Method and device for testing visual heat conductivity coefficient of whole pipe of non-metal composite material object

Abstract

The invention belongs to the technical field of petroleum non-metal composite pipe performance testing, and particularly relates to a non-metal composite material whole pipe apparent heat conductivity coefficient testing method and device. The invention relates to a method for testing the visual heat conductivity coefficient of a whole pipe of a non-metal composite material object. The method comprises the following steps: filling a cavity of a test pipe section with water; a plurality of pipe body temperature measuring points are laid on the outer surface of the test pipe section, and environment temperature measuring points are arranged near the test pipe section; respectively connecting two ends of the test pipe section with a constant-temperature water bath inlet and outlet; setting the constant-temperature water bath temperature, starting a circulating pump after the temperature is constant, and keeping the temperature of the inner and outer surfaces of the to-be-tested pipe section constant; and performing heat flux density measurement on the test pipe section by adopting an unsteady-state heat dissipation method, and determining the apparent heat conductivity coefficient of the test pipe section. The non-heat-flux density is determined by testing the fixed-mass hot water enthalpy drop in the pipe section and the outer side surface area in a short time through a steady-state heat dissipation method, and compared with existing direct measurement of the heat flux density, the error is small, and the whole-pipe apparent heat conductivity coefficient of a non-metal composite material object can be reflected more accurately.

Description

Technical Field

[0001] The present invention belongs to the technical field of performance testing of non-metallic composite pipes for oil, and particularly relates to a method and device for testing the apparent thermal conductivity of a non-metallic composite physical whole pipe. Background Art

[0002] Geothermal energy is a clean and renewable energy source. Replacing high-carbon energy with geothermal energy is one of the effective ways to reduce carbon emissions. To avoid waste of energy during the transfer of underground geothermal energy to the ground, heat-insulating pipes are used to transport geothermal energy. The research on the heat-insulating performance of heat-insulating pipes is of great significance for improving the utilization rate of geothermal energy. However, with the continuous innovation of the manufacturing technology of non-metallic composite heat-insulating pipes and their extensive use in the field of geothermal energy, the results show that the non-metallic composite heat-insulating pipes have good effects, but there is a lack of a corresponding test method for the thermal conductivity of the physical whole pipe.

[0003] Currently, in enterprises, tests are only carried out on sheets, and there is no special equipment for detecting physical whole pipes. Through retrieval, it is found that Chinese invention CN103267774A discloses a pipe thermal conductivity tester and test method with hyperbolic reality. However, in the oil and gas extraction and transportation in oilfields, heating and temperature control are often required, while the fluid medium in the pipe of this invention is 0°C brine, which cannot be heated and temperature-controlled, and can only be tested at room temperature conditions (23 - 25°C). Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide a method and device for testing the apparent thermal conductivity of a non-metallic composite physical whole pipe. This method determines the non-thermal flux density by measuring the enthalpy drop of a fixed mass of hot water inside the pipe section and the outer surface area through the steady-state heat dissipation method in a short time. Compared with the existing direct measurement of the heat flux density, the error is small, and it can more accurately reflect the apparent thermal conductivity of the non-metallic composite physical whole pipe.

[0005] The technical solution of the present invention lies in: a method for testing the apparent thermal conductivity of a non-metallic composite physical whole pipe, comprising the following steps: S1: Cut a non-metallic composite pipe with a set length according to the test requirements as the test pipe section for the apparent thermal conductivity of the whole pipe, seal the two ends of the test pipe section, and fill the cavity of the test pipe section with water; S2: Vertically place the test pipe section, and lay a plurality of pipe body temperature measurement points on the outer surface of the test pipe section, and set an ambient temperature measurement point near the test pipe section; S3: Connect the two ends of the test pipe section to the inlet and outlet of a constant temperature water bath respectively, and perform heat insulation treatment; S4: Set the temperature of the constant temperature water bath according to the test requirements. After the temperature is constant, turn on the circulation pump, observe the change in the surface temperature of the test pipe section. After the inner and outer surface temperatures of the test pipe section are constant, conduct the experiment; S5: Measure the heat flux density of the test pipe section using the unsteady heat dissipation method. Determine the apparent thermal conductivity of the test pipe section by measuring the temperature gradients and heat flux density on the inner and outer walls of the test pipe section.

