Method for effectively measuring temperature of hot fluid in chemical heater offline test

Abstract

The invention belongs to the technical field of military ignition systems, and particularly relates to a method for measuring the dynamic temperature of a thermal fluid in a chemical heater off-line test, in particular to a method for effectively measuring the temperature of the thermal fluid in the chemical heater off-line test, which comprises a chemical heater, a liquid receiver and a transition pipe for connecting the chemical heater and the liquid receiver, the chemical heater contains test liquid, and the method comprises the following steps: a, sensor installation: installing an infrared temperature sensor on the outer wall of a transition pipe in a non-contact manner, b, temperature signal acquisition: acquiring transient temperature data of the outer wall of the transition pipe in real time through the infrared temperature sensor; c, heat conduction modeling: establishing a dynamic relation model of the pipe wall temperature and the liquid temperature based on a transient heat conduction equation, wherein the model meets a one-dimensional heat conduction equation; and d, liquid temperature inversion: taking the pipe wall outer surface temperature actually measured by the infrared sensor as a boundary condition, solving the heat conduction model through numerical iteration, and performing inversion to obtain the dynamic temperature of the test liquid flowing through the transition pipe.

Description

Technical Field

[0001] The invention belongs to the technical field of military ignition systems, and in particular relates to a method for measuring the dynamic temperature of a hot fluid in an offline test of a chemical heater. Background Art

[0002] Chemical heaters are used in devices or weapon systems involved in the military industry. Electronic control systems are used to accurately control their preset actions. As basic driving components, such heaters play a very important role in military operations. They are related to whether the device or weapon system can safely and effectively perform specific tasks. After receiving a controllable ignition signal, the temperature of the working fluid inside the heater rises sharply in a very short time, and then flows to the driven components through the connected small-sized transition pipe. As a reliable power source, it drives the corresponding components to complete the action, so as to realize the orderly operation of the overall device. Before the heater goes offline, it needs to be fully tested. It can only be used after passing the test. One of the test tasks is to measure the dynamic temperature data of the working fluid in a certain time interval (0s-2s) during the ignition process. The starting time is 0s when the power controller sends an ignition signal to the generator. After the temperature measurement device collects the temperature data, the corresponding application software processes and analyzes the temperature data within a period of time (latter section) to judge the ignition performance of the heater. The temperature index requirements in the test execution process are as follows: temperature measurement range - room temperature to 300℃, temperature measurement accuracy ±5℃, qualified heaters should perform fluid temperature measurement tests according to process requirements and the temperature range should be between 100℃ and 200℃.

[0003] At present, the mainstream solution adopts thermocouple contact temperature measurement, such as Figure 1 As shown in the figure: the thermocouple sensor is embedded into the inner wall of the transition pipe through the sealing thread, directly contacting the fluid; its working principle is to convert the fluid temperature into an electrical signal through the thermoelectric effect, and the temperature curve is displayed by the data acquisition system. This solution has the following defects: 1. Measurement accuracy attenuation: The test liquid is corrosive, and the surface of the thermocouple is prone to scaling, such as sulfate crystals, which leads to a decrease in heat conduction efficiency and the measured value deviates from the actual temperature.

[0004] 2. Insufficient dynamic response: The response time of thermocouples is usually 50 to 100ms, which cannot accurately track millisecond changes in fluid temperature.

[0005] 3. Risks of invasive installation: Installing sensors in the transition pipe opening will weaken the strength of the pipe. Seal failure occurred multiple times during the test, posing a safety hazard. Sensor replacement requires disassembly of the pipe, and a single maintenance takes more than 2 hours, affecting test efficiency. Summary of the invention

[0006] The object of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a method for effectively measuring the temperature of a hot fluid in a chemical heater test.

[0007] The present invention is achieved through the following technical solutions: A method for effectively measuring the temperature of a hot fluid in an off-line test of a chemical heater comprises a chemical heater, a liquid receiver and a transition pipe connecting the two, wherein the chemical heater contains a test liquid, and comprises the following steps: a. Sensor installation: The infrared temperature sensor is non-contact mounted on the outer wall of the transition pipe, and the transition pipe is made of thermally conductive material; b. Temperature signal acquisition: The transient temperature data of the outer wall of the transition tube is collected in real time through the infrared temperature sensor; c. Heat conduction modeling: A dynamic relationship model between the pipe wall temperature and the liquid temperature is established based on the transient heat conduction equation. The model satisfies the one-dimensional heat conduction equation: in, is the thermal diffusivity, k is the thermal conductivity of the tube wall, ρ is the density, is the specific heat capacity; d. Liquid temperature inversion: Using the outer surface temperature of the pipe wall measured by the infrared sensor as the boundary condition, the heat conduction model is solved by numerical iteration to invert the dynamic temperature of the test liquid flowing through the transition pipe.

[0008] In the above solution, the boundary conditions of the heat conduction model include: Internal surface boundary conditions: Where h is the convective heat transfer coefficient between the liquid and the tube wall, The above solution further has the feature that, in step a, the infrared temperature sensor is fixed to the outer wall of the transition pipe by means of a welding bracket, and the material of the bracket is the same as that of the transition pipe.

[0009] The above scheme further has the feature that the infrared temperature sensor is calibrated using transformer oil and a standard oil bath as calibration standards to verify the linear response range of the infrared sensor in the range of room temperature to 300°C.

[0010] The above solution further has the feature that the transition tube is made of red copper.

