A high thermal conductivity calorimeter for thermal power measurement

Abstract

The present invention discloses a high-thermal-conductivity calorimeter for measuring thermal power. The calorimeter comprises 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. The sample to be measured is placed in the calorimetric cup cavity and secured by the positioning block. The calorimetric cup cavity is filled with the fine-grained crystalline thermally conductive medium. The calorimetric cup is placed in the vacuum chamber, creating a vacuum environment. The calorimetric cup and the vacuum chamber are connected by a metal thermally conductive beam. The metal thermally conductive beam has a double-ring structure at both ends, with the inner ring structure precisely fitting the outer wall of the calorimetric cup and the outer ring structure precisely fitting the inner wall of the vacuum chamber. The fitting portions are coated with high-temperature-resistant vacuum thermal grease. A temperature sensor is mounted on the metal thermally conductive beam to accurately measure the temperature difference across the metal thermally conductive beam. The calorimetric cup and the vacuum chamber are separated by an anti-radiation screen. The present invention can effectively improve the accuracy and safety of measuring the thermal power parameters of the sample.

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] Thermal power measurement is widely needed. For example, nuclear batteries used in space exploration, anti-submarine surveillance, and uninhabited island lighthouses require thermal power measurement of radioisotope materials. Nuclear material processing also requires thermal power measurement of raw materials. International trade also requires thermal power measurement of isotope samples. Currently, China lacks effective traceability methods for thermal power. Thermal power calorimeters have limited range, low accuracy, and a lack of thermal power measurement standards, making it difficult to meet these needs.

[0003] In recent years, metrology institutions and research institutes in major countries around the world have conducted research on thermal power measurement and have found that the thermal conductivity of the calorimeter cup directly affects the accuracy and safety of thermal power measurements. A calorimeter cup with low thermal conductivity results in a disproportionate share of heat transfer via radiation and convection, reducing the accuracy of thermal power measurements. This also prevents heat from being smoothly transferred to the external environment, causing heat accumulation inside the cup and excessively high temperatures, compromising its safety. Summary of the Invention

[0004] The purpose of the present invention is to address the problems of low measurement accuracy and low safety during thermal power measurement caused by the low thermal conductivity of the calorimetric cup. A high thermal conductivity calorimeter for thermal power measurement is provided, which can effectively improve the accuracy and safety of the measurement of the thermal power parameters of the sample.

[0005] 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 cover and a calorimetric cup cavity. The sample to be measured 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 calorimetric cup cavity is filled with fine-grained crystalline heat-conducting medium to form a heat conduction path between the sample to be measured and the calorimetric cup.

[0007] The calorimetric cup is placed in a vacuum chamber, and a vacuum environment is formed in the vacuum chamber. The calorimetric cup and the vacuum chamber are connected by a metal thermal beam, which is used to transfer heat from the calorimetric cup to the vacuum chamber. The metal thermal beam has 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. 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. By adjusting the cross-sectional area and 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.

[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 thermal insulation bracket is made of thermal insulation 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 measuring the thermal power parameters of a sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions 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. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts.

[0017] Figure 1 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 Schematic diagram of the structure of the metal heat-conducting beam according to the embodiment of the present invention. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0020] The 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, a calorimetric cup includes a calorimetric cup cover 1 and a calorimetric cup cavity 2. The calorimetric cup cavity 2 is a cylindrical cavity structure with a circular calorimetric cup cover 1 disposed on top. The calorimetric cup cavity 2 and the calorimetric cup cover 1 are made of metal, with a sealing ring disposed therebetween, forming a sealed calorimetric cup. The calorimetric cup cavity 2 is filled with a fine-grained crystalline heat-conducting medium 8, which forms 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, separated from the vacuum chamber 4 by an anti-radiation shield. The calorimetric cup and the vacuum chamber 4 are connected by a metal heat-conducting beam 7, on which a small, high-precision temperature sensor is disposed.

[0022] The sample 5 to be tested is placed in the calorimetric cup cavity 2 and fixed by a positioning block 9. Due to the differences in sample size, in order to ensure a 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 uneven temperature fields caused by sample displacement. The positioning block 9 is made of 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 thermal conductive medium 8 to ensure that the heat of the sample is fully transferred to the calorimetric cup. Compared with fat thermal conductive medium, fine-grained crystalline thermal conductive medium 8 can more evenly fill the gap between the sample and the calorimetric cup cavity 2. In addition, the uniformity of the distribution of fat thermal conductive 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. Thermal silicone oil will partially vaporize when encountering a high-temperature sample, reducing its thermal conductivity while posing the risk of high-pressure explosion.

