High-heat-conduction-efficiency calorimeter for thermal power measurement

Abstract

The invention discloses a high-heat-conduction-efficiency calorimeter for thermal power measurement. The calorimeter comprises a calorimetric cup, a vacuum cavity, a to-be-measured sample, an anti-radiation screen, a metal heat conduction beam, a fine-particle crystalline heat conduction medium, a positioning block and a high-precision temperature sensor. A to-be-measured sample is placed in the cavity of the calorimetric cup and is fixed by the positioning block, and the cavity of the calorimetric cup is filled with a fine-particle crystalline heat-conducting medium; the calorimetric cup is arranged in the vacuum cavity, a vacuum environment is formed in the vacuum cavity, the calorimetric cup and the vacuum cavity are connected through the metal heat conduction beam, the metal heat conduction beam is of a two-end double-ring structure, the inner-end ring structure and the outer wall of the calorimetric cup are in precise fit, and the outer-end ring structure and the inner wall of the vacuum cavity are in precise fit. The matching part is coated with high-temperature-resistant vacuum heat-conducting grease; the temperature sensor is mounted on the metal heat-conducting beam and is used for accurately measuring the temperature difference on the metal heat-conducting beam; and the heat measuring cup and the vacuum cavity are separated by an anti-radiation screen. According to the invention, the accuracy and safety of thermal power parameter measurement of the sample can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal power parameter measurement, and in particular relates to a high thermal conductivity calorimeter for thermal power measurement. Background Art

[0002] There is a wide demand for thermal power measurement. For example, nuclear batteries used in space exploration, anti-submarine monitoring, and uninhabited island lighthouses have a demand for measuring the thermal power of radioactive isotope materials, nuclear material processing has a demand for measuring the thermal power of raw materials, and international trade has a demand for measuring the thermal power of isotope samples. At present, there is a lack of effective traceability methods for thermal power in China, the thermal power calorimeter has a small range, low accuracy, and a lack of thermal power measurement standards, making it difficult to meet the above needs.

[0003] In recent years, metrology institutions and research institutes in major countries around the world have conducted research on thermal power measurement and found that the thermal conductivity of the calorimeter cup directly affects the accuracy and safety of thermal power measurement. A calorimeter cup with low thermal conductivity will cause a large proportion of heat to be transferred through radiation and convection, reducing the accuracy of thermal power measurement. At the same time, it will prevent heat from being smoothly transferred to the external environment, causing heat accumulation inside the calorimeter cup, excessively high temperature, and reducing the safety of the calorimeter cup. Summary of the invention

[0004] The purpose of the present invention is to provide a high thermal conductivity calorimeter for thermal power measurement to address the problems of low measurement accuracy and low safety in the thermal power measurement process caused by the low thermal conductivity of the calorimetric cup, which can effectively improve the accuracy and safety of the thermal power parameter measurement of the sample.

[0005] In order to achieve the above-mentioned object, one aspect of the present invention provides a high thermal conductivity calorimeter for thermal power measurement, comprising a calorimetric cup, a vacuum chamber, a sample to be measured, an anti-radiation screen, a metal thermally conductive beam, a fine-grained crystalline thermally conductive medium, a positioning block, and a high-precision temperature sensor;

[0006] The calorimetric cup is a sealed structure, including a calorimetric cup upper cover and a calorimetric cup cavity. The sample to be tested is placed in the calorimetric cup cavity and fixed by a positioning block. The positioning block is precisely matched with the inner wall of the calorimetric cup and the outer wall of the sample, so that the centroid of the sample coincides with the centroid of the calorimetric cup. The cavity of the calorimetric cup is filled with fine-grained crystalline heat-conducting medium to form a heat-conducting path between the sample to be tested and the calorimetric cup.

[0007] The calorimetric cup is placed in a vacuum chamber, a vacuum environment is formed in the vacuum chamber, the calorimetric cup and the vacuum chamber are connected by a metal heat-conducting beam, which is used to transfer the heat on the calorimetric cup to the vacuum chamber. The metal heat-conducting beam is a double-ring structure at both ends, the inner ring structure forms a precise fit with the outer wall of the calorimetric cup, and the outer ring structure forms a precise fit with the inner wall of the vacuum chamber, and the fitting part is coated with high-temperature resistant vacuum thermal grease;

[0008] The metal heat-conducting beam is processed with a sensor mounting hole, and a high-precision temperature sensor is installed in the sensor mounting hole to accurately measure the temperature difference on the metal heat-conducting beam;

[0009] The calorimetric cup and the vacuum chamber are separated by an anti-radiation screen, which includes multiple layers of metal foil and an insulating bracket for supporting the multiple layers of metal foil. The calorimetric cup is wrapped by the anti-radiation screen to reduce radiation heat transfer between the calorimetric cup and the vacuum chamber. The temperature sensor is located outside the anti-radiation screen.

