CN117516760A - A portable dry body temperature calibration device based on a small Stirling refrigerator - Google Patents

Abstract

The invention discloses a portable dry body temperature calibration device based on a small Stirling refrigerator, which comprises: a vacuum device for providing a vacuum environment; a "well" type heat-conducting device, partially housed inside said vacuum device, internally able to house a thermometer to be calibrated; a refrigeration device comprising a Stirling refrigerator partially disposed within the vacuum device, the Stirling refrigerator delivering cold to the "well" type heat transfer device; and one part of the calibration device is arranged in the well-type heat conduction device, and the other part of the calibration device is arranged in the external environment and is used for calibrating the thermometer to be calibrated. The temperature calibration device disclosed by the invention does not need to consume low-temperature fluid such as liquid nitrogen and the like, can realize high-precision temperature control in a wide temperature range from a liquid nitrogen temperature range to room temperature by only supplying power with low power from a commercial power, can be conveniently moved to a calibration site to provide calibration service, and has good operability.

Description

A portable dry body temperature calibration device based on a small Stirling refrigerator

Technical field

The present invention relates to the technical field of temperature calibration, and in particular to a portable dry body temperature calibration device based on a small Stirling refrigerator.

Background technique

Dry temperature calibrator is a common measurement supporting equipment in industrial temperature field calibration. It is widely used due to its compact structure, strong portability, fast temperature rise and fall speed, wide temperature control range, strong anti-interference and simple operation. Calibration and calibration of temperature systems.

With the vigorous development of scientific research based on low-temperature environments, experimental measurements in research on cell cryopreservation technology, liquid fuel low-temperature storage technology, etc. are becoming increasingly frequent. In these studies, the use of cryogenic thermometers for temperature measurements in experiments is a common means. Calibration of low-temperature thermometers is an indispensable part to ensure the accuracy of low-temperature thermometer measurements. Equipment used for low-temperature thermometer calibration can usually be divided into two categories: wet devices using cryogenic liquid as the cold source and dry devices based on refrigeration technology. Among them, the latter is easy to use and is particularly suitable for on-site calibration.

In the existing technology, the lower limit of the applicable range of most commercial "low temperature" dry temperature calibrators is usually above -100°C, which cannot meet the calibration needs of deep cryogenic thermometers. For example, OMEGA's TCL-165S-D dry body furnace has a measuring range between -35°C and 165°C; FLUKE's 9190A dry body furnace has a measuring range between -95°C and 145°C; AMETEK's RTC159 dry body furnace , the measuring range is between -100℃ and 155℃. In terms of dry temperature calibration devices that emphasize portability, some portable temperature calibrators of temperature measurement systems have a use range from room temperature to 400°C and cannot be calibrated for low-temperature thermometers; some portable temperature calibrators with contrast functions, although they are shock-resistant Protection capability, but the temperature range does not involve low temperature; other temperature calibrator control systems focus on the collection, storage and display of temperature signals, and do not involve low temperature. These calibration devices are not suitable for the calibration of portable cryogenic thermometers as low as the liquid nitrogen temperature range, and their operability is low.

In order to achieve temperature calibration in the liquid nitrogen temperature zone, existing calibration devices usually use low-temperature liquid as the cold source, which requires frequent filling of liquid, which is costly and difficult to carry.

Therefore, those skilled in the art are committed to providing a portable dry body temperature calibration device based on a small Stirling refrigerator, which can achieve temperature calibration as low as the liquid nitrogen temperature range, is highly portable and has good operability.

Contents of the invention

In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is how to provide a portable temperature calibration device that can achieve low-temperature calibration.

In order to achieve the above objectives, the present invention provides a portable dry body temperature calibration device based on a small Stirling refrigerator, including:

A vacuum device used to provide a vacuum environment;

A "well" type thermal conduction device is partially placed in the vacuum device and can accommodate a thermometer to be calibrated inside;

A refrigeration device, which includes a Stirling refrigerator partially placed within the vacuum device, and the Stirling refrigerator delivers cold energy to the "well" heat transfer device;

A calibration device, one part of which is placed in the "well" heat conduction device, and the other part is placed in the external environment, is used to calibrate the thermometer to be calibrated.

