A device and method for measuring the coking speed of a heat-conducting oil-based magnetic nanofluid

Abstract

The application discloses a kind of determination device and method of heat conducting oil-based magnetic nanofluid coking speed, it is related to with heat conducting oil as heat transfer medium in the technical field of medium-temperature solar thermal power generation system, oilfield ground gathering and transportation heating system etc., the method comprises: after heating heat conducting oil tank inside heat conducting oil-based nanofluid by electric heater, it is transported to steel pipe by heat conducting oil pump, the strength of magnetic field is adjusted by adjusting the number of magnetic block and the distance between adjacent magnetic blocks, different intensity magnetic field is applied to the fluid received in steel pipe;The coking product on the first hanger sheet in heat conducting oil tank and the second hanger sheet in steel pipe after applying for a period of time is dried respectively, the mass of coking product in two states before and after applying magnetic field is obtained, so as to calculate the coking speed;By changing magnetic field, the turbulence degree of heat conducting oil can be increased, the convective heat transfer coefficient can be improved, the fluid heat transfer can be strengthened, the formation of heat conducting oil coking can be slowed down, and the service life can be prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medium-temperature solar thermal power generation systems, oilfield ground gathering and heating systems and the like using heat-conducting oil as a heat transfer medium, and particularly relates to a device and method for measuring coking speed of heat-conducting oil-based magnetic nanofluid. BACKGROUND

[0002] A trough-type solar thermal power generation system concentrates sunlight on a solar heat collection tube through a trough-type reflector, the heat collection tube has a heat absorbing tube for absorbing sunlight to heat the heat transfer medium, heat-conducting oil, to about 400 DEG C, and then a heat exchanger can be used to heat water to about 300 DEG C to form steam, and finally the steam is used to drive a steam turbine to rotate and drive a generator to generate electricity. In the process of absorbing solar energy, the heat-conducting oil is easily oxidized, and in places where the heat intensity is too large or the flow is restricted, the heating surface temperature rises above the thermal decomposition limit temperature, causing overheating. In this case, cracking and thermal decomposition cause coking on the heating surface, affecting heat transfer, accelerating the aging and failure of the heat-conducting oil, and also causing local overheating of the heat collection tube, damaging the mechanical strength, and in severe cases, endangering personal safety.

[0003] The coking problem of heat-conducting oil relates to the safe operation of the entire solar thermal power generation heat absorption system. By increasing the turbulence of the heat-conducting oil, improving the convective heat transfer coefficient, and strengthening the fluid heat transfer, the thickness of the stagnant bottom layer in the heat transfer boundary layer between the heat-conducting oil and the heating surface and the convective heat transfer thermal resistance can be reduced, the coking formation speed of the heat-conducting oil can be slowed down, and the service life thereof can be prolonged. As a new type of heat transfer medium, nanofluid has excellent heat conduction performance, and the heat transfer strengthening effect is very obvious. The nanofluid has the advantages of enhancing heat exchange between media, accelerating temperature transfer, and improving heat exchange efficiency of the medium. The magnetic nanofluid is a special fluid, which has good magnetic guiding property. By changing the magnetic field, the thermodynamic, kinetic and rheological properties of the magnetic nanofluid can be adjusted.

[0004] At present, the research on slowing down the coking of heat-conducting oil mainly focuses on the process, such as controlling the flow rate of heat-conducting oil and limiting the heating temperature, but it does not solve the problem from the essence. The research on the coking change of heat-conducting oil-based magnetic nanofluid under the action of a magnetic field mainly from the perspective of numerical simulation, and the accuracy cannot be verified. Therefore, the present application provides a device and method for measuring the coking speed of heat-conducting oil-based magnetic nanofluid to solve the above problems. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a device and method for measuring the coking speed of heat-conducting oil-based magnetic nanofluid, which utilizes the guiding property of heat-conducting oil-based magnetic nanofluid under the action of a magnetic field to break the conditions for coking of heat-conducting oil, prolong the service life of the heat transfer medium, and solve the problems in the prior art.

[0006] A method for measuring the coking speed of a heat conducting oil-based magnetic nanofluid, comprising the following steps:

[0007] A heat conducting oil tank;

[0008] An electric heater arranged in the heat conducting oil tank;

[0009] A heat conducting oil pump, one end of which is in communication with the heat conducting oil tank;

[0010] A plurality of first hangers arranged on the inner wall of the heat conducting oil tank;

[0011] An electromagnetic induction device for providing a magnetic field environment for the heated heat conducting oil-based nanofluid; the electromagnetic induction device comprises:

[0012] A base provided with a groove;

[0013] A steel pipe placed in the groove, one end of which is in communication with the other end of the heat conducting oil pump, and the other end of which is in communication with the heat conducting oil tank, the steel pipe being provided with a plurality of second hangers;

[0014] A plurality of magnetic blocks arranged on the base on both sides of the steel pipe.