[0006] In the step S2, multiple pipe body temperature measurement points are arranged evenly in a spiral shape from top to bottom along the test pipe section, and the number of the pipe body temperature measurement points ≥ 6.

[0007] In the step S4, the set range of the constant temperature water bath temperature is 40~70 °C.

[0008] In the step S5, the parameters required to be measured by using the unsteady heat dissipation method include: the mass of water in the test pipe section, the temperature difference between the outer wall of the test pipe section and the environment, and the temperature drop time.

[0009] In the step S5, measure the heat flux density of the test pipe section by using the unsteady heat dissipation method. Determine the apparent thermal conductivity of the test pipe section by the temperature gradients and heat flux density on the inner and outer walls of the test pipe section. The processing procedure is as follows: The total heat dissipation Q1 of the water in the test pipe section is: Q1 = cmTc’ (1) In the formula, c is the specific heat capacity of water, m is the mass of water in the test pipe section, and Tc’ is the temperature difference between the outer wall of the test pipe section and the environment; The heat released by the comprehensive heat transfer on the outer wall of the test pipe section Q2 is: Q2 = htATc’ (2) In the formula, A is the total area of the outer wall of the test pipe section, t is the temperature drop time, c is the specific heat capacity of water, and h is the comprehensive heat transfer coefficient; According to the law of conservation of energy, Q1 = Q2, and the comprehensive heat transfer coefficient h of the test pipe section is obtained; The heat flux density q on the outer wall of the test pipe section is: (3) In the formula, Tc is the temperature difference between the outer wall temperature of the test pipe section and the hot water bath, R1 is the inner pipe inner diameter, and R2 is the outer pipe outer diameter; The comprehensive heat transfer heat flux density q’ from the outer wall to the environment is: q’ = hTc’ (4) According to the law of conservation of energy, q = q’: (5) The obtained thermal conductivity of the test pipe section is: (6) In the formula, Tc is the temperature difference between the outer wall temperature of the test pipe section and the hot water bath, Tc’ is the temperature difference between the outer wall of the test pipe section and the environment, h is the comprehensive heat transfer coefficient, R1 is the inner pipe inner diameter, and R2 is the outer pipe outer diameter.

[0010] A non-metallic composite physical whole-tube apparent thermal conductivity testing device, comprising a test pipe section, the test pipe section is vertically fixed in a fixed groove body, both ends of the test pipe section are connected with a constant temperature water bath unit through pipelines, a plurality of pipe body temperature measuring points are arranged on the outer surface of the test pipe section, an ambient temperature measuring point is arranged near the test pipe section, and the pipe body temperature measuring points and the ambient temperature measuring point are respectively electrically connected to a data acquisition unit.

[0011] The technical effect of the present invention is that: the present invention determines the non-thermal flux density by measuring the enthalpy drop of a fixed mass of hot water inside the pipe section and the outer surface area in a short time through the steady-state heat dissipation method. Compared with the existing direct measurement of the heat flux density, the error is small, and it can more accurately reflect the apparent thermal conductivity of the non-metallic composite physical whole tube.

[0012] The following will be further described in conjunction with the drawings. Description of the Drawings

[0013] Figure 1 It is a schematic structural diagram of a method for testing the apparent thermal conductivity of a non-metallic composite physical whole tube according to an embodiment of the present invention.

