Drag reduction and heat transfer characteristics testing device and method for water-soluble drag reduction solution

Abstract

The present invention discloses a device for testing the drag reduction and heat exchange characteristics of a water-soluble drag-reducing solution. The device comprises: a liquid storage tank, an agitator, a variable frequency water pump, a preheating section, a heat exchange test section, a differential pressure test section, a cooler, a heating controller, a cooling tower, a temperature sensor, a pressure sensor, a differential pressure sensor, a data acquisition instrument, and a computer. The device of the present invention overcomes the problem that existing devices can only test the drag reduction characteristics but cannot test the heat exchange characteristics at the same time, and can only perform tests at room temperature. In addition, the experimental section of the device adopts a snap-on connection, which is easy to replace, and the heating method adopts efficient, uniform, and energy-saving electromagnetic induction heating. The device can realize the drag reduction and heat exchange characteristic tests of different flow rates, different temperatures, different pipe structures, and different types of drag reducing solutions. It is easy to operate and has excellent experimental test results.

Description

Technical Field

[0001] The present invention belongs to the field of testing technology, relates to turbulent drag reduction and heat exchange experimental testing of drag reducers, and in particular to a device and method for testing the drag reduction and heat exchange characteristics of a water-soluble drag reducing solution. Background Art

[0002] Turbulent flow drag reduction technology with drag reducers is an energy-saving measure that significantly reduces the resistance of turbulent liquid flow in pipelines, thereby reducing pump work. It has broad application prospects. Currently, this technology has been successfully applied in oil production and transportation systems, fire water supply systems, and district heating or cooling circulation systems. For different application areas, experimental research is needed to study the drag reduction and heat transfer characteristics of different drag reducer solutions to identify drag reducers with excellent performance and stable properties.

[0003] The application of drag reducers has revealed that while they reduce drag, they also inhibit the fluid's heat transfer capacity. This is because the addition of drag reducers suppresses turbulence during fluid flow, thereby reducing energy losses. Simultaneously, due to the reduced turbulence, the fluid's heat transfer capacity also decreases. However, most current research and experimental setups have overlooked the impact of drag reducers on heat transfer capacity. Furthermore, most current research on drag reducers has been conducted at room temperature or in the temperature range of 20-70°C, lacking experimental studies on drag reducers at higher temperatures. Summary of the Invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a device and method for testing the drag reduction and heat transfer characteristics of a water-soluble drag reducing solution, which can take into account the testing of the drag reduction and heat transfer characteristics of the drag reducer solution. Furthermore, it can also conduct experimental research on the drag reducer solution at higher temperatures.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A device for testing the drag reduction and heat exchange characteristics of a water-soluble drag-reducing solution comprises a preheating section, a heat exchange test section, a differential pressure test section, and a test instrument. The water-soluble drag-reducing solution is composed of a drag reducer dissolved in clean water and flows through the preheating section, the heat exchange test section, and the differential pressure test section in sequence.

[0007] The preheating section is equipped with a heating component to regulate the temperature of the fluid flowing into the heat exchange test section; the heat exchange test section is equipped with a heating component to regulate the temperature of the fluid flowing out of the heat exchange test section;

[0008] The test instrument measures the flow rate of the water-soluble drag-reducing solution and the average inlet interface temperature T of the heat exchange test section. in , average outlet interface temperature T out and the average wall temperature and the inlet and outlet pressure difference Δp of the differential pressure test section;

[0009] The drag reduction characteristics of the water-soluble drag reducing solution are represented by the drag reduction ratio DR, and the heat transfer characteristics are represented by the heat transfer reduction ratio HTR; Where f0 represents the Fanning friction coefficient of clear water flow, f represents the Fanning friction coefficient of drag-reducing fluid flow, ρ is the density of water, L is the length of the differential pressure test section, Q is the flow rate through the differential pressure test section; Nu0 represents the Nusselt number of clean water flow, Nu represents the Nusselt number of drag reduction fluid flow, h is the surface heat transfer coefficient of the flow, D is the inner diameter of the heat exchange test section, λ is the thermal conductivity of water, Where q is the heating power of the heat exchange test section, and A is the inner surface area of ​​the heat exchange test section.

