Portable low-temperature dry furnace

Abstract

The invention relates to the technical field of temperature verification, in particular to a portable low-temperature dry furnace which comprises a furnace core, a multi-element mixed working medium refrigerating system acting on the furnace core and a control system for controlling the temperature of the furnace core. The multi-element mixed working medium refrigerating system comprises a compressor, a condenser, a gas-liquid separator, a heat regenerator, a first throttling element and an evaporator arranged around the furnace core, and the evaporator makes contact with the surface of the furnace core. Through the integrated design of the multi-element mixed working medium refrigerating system and the furnace core, the temperature of the furnace core can be reduced to-120 DEG C or below by utilizing the deep refrigerating effect of a mixed working medium in the throttling expansion and phase change process, and the low-temperature limit of-100 DEG C of an existing portable dry body furnace is broken through; and stable and continuous cooling capacity output is ensured through controllable output of the compressor and the multi-component phase change latent heat superposition characteristic of the mixed working medium, and the cooling speed is remarkably increased by combining the direct contact structure of the evaporator and the surface of the furnace core.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of temperature calibration, in particular to a portable low-temperature dry body furnace. BACKGROUND

[0002] Accurate temperature measurement is the basic guarantee of industrial production and scientific research. Since the resistance of the thermometer is related to the temperature, it needs to be calibrated regularly. In the commonly used calibration device, the constant temperature tank has high precision but is large in size and not portable, and is mainly suitable for laboratory; the dry body furnace uses solid block as heat conduction medium, and has fast temperature control and portability, and is widely used in industrial field. With the development of energy chemical industry, low-temperature refrigeration, biological medicine, food freezing and other fields, the demand for rapid and accurate on-site calibration of low-temperature thermometer is increasing day by day, and the minimum temperature of the existing portable low-temperature dry body furnace on the market is only to-100 DEG C (such as Fluke9190A, Ametek RTC-159, etc.), which is difficult to meet the on-site measurement demand below-100 DEG C.

[0003] The existing portable low-temperature dry body furnace at home and abroad all uses Stirling refrigeration machine as cold source, and has the problems of single cold output head section, which is not conducive to rapid cooling and high-precision temperature field construction, and the structure of Stirling refrigeration machine is complex and the maintenance cost is high. Therefore, developing a portable dry body furnace with wider low-temperature range, stable cold output and fast cooling speed has become a difficult problem to be solved in the technical field of temperature calibration. The present application aims at the above-mentioned problems, and proposes a new type of portable low-temperature dry body furnace based on a mixed working medium refrigeration system. SUMMARY

[0004] In view of the defects in the prior art, the present application provides a portable low-temperature dry body furnace, which aims to solve the problems in the prior art.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: a portable low-temperature dry body furnace, comprising: a furnace core, a multi-component mixed working medium refrigeration system acting on the furnace core, and a control system for controlling the temperature of the furnace core, wherein the multi-component mixed working medium refrigeration system comprises a compressor, a condenser, a gas-liquid separator, a regenerator, a first throttling element and an evaporator arranged around the furnace core, the evaporator is in contact with the surface of the furnace core, the outlet of the compressor is connected with the inlet of the condenser, the outlet of the condenser is connected with the inlet of the gas-liquid separator, the gas phase outlet of the gas-liquid separator is connected with the hot fluid inlet of the regenerator, the liquid phase outlet of the gas-liquid separator is connected with the inlet of the compressor, one end of the regenerator is connected with the hot fluid outlet of the regenerator, the other end of the first throttling element is connected with the inlet of the evaporator, the outlet of the evaporator is connected with the cold fluid inlet of the regenerator, and the cold fluid outlet of the regenerator is connected with the inlet of the compressor.

[0006] Further, a plurality of semicircular grooves are opened on the surface of the furnace core, and the groove surface is attached to the surface of the copper pipe of the evaporator.

[0007] Further, the furnace core is cylindrical, and the regenerator is coiled into a spiral shape, and the furnace core and the evaporator are arranged in the center of the spiral-shaped regenerator.

[0008] Further, the furnace core comprises a furnace core body, a heating rod arranged in the furnace core body, and a platinum resistance thermometer.

[0009] Further, a temperature equalizing block is further arranged in the furnace core body, the furnace core body is cylindrical, a plurality of cylindrical first deep wells are arranged at the top of the furnace core body, and the temperature equalizing block, the heating rod and the platinum resistance thermometer are arranged in the first deep wells.

[0010] Further, the temperature equalizing block is arranged in the first deep well at the center of the top of the furnace core body, a cylindrical second deep well is arranged at the top of the temperature equalizing block, and a temperature measuring thermometer is arranged in the second deep well.

[0011] Further, a second throttling element is further arranged, one end of the liquid phase outlet of the gas-liquid separator is connected with the second throttling element, and the other end of the second throttling element is connected with the inlet of the compressor.