Preferably, the vacuum device includes a vacuum barrel, one end of the vacuum barrel is provided with a top annular flange plate, and a side wall of the vacuum barrel is provided with an air extraction nozzle; the Stirling refrigerator passes through the The side wall of the vacuum barrel, the cold head of the Stirling refrigerator is placed in the vacuum barrel, and the Stirling refrigerator is sealed with the side wall of the vacuum barrel.

Further, the "well" heat conduction device includes a thin-walled tube, a copper sleeve and a thermostatic block. One end of the copper sleeve is connected to one end of the thin-walled tube, and the thin-walled tube passes through the top annular The flange plate, the copper sleeve is placed in the vacuum barrel, the thermostatic block is placed in the "well" of the copper sleeve, and the thermometer to be calibrated is placed in the thermostatic block.

Further, the refrigeration device further includes a copper braid, one end of the copper braid is connected to the cold head of the Stirling refrigerator, and the other end of the copper braid is connected to the "well" heat conduction device, so A thermal resistor sheet is sandwiched between the copper braid and the copper sleeve.

Further, a copper wire pressing block is provided in the groove of the copper sleeve, and the copper wire pressing block is located on the side close to the top annular flange plate.

Further, a heating device is provided in the thermostatic block, and a foam plug is provided at the other end of the thin-walled tube.

Further, the calibration device includes a temperature-controlled thermometer and a standard temperature sensor. The standard temperature sensor is located in the constant temperature block. The thermometer to be calibrated, the standard temperature sensor and the temperature-controlled thermometer are electrically connected. connect.

Preferably, it also includes a housing, the vacuum device, the "well" heat conduction device, and the refrigeration device are located inside the housing, and the temperature controller is located outside the housing.

Preferably, it also includes a cooling air duct, and the cooling air duct is provided on the side of the housing.

Preferably, the housing is provided with a control panel, a fan switch, and a power switch.

The present invention has at least the following beneficial technical effects:

The portable dry body temperature calibration device based on a small Stirling refrigerator provided by the present invention uses a small Stirling refrigerator as a cold source. It is small in size and light in weight. It does not need to add low-temperature liquid. It is highly portable and can be used in liquid nitrogen. The temperature zone provides sufficient cooling capacity to meet the calibration requirements; it adopts the design of a vacuum heat insulation cavity, with multiple layers of insulation materials wrapped inside, and a copper crimping block is installed to eliminate heat leakage from the leads, allowing the system to cool down to the liquid nitrogen temperature zone, through heating The device can be reheated to room temperature, achieving temperature adjustment from the liquid nitrogen low-temperature zone to room temperature, with high calibration accuracy; it adopts a "well" design to isolate the thermometer and thermostatic block outside the vacuum insulation cavity, which can be achieved without damaging the vacuum system. Take out the thermostat block under the premise, which is convenient for installing the calibrated thermometer and has strong operability. The temperature calibration device of the present invention does not need to consume low-temperature fluids such as liquid nitrogen, and only needs small power supply from the mains to achieve high-precision temperature control in a wide temperature range from the liquid nitrogen temperature zone to room temperature, and can be conveniently moved to the calibration site to provide calibration Service, good operability.

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, features and effects of the present invention.

Description of drawings

Figure 1 is a schematic structural diagram of a portable dry body temperature calibration device based on a small Stirling refrigerator according to an embodiment of the present invention;

Figure 2 is a schematic view of the housing of a portable dry body temperature calibration device based on a small Stirling refrigerator according to an embodiment of the present invention;

Figure 3 is a schematic diagram of the "well" heat conduction device of the portable dry body temperature calibration device based on a small Stirling refrigerator according to an embodiment of the present invention.

In the picture, 1-shell, 2-temperature control thermometer, 3-Stirling refrigerator, 4-vacuum barrel, 5-top annular flange plate, 6-bottom annular flange plate, 7-thin Wall tube, 8-oxygen-free copper sleeve, 9-copper crimping block, 10-thermostat block, 11-foam plug, 12-thermal resistor, 13-copper braid, 14-heating device, 15-standard temperature sensor, 16 -Temperature sensor lead, 17-refrigeration head, 18-self-sealing air nozzle, 19-cooling duct, 20-control panel, 21-fan switch, 22-power switch, 23-aviation plug, 24-USB interface .