[0010] In one embodiment, the preheating section, the heat exchange test section and the differential pressure test section are arranged in a flow loop, and the flow loop is provided with a liquid storage tank and a cooler, the liquid storage tank is arranged upstream of the preheating section, and the cooler is arranged downstream of the differential pressure test section; a first valve and a first water pump are arranged between the outlet of the liquid storage tank and the inlet of the preheating section, a second valve is arranged between the outlet of the preheating section and the inlet of the heat exchange test section, a third valve is arranged between the outlet of the differential pressure test section and the inlet of the cooler, and a fourth valve is arranged between the outlet of the cooler and the inlet of the liquid storage tank.

[0011] In one embodiment, the cooler is a shell and tube heat exchanger, in which the inner tube is placed in the outer tube in the form of a spiral coil. The cooler is connected to the second water pump and the cooling tower through pipelines to cool the water-soluble drag reduction solution flowing back into the liquid storage tank, and the cooling capacity is adjusted by adjusting the cooling water flow rate.

[0012] In one embodiment, the test instrument includes a flow meter, a temperature sensor and a differential pressure sensor; the flow meter is set at the inlet of the preheating section, and there are multiple temperature sensors, which are arranged at least at the inlet, outlet and pipe wall of the heat exchange test section. The pipe wall of the heat exchange test section is evenly arranged with multiple temperature sensors, and the average wall temperature is Among them (T w ) i represents the temperature measured by the i-th temperature sensor arranged on its wall, and n is the number of temperature sensors arranged on the wall; the differential pressure sensor is arranged between the inlet and outlet of the differential pressure test section to measure the inlet and outlet pressure difference Δp. A pressure sensor is provided at the inlet of the differential pressure test section, and temperature sensors are provided at both the inlet and outlet.

[0013] In one embodiment, the heat exchange test section and the differential pressure test section have equal inner diameters.

[0014] In one embodiment, the preheating section adopts electromagnetic induction heating, and its exterior is wrapped with thermal insulation cotton and then wound with electromagnetic induction heating wire, which is connected to a first heating controller. The heating power is controlled by the first heating controller, thereby controlling the temperature of the fluid flowing into the heat exchange test section.

[0015] The heat exchange test section adopts electromagnetic induction heating. Its exterior is wrapped with thermal insulation cotton and then wrapped with electromagnetic induction heating wire. The electromagnetic induction heating wire is connected to the second heating controller. The heating power is controlled by the second heating controller, thereby controlling the temperature of the fluid flowing out of the heat exchange test section.

[0016] In one embodiment, the average inlet interface temperature T in The feedback of the first heating controller and the PID control automatically adjust the temperature of the fluid flowing into the heat exchange test section; the average outlet interface temperature T out The feedback and PID control of the second heating controller automatically adjust the temperature of the fluid flowing out of the heat exchange test section.

[0017] In one embodiment, it further includes: a data acquisition device and a computing device;

[0018] The data acquisition device is connected to the test instrument to collect the measurement data of the test instrument; the computing device is connected to the data acquisition device to use the data collected by the computing device to complete the calculation of the drag reduction rate DR and the heat exchange reduction rate HTR.

[0019] The present invention also provides a method for testing the drag reduction and heat exchange characteristics of the water-soluble drag reducing solution using the device for testing the drag reduction and heat exchange characteristics of the water-soluble drag reducing solution, comprising the following steps:

[0020] Step 1, preparing a water-soluble drag-reducing solution;

[0021] Step 2: The water-soluble drag-reducing solution enters a preheating section, and the preheating section heats the water-soluble drag-reducing solution flowing through the preheating section to a temperature point to be measured;

[0022] Step 3: The water-soluble drag-reducing solution from the preheating section enters the heat exchange test section, and the heat exchange test section is used to continue heating the water-soluble drag-reducing solution flowing through. The test instrument is used to measure the average inlet interface temperature T of the heat exchange test section. in , average outlet interface temperature T out and the average wall temperature Keep the inlet and outlet temperature difference of the heat exchange test section greater than the set value;

[0023] Step 4: The water-soluble drag reduction solution exiting the heat exchange test section enters the differential pressure test section, and the test instrument is used to measure the inlet and outlet pressure difference Δp of the differential pressure test section;

[0024] Step 5: Calculate the drag reduction rate DR and heat transfer reduction rate HTR using the formula.

[0025] In one embodiment, during the measurement of the drag reduction rate DR and the heat transfer reduction rate HTR at a certain temperature and a certain Reynolds number, the flow rate is kept stable; after the measurement is completed, if another working condition needs to be measured, the measurement is continued by adjusting the flow rate or adjusting the set temperature value of the heater.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The experimental device designed based on the present invention can simultaneously test the drag reduction and heat transfer characteristics of the drag reduction solution, which makes up for the defect that the existing device can only test the drag reduction characteristics but cannot test the heat transfer characteristics at the same time.

[0028] (2) The experimental device designed based on the present invention has a large temperature control range and includes high-temperature working conditions, which enables experimental research on drag reduction solutions at different temperatures (especially high-temperature working conditions, such as 50-80°C).

[0029] (3) The experimental device designed based on the present invention adopts a snap-on connection for the experimental section, which is easy to replace. It also adopts an efficient, uniform, and energy-saving electromagnetic induction heating method, which is easy to operate and has excellent experimental test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of the present invention.

[0031] Figure 2 It is a structural schematic diagram (loop) of the present invention.

[0032] Figure 3 It is a schematic diagram of the structure of the present invention (loop, and using a computing device).

[0033] Figure 4 It is a three-dimensional schematic diagram of the heat exchange test section.

[0034] Figure 5 This is a partial enlarged view of the heat exchange test section.

[0035] Figure 6 It is a control logic diagram.

[0036] Figure 7 Schematic diagram of force analysis of viscous fluid flow in a circular tube. DETAILED DESCRIPTION

[0037] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0038] This invention designs a device for testing the drag reduction and heat transfer properties of a water-soluble drag-reducing solution, aiming to balance testing the drag reduction and heat transfer properties of the drag-reducing solution and broaden the temperature range for experimental research (especially under high-temperature conditions). The water-soluble drag-reducing solution described in this invention is a solution obtained by dissolving a drag reducer in water, such as an aqueous solution of hexadecyltrimethylammonium chloride, an aqueous solution of behenyltrimethylammonium chloride, or an aqueous solution of xanthan gum. To ensure fluidity, its viscosity should not be too high, generally not exceeding 80 mPas.

[0039] The test device of the present invention mainly includes a flow pipeline and some test instruments on the pipeline. Figure 1 The arrow in the figure indicates the flow direction of the water-soluble drag-reducing solution. Along this direction, its circulation pipeline can be configured as a preheating section 6, a heat exchange test section 8 and a differential pressure test section 9 in sequence, that is, the water-soluble drag-reducing solution of the present invention flows through the preheating section 6, the heat exchange test section 8 and the differential pressure test section 9 in sequence.

[0040] The preheating section 6 is equipped with a heating component, whose main function is to regulate the temperature of the fluid flowing into the heat exchange test section 8. The heat exchange test section 8 also needs to be equipped with a heating component, whose main function is to regulate the temperature of the fluid flowing out of the heat exchange test section 8.

[0041] The test instrument of the present invention mainly comprises a flow meter, a temperature sensor and a pressure difference sensor, and the parameters measured include at least: the flow rate of the water-soluble drag reduction solution, especially the flow rate when entering the preheating section 6; the average temperature T of the inlet interface of the heat exchange test section 8; in , average outlet interface temperature T out and the average wall temperature The inlet and outlet pressure difference Δp of the differential pressure test section 9.

[0042] In the present invention, the drag reduction characteristics of the water-soluble drag reducing solution are represented by the drag reduction ratio DR, which is calculated as follows:

[0043]

[0044] The heat transfer characteristics of the water-soluble drag reduction solution are expressed by the heat transfer reduction rate HTR, which is calculated as follows:

[0045]

[0046] Where f0 represents the Fanning friction coefficient of clear water flow, f represents the Fanning friction coefficient of water-soluble drag reduction solution flow, ρ is the density of the solvent, i.e., clean water; L is the length of the differential pressure test section 9; Q is the flow rate through the differential pressure test section 9; Nu0 represents the Nusselt number of the clean water flow; Nu represents the Nusselt number of the water-soluble drag reducing solution flow; h is the surface heat transfer coefficient of the flow, D is the inner diameter of the heat exchange test section 8, λ is the thermal conductivity of water, Wherein, q is the heating power of the heat exchange test section 8, and A is the inner surface area of ​​the heat exchange test section 8.