[0012] Further, a heat preservation layer is further arranged, the heat preservation layer is made of a foaming agent, and the heat preservation layer is tightly coupled with the regenerator, the evaporator and the furnace core to form an integrated whole.

[0013] Further, the multi-component mixed working medium comprises methane, ethane, ethylene, propane, isobutane and isopentane.

[0014] The portable low-temperature dry body furnace has the advantages that: through the integrated design of the multi-component mixed working medium refrigeration system and the furnace core, the deep refrigeration effect of the mixed working medium in the throttling expansion and phase change process is utilized, so that the temperature of the furnace core can be reduced to below-120 DEG C, the low-temperature limit of-100 DEG C of the existing portable dry body furnace is broken through, and through the controllable output of the compressor and the superposition characteristics of the multi-component phase change latent heat of the mixed working medium, the stable and continuous cold output is ensured, and the direct contact structure of the evaporator and the surface of the furnace core is combined, so that the cooling speed is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic diagram of the portable low-temperature dry body furnace system of the embodiment of the present application;

[0016] Figure 2 is a schematic diagram of the mixed working medium refrigeration system of the embodiment of the present application;

[0017] Figure 3 is a schematic diagram of the furnace core structure of the embodiment of the present application;

[0018] Figure 4 is a schematic diagram of the temperature equalizing block structure of the embodiment of the present application.

[0019] Explanation of reference signs: 1, refrigeration system; 101, compressor; 102, condenser; 103, gas-liquid separator; 104, regenerator; 105, first throttling element; 106, evaporator; 107, second throttling element; 2, furnace core; 201, furnace core main body; 202, heating rod; 203, platinum resistance thermometer; 204, first deep well; 3, temperature equalizing block; 301, second deep well; 302, temperature measuring thermometer; 4, heat insulation layer; 5, control system. DETAILED DESCRIPTION

[0020] The typical embodiments embodying the features and advantages of the present application will now be described in detail. It should be understood that the application can be carried out in various ways and that the description and drawings should be regarded as illustrative in nature and not as restrictive.

[0021] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only used for description purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0022] In order to further illustrate the principles and structures of the present application, the preferred embodiments of the present application will be described in detail in conjunction with the drawings.

[0023] As Figures 1-4As shown, the embodiment of the present application provides a portable low-temperature dry body furnace, mainly composed of a furnace core 2, a multi-component mixed working medium refrigeration system 1 and a control system 5. Among them, the multi-component mixed working medium refrigeration system 1 includes a compressor 101, a condenser 102, a gas-liquid separator 103, a regenerator 104, a first throttling element 105, a second throttling element 107 and an evaporator 106 arranged around the furnace core 2. The specific connection relationship is: the outlet of the compressor 101 is connected with the inlet of the condenser 102, the outlet of the condenser 102 is connected with the inlet of the gas-liquid separator 103, the gas phase outlet of the gas-liquid separator 103 is communicated with the hot fluid inlet of the regenerator 104, the liquid phase outlet of the gas-liquid separator 103 is connected with one end of the second throttling element 107, and the other end of the second throttling element 107 is connected with the inlet of the compressor 101; the hot fluid outlet of the regenerator 104 is connected with one end of the first throttling element 105, and the other end is connected with the inlet of the evaporator 106, and the outlet of the evaporator 106 is connected with the cold fluid inlet of the regenerator 104 and the inlet of the compressor 101 in turn, forming a circulating loop. The control system 5 adjusts the parameters of the refrigeration system 1 and the power of the heating rod 202 of the furnace core 2 to realize precise control of the temperature of the furnace core 2.

[0024] Further, the above-mentioned furnace core 2 includes a furnace core body 201, and a heating rod 202 and a platinum resistance thermometer 203 arranged in the furnace core body 201. Among them, the furnace core body 201 serves as a basic structure to provide a mounting carrier for the heating rod 202 and the platinum resistance thermometer 203: the heating rod 202 is used for heating the furnace core body 201 by converting electrical energy into heat energy to realize the increase of the temperature of the furnace core 2; the platinum resistance thermometer 203 utilizes the characteristic that the resistance value of platinum resistance changes with temperature to monitor the temperature of the furnace core body 201 in real time, and provides a temperature feedback signal for the control system 5 to precisely adjust the temperature of the furnace core 2.