[0010] Preferably, there are multiple metal heat-conducting beams, and the temperature difference between the core temperature in the calorimetric cup and the two ends of the metal heat-conducting beams can be controlled by adjusting the cross-sectional area and the number of the metal heat-conducting beams.

[0011] Preferably, the multiple layers of metal foil are separated by a low thermal conductivity gauze.

[0012] Preferably, the multi-layer metal foil has four layers, and the overall thickness is less than 4 mm.

[0013] Preferably, the vacuum chamber has an upper cover, which ensures the airtightness of the interior of the vacuum chamber through an O-ring, and a vacuum tube is welded on the upper cover to ensure the vacuum environment inside the vacuum chamber through a vacuum pump.

[0014] Preferably, the positioning block is made of ceramic material, the heat-insulating bracket is made of insulating material, and the calorimetric cup cavity and the calorimetric cup upper cover are made of metal material.

[0015] The high thermal conductivity calorimeter for thermal power measurement according to the above aspects of the present invention can effectively improve the accuracy and safety of thermal power parameter measurement of the sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0017] Figure 1 is a schematic structural diagram of a high thermal conductivity calorimeter for thermal power measurement according to an embodiment of the present invention;

[0018] Figure 2 It is a schematic structural diagram of a metal heat-conducting beam according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Embodiments of the present invention provide a high thermal conductivity calorimeter for thermal power measurement, such as Figure 1 As shown, the high thermal conductivity calorimeter for thermal power measurement according to the embodiment of the present invention includes a calorimetric cup, a vacuum chamber 4, a sample to be measured 5, an anti-radiation screen, a metal thermal beam 7, a fine-grained crystalline thermal conductive medium 8, a positioning block 9 and a high-precision temperature sensor.

[0021] In one embodiment, the calorimetric cup includes a calorimetric cup cover 1 and a calorimetric cup cavity 2. The calorimetric cup cavity 2 is a cylindrical cavity structure, and a circular calorimetric cup cover 1 is arranged on the upper part. The calorimetric cup cavity 2 and the calorimetric cup cover 1 are made of metal, and a sealing ring is arranged therebetween, forming a calorimetric cup with a sealed structure as a whole. The calorimetric cup cavity 2 is filled with a fine-grained crystalline heat-conducting medium 8, which is used to form a heat-conducting path between the sample 5 to be tested and the calorimetric cup. The calorimetric cup is placed in a vacuum chamber 4, and the calorimetric cup and the vacuum chamber 4 are separated by an anti-radiation screen. The calorimetric cup and the vacuum chamber 4 are connected by a metal heat-conducting beam 7, and a small high-precision temperature sensor is arranged on the metal heat-conducting beam 7.

[0022] The sample 5 to be tested is placed in the calorimetric cup cavity 2 and fixed by the positioning block 9. Due to the difference in the size of the samples, in order to ensure the uniform temperature field inside the calorimetric cup, the positioning block 9 is designed according to the size and shape of the sample. The positioning block 9 is precisely matched with the inner wall of the calorimetric cup and the outer wall of the sample (heat source), so that the centroid of the sample 5 coincides with the centroid of the calorimetric cup, and no offset occurs during the entire thermal power measurement process, avoiding the uneven temperature field caused by the displacement of the sample. The positioning block 9 is processed by ceramic material, which has the characteristics of insulation, high temperature resistance, similar specific heat capacity to the calorimetric cup, and extremely low thermal expansion coefficient. The gap between the sample and the calorimetric cup is filled with fine-grained crystalline heat-conducting medium 8 to ensure that the heat of the sample is fully transferred to the calorimetric cup. Compared with the fat heat-conducting medium, the fine-grained crystalline heat-conducting medium 8 can fill the gap between the sample and the calorimetric cup cavity 2 more evenly. In addition, the uniformity of the distribution of the fat heat-conducting medium is affected by the manual application method, and the thermal conductivity will continue to decrease over time. In addition, compared with thermal silicone oil, the properties of the fine-grained crystalline thermal conductive medium 8 do not change with the sample temperature. When encountering a high-temperature sample, the thermal silicone oil will partially vaporize, reducing the thermal conductivity while posing the risk of high-pressure explosion.

[0023] like Figure 2As shown, the metal heat-conducting beam 7 is a double-ring structure at both ends, the inner end ring structure forms a precise fit with the outer wall of the calorimetric cup, and the outer end ring structure forms a precise fit with the inner wall of the vacuum chamber 4, and the gap of the fitting part is filled with evenly applied high-temperature resistant vacuum thermal grease. This design can effectively increase the contact area between the metal heat-conducting beam 7 and the outer wall of the calorimetric cup and the inner wall of the vacuum chamber 4, ensuring that the heat generated by the sample 5 to be tested will not accumulate in the core of the calorimetric cup, and can be transferred to the external environment through the metal heat-conducting beam 7. By designing the cross-sectional area and number of the metal heat-conducting beam 7, the size of the heat-conducting path between the calorimetric cup and the inner wall of the vacuum chamber 4 can be adjusted, thereby effectively controlling the core temperature in the calorimetric cup and the temperature difference at both ends of the metal heat-conducting beam 7. In addition, by using vacuum thermal grease to fill the gap, it is ensured that the heat of the calorimetric cup is only conducted out through the metal heat-conducting beam 7 based on the heat conduction effect, minimizing the radiation heat exchange and convection heat exchange between the calorimetric cup and the vacuum chamber 4. The metal heat-conducting beam 7 is processed with a precision temperature sensor mounting hole, and a small high-precision temperature sensor is installed. In one embodiment, two small high-precision temperature sensors are arranged on the metal heat-conducting beam 7 to accurately measure the temperature difference on the metal heat-conducting beam 7 and calculate the thermal power parameters of the sample to be measured in the calorimetric cup.

[0024] The anti-radiation screen includes multiple layers of polished metal foil and a heat-insulating bracket 6, the purpose of which is to reduce the radiation heat transfer between the calorimetric cup and the inner wall of the vacuum chamber. The anti-radiation screen is located between the calorimetric cup and the inner wall of the vacuum chamber, and the calorimetric cup is completely wrapped by the anti-radiation screen. The distance between the calorimetric cup and the inner wall of the vacuum chamber is very narrow, and the temperature sensor should be located outside the anti-radiation screen, so the anti-radiation screen needs to be very thin. The polished metal foil is extremely thin and has very low rigidity, and is very easy to deform under the action of external force. In order to increase the rigidity of the entire anti-radiation screen, a heat-insulating bracket 6 is designed. The heat-insulating bracket 6 is made of insulating material and can effectively support multiple layers of metal foil. In order to ensure that each layer of metal foil does not contact each other, a gauze with extremely low thermal conductivity is used as a spacer between the metal foils. For example, the anti-radiation screen has four layers, and the overall thickness is controlled to be less than 4 mm.

[0025] The vacuum chamber 4 has a vacuum chamber upper cover 3, which ensures the airtightness of the inside of the vacuum chamber 4 through an O-ring or the like. A KF series vacuum tube is welded at the interface of the vacuum chamber upper cover 3, and a high-performance vacuum pump ensures the vacuum environment inside the vacuum chamber 4, so that the external environment of the calorimetric cup is maintained in a vacuum environment.

[0026] The working process of the high thermal conductivity calorimeter for thermal power measurement in the embodiment of the present invention is as follows: the sample 5 is placed in the calorimetric cup and fixed in the center of the calorimetric cup by the positioning block 9. The calorimetric cup is filled with fine granular crystalline heat-conducting medium 8 of the size of 100 meshes, and the heat-conducting crystal particles completely fill the gap between the sample and the calorimetric cup to form a uniform and stable heat-conducting path, so that the heat generated by the sample can be smoothly transmitted to the calorimetric cup. The calorimetric cup is placed in the vacuum chamber 4, and is connected to the vacuum chamber 4 by a metal heat-conducting beam 7, so that the heat on the calorimetric cup can be efficiently transferred to the vacuum chamber 4. Two small high-precision temperature sensors are arranged on the metal heat-conducting beam 7, which can accurately measure the temperature difference on the metal heat-conducting beam 7, and the heating power of the sample can be accurately measured by calibration. When the calorimetric cup is working, the outside is a vacuum environment, and four layers of anti-radiation screens are arranged between the calorimetric cup and the vacuum chamber, which can minimize the errors caused by convective heat transfer and radiation heat transfer.