[0047] The method for testing the drag reduction and heat exchange characteristics of the water-soluble drag reducing solution of the present invention comprises the following steps:

[0048] Step 1: prepare a water-soluble drag-reducing solution.

[0049] In step 2, the water-soluble drag-reducing solution enters the preheating section 6, and the preheating section 6 heats the water-soluble drag-reducing solution flowing through the preheating section to a temperature point to be measured.

[0050] Step 3: The water-soluble drag-reducing solution from the preheating section 6 enters the heat exchange test section 8, and the heat exchange test section 8 is used to continue heating the water-soluble drag-reducing solution flowing through. The test instrument is used to measure the average inlet interface temperature T of the heat exchange test section 8. in , average outlet interface temperature T out and the average wall temperature T in 、T out Generally, it is between 30-80℃, and the temperature difference between the inlet and outlet of the heat exchange test section 8 is kept greater than the set value by 5℃.

[0051] Step 4: the water-soluble drag reduction solution exiting the heat exchange test section 8 enters the differential pressure test section 9 , and the pressure difference Δp between the inlet and outlet of the differential pressure test section 9 is measured using the test instrument.

[0052] Step 5: Calculate the drag reduction rate DR and heat transfer reduction rate HTR using the formula.

[0053] The drag reduction and heat transfer characteristics test device of the drag reduction solution shown in this embodiment can simultaneously test the drag reduction and heat transfer characteristics of the drag reduction solution. The temperature adjustment range is 50-90°C and the flow rate adjustment range is 0-4m 3 / h.

[0054] In some embodiments of the present invention, in order to avoid the loss of water-soluble drag reducing solution during the test and adapt to various test conditions, the circulation pipeline is set as a flow loop, that is, the preheating section 6, the heat exchange test section 8 and the differential pressure test section 9 are set in one flow loop. Figure 2As shown, this flow loop also includes a liquid storage tank 1 and a cooler 11. The liquid storage tank 1 is located upstream of the preheating section 6 and may contain an agitator 2. The liquid storage tank 1 not only stores liquid but also serves as a container for preparing a water-soluble drag-reducing solution. Its outlet may be located at the bottom. The cooler 11 is located downstream of the differential pressure testing section 9 to ensure that the temperature of the water-soluble drag-reducing solution returning to the liquid storage tank 1 is lowered to its initial temperature. To achieve these controls, a first valve 3 and a first water pump 4 are located between the outlet of the liquid storage tank 1 and the inlet of the preheating section 6. Specifically, the outlet at the bottom of the liquid storage tank 1 is connected to the first valve 3 and the first water pump 4 via a pipeline. The first water pump 4 is connected to the inlet of the preheating section 6, and a flowmeter 5 may be located at the inlet of the preheating section 6. A third valve 10 is located between the outlet of the differential pressure testing section 9 and the inlet of the cooler 11, and a fourth valve 12 is located between the outlet of the cooler 11 and the inlet of the liquid storage tank 1. A second valve 7 can be set between the outlet of the preheating section 6 and the inlet of the heat exchange test section 8. The test section can be replaced by the second valve 7 and the third valve 10. The first water pump 4 cooperates with the fourth valve 12 to adjust the flow and pressure in the pipeline according to demand.

[0055] For example, in this embodiment, cooler 11 can be implemented as a double-tube heat exchanger, with an inner tube having an outer diameter of 10 mm and a wall thickness of 2 mm, and an outer tube having an outer diameter of 159 mm and a wall thickness of 4.5 mm. The inner tube is placed in a spiral coil within the outer tube. Cooler 11 is connected to a second water pump 16 and a cooling tower 15 via pipelines, cooling the aqueous drag-reducing solution returning to the liquid storage tank 1. The cooling capacity can be adjusted by adjusting the cooling water flow rate.

