CN101514968A - Heat current densimeter - Google Patents

Abstract

The invention relates to the field of heat energy power engineering measurement, in particular to a densimeter for measuring heat current under high temperature and high pressure. A heat current densimeter comprises a thermocouple, a copper pipe and connection line conductors. The heat current densimeter is characterized in that the copper pipe is a tubular structure with a closed end and an opening end; the pipe wall and the end of the pipe wall are all provided with holes; each hole is internally provided with at least one thermocouple; each conducting wire which is connected with the tail of the thermocouple is led out of the opening end of the copper pipe; and the external wall of the copper pipe is provided with a fixing device. The heat current densimeter can bear the working environment under high temperature and high pressure, and the heat current densimeter can measure liquid temperature synchronously and has smaller error of obtained heat transfer coefficient after the measurement.

Description

A heat flux density meter

technical field

The invention relates to the field of thermal power engineering measurement, in particular to a heat flux density meter for measuring high temperature and high pressure.

Background technique

In many occasions of thermal power engineering, it is necessary to measure the amount of heat exchange during heat exchange between the fluid and the solid wall, and then conduct thermal analysis and deeper thermal stress analysis on the heating of the solid wall. For example, there are many nozzles in the reactor coolant system, some fluids are injected into the system through these nozzles, and the temperature of these injected fluids is very different from the temperature of the fluid inside the system, so these nozzles will be subject to huge and frequent heat shock. In order to conduct a definite theoretical analysis and calculation of such thermal shock, it is necessary to understand the heat exchange between the fluid and the solid wall of the nozzle at this time. For such a complex flow process, it is difficult to obtain the local heat flux density and heat transfer coefficient by means of theoretical calculation, so the heat flux density must be determined by measurement. However, such measuring instruments usually work under high temperature and high pressure conditions, so it is necessary to develop a heat flux density meter that can work under high temperature and high pressure conditions. A similar measurement process can also be found in various thermal power equipment such as boiler drums.

For the measurement of heat flux, due to the needs of industrial development, related instruments and equipment have appeared very early. At present, there are many measuring instruments for measuring the heat flux density of solid walls, such as the measurement of the heat flux density inside the walls of buildings, and the measurement of the heat flux density inside the furnace wall of industrial furnaces. Patent 200610028865.4 provides an on-site detection method for the heat transfer coefficient of building walls, which uses a constant power half-surface heat source for constant heating of the measured wall through the heating device and its control equipment, forming a local steady state in the measured area Uniform heat flow, so that the wall is tested under the artificially constructed stable heat transfer state. Patent 200410026343.1 also provides a method for measuring the heat transfer coefficient of the building wall, which also uses artificial methods to cause heat flow in the wall, and measures the temperature change through the pasted temperature sensor to obtain the heat flux. Patent 200620091887.0 provides a device for measuring the heat transfer coefficient of solid interface contact. The device actually obtains the heat flux density and heat transfer coefficient by measuring the temperature difference at different distances along the heat flow direction. Patent 200610009794.3 provides a device and method for measuring heat flux that can be applied to flow field environments with ultra-high temperature, strong electricity, and large disturbances.

From the perspective of measurement principle, the measurement of heat flux is basically by measuring the temperature change at different distances along the heat flow direction, and then calculating the heat flux through the theory of heat conduction problems. However, with different applications, there will be different requirements for the heat flux density meter. For some complex environments, such as the flow in the high-temperature and high-pressure measured pipeline, it is very difficult to measure the heat flux density of the high-temperature and high-pressure fluid along the wall thickness direction of the tested pipeline. If the local heat transfer coefficient is further required, synchronous measurement is required. The temperature near the wall of the exiting fluid. For this complicated situation, none of the above-mentioned heat flux density meters can be applied.