[0023] like Figure 2As shown, the metal thermal beam 7 comprises a double-ring structure at each end. The inner ring forms a precise fit with the outer wall of the calorimeter cup, while the outer ring forms a precise fit with the inner wall of the vacuum chamber 4. The gaps between these fits are filled with an evenly applied, high-temperature-resistant vacuum thermal grease. This design effectively increases the contact area between the metal thermal beam 7 and both the outer and inner walls of the calorimeter cup, ensuring that heat generated by the sample 5 under test does not accumulate within the calorimeter cup, but is instead transferred to the external environment through the metal thermal beam 7. By designing the cross-sectional area and number of the metal thermal beams 7, the size of the heat conduction path between the calorimeter cup and the inner wall of the vacuum chamber 4 can be adjusted, effectively controlling the temperature difference between the core temperature of the calorimeter cup and the temperature across the metal thermal beam 7. Furthermore, by filling the gaps with vacuum thermal grease, heat from the calorimeter cup is transferred solely through the metal thermal beam 7 via thermal conduction, minimizing both radiative and convective heat transfer between the calorimeter cup and the vacuum chamber 4. The metal thermal beam 7 is provided with a precision temperature sensor mounting hole for a small, high-precision temperature sensor. 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 thermal insulation bracket 6, the purpose of which is to reduce radiative 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, making it very easy to deform under external forces. In order to increase the rigidity of the entire anti-radiation screen, a thermal insulation bracket 6 is designed. The thermal insulation bracket 6 is made of an insulating material and can effectively support the multiple layers of metal foil. To ensure that each layer of metal foil does not contact each other, the metal foil is separated by a mesh with an extremely low thermal conductivity coefficient. For example, the anti-radiation screen has four layers, and the overall thickness is controlled to be less than 4mm.

[0025] The vacuum chamber 4 has a vacuum chamber upper cover 3, which ensures the airtightness 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 high-efficiency thermal conductivity calorimeter for measuring thermal power according to an embodiment of the present invention operates as follows: a sample 5 is placed in a calorimetric cup and secured in the center of the cup via a positioning block 9. The cup is filled with a 100-mesh-sized, fine-grained, crystalline thermally conductive medium 8. The thermally conductive crystal particles completely fill the gap between the sample and the cup, forming a uniform and stable thermal conduction path, allowing heat generated by the sample to be smoothly transferred to the cup. The cup is placed in a vacuum chamber 4 and connected to the chamber by a metal thermal beam 7, allowing heat from the cup to be efficiently transferred to the chamber. Two small, high-precision temperature sensors are mounted on the metal thermal beam 7, which accurately measure the temperature difference across the beam. Through calibration, the sample's heating power can be accurately measured. The calorimetric cup operates in a vacuum environment. Four layers of anti-radiation shields are placed between the cup and the vacuum chamber to minimize errors caused by convective and radiative heat transfer.

[0027] The high-thermal-conductivity calorimeter for thermal power measurement according to the present invention can be used in a (1-150)W steady-state thermal power measurement device, improving the accuracy of thermal power measurements and enhancing the safety of the calorimetric device. By filling the calorimetric cup cavity with a fine-grained crystalline thermally conductive medium and using a double-ring metal heat-conducting beam with vacuum thermal grease applied to the contact portion, the device maximizes heat conduction efficiency, avoids heat accumulation caused by excessive thermal resistance, and minimizes convective and radiative heat transfer losses through the vacuum environment and anti-radiation shield. Furthermore, the present invention has a simple internal structure, low processing costs, and good practical results.

[0028] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

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 cover and a calorimetric cup cavity. The sample to be measured 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 calorimetric cup cavity is filled with fine-grained crystalline heat-conducting medium to form a heat conduction path between the sample to be measured and the calorimetric cup. The calorimetric cup is placed in a vacuum chamber, and a vacuum environment is formed in the vacuum chamber. The calorimetric cup and the vacuum chamber are connected by a metal thermal beam, which is used to transfer heat from the calorimetric cup to the vacuum chamber. The metal thermal beam has 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. 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 a heat-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. There are multiple metal thermal beams. By adjusting the cross-sectional area and number of the metal thermal beams, the size of the heat conduction path between the calorimetric cup and the inner wall of the vacuum chamber can be adjusted, thereby controlling the temperature difference between the core temperature in the calorimetric cup and the two ends of the metal thermal beams.

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

3. The high thermal conductivity calorimeter for thermal power measurement according to claim 2, characterized in that: The multi-layer metal foil consists of four layers, and the overall thickness is less than 4mm.

4. The high thermal conductivity calorimeter for thermal power measurement according to claim 1, 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. A vacuum tube is welded on the upper cover, and a vacuum environment inside the vacuum chamber is ensured by a vacuum pump.

5. The high thermal conductivity calorimeter for thermal power measurement according to claim 1, 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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