[0056] In some embodiments of the present invention, the test instrument includes a flow meter 5, a temperature sensor and a differential pressure sensor; wherein the flow meter 5 is set at the inlet of the preheating section 6 to measure the flow of the fluid entering the preheating section 6, and there are multiple temperature sensors, which are arranged at least at the inlet, outlet and pipe wall of the heat exchange test section 8. The pipe wall of the heat exchange test section 8 is evenly arranged with multiple temperature sensors, and its average wall temperature is 0. The calculation formula is: Among them (T w ) i represents the temperature measured by the i-th temperature sensor installed on the wall, and n is the number of temperature sensors installed on the wall. A differential pressure sensor is deployed between the inlet and outlet of the differential pressure test section 9 to measure the inlet and outlet pressure difference Δp. Specifically, the two pressure tapping ports of the differential pressure transmitter are located at the inlet and outlet of the differential pressure test section 9. Furthermore, a pressure sensor can be installed at the inlet of the differential pressure test section 9, and temperature sensors can be installed at both the inlet and outlet.

[0057] In some embodiments of the present invention, the heat exchange test section 8 and the differential pressure test section 9 have the same inner diameter.

[0058] In some embodiments of the present invention, reference Figure 3 The test device of the present invention further includes a data acquisition device 17 and a computing device 18. The data acquisition device 17 is connected to the test instrument to collect the test instrument's measurement data. The positive and negative electrodes of the temperature sensor are respectively connected to the positive and negative electrodes of the signal acquisition channel, and a four-wire platinum resistor is used for temperature compensation. The pressure sensor and differential pressure sensor are both connected to the signal acquisition channel using a two-wire connection. The computing device 18 is connected to the data acquisition device 17 and uses the data it collects to calculate the drag reduction rate DR and the heat transfer reduction rate HTR. The computing device 18 can be a computer or other device with computing processing capabilities.

[0059] In some embodiments of the present invention, the preheating section 6 adopts electromagnetic induction heating, and its outside is wrapped with insulation cotton and then wrapped with electromagnetic induction heating wire. The electromagnetic induction heating wire is connected to the first heating controller 13. The heating power is controlled by the first heating controller 13, and then the temperature of the fluid flowing into the heat exchange test section 8 is controlled.

[0060] Similarly, the heat exchange test section 8 adopts electromagnetic induction heating. Its exterior is wrapped with thermal insulation cotton and then wrapped with electromagnetic induction heating wire. The electromagnetic induction heating wire is connected to the second heating controller 14. The heating power is controlled by the second heating controller 14, thereby controlling the temperature of the fluid flowing out of the heat exchange test section 8.

[0061] For example, in this embodiment, the first heating controller 13 and the second heating controller 14 are both electromagnetic induction heating controllers, and the flow rate into the preheating section 6 can be adjusted to a range of 0-4m 3 / h. The preheating section 6 is a 430 stainless steel tube with an inner diameter of 20mm, a wall thickness of 3mm, and a length of 3m. The tube is wrapped with 1-3cm thick (preferably 2cm) thermal insulation cotton, and a heating wire is wound around the thermal insulation cotton. The heating wire is 1-3cm (preferably 2cm) away from the tube wall and the winding is more than 40m (preferably about 50m). The inlet temperature value of the heat exchange test section 8 can be set by the average interface temperature T in The feedback and the PID control of the first heating controller 13 automatically adjust the temperature of the fluid flowing into the heat exchange test section 8.

[0062] refer to Figure 4 and Figure 5The heat exchange test section 8 is a 430 stainless steel tube with an inner diameter of 20mm, a wall thickness of 3mm, and a length of 3m. The tube is wrapped with 1-3cm thick (preferably 2cm) thermal insulation cotton 81, and a heating wire is wound on the thermal insulation cotton 81, wherein the heating wire is 1-3cm away from the tube wall (preferably 2cm), and the winding is more than 40m (preferably about 50m). The outer wall of the tube is provided with temperature sensors T at symmetrical positions above and below the tube every 60cm, wherein the temperature sensors T are all T-grade thermocouples, which are welded to the outer wall of the tube by a spot welder, and a temperature sensor T is set at 10-20cm (preferably 12cm) before and after the heat exchange test section to measure the temperature of the fluid in the tube. The outlet temperature value of the heat exchange test section can be set by the average outlet interface temperature T out The feedback and PID control of the second heating controller 14 automatically adjust the temperature of the fluid flowing out of the heat exchange test section 8. Finally, the HTR calculation is completed based on the temperatures measured by the inlet and outlet temperature sensors and the pipe wall temperature sensor of the heat exchange test section 8, the electromagnetic induction heating power, the pipe geometry parameters, and the physical properties of the solution.