[0014] Reference numerals: 1 - constant temperature water bath unit; 2 - fixed groove body; 3 - data acquisition unit; 4 - ambient temperature measuring point; 5 - test pipe section; 6 - pipe body temperature measuring point. Detailed Embodiment Embodiment 1

[0015] A method for testing the apparent thermal conductivity of a non-metallic composite physical whole tube, comprising the following steps: S1: Cut a non-metallic composite pipe with a set length according to the test requirements as the test pipe section for the apparent thermal conductivity of the whole tube, seal both ends of the test pipe section, and fill the cavity of the test pipe section with water; S2: Vertically place the test pipe section, and lay a plurality of pipe body temperature measuring points on the outer surface of the test pipe section, and set an ambient temperature measuring point near the test pipe section; S3: Connect both ends of the test pipe section to the inlet and outlet of the constant temperature water bath respectively, and perform heat insulation treatment; S4: Set the temperature of the constant temperature water bath according to the test requirements, start the circulation pump after the temperature is constant, observe the change of the surface temperature of the test pipe section, and conduct the experiment after the inner and outer surface temperatures of the test pipe section are constant; S5: Use the non-steady-state heat dissipation method to measure the heat flux density of the test pipe section, and determine the apparent thermal conductivity of the test pipe section through the temperature gradient and heat flux density of the inner and outer walls of the test pipe section.

[0016] In step S2, a plurality of pipe body temperature measuring points are uniformly arranged in a spiral shape from top to bottom along the test pipe section, and the number of the pipe body temperature measuring points ≥ 6.

[0017] In the step S4, the set range of the constant temperature water bath temperature is 40~70 °C.

[0018] In the step S5, the parameters to be measured by the unsteady heat dissipation method include: the mass of water in the test pipe section, the temperature difference between the outer wall of the test pipe section and the environment temperature, and the temperature drop time.

[0019] In the step S5, the unsteady heat dissipation method is used to measure the heat flux density of the test pipe section. By the temperature gradient and heat flux density of the inner and outer walls of the test pipe section, the apparent thermal conductivity of the test pipe section is determined. The processing process is as follows: The total heat dissipation Q1 of the water in the test pipe section is: Q1 = cmTc’ (1) In the formula, c is the specific heat capacity of water, m is the mass of water in the test pipe section, and Tc’ is the temperature difference between the outer wall of the test pipe section and the environment temperature; The heat released Q2 by the comprehensive heat transfer of the outer wall of the test pipe section is: Q2 = htATc’ (2) In the formula, A is the total area of the outer wall of the test pipe section, t is the temperature drop time, c is the specific heat capacity of water, and h is the comprehensive heat transfer coefficient; According to the law of conservation of energy, Q1 = Q2, and the comprehensive heat transfer coefficient h of the test pipe section is obtained; The heat flux density q of the outer wall of the test pipe section is: (3) In the formula, Tc is the temperature difference between the outer wall temperature of the test pipe section and the hot water bath, R1 is the inner pipe inner diameter, and R2 is the outer pipe outer diameter; The comprehensive heat transfer heat flux density q’ from the outer wall to the environment is: q’ = hTc’ (4) According to the law of conservation of energy, q = q’; (5) The obtained thermal conductivity of the test pipe section is: (6) In the formula, Tc is the temperature difference between the outer wall temperature of the test pipe section and the hot water bath, Tc’ is the temperature difference between the outer wall of the test pipe section and the environment temperature, h is the comprehensive heat transfer coefficient, R1 is the inner pipe inner diameter, and R2 is the outer pipe outer diameter.

[0020] Compared with the direct measurement method, which is easily affected by various factors, it is more difficult to accurately characterize, has a large error in the heat flux density, and is difficult to accurately measure the comprehensive performance of the pipe material. The present invention calculates the heat flux density of the experimental piece based on the conservation of energy, which is closer to the service condition of the pipe material, has a smaller error, and can more accurately reflect the apparent thermal conductivity of the non-metallic composite integral pipe. Example 2

[0021] As shown Figure 1 in the figure, a non-metallic composite physical whole-pipe apparent thermal conductivity testing device includes a test pipe section 5, the test pipe section 5 is vertically fixed in a fixed tank body 2, both ends of the test pipe section 5 are connected with a constant temperature water bath unit 1 through pipelines, a plurality of pipe body temperature measurement points 6 are arranged on the outer surface of the test pipe section 5, an ambient temperature measurement point 4 is arranged near the test pipe section 5, and the pipe body temperature measurement points 6 and the ambient temperature measurement point 4 are respectively electrically connected to a data acquisition unit 3.