Contents of the invention

In view of the fact that the measuring instruments in the prior art cannot meet the conditions of heat flux measurement under high temperature and high pressure, the purpose of the present invention is to provide a simple structure, which can be applied to measure the heat flow between the fluid in the pipeline under high temperature and high pressure and the pipe wall. A heat flux density meter for heat flux density and heat transfer coefficient during exchange, and the density meter of the present invention can simultaneously measure fluid temperature.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A kind of heat flux density meter, comprises thermocouple, copper tube, connecting wire; Copper tube is a tubular structure with one end closed and the other end open, and holes are arranged on the tube wall and the end of the tube wall, and thermocouples are arranged in the holes, Each wire connected to the tail of the thermocouple is led out from the open end of the copper tube, and the outer wall of the copper tube is provided with a fixing device.

The thermocouple has at least one hole passing through the end of the copper tube and protruding from the hole. The ends of the thermocouples are not higher than the outer contour of the tube wall of the copper tube. The wires at the tails of the thermocouples are insulated from each other and must not be twisted and wound. The thermocouple is at least one.

The method of fusion welding is used to connect the thermocouple and the copper pipe. The copper tube is a copper tube.

The contour line at the end of the copper pipe is perpendicular to the axis of the copper pipe or symmetrical to the axis of the copper pipe.

The fixing device provided on the copper pipe includes: a lower base, a hoop, and a ferrule.

The heat flux density meter of the present invention can withstand the working environment conditions of high temperature and high pressure, the heat flux density meter can measure the fluid temperature synchronously, and the error of the measured heat transfer coefficient is smaller.

Description of drawings

Fig. 1 is a schematic diagram of a copper tube of the present invention and a thermocouple;

Fig. 2 is a schematic diagram of the clamp type connecting device of the present invention

Fig. 3 is a schematic diagram of the connection between the present invention and the fixing device.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in FIG. 1 , the body of the heat flux density meter is composed of a copper tube 2 and thermocouples 1-a, 1-b, 1-c, and 1-d. The shell of the heat flux density meter is a hollow red copper rod, and the center of the red copper rod is drilled with a precision machining machine to form an internal hollow tubular structure. One end of the copper tube 2 is in a closed state, and the red copper rod The contour line of the end portion 7 of the tube 2 is perpendicular to the axis of the copper tube or symmetrical to the axis of the copper tube. The small holes of φ1.5mm are respectively drilled at the copper pipe 2 sides apart from the end 4mm, 8mm, and 12mm, and the small holes of the same size are drilled at the copper pipe end 7 equally. Insert three thermocouple wires into the small holes on the side of the copper tube 2, so that the ends of the thermocouples 1-a, 1-b, and 1-c do not protrude from the outline of the outer wall of the copper tube 2, and are consistent with the thermocouple 1-a , 1-b, 1-c, 1-d lead wires 3 connected at the tail end are drawn from the opening end of the copper pipe 2, and the lead wires 3 at the tail portions of the thermocouples 1-a, 1-b, 1-c, 1-d Insulate from each other and do not twist or twist. The thermocouple 1-d, which is arranged at the copper pipe end 7 to measure the fluid temperature, protrudes 1 mm outside the copper pipe end 7 through the small hole. The small hole is sealed by welding, and the thermocouple wires are also integrated with the copper pipe due to welding.

The clamp connection device of the heat flux density meter is shown in Figure 2 and Figure 3. The threaded ferrule 4 is connected with the lower base 6 through a thread structure, and the clip 8 is located in the cone of the mouth of the lower base 6 . During installation and use, a hole is drilled in the inner wall of the tested pipeline 9, and the lower base 6 of the connecting device is welded to the outer wall of the tested pipeline, and the upper part of the lower base 6 is provided with external threads. The copper tube 2 for measurement is inserted into the hole so that the end 7 of the copper tube 2 for measurement is substantially flush with the inner wall of the pipe 9 to be tested. Then the upper threaded ferrule 4 and the lower base 6 are threadedly connected, and the clamp 8 between the upper threaded ferrule 4 and the lower base 6 will tightly compress the copper tube 2 under the action of continuous tightening of the thread, and complete the pairing. The sealing of the copper tube 2. Clamp 8 is also made of red copper material, which can ensure that it can still compress the red copper tube under the action of high temperature, so that the red copper tube is sealed well.