[0063] The control logic of the present invention can be referred to Figure 6 shown.

[0064] The differential pressure test section 9 is a 304 stainless steel tube with an inner diameter of 20 mm, a wall thickness of 3 mm, and a length of 3 m. A hole is opened at the front end 10-20 cm (preferably 18 cm and 12 cm) to provide pressure holes for the pressure sensor p and the differential pressure sensor Δp, as well as an insertion hole for the temperature sensor T. A hole is opened at the rear end 10-20 cm (preferably 18 cm and 12 cm) to provide an insertion hole for the temperature sensor T and a pressure hole for the differential pressure sensor Δp. The differential pressure sensor Δp ​​is equidistant from the front and rear pressure holes. The drag reduction rate DR is calculated based on the pressure difference measured by the differential pressure transmitter Δp.

[0065] The device of the present invention can measure DR and HTR at different temperatures and different Reynolds numbers. When measuring the drag reduction rate DR and heat transfer reduction rate HTR at a certain temperature and a certain Reynolds number, the flow rate needs to be kept stable. After the measurement is completed, if another working condition needs to be measured, the flow rate is adjusted through the water pump / gate valve, or the heater set temperature value is adjusted to continue the measurement.

[0066] The various sections of the present invention can be connected in a snap-on manner, which is easy to replace. The heating method adopts efficient, uniform and energy-saving electromagnetic induction heating, which realizes the drag reduction and heat exchange characteristic testing of different flow rates, different temperatures, different tube structures and different types of drag reduction solutions. The operation is convenient and the experimental test effect is excellent.

[0067] The testing principle of the present invention can be described in detail as follows:

[0068] 1. Measurement of drag reduction rate DR:

[0069] When a viscous fluid flows steadily in a tube, due to the viscosity of the fluid, the inner wall of the tube will generate frictional resistance, which is balanced with the driving force provided by the front and rear pressure difference (ignoring frictional heat), such as Figure 7 shown.

[0070] Take a cylinder with a length of L and a diameter of D with the tube axis as the central axis. The external force acting on the fluid in the cylinder is balanced, that is:

[0071]

[0072] The average wall shear stress of this section is obtained:

[0073]

[0074] After measuring the shear stress on the inner wall of the pipe, the wall friction coefficient can be obtained. Generally, the Fanning friction coefficient is used, which is defined as:

[0075]

[0076] Where: ρ is the density of the fluid, in kg·m -3 ; u is the average flow velocity in the pipeline, in m·s -1 The average flow rate is:

[0077]

[0078] Where: Q is the pipe volume flow rate, unit is m 3 ·s -1 . We can get:

[0079]

[0080] The drag reduction characteristics of the water-soluble drag reduction solution are expressed by the drag reduction rate DR, which is calculated as follows:

[0081]

[0082] Where f0 represents the Fanning friction coefficient for clear water flow, and f represents the Fanning friction coefficient for the flow of a water-soluble drag-reducing solution. Thus, by measuring the pressure differential Δp across the pipeline, the pipeline inner diameter D, the pipeline length L, the fluid (water) density ρ, and the volume flow rate Q, the pipeline friction coefficient f can be calculated, thereby obtaining the drag reduction rate DR.

[0083] 2. Measurement of heat transfer reduction rate (HTR)

[0084] For the measurement of the average surface heat transfer coefficient between the fluid and the surface of a long channel, a constant heat flux heating method, i.e. constant power heating, is usually adopted. In this case,

[0085] hAΔtm =c p ρQ(T out -T in )

[0086] Where: Δt m Take the logarithmic mean temperature difference; c p is the specific heat capacity at constant pressure, in J·kg -1 ·K -1 ; A is the surface area of ​​the heat exchange test section, unit is m 2 ;T in , T out are the average temperatures of the inlet and outlet sections of the heat exchange test section, respectively, in °C.