Detailed ways

Preferred embodiments of the present invention are introduced below to make the technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned herein.

In the drawings, components with the same structure are denoted by the same numerals, and components with similar structures or functions are denoted by similar numerals. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustrations clearer, the thickness of components is exaggerated in some places in the drawings.

The present invention provides a portable dry body temperature calibration device based on a small Stirling refrigerator. Using the small Stirling refrigerator as a cold source, it can achieve precise temperature control in the temperature range from 78K to 300K; through the comparison method, Place the standard temperature sensor and the thermometer to be calibrated in the same temperature field, and use the "temperature-resistance" graduation table of the standard temperature sensor to calibrate the thermometer to be calibrated.

As shown in Figure 1, the portable dry body temperature calibration device based on a small Stirling refrigerator in this embodiment includes a vacuum device, a "well" heat conduction device, a refrigeration device and a calibration device. The vacuum device provides a vacuum environment and the "well" "" type heat conduction device provides a stable temperature environment, and the two together form a vacuum insulation cavity; the refrigeration device inputs cold energy to achieve low-temperature calibration, and the calibration device calibrates the thermometer to be calibrated.

In this embodiment, the vacuum device includes a vacuum barrel 4. The bottom of the vacuum barrel 4 is provided with a bottom annular flange plate 6 for supporting the vacuum barrel 4; the top of the vacuum barrel 4 is connected with a top annular flange plate 5. , used to provide support for the "well" heat transfer device. The side wall of the vacuum barrel 4 is provided with two flange interfaces, one of which is used to connect the self-sealing air extraction nozzle 18, and the other flange interface is used to connect the refrigeration device. The self-sealing air evacuation nozzle 18 serves as a vacuum air evacuation port and can be connected to the molecular pump unit to evacuate the vacuum barrel 4; after the vacuuming stage is completed, the long-term vacuum state of the vacuum barrel 4 is maintained by sealing the self-sealing air evacuation nozzle 18. .

In a specific embodiment, the inner diameter of the vacuum barrel 4 is 150mm and the height is 400mm. The upper flange interface connected to the self-sealing suction nozzle 18 is a KF16 flange, and the lower flange interface connected to the refrigeration device is a KF40 flange. .

The refrigeration device includes a Stirling refrigerator 3 and a copper braid 13. The Stirling refrigerator 3 passes through another flange interface on the vacuum barrel 4, and the cold head 17 of the refrigerator is located inside the vacuum barrel 4. One end of the copper braid 13 is connected to the cold head 17 of the refrigerator through bolts, and the other end is connected to the "well" heat conduction device. In a specific embodiment, the copper braid 13 has a total length of 70 mm, a thickness of 4 mm, and is folded into a "W"-shaped structure.

As shown in Figure 3, the "well" heat conduction device includes a thin-walled tube 7 and an oxygen-free copper sleeve 8. The thin-walled tube 7 is made of stainless steel. The oxygen-free copper sleeve 8 has a groove inside. One end of the thin-walled tube 7 and The open ends of the oxygen-free copper sleeves 8 are sealed by dissimilar metal welding to form a "well"-type groove. In a specific embodiment, the thin-walled tube 7 has an inner diameter of 40mm, a wall thickness of 0.3mm, and a height of 160mm; the oxygen-free copper sleeve 8 has an inner diameter of 30mm, a wall thickness of 10mm, and a height of 205mm. The thin-walled tube 7 passes through the top annular flange plate 5, and the thin-walled tube 7 and the oxygen-free copper sleeve 8 are placed in the vacuum barrel 4. The other end of the copper braid 13 and the oxygen-free copper sleeve 8 are connected by bolts, and the thermal resistor 12 is sandwiched between the copper braid 13 and the oxygen-free copper sleeve 8 .