Since at least one or more thermocouple wires are arranged along the axial direction of the copper tube 2, there will be corresponding heat flow transfer inside the copper tube 2 during use. In this way, the temperature change measured by the thermocouple can be used to measure the heat flux transmitted along the copper tube. A thermocouple wire is stretched out of the copper tube through the hole at the end 7 of the copper tube. After the measuring copper tube 2 is installed in the wall of the pipeline 9 to be tested through the fixing device, the thermocouple can simultaneously measure the temperature of the fluid flowing therethrough. In this way, the heat transfer coefficient at this place can be measured according to Fourier's heat conduction law and the definition of fluid heat transfer coefficient. Since the thermocouple wires are connected to the copper tube by fusion welding, and the small hole is sealed by fusion welding technology, it can withstand a high pressure of 20MPa. After testing, the small hole will not be welded under a pressure of 20MPa. Leakage occurs, and the heat flux density meter is fixed by a clamp-type fixing device, which can be applied under complex conditions of high temperature and high pressure.

After the body of the heat flux density meter is completed, it is connected to the wall surface of the measured pipeline 9 through a clamp type connection device. The heat flux density meter must be in contact with the fluid inside the tested pipeline 9 to measure the corresponding heat flux density and heat transfer coefficient. It must be ensured that the fluid in the tested pipeline 9 will not leak out through the heat flow meter, especially when the internal pressure of the tested pipeline 9 When it is relatively high; this connection method has to withstand the test of high temperature environment, and the present invention adopts the clamp type connection so that the heat flow meter can withstand both high pressure and high temperature.

When working, the heat flow is transmitted along the copper tube from the end 7 to the opening. The thermocouples installed in the copper tube can sense the temperature at different positions, and the heat flux density can be measured, and then the heat transfer coefficient of the fluid can be measured synchronously. In specific applications, all thermocouple signals are collected and processed by a real-time data acquisition system, and the corresponding heat flux density and convective heat transfer coefficient can be measured while physical phenomena occur.

Claims (9)

1, a kind of heat flow density meter, comprise thermopair, copper pipe (2), connect lead (3), it is characterized in that: copper pipe (2) is the tubular structure of end sealing other end opening, and the end (7) with tube wall on tube wall is provided with the hole, is provided with thermopair (1-a, 1-b, 1-c, 1-d) in the hole, draw from opening one end of copper pipe with each lead (3) that thermopair (1-a, 1-b, 1-c, 1-d) afterbody is connected, the outer wall of described copper pipe (2) is provided with stationary installation.

2. heat flow density meter according to claim 1 is characterized in that: have at least in the Kong Bingcong hole by the copper pipe end in the described thermopair (1-a, 1-b, 1-c, 1-d) and stretch out.

3. heat flow density meter according to claim 2 is characterized in that: the end of described thermopair (1-a, 1-b, 1-c) is not higher than the outer contour of the tube wall of copper pipe (2).

4. heat flow density meter according to claim 2 is characterized in that: lead (3) mutually insulated of the afterbody of described thermopair (1-a, 1-b, 1-c, 1-d), must not twist winding.

5. heat flow density meter according to claim 4 is characterized in that: described thermopair is at least one.

6. heat flow density meter according to claim 1 is characterized in that: use the method for melting welding to be connected between described thermopair (1) and the copper pipe (2).

7. heat flow density meter according to claim 1 is characterized in that: described copper pipe (2) is a copper tube.

8. heat flow density meter according to claim 1 is characterized in that: described copper pipe (2) end (7) outline line is perpendicular to the copper pipe axis or be symmetrical in the copper pipe axis.

9. heat flow density meter according to claim 1 is characterized in that: described copper pipe (2) is gone up the stationary installation that is provided with, and comprising: lower bottom base (6), clip (8), cutting ferrule (4).

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