[0087]

[0088] Where:

[0089] but:

[0090]

[0091] The strength of convective heat transfer capacity is generally measured by the Nusselt number Nu.

[0092]

[0093] The heat transfer characteristics of the water-soluble drag reduction solution are expressed by the heat transfer reduction rate HTR, which is calculated as follows:

[0094]

[0095] Where: Nu0 represents the Nusselt number of clean water flow, Nu represents the Nusselt number of water-soluble drag reduction solution flow. It can be seen that by measuring the inlet and outlet temperature T in 、T out , the average temperature of the pipe wall Fluid (water) density ρ, fluid (water) constant pressure specific heat capacity c p , volume flow rate Q, surface area A of the heat transfer test section, inner diameter D of the pipe and thermal conductivity λ of the fluid (water), the surface heat transfer coefficient h, Nusselt number Nu and heat transfer reduction rate HTR can be calculated.

Claims

1. A device for testing the drag reduction and heat transfer characteristics of a water-soluble drag reduction solution, characterized in that: The apparatus comprises a preheating section (6), a heat exchange test section (8), a differential pressure test section (9) and a test instrument; the water-soluble drag reducing solution is composed of a drag reducing agent dissolved in clean water and flows sequentially through the preheating section (6), the heat exchange test section (8) and the differential pressure test section (9); the heat exchange test section (8) and the differential pressure test section (9) have equal inner diameters; The preheating section (6) is equipped with a heating component to regulate the temperature of the fluid flowing into the heat exchange test section (8); the heat exchange test section (8) is equipped with a heating component to regulate the temperature of the fluid flowing out of the heat exchange test section (8); The test instrument measures the flow rate of the water-soluble drag-reducing solution and the average inlet interface temperature T of the heat exchange test section (8). in , average outlet interface temperature T out and the average wall temperature and the inlet and outlet pressure difference Δp of the differential pressure test section (9); The drag reduction characteristics of the water-soluble drag reducing solution are represented by the drag reduction ratio DR, and the heat transfer characteristics are represented by the heat transfer reduction ratio HTR; Where f0 represents the Fanning friction coefficient of clear water flow, f represents the Fanning friction coefficient of drag-reducing fluid flow, ρ is the density of water, L is the length of the differential pressure test section (9), Q is the flow rate through the differential pressure test section (9); Nu0 represents the Nusselt number of the flow of clean water, Nu represents the Nusselt number of the flow of the drag reducing fluid, h is the surface heat transfer coefficient of the flow, D is the inner diameter of the heat exchange test section (8), λ is the thermal conductivity of water, Wherein, q is the heating power of the heat exchange test section (8), and A is the inner surface area of ​​the heat exchange test section (8); The test instrument comprises a flow meter (5), a temperature sensor and a differential pressure sensor; the flow meter (5) is arranged at the inlet of the preheating section (6); there are multiple temperature sensors, which are arranged at least at the inlet, outlet and pipe wall of the heat exchange test section (8); the pipe wall of the heat exchange test section (8) is evenly arranged with multiple temperature sensors, and the average wall temperature is Among them (T w ) i represents the temperature measured by the i-th temperature sensor arranged on the wall, and n is the number of temperature sensors arranged on the wall; the differential pressure sensor is arranged between the inlet and outlet of the differential pressure test section (9) to measure the inlet and outlet pressure difference Δp; a pressure sensor is provided at the inlet of the differential pressure test section (9), and temperature sensors are provided at both the inlet and outlet.