[0027] The high thermal conductivity calorimeter for thermal power measurement of the embodiment of the present invention can be used in a (1-150)W steady-state thermal power measurement device, can improve the accuracy of thermal power measurement, and enhance the safety of the calorimetric device. By filling the calorimetric cup cavity with fine-grained crystalline thermal conductive medium and matching the double-ring structure metal thermal conductive beam with vacuum thermal conductive grease applied to the contact part, the thermal conduction efficiency is maximized, and the heat accumulation caused by excessive thermal resistance is avoided. At the same time, the loss of convective heat transfer and radiation heat transfer is minimized through the vacuum environment and the anti-radiation screen. Moreover, the present invention has a simple internal structure, low processing cost, and good practical effect.

[0028] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A high thermal conductivity calorimeter for thermal power measurement, characterized in that: It includes a calorimetric cup, a vacuum chamber, a sample to be tested, an anti-radiation screen, a metal heat-conducting beam, a fine-grained crystalline heat-conducting medium, a positioning block, and a high-precision temperature sensor; The calorimetric cup is a sealed structure, including a calorimetric cup upper cover and a calorimetric cup cavity. The sample to be tested is placed in the calorimetric cup cavity and fixed by a positioning block. The positioning block is precisely matched with the inner wall of the calorimetric cup and the outer wall of the sample, so that the centroid of the sample coincides with the centroid of the calorimetric cup. The cavity of the calorimetric cup is filled with fine-grained crystalline heat-conducting medium to form a heat-conducting path between the sample to be tested and the calorimetric cup. The calorimetric cup is placed in a vacuum chamber, a vacuum environment is formed in the vacuum chamber, the calorimetric cup and the vacuum chamber are connected by a metal heat-conducting beam, which is used to transfer the heat on the calorimetric cup to the vacuum chamber. The metal heat-conducting beam is a double-ring structure at both ends, the inner ring structure forms a precise fit with the outer wall of the calorimetric cup, and the outer ring structure forms a precise fit with the inner wall of the vacuum chamber, and the fitting part is coated with high-temperature resistant vacuum thermal grease; The metal heat-conducting beam is processed with a sensor mounting hole, and a high-precision temperature sensor is installed in the sensor mounting hole to accurately measure the temperature difference on the metal heat-conducting beam; The calorimetric cup and the vacuum chamber are separated by an anti-radiation screen, which includes multiple layers of metal foil and an insulating bracket for supporting the multiple layers of metal foil. The calorimetric cup is wrapped by the anti-radiation screen to reduce radiation heat transfer between the calorimetric cup and the vacuum chamber. The temperature sensor is located outside the anti-radiation screen.

2. The high thermal conductivity calorimeter for thermal power measurement according to claim 1, characterized in that: There are multiple metal heat-conducting beams. By adjusting the cross-sectional area and the number of the metal heat-conducting beams, the temperature difference between the core temperature in the calorimetric cup and the two ends of the metal heat-conducting beams can be controlled.

3. The high thermal conductivity calorimeter for thermal power measurement according to claim 1 or 2, characterized in that: The layers of metal foil are separated by low thermal conductivity gauze.

4. The high thermal conductivity calorimeter for thermal power measurement according to claim 3, characterized in that: The multi-layer metal foil has four layers and the overall thickness is less than 4mm.

5. The high thermal conductivity calorimeter for thermal power measurement according to claim 1 or 2, characterized in that: The vacuum chamber has an upper cover, which ensures the airtightness of the interior of the vacuum chamber through an O-ring, and a vacuum tube is welded on the upper cover to ensure the vacuum environment inside the vacuum chamber through a vacuum pump.

6. The high thermal conductivity calorimeter for thermal power measurement according to claim 1 or 2, characterized in that: The positioning block is made of ceramic material, the heat insulation bracket is made of insulation material, and the calorimetric cup cavity and the calorimetric cup upper cover are made of metal material.

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