[0022] During actual use, the present invention vertically places the test pipe section 5, and according to the test requirements, a plurality of pipe body temperature measurement points 6 are evenly laid on the outer side of the test pipe section 5 from top to bottom, an ambient temperature measurement point 4 is arranged near the test pipe section 5, and the pipe body temperature measurement points 6 and the ambient temperature measurement point 4 are respectively electrically connected to the data acquisition unit 3; the data acquisition unit 3 is used to set the acquisition frequency and save the corresponding data; the apparent thermal conductivity of the non-metallic composite pipe material is obtained through calculation. The non-metallic composite physical whole-pipe apparent thermal conductivity testing device of the present invention can detect the whole pipe of the composite pipe, the device design is simple and reasonable, the operation is convenient, the test accuracy is high, and the cost is low. Example 3

[0023] According to the non-metallic composite physical whole-pipe apparent thermal conductivity testing device described in Example 2, using the non-metallic composite physical whole-pipe apparent thermal conductivity testing method in Example 1, the apparent thermal conductivity of a certain polyethylene pipe composite pipe is tested. The specific process is as follows: S1: Cut a certain polyethylene pipe composite pipe with a set length according to the test requirements as the test pipe section for the whole-pipe apparent thermal conductivity, seal the two ends of the test pipe section with a polymer material, and fill the cavity of the test pipe section with water; S2: Vertically place the test pipe section, and lay 8 pipe body temperature measurement points on the outer surface of the test pipe section, and set an ambient temperature measurement point near the test pipe section; S3: Connect the two ends of the test pipe section to the inlet and outlet of the constant temperature water bath respectively, and perform heat preservation treatment; S4: Set the constant temperature water bath temperature to 70°C according to the test requirements, start the circulation pump after the temperature is constant, observe the change of the surface temperature of the test pipe section, and conduct the experiment after the inner and outer surface temperatures of the test pipe section are constant; S5: Use the non-steady state heat dissipation method to measure the heat flux density of the test pipe section. Through the temperature gradient and heat flux density of the inner and outer walls of the test pipe section, the total outer wall area A of the polyethylene pipe composite pipe is 3.7322 m 2, during the experiment, the temperature drop time t was 60 s, and the specific heat capacity c of water was 4200 J / (kg·°C). According to the formula Q1 = cmTc’ = Q2 = htATc’, h = 1.14368 could be calculated, and then the apparent thermal conductivity of the test pipe section was determined, as shown in Table 1.

[0024] Table 1 shows the data table of the apparent thermal conductivity obtained by the test method of the present invention, the apparent thermal conductivity obtained by the existing direct measurement, and the thermal conductivity of polyethylene particles. It can be seen from Table 1 that through the thermal conductivity test of polyethylene pellets, the apparent thermal conductivity obtained by the test method of the present invention is closer to the thermal conductivity of the polyethylene pellets of the polyethylene composite pipe than the apparent thermal conductivity obtained by direct measurement. The test method of the present invention has a small error and can more accurately reflect the apparent thermal conductivity of the non-metallic composite pipe.