2. The drag reduction and heat transfer characteristics testing device of the water-soluble drag reducing solution according to claim 1, characterized in that: The preheating section (6), the heat exchange test section (8) and the differential pressure test section (9) are arranged on a flow loop, and a liquid storage tank (1) and a cooler (11) are arranged on the flow loop, the liquid storage tank (1) is arranged upstream of the preheating section (6), and the cooler (11) is arranged downstream of the differential pressure test section (9); a first valve (3) and a first water pump (4) are arranged between the outlet of the liquid storage tank (1) and the inlet of the preheating section (6), a second valve (7) is arranged between the outlet of the preheating section (6) and the inlet of the heat exchange test section (8), a third valve (10) is arranged between the outlet of the differential pressure test section (9) and the inlet of the cooler (11), and a fourth valve (12) is arranged between the outlet of the cooler (11) and the inlet of the liquid storage tank (1).

3. The drag reduction and heat transfer characteristics testing device of the water-soluble drag reduction solution according to claim 2, characterized in that: The cooler (11) is a shell-and-tube heat exchanger, wherein the inner tube is placed in the outer tube in the form of a spiral coil. The cooler (11) is connected to the second water pump (16) and the cooling tower (15) through pipelines, cools the water-soluble drag reduction solution that flows back into the liquid storage tank (1), and adjusts the cooling capacity by adjusting the cooling water flow rate.

4. The drag reduction and heat transfer characteristics testing device of the water-soluble drag reduction solution according to claim 1, characterized in that: The preheating section (6) adopts electromagnetic induction heating, and its exterior is wrapped with heat-insulating cotton and then wound with electromagnetic induction heating wire, which is connected to a first heating controller (13). The heating power is controlled by the first heating controller (13), thereby controlling the temperature of the fluid flowing into the heat exchange test section (8); The heat exchange test section (8) is heated by electromagnetic induction. The exterior of the heat exchange test section (8) is wrapped with heat-insulating cotton and then wound with an electromagnetic induction heating wire. The electromagnetic induction heating wire is connected to a second heating controller (14). The heating power is controlled by the second heating controller (14), thereby controlling the temperature of the fluid flowing out of the heat exchange test section (8).

5. The drag reduction and heat transfer characteristics testing device of the water-soluble drag reduction solution according to claim 4, characterized in that: The average temperature of the inlet interface T in The feedback of the first heating controller (13) and the PID control automatically adjust the temperature of the fluid flowing into the heat exchange test section (8); the average temperature T out The feedback and the PID control of the second heating controller (14) automatically adjust the temperature of the fluid flowing out of the heat exchange test section (8).

6. The drag reduction and heat transfer characteristics testing device of the water-soluble drag reduction solution according to claim 1, characterized in that: Also includes: Data acquisition device (17) and computing device (18); The data acquisition device (17) is connected to the test instrument to collect the measurement data of the test instrument; the computing device (18) is connected to the data acquisition device (17) to use the collected data to complete the calculation of the drag reduction rate DR and the heat exchange reduction rate HTR.

7. A method for testing the drag reduction and heat transfer characteristics of the water-soluble drag reducing solution according to claim 1, comprising the following steps: Step 1, preparing a water-soluble drag-reducing solution; Step 2, the water-soluble drag-reducing solution enters the preheating section (6), and the preheating section (6) heats the water-soluble drag-reducing solution flowing through to a temperature point to be measured; Step 3: The water-soluble drag-reducing solution from the preheating section (6) enters the heat exchange test section (8), and the heat exchange test section (8) is used to continue heating the water-soluble drag-reducing solution flowing through, and the test instrument is used to measure the average interface temperature T at the inlet of the heat exchange test section (8). in , average outlet interface temperature T out and the average wall temperature Maintaining the inlet and outlet temperature difference of the heat exchange test section (8) greater than the set value; Step 4, the water-soluble drag reduction solution exiting the heat exchange test section (8) enters the differential pressure test section (9), and the pressure difference Δp between the inlet and outlet of the differential pressure test section (9) is measured using the test instrument; Step 5: Calculate the drag reduction rate DR and heat transfer reduction rate HTR using the formula.

8. The testing method according to claim 7, characterized in that: The average inlet interface temperature T in and the average outlet interface temperature T out The range is 30-80℃; when measuring the drag reduction rate DR and heat transfer reduction rate HTR at a certain temperature and Reynolds number, keep the flow rate stable; after the measurement is completed, if another working condition needs to be measured, continue the measurement by adjusting the flow rate or adjusting the heater set temperature value.

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