[0011] The above solution further has the feature that the infrared temperature sensor is integrated with a sensor, an optical system and an electronic circuit.

[0012] The above solution further has the feature that the welding bracket can adjust the distance between the infrared sensor and the outer wall of the transition pipe.

[0013] The present invention adopts an infrared sensor to measure the outer surface temperature of the pipe wall to avoid direct contact between the sensor and the fluid, and at the same time establishes a transient heat conduction model from the pipe wall to the fluid, inverts the real temperature of the fluid through the outer wall temperature, and designs a thin-walled copper transition tube and an adjustable bracket to balance the thermal conductivity and mechanical strength, thereby realizing the function of stably measuring the test liquid temperature in the chemical heater. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Attached Figure 1 ——Schematic diagram of operation of chemical heater in prior art Attached Figure 2 ——Schematic diagram of operation of the present invention

[0015] 1——Chemical heater 2——Liquid receiver 3——Test liquid 4——Transition pipe 41——Adjustable bracket 42——Infrared temperature sensor DETAILED DESCRIPTION

[0016] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention.

[0017] It should be noted that, in the description of the present invention, terms such as "left side", "right side", "top", "middle", "middle" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0018] like Figure 2 As shown, the left side of the figure is a chemical heater 1, and the right side of the figure is a liquid receiver 2. A transition pipe 4 is connected between the chemical heater 1 and the liquid receiver 2. An adjustable bracket 41 is fixedly provided above the middle position of the transition pipe 4. The transition pipe 4 and the adjustable bracket 41 are both made of copper. An infrared temperature sensor 42 is installed in the middle of the adjustable bracket 41. The infrared temperature sensor 42 is integrated with a sensor, an optical system and an electronic circuit.

[0019] When the off-line test of the chemical heater 1 begins, the test liquid 3 is injected into the chemical heater 1. After the chemical heater 1 receives the ignition signal, the test liquid 3 flows to the liquid receiver 2 via the transition pipe 4. At this time, the infrared temperature sensor 42 installed above the transition pipe 4 is used to measure and collect the instantaneous temperature data of the outer wall of the transition pipe 4.

[0020] The data measured and collected by the infrared temperature sensor 42 is used to establish a dynamic relationship model between the pipe wall temperature and the liquid temperature. The model satisfies the one-dimensional heat conduction equation: in, is the thermal diffusivity, k is the thermal conductivity of the tube wall, ρ is the density, is the specific heat capacity; The boundary adjustments for this heat conduction model include:

[0021] Where h is the convective heat transfer coefficient between the liquid and the tube wall, The infrared temperature sensor 42 is calibrated using transformer oil and a standard oil bath as calibration standards to verify the linear response range of the infrared temperature sensor 42 in the range of room temperature to 300°C.

[0022] The present invention adopts an infrared sensor to measure the outer surface temperature of the pipe wall to avoid direct contact between the sensor and the fluid, and at the same time establishes a transient heat conduction model from the pipe wall to the fluid, inverts the real temperature of the fluid through the outer wall temperature, and designs a thin-walled copper transition tube and an adjustable bracket to balance the thermal conductivity and mechanical strength, thereby realizing the function of stably measuring the test liquid temperature in the chemical heater.

[0023] It should be stated that the above-mentioned specific implementation methods are only preferred embodiments of the present invention and the technical principles used. Within the technical scope disclosed by the present invention, any changes or substitutions that can be easily thought of by technicians familiar with this technical field should be included in the protection scope of the present invention.

Claims

1. A method for effectively measuring the temperature of a hot fluid in an off-line test of a chemical heater, comprising a chemical heater, a liquid receiver and a transition pipe connecting the two, wherein the chemical heater contains a test liquid, characterized in that The following steps are involved: a. Sensor installation: The infrared temperature sensor is non-contact mounted on the outer wall of the transition pipe, and the transition pipe is made of thermally conductive material; b. Temperature signal acquisition: The transient temperature data of the outer wall of the transition tube is collected in real time through the infrared temperature sensor; c. Heat conduction modeling: A dynamic relationship model between the pipe wall temperature and the liquid temperature is established based on the transient heat conduction equation. The model satisfies the one-dimensional heat conduction equation: in, is the thermal diffusivity, k is the thermal conductivity of the tube wall, ρ is the density, is the specific heat capacity; d. Liquid temperature inversion: Using the outer surface temperature of the pipe wall measured by the infrared sensor as the boundary condition, the heat conduction model is solved by numerical iteration to invert the dynamic temperature of the test liquid flowing through the transition pipe.

2. The method according to claim 1, characterized in that: The boundary conditions of the heat conduction model include: The inner surface boundary conditions are: Where h is the convective heat transfer coefficient between the liquid and the tube wall, is the inner surface temperature of the pipe wall.

3. The method according to claim 1, characterized in that: In step a, the infrared temperature sensor is fixed to the outer wall of the transition pipe by welding a bracket, and the material of the bracket is the same as that of the transition pipe.

4. The method according to claim 1, characterized in that: The calibration of the infrared temperature sensor uses transformer oil and a standard oil bath as calibration standards to verify the linear response range of the infrared sensor in the range of room temperature to 300°C.

5. The method according to claim 1, characterized in that: The transition tube is made of red copper.

6. The method according to claim 1, characterized in that: The infrared temperature sensor is integrated with a sensor, an optical system and an electronic circuit.

7. The method according to claim 3, characterized in that: The welding bracket is an adjustable bracket, which can adjust the distance between the infrared sensor and the outer wall of the transition pipe.

Images