[0025] Further, the furnace core body 201 is cylindrical, a plurality of cylindrical first deep wells 204 are formed at the top of the furnace core body 201, a uniform temperature block 3 is further arranged in the furnace core body 201, and the uniform temperature block 3, the heating rod 202 and the platinum resistance thermometer 203 are all mounted in the first deep wells 204. Specifically, the first deep wells 204 at the top of the cylindrical furnace core body 201 are designed in size and position according to the functional requirements of each component: the uniform temperature block 3 is used to uniformly distribute the temperature of the furnace core 2 to ensure the consistency of the temperature field; the heating rod 202 and the platinum resistance thermometer 203 are respectively mounted through the corresponding first deep wells 204, so that the functions of heating and temperature measurement are integrated in the interior of the furnace core body 201, forming a compact structure layout, which is convenient for the control system 5 to real-time regulate and balance the temperature of the furnace core 2.

[0026] Further, the furnace core 2 is provided with a plurality of semicircular grooves on the surface, and the groove surface is closely attached to the surface of the copper pipe of the evaporator 106. The design forms a surface contact between the curved surface structure of the groove and the outer wall of the copper pipe, maximizes the heat exchange area between the evaporator 106 and the furnace core 2, and reduces the contact thermal resistance. When the low-temperature working medium in the evaporator 106 evaporates, the cold energy is quickly transferred to the furnace core 2 through the attached groove surface, ensuring that the temperature of the furnace core 2 uniformly decreases.

[0027] Further, the furnace core 2 is cylindrical, and the regenerator 104 is coiled into a spiral shape, and the furnace core 2 and the evaporator 106 are located at the center of the spiral regenerator 104. The annular structure of the spiral regenerator 104 increases the heat exchange area, and also forms a radial temperature gradient between the furnace core 2 and the evaporator 106 at the center when the gas-phase working medium flows in the regenerator 104, reducing the loss of cold energy. At the same time, the furnace core 2 and the evaporator 106 are located at the center of the regenerator 104, which can maintain their own temperature in the low-temperature environment of the pre-cooled regenerator 104.

[0028] The above-mentioned mixed working medium contains methane, ethane, ethylene, propane, isobutane and isopentane, and the mass percentage ranges of each component are: methane 10% to 50%, ethylene 0% to 50%, ethane 5% to 40%, propane 10% to 50%, isobutane 10% to 50%, and isopentane 0% to 20%; and the multi-component mixed working medium contains at least four of the above-mentioned six components. The operating personnel can adjust the above-mentioned component allocation according to the actual situation. The allocation design realizes deep refrigeration and stable cold energy output through the synergistic effect of low-boiling-point components (such as methane and ethylene) and medium-high-boiling-point components (such as propane and isobutane): methane (boiling point -161.5°C) and ethylene (boiling point -103.7°C) are responsible for throttling expansion and phase change heat absorption in the low-temperature section below -100°C, ensuring that the furnace core temperature can be reduced to below -120°C; medium-high-boiling-point components such as propane (boiling point -42.1°C) and isobutane (boiling point -11.7°C) provide auxiliary refrigeration in the medium-temperature section, and through the superposition of multi-component phase change latent heat, the cold energy fluctuation of a single working medium in a wide temperature range (-120°C to 80°C) is avoided.

[0029] In operation, the mixed working medium is compressed into high-temperature and high-pressure gas by the compressor 101, and the high-boiling-point component is liquefied first, and the high-temperature and high-pressure gas enters the condenser 102, which can be air-cooled or water-cooled to dissipate heat, and part of the working medium is condensed into liquid mixed working medium after releasing heat, forming a gas-liquid mixed working medium, and the condensed working medium enters the gas-liquid separator 103, and the liquid phase part is returned to the inlet of the compressor 101 after being decompressed by the second throttling element 107; the gas phase part enters the regenerator 104, and the gas phase working medium is pre-cooled to -80℃ to -100℃ in the spiral regenerator 104 by heat exchange with the low-temperature gas at the outlet of the evaporator 106, and the low-temperature gas is preheated to reduce the loss of cold energy, and the pre-cooled gas phase working medium passes through the first throttling element 105, the mixed working medium is expanded and absorbs heat, the temperature is reduced to below -120℃, and the low-temperature wet steam enters the evaporator 106 surrounding the furnace core 2, the copper pipe is attached to the semicircular groove on the surface of the furnace core 2, the working medium is vaporized at low pressure, absorbs the heat of the furnace core 2, and the temperature of the furnace core 2 is reduced to below -100℃, and the vaporized low-temperature gas enters the cold fluid channel of the regenerator 104 and returns to the compressor 101 after heat exchange, completing the refrigeration cycle.

[0030] The present application solves the problem that the prior art cannot meet the lower temperature calibration requirement by integrating the multi-component mixed working medium refrigeration system 1 and the furnace core 2, the low-boiling-point components such as methane in the mixed working medium are expanded and phase-change heat-absorbed by throttling, so that the temperature of the furnace core 2 can be reduced to below -120℃, and the synergistic refrigeration of components such as ethane and propane in the medium-high temperature section is realized to cover a wide temperature range of -120℃ to 80℃; in view of the defects of single cold energy output and slow cooling of the existing Stirling refrigerