section can be installed and the working end of the temperature measuring element shall be opposite to the flow direction.

7.3.2.2 The temperature measuring element shall be set at the specified position of the measuring section (see Figure 1), and the pipeline and air duct shall be well insulated.

The upstream (inlet) and downstream (outlet) range of 600 mm of the temperature measuring point shall also be insulated.

7.3.2.3 The air inlet and outlet temperatures shall only be measured as dry bulb temperature. There should be no less than three temperature measurement points on each testing section, and the average value should be taken.

7.3.3 Pressure measurement

7.3.3.1 Steam pressure and air pressure shall be measured using a standard pressure gauge or a pressure transmitter. The installation and operation procedures shall be carried out in accordance with the instruction manual.

7.3.3.2 The ambient atmospheric pressure shall be measured using a mercury barometer.

The installation and operation procedures shall be carried out in accordance with the instruction manual.

7.3.3.3 The air pressure measuring hole in the air duct shall be perpendicular and flush with the inner surface of the air duct; all internal protrusions shall be removed; the edge of the hole shall be rounded; the diameter of the hole shall not be less than 1.5 mm and not more than 5 mm.

7.3.3.4 The air pressure measuring holes in the air duct shall be set on the section about 0.5 m away from the test sample. Four pressure measuring holes should be set on each pressure measuring section of the rectangular channel, and the measuring holes should be distributed at the centers of the four sides of the section.

7.3.4 Humidity measurement

7.3.4.1 For laboratory humidity measurement, wet and dry bulb hygrometer, hair hygrometer, capacitance hygrometer or resistance hygrometer should be used.

7.3.4.2 The installation and operation procedures of the hygrometer shall be carried out in accordance with the instruction manual.

8.1 Test conditions

8.1.1 All steam piping systems shall be insulated.

8.1.2 The entire length of the test sample, except the testing section, shall be insulated.

The superheat of steam entering the test sample shall be maintained in the range of 1 °C ~ 3 °C.

8.1.3 If the weighing method is used to measure the condensate, in order to prevent the condensate from evaporating again, the subcooling degree of the condensate entering the metering device shall be at least 2 °C.

8.1.4 The test sample shall be installed straight and tilted downward by 1° ~ 3° toward the steam condensate outlet.

8.1.5 The testing section shall be selected in the middle of the test sample. The length of the heat transfer tube test sample shall not be less than 500 mm. The length and width of the heat transfer tube bundle test sample shall not be less than 600 mm × 600 mm.

The tube bundle shall not be less than 3 rows in the air flow direction. The length of the heat transfer plate bundle test sample shall not be less than 600 mm. The number of single-side flow channels shall not be less than 10. […]