[0015] Further, a cooler is arranged between the heat conducting oil tank and the electromagnetic induction device, one end of the cooler being in communication with the other end of the steel pipe, and the other end of the cooler being in communication with the heat conducting oil tank.

[0016] Further, the bottom of the steel pipe is provided with a movable window.

[0017] Further, a stirrer is arranged at the bottom of the heat conducting oil tank.

[0018] Further, an adjustable transformer is arranged on one side of the heat conducting oil tank, the adjustable transformer being electrically connected with the electric heater.

[0019] Further, a method for measuring the coking speed of a heat conducting oil-based magnetic nanofluid measuring device, comprising the following steps:

[0020] Heating the heat conducting oil-based nanofluid in the heat conducting oil tank by the electric heater;

[0021] Delivering the heated heat conducting oil-based nanofluid to the steel pipe in the electromagnetic induction device through the heat conducting oil pump to homogenize the magnetic field;

[0022] Applying a magnetic field to the fluid received in the steel pipe through the magnetic blocks on both sides of the steel pipe to obtain the coking product of the heat conducting oil-based magnetic nanofluid under the applied magnetic field strength;

[0023] The coking products on the first hanging piece in the heat conducting oil tank and the coking products on the second hanging piece in the steel pipe after the magnetic field is applied are dried respectively to obtain the mass of the coking products in two states before and after the magnetic field is applied;

[0024] According to the mass of the obtained coking products, the change amount of the mass of the coking products before and after the magnetic field is applied is calculated, so that the coking speed of the heat conducting oil-based magnetic nanofluid corresponding to the magnetic field is obtained.

[0025] Further, the heating power of the electric heater is adjusted by the adjustable transformer to change the heating temperature of the heat conducting oil-based nanofluid.

[0026] Further, the magnetic field strength is adjusted by adjusting the number of magnetic blocks on both sides of the steel pipe and the distance between adjacent magnetic blocks, and the fluid received in the steel pipe is applied with magnetic fields of different strengths.

[0027] Further, the heat conducting oil-based nanofluid is stirred by the motor-controlled stirrer during the heating process of the heat conducting oil-based nanofluid.

[0028] Further, the formula for calculating the coking speed is:

[0029]

[0030] Wherein, M0 is the mass of the coking products on the first hanging piece, M1 is the mass of the coking products on the second hanging piece, and T is the test time.

[0031] The present application provides a kind of heat conducting oil-based magnetic nanofluid coking speed determination device and method, with the following beneficial effects:

[0032] The present application provides a kind of heat conducting oil-based magnetic nanofluid coking speed determination device and method, with the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is the working schematic diagram of the heat conducting oil-based magnetic nanofluid coking under the action of the magnetic field of the present application;

[0034] Figure 2 It is the position schematic diagram of the hanging piece arrangement in the heat conducting oil tank of the present application;

[0035] Figure 3 It is the overhead schematic diagram of the electromagnetic induction device in the present application;

[0036] Figure 4 Fig. 1 is a left view of the electromagnetic induction device in the present application;

[0037] Figure 5 Fig. 2 is a schematic diagram of the arrangement of the movable window on the steel pipe in the present application.

[0038] In the figure: 1-electric heater, 2-heat conducting oil tank, 3-heat conducting oil pump, 4-electromagnetic induction device, 5-cooler, 6-stirrer, 7-hanging piece, 8-adjustable transformer, 9-steel pipe, 10-magnetic block, 11-base, 12-movable window. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments.

[0040] Please refer to Figures 1-5 , the technical solutions provided by the present application:

