GB/T 27698.2-2023Test methods for the performance of heat exchangers and heat exchange elements - Part 2: Heat exchangers (English PDF)

4.2 Plate heat exchangers

4.2.1 The number of plates in the plate heat exchanger sample shall be determined by considering the uniformity of fluid distribution within the measured flow rate range, and the number of plates installed shall not be less than 9.

4.2.2 When testing plate heat exchangers, 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;

i) Clamping dimensions;

j) Process combination;

k) Design temperature;

l) Design pressure. The above structure and design data shall be determined in accordance with the requirements of GB/T 27698.1 and NB/T 47004.1, NB/T 47004.2 as well as NB/T 47045.

4.2.3 When the product model or any of the parameters

4.2.2 changes, the performance test shall be repeated.

4.3 Spiral plate heat exchangers

4.3.1 When testing spiral plate heat exchanger, the product model and the following parameters shall be clearly stated:

a) Layout and geometric dimensions of spacing columns;

b) Spacing between plates;

c) Equivalent diameter;

d) Flow cross-sectional area;

e) Flow channel length;

f) Heat transfer plate material;

g) Heat transfer plate thickness;

h) Heat transfer area (based on the neutral surface of the heat transfer plate);

i) Design temperature;

j) Design pressure. The above structure and design data shall be determined in accordance with the requirements of GB/T 27698.1 and NB/T 47048.

4.3.2 When the product model or any of the parameters

4.3.1 changes, the performance test shall be repeated.

5.1 Liquid-liquid turbulence performance test without phase change

5.1.1 Before testing, the reliability of the test sample, pipeline and measuring instruments shall be checked.

5.1.2 After starting operation, the gas in the test sample shall be exhausted in time, so that the test sample can be operated under the condition of being fully filled with test fluid and adjusted to the standard condition according to Table 1.

5.1.3 After running stably for 30 minutes under standard conditions, the following test requirements should be followed:

a) The fluid flow rate on both sides remains the same, the flow rate changes within the range of Table 1, and the change interval meets the requirements of Table 1;

b) The fluid on one side (hot side or cold side) is fixed at the flow rate under standard conditions; the flow rate of the fluid on the other side varies within the range of Table 1, and the variation interval meets the requirements of Table 1;

5.4.2 After starting operation, the non-condensable gas in the test sample shall be discharged in time and adjusted to the standard condition.

5.4.3 After running stably for 30 minutes under standard condition, the following test requirements should be followed:

a) Keep the steam temperature entering the pre-heater and the test sample inlet at 1 °C ~ 3 °C superheat, and the condensate temperature slightly lower than the saturation temperature corresponding to the outlet steam pressure, but within the range of 2 °C; obtain the steam flow rate by measuring the condensate;

b) The flow rate of the cold fluid varies within the range of Table 1, and the variation interval meets the requirements of Table 1;

c) The inlet dryness of the cold fluid of the test sample is adjusted by the pre- heater, and the minimum inlet dryness is 0;

d) The average dryness of the cold fluid of the test sample changes according to the use range, and the change interval increases with the increase of dryness;

e) When each test condition is stable for more than 5 minutes, carry out data collection simultaneously. During the condensate metering process, the condition remains relatively stable;

f) Repeat the measurement at each test point at least 3 times, with an interval of more than 5 minutes between each measurement; take the average value of the measurement results.

5.4.4 The test conditions can be determined through negotiation based on user requirements and equipment characteristics.

5.5 Pool boiling heat transfer performance test

5.5.1 Before testing, the reliability of the test sample, pipeline and measuring instruments shall be checked.

5.5.2 After running stably for 30 minutes, the test should be carried out according to the following test requirements:

a) Ensure that the liquid level of the cold fluid is higher than that of the test sample;

b) When each test condition is stable for more than 5 minutes and the relative error of thermal balance is no more than 5%, carry out data collection synchronously; the condition remains relatively stable during the condensate metering process;

c) Change the heat load at least 5 times during the test; collect at least 3 sets of data simultaneously at each test point.

5.5.3 The test conditions can be determined through negotiation based on user requirements and equipment characteristics.

6.1 Liquid-liquid performance test without phase change

6.1.1 Give the test curve of total heat transfer coefficient (k) and flow rate (u).

6.1.2 Summarize the criterion relation between the Nusselt number (Nu) and the Reynolds number (Re) as well as the Prandtl number (Pr).

6.1.3 In the same coordinate system, calculate the relationship curve between the total heat transfer coefficient (k) and the flow rate (u) when the reference temperatures of the cold/hot fluids are 20 °C/40 °C, 30 °C/50 °C, and 40 °C/60 °C respectively.

6.1.4 Provide the test curve of pressure drop (Deltap) and flow rate (u).

6.1.5 Summarize the criterion relation between the Euler number (Eu) and the Reynolds number (Re).

6.1.6 In the same coordinate system, calculate the relationship curve between the pressure drop (Deltap) and the flow rate (u) of the cold fluid when the reference temperatures are 20 °C, 30 °C and 40 °C, respectively.

6.1.7 In the same coordinate system, calculate the relationship curve between the pressure drop (Deltap) and flow rate (u) of the hot fluid when the reference temperatures are 40 °C, 50 °C, and 60 °C, respectively.

6.1.8 Give the values of the total heat transfer coefficient (k) and pressure drop (Deltap) at the flow rate under standard condition when the hot fluid reference temperature is 50 °C and the cold fluid reference temperature is 30 °C.

6.2 Vapor-liquid condensation performance test

6.2.1 Provide the test curve of the total heat transfer coefficient (k) and the liquid side flow rate (u) or Reynolds number (Re).

6.2.2 Summarize the relationship between the condensation convection heat transfer coefficient (alpha) and the flow rate (u) or the Reynolds number (Re).