[0025] Table 1 Apparent thermal conductivity obtained by the test method of the present invention and apparent thermal conductivity obtained by the existing direct measurement The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for testing the apparent thermal conductivity of a non-metallic composite physical integral pipe, characterized in that: It includes the following steps: S1: Cut a non-metallic composite pipe with a set length according to the test requirements as the test pipe section for the apparent thermal conductivity, seal the two ends of the test pipe section, and fill the cavity of the test pipe section with water; S2: Vertically place the test pipe section, lay multiple pipe body temperature measurement points on the outer surface of the test pipe section, and set an ambient temperature measurement point near the test pipe section; S3: Connect the two ends of the test pipe section to the inlet and outlet of a constant temperature water bath respectively, and perform heat preservation treatment; S4: Set the temperature of the constant temperature water bath according to the test requirements. After the temperature is constant, turn on the circulation pump, observe the change of the surface temperature of the test pipe section. After the inner and outer surface temperatures of the test pipe section are constant, conduct the experiment; S5: Use the unsteady heat dissipation method to measure the heat flux density of the test pipe section. Determine the apparent thermal conductivity of the test pipe section through the temperature gradient and heat flux density on the inner and outer walls of the test pipe section.

2. The method for testing the apparent thermal conductivity of a non-metallic composite physical integral pipe according to claim 1, characterized in that: In the step S2, a plurality of pipe body temperature measurement points are evenly arranged in a spiral shape from top to bottom along the test pipe section, and the number of the pipe body temperature measurement points ≥ 6.

3. The method for testing the apparent thermal conductivity of a non-metallic composite physical integral pipe according to claim 1, characterized in that: In the step S4, the set temperature range of the constant temperature water bath is 40~70 °C.

4. The method for testing the apparent thermal conductivity of a non-metallic composite physical integral pipe according to claim 1, characterized in that: In the step S5, the parameters required to be measured by the unsteady heat dissipation method include: the mass of water in the test pipe section, the temperature difference between the outer wall of the test pipe section and the ambient temperature, and the temperature drop time.

5. The method for testing the apparent thermal conductivity of a non-metallic composite physical integral pipe according to claim 1, characterized in that: In the step S5, use the unsteady heat dissipation method to measure the heat flux density of the test pipe section. Determine the apparent thermal conductivity of the test pipe section through the temperature gradient and heat flux density on the inner and outer walls of the test pipe section. The processing process is as follows: The total heat dissipation Q1 of the water in the test pipe section is: Q1 = cmTc’ (1) In the formula, c is the specific heat capacity of water, m is the mass of water in the test pipe section, and Tc’ is the temperature difference between the outer wall of the test pipe section and the ambient temperature; The heat released by the comprehensive heat transfer of the outer wall of the test pipe section is Q2: Q2 = htATc’ (2) In the formula, A is the total outer wall area of the test pipe section, t is the temperature drop time, c is the specific heat capacity of water, and h is the comprehensive heat transfer coefficient; According to the law of conservation of energy, Q1 = Q2, and the comprehensive heat transfer coefficient h of the test pipe section is obtained; The heat flux density q of the outer wall of the test pipe section is: （3） In the formula, Tc is the temperature difference between the outer wall temperature of the test pipe section and the hot water bath, R1 is the inner pipe inner diameter, and R2 is the outer pipe outer diameter; The comprehensive heat transfer heat flux density q’ from the outer wall to the environment is: q’ = hTc’ (4) According to the law of conservation of energy, q = q’: （5） The thermal conductivity of the test pipe section is obtained as: （6） Wherein, Tc is the temperature difference between the outer wall temperature of the test pipe section and the hot water bath, Tc’ is the temperature difference between the outer wall of the test pipe section and the ambient temperature, h is the comprehensive heat transfer coefficient, R1 is the inner diameter of the inner pipe, and R2 is the outer diameter of the outer pipe.

6. A test device for the apparent thermal conductivity of a non-metallic composite integral pipe, characterized in that: it includes a test pipe section (5), the test pipe section (5) is vertically fixed in a fixed groove body (2), both ends of the test pipe section (5) are connected with a constant temperature water bath unit (1) through pipelines, a plurality of pipe body temperature measurement points (6) are arranged on the outer surface of the test pipe section (5), an ambient temperature measurement point (4) is arranged near the test pipe section (5), and the pipe body temperature measurement points (6) and the ambient temperature measurement point (4) are respectively electrically connected to a data acquisition unit (3).

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