[0041] A device for measuring the coking speed of heat conducting oil-based magnetic nanofluid, comprising: a heat conducting oil tank 2; an electric heater 1 arranged in the heat conducting oil tank 2; a heat conducting oil pump 3, one end of which is in communication with the heat conducting oil tank 2; a plurality of first hanging pieces 7 arranged on the inner wall of the heat conducting oil tank 2; an electromagnetic induction device 4 for providing a magnetic field environment for the heated heat conducting oil-based nanofluid; the electromagnetic induction device comprises: a base 11, a groove being arranged on the base 11; a steel pipe 9 placed in the groove, one end of the steel pipe 9 being in communication with the other end of the heat conducting oil pump 3, the other end of the steel pipe 9 being in communication with the heat conducting oil tank 2, a plurality of second hanging pieces being arranged in the steel pipe 9; a plurality of magnetic blocks 10 arranged on the base 11 on both sides of the steel pipe 9; the present application adopts the hanging piece method to measure the coking speed of the medium. The experimental data of the hanging pieces 7 arranged in the heat conducting oil tank 2 are used as the comparative results of the coking speed without an external magnetic field at this temperature. A circle of hanging pieces 7 is arranged at the middle position of the height direction of the heat conducting oil tank 2, and four hanging pieces are arranged in the symmetric direction (the specific positions are shown in Figure 2 The magnetic induction system comprises a magnetic field device and a magnetic field homogenization device, as shown in Figure 3 and Figure 4 . The magnetic field device is composed of the magnetic blocks 10 (permanent magnets, such as neodymium-iron-boron magnets) and the base 11 (non-magnetic materials, such as aluminum, copper, etc.). The magnetic field homogenization device is the steel pipe 9, which is used to homogenize the magnetic field received by the medium in the electromagnetic induction device 4. The corresponding hanging pieces are arranged in the steel pipe 9 to observe the influence of the magnetic field on the coking speed of the heat conducting oil.

[0042] The electric heater 1 is arranged in the heat conducting oil tank 2, and an adjustable transformer 8 is arranged on the other side of the heat conducting oil tank 2 and electrically connected with the electric heater 1; the electric heating system is arranged in the heat conducting oil tank 2 and comprises the electric heater 1 and the adjustable transformer 8. In order to realize safe heating, power supply is performed in a large-current low-voltage mode. The adjustable transformer 8 is used to adjust the heating power of the electric heater 1; under the same magnetic field intensity, the coking speed of the heat conducting oil-based magnetic nanofluid is different at different temperatures, so the electric heating system is used to provide heat conducting oil-based magnetic nanofluids at different temperatures for the electromagnetic induction device.

[0043] The cooler 5 is arranged between the heat conducting oil tank 2 and the electromagnetic induction device, one end of the cooler 5 is communicated with the other end of the steel pipe 9, and the other end of the cooler 5 is communicated with the heat conducting oil tank 2; the cooling system comprises the cooler 6 and is arranged to ensure that the temperature of the medium returned to the heat conducting oil tank 2 is constant; the movable window 10 is arranged at the bottom of the steel pipe 9. Figure 5

[0044] The stirrer 6 is arranged at the bottom of the heat conducting oil tank 2 and is controlled by a motor. Because the nanometer particles will settle down in the liquid for a long time, the stirrer is arranged to ensure that the nanometer particles can be uniformly distributed in the heat conducting oil.

[0045] The application mainly comprises an electric heating system, a cooling system, an electromagnetic induction system and a data acquisition system. The structural schematic diagram of the application device is shown in the figure. Figure 1 The heat conducting oil-based nanofluid in the heat conducting oil tank 2 is heated by the electric heater 1 and flows out of the heat conducting oil tank 2 when the temperature reaches the required temperature. Then the heat conducting oil-based nanofluid is pumped to the electromagnetic induction system by the heat conducting oil pump 3, is heat-exchanged in the cooler 5 and then enters the heat conducting oil tank 2. The data acquisition system is used to acquire signals such as temperature and magnetic field intensity; the magnetic nanofluid is a special fluid and has good magnetic guiding property; the magnetic nanometer particles are added to the heat conducting oil, the turbulence degree of the heat conducting oil can be increased and the convective heat transfer coefficient can be improved by changing the magnetic field, the coking of the heat conducting oil is slowed down and the service life is prolonged.

[0046] Based on the same inventive concept, the application further provides a heat conducting oil-based magnetic nanofluid coking speed measuring method, which comprises the following steps:

[0047] The heat conducting oil-based nanofluid in the heat conducting oil tank is heated by the electric heater;

[0048] The heated heat conducting oil-based nanofluid is delivered to the steel pipe in the electromagnetic induction device by the heat conducting oil pump to be subjected to magnetic field homogenization;

[0049] ​The magnetic field strength is adjusted by adjusting the number of magnetic blocks on both sides of the steel pipe and the distance between adjacent magnetic blocks, different strength magnetic fields are applied to the fluid received in the steel pipe, and the coking products of the heat conducting oil-based magnetic nanofluid under different magnetic field strengths are obtained; the coking products on the first hanging piece in the heat conducting oil tank and the coking products on the second hanging piece in the steel pipe after different magnetic field strengths are applied are dried respectively to obtain the mass of the coking products in two states before and after the magnetic field is applied; the test section 4 is horizontally placed in the magnetic field, after T hours of testing under a certain magnetic field strength, the coking products on the hanging piece in the heat conducting oil tank 2 and the test section are dried respectively to obtain the product mass M0 and M1 in two states. The change amount of the mass of the coking products before and after the magnetic field is applied, that is, the coking speed V, can be calculated by the following formula. The magnetic field strength is adjusted by adjusting the number of magnetic blocks 10 and the distance between adjacent magnetic poles. The magnetic field strength is measured by a digital tesla meter. Thus, the coking speed of the heat conducting oil-based magnetic nanofluid corresponding to different magnetic fields is obtained;

[0050] The change amount of the mass of the coking products before and after the magnetic field is applied is calculated according to the obtained mass of the coking products, so that the coking speed of the heat conducting oil-based magnetic nanofluid corresponding to different magnetic fields is obtained, and the influence of the magnetic field on the coking speed is determined.

[0051]

[0052] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A device for determining the coking rate of a heat conducting oil-based magnetic nanofluid, characterized by, The application relates to a heat-conducting oil tank (2), an electric heater (1) arranged in the heat-conducting oil tank (2), a heat-conducting oil pump (3) in communication with one end of the heat-conducting oil tank (2), a plurality of first hangers (7) arranged on the inner wall of the heat-conducting oil tank (2), and an electromagnetic induction device (4) for providing a magnetic field environment for heated heat-conducting oil-based nanofluid. The electromagnetic induction device comprises a base (11) provided with a groove, a steel pipe (9) placed in the groove and in communication with the other end of the heat-conducting oil pump (3) and the heat-conducting oil tank (2), and a plurality of second hangers arranged in the steel pipe (9). A cooler (5) is arranged between the heat-conducting oil tank (2) and the electromagnetic induction device (4) and in communication with the other end of the steel pipe (9) and the heat-conducting oil tank (2). The bottom of the steel pipe (9) is provided with a movable window (12). The bottom of the heat-conducting oil tank (2) is provided with a stirrer (6). One side of the heat-conducting oil tank (2) is provided with an adjustable transformer (8) in electrical connection with the electric heater (1). The application further relates to a method for testing the coking speed of heat-conducting oil-based nanofluid. The method comprises the following steps: heating the heat-conducting oil-based nanofluid in the heat-conducting oil tank by the electric heater; conveying the heated heat-conducting oil-based nanofluid into the steel pipe of the electromagnetic induction device by the heat-conducting oil pump to realize magnetic field homogenization; applying a magnetic field to the received fluid in the steel pipe by the magnetic blocks arranged on the two sides of the steel pipe to obtain the coking product of the heat-conducting oil-based magnetic nanofluid under the applied magnetic field intensity; drying the coking product on the first hanger in the heat-conducting oil tank and the coking product on the second hanger in the steel pipe after the application of the magnetic field to obtain the mass of the coking product in the two states before and after the application of the magnetic field; calculating the change of the mass of the coking product before and after the application of the magnetic field according to the obtained mass of the coking product to obtain the coking speed of the heat-conducting oil-based magnetic nanofluid corresponding to the magnetic field. The heating power of the electric heater is adjusted by the adjustable transformer to change the heating temperature of the heat-conducting oil-based nanofluid. The magnetic field intensity is adjusted by adjusting the number of the magnetic blocks arranged on the two sides of the steel pipe and the distance between the adjacent magnetic blocks to apply different-intensity magnetic fields to the received fluid in the steel pipe.

2. The device for determining the coking rate of a heat conducting oil-based magnetic nanofluid according to claim 1, characterized in that, The heat-conducting oil-based nanofluid is stirred by the stirrer controlled by the motor during the heating process.

3. The device for determining the coking rate of a heat conducting oil-based magnetic nanofluid according to claim 1, characterized in that, The calculation formula of the coking speed is: M1 / M0=T, wherein M0 is the mass of the coking product on the first hanger, M1 is the mass of the coking product on the second hanger, and T is the test time.

4. The device for determining the coking rate of a heat conducting oil-based magnetic nanofluid according to claim 1, characterized in that, ​ 5. The device for determining the coking rate of a heat transfer oil-based magnetic nanofluid according to claim 1, characterized in that, ​ 6. A measuring method of a coking speed of a heat conducting oil-based magnetic nanofluid based on the measuring device according to any one of claims 1 to 5, characterized by, ​ ​ ​ ​ ​ ​ 7. A method for determining the coking rate of a heat transfer oil-based magnetic nanofluid according to claim 6, characterized in that, ​ 8. A method of determining the coking rate of a heat transfer oil-based magnetic nanofluid according to claim 6, characterized in that, ​ 9. A method of determining the coking rate of a heat transfer oil-based magnetic nanofluid according to claim 6, characterized in that, ​ 10. A method of determining the coking rate of a heat transfer oil-based magnetic nanofluid according to claim 6, characterized in that, ​ ​

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