A thermostatic block 10 is disposed in the "well" groove of the oxygen-free copper sleeve 8, and a copper pressing block 9 is disposed above the thermostat block 10. The end of the thin-walled tube 7 close to the top annular flange plate 5 is provided with a foam plug 11. The foam plug 11 is used to isolate the air convection between the outside world and the well-shaped groove of the oxygen-free copper sleeve 8. A hole is drilled in the center of the top surface of the thermostatic block 10 for installing the heating device 14; four centrally symmetrical holes are drilled around the central hole, one of which is used to place the standard temperature sensor 15, and the remaining ones are used to place the calibration sensor. thermometer. The direction of the holes is along the length direction of the oxygen-free copper sleeve 8. The number and size of the holes can be increased or decreased according to actual needs, but each hole must be ensured to be centrally symmetrical.

In a specific embodiment, the thermostatic block 10 is a cylinder with a bottom surface diameter of 30mm and a height of 206mm, the copper pressure block 9 is a truncated cone with a top surface diameter of 40mm, a bottom surface diameter of 30mm and a height of 10mm, and the foam plug 11 is a cylindrical cylinder with a diameter of 40mm and a height of 20mm. Cylindrical, the thermal resistance sheet 12 is made up of five square sheets with a side length of 28 mm, and the total thickness is 1 mm; the diameter of the opening in the thermostatic block 10 is 6 mm.

The calibration device includes a temperature control thermometer 2 and a standard temperature sensor 15. The standard temperature sensor 15 is located in the hole of the thermostat block 10 and is connected to the temperature control thermometer 2 through a temperature sensor lead 16. The thermometer to be calibrated also passes through the temperature sensor. The lead 16 is connected to the temperature control thermometer 2, and the temperature control thermometer 2 displays and controls the standard temperature sensor 15 and the thermometer to be calibrated. Channels are reserved on the side of the copper pressing block 9 and the foam plug 11 so that the temperature sensor lead 16 can pass through.

This embodiment also includes a housing 1. Except for the temperature control thermometer 2, other components are placed inside the housing 1, making the temperature calibration device of this embodiment portable. The outer wall of the housing 1 is also provided with a heat dissipation channel 19 for heat dissipation of the Stirling refrigerator 3 . As shown in Figure 2, a control panel 20 and a fan switch 21 are provided on the front of the housing 1. The control panel 20 is used to control the internal components, and the fan switch 21 is used to control the start and stop of the fan in the cooling air duct 19; The back of the housing 1 is provided with a power switch 22, an aviation plug 23 and a USB interface 24. The power switch 22 is used to control the circuit on and off, and the aviation plug 23 and the USB interface 24 provide interfaces for power and data exchange. In this embodiment, the housing 1 is an aluminum alloy housing.

The working process of the portable dry body temperature calibration device based on a small Stirling refrigerator in this embodiment is as follows: First, insert a standard thermometer and several thermometers to be measured into the round hole on the top of the thermostatic block 10. As needed, the outside of the thermometer can be Apply thermal silicone grease; then place the copper crimp block 9 on the top of the thermostat block 10 as a lead heat sink, and plug the foam plug 11 on the top; after the system is assembled, use a tool to pull out the sealing core in the self-sealing exhaust nozzle 18 plug, use the molecular pump unit to pump the vacuum degree of the vacuum barrel 4 to 10 ^-3 Pa, push back the plug core, disconnect the vacuum pump system, and start the small Stirling refrigerator 3 and the fan in the cooling air duct 19; After the reading of the standard thermometer in the constant temperature block 10 displayed by the temperature control thermometer 2 drops below 90K, turn on the temperature control thermometer 2 and set the standard thermometer temperature to the predetermined value, and then enter the calibration phase; during the calibration process, The target temperature of the temperature control thermometer 2 needs to be adjusted frequently to make the thermometer indication stable at multiple temperatures; when the temperature fluctuations of the standard thermometer and the thermometer to be measured are both less than 0.05K within 30 minutes, it means that the calibration condition has been Stable, at this time, take the temperature reading of the standard thermometer and the resistance reading of the thermometer to be measured, and draw a graduation table.

This embodiment uses a small Stirling refrigerator as the cold source. Compared with other cold sources, the small Stirling refrigerator itself is small in size and light in weight. It does not need to add low-temperature liquid and can provide sufficient cooling in the liquid nitrogen temperature zone. quantity to meet the calibration requirements; the volume of the calibration device can reach 500*300*450mm, the mass can reach 25kg, and it is highly portable. This embodiment adopts the design of a vacuum heat insulation cavity, which is wrapped with multiple layers of heat insulation materials inside, and a copper crimping block is installed to eliminate heat leakage from the leads, so that the system can be cooled down to the liquid nitrogen temperature zone, and can be reheated to room temperature through the heating device, achieving Temperature adjustment from liquid nitrogen low temperature zone to room temperature with high calibration accuracy. This embodiment adopts a "well" design to isolate the thermometer and thermostat block outside the vacuum insulation cavity. The thermostat block can be taken out without damaging the vacuum system, which facilitates the installation of the calibrated thermometer and has strong operability; at the same time, heat conduction is utilized The effect absorbs the cold energy from the refrigerator to achieve the cooling effect.

The preferred embodiments of the present invention are described in detail above. It should be understood that those skilled in the art can make many modifications and changes based on the concept of the present invention without creative efforts. Therefore, any technical solutions that can be obtained by those skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention and on the basis of the existing technology should be within the scope of protection determined by the claims.

Claims (10)

1. A portable dry body temperature calibration device based on a small Stirling refrigerator, which is characterized by including: Vacuum device, which is used to provide a vacuum environment; A "well" type thermal conduction device is partially placed in the vacuum device and can accommodate a thermometer to be calibrated inside; A refrigeration device, which includes a Stirling refrigerator partially placed within the vacuum device, and the Stirling refrigerator delivers cold energy to the "well" heat transfer device; A calibration device, one part of which is placed in the "well" heat conduction device, and the other part is placed in the external environment, is used to calibrate the thermometer to be calibrated. 2. The portable dry body temperature calibration device based on a small Stirling refrigerator as claimed in claim 1, wherein the vacuum device includes a vacuum barrel, and one end of the vacuum barrel is provided with a top annular flange plate. , an air extraction nozzle is provided on the side wall of the vacuum barrel; the Stirling refrigerator passes through the side wall of the vacuum barrel, and the cold head of the Stirling refrigerator is placed in the vacuum barrel, The Stirling refrigerator is sealed with the side wall of the vacuum barrel. 3. The portable dry body temperature calibration device based on a small Stirling refrigerator as claimed in claim 2, wherein the "well" heat conduction device includes a thin-walled tube, a copper sleeve and a thermostatic block, and the copper One end of the sleeve is connected to one end of the thin-walled tube, the thin-walled tube passes through the top annular flange plate, the copper sleeve is placed in the vacuum barrel, and the thermostatic block is placed in the copper In the "well" of the sleeve, the thermometer to be calibrated is placed in the thermostatic block. 4. The portable dry body temperature calibration device based on a small Stirling refrigerator as claimed in claim 3, wherein the refrigeration device further includes a copper braid, one end of the copper braid is connected to the Stirling refrigeration device. The cold head of the machine is connected, and the other end of the copper braid is connected to the "well" type heat conduction device, and a thermal resistor is sandwiched between the copper braid and the copper sleeve. 5. The portable dry body temperature calibration device based on a small Stirling refrigerator according to claim 3, characterized in that a copper crimping block is provided in the groove of the copper sleeve, and the copper crimping block is located at The side close to the top annular flange plate. 6. The portable dry body temperature calibration device based on a small Stirling refrigerator according to claim 5, characterized in that a heating device is provided in the thermostatic block, and a foam plug is provided at the other end of the thin-walled tube. . 7. The portable dry body temperature calibration device based on a small Stirling refrigerator according to claim 5, characterized in that the calibration device includes a temperature control thermometer and a standard temperature sensor, and the standard temperature sensor is located on In the thermostatic block, the thermometer to be calibrated, the standard temperature sensor and the temperature control thermometer are electrically connected. 8. The portable dry body temperature calibration device based on a small Stirling refrigerator according to claim 7, characterized in that it also includes a shell, and the vacuum device, the "well" heat conduction device, and the refrigeration device are located in the Inside the housing, the temperature controller is located outside the housing. 9. The portable dry body temperature calibration device based on a small Stirling refrigerator according to claim 8, further comprising a cooling air duct, and the cooling air duct is provided on the side of the housing. 10. The portable dry body temperature calibration device based on a small Stirling refrigerator according to claim 8, wherein the housing is provided with a control panel, a fan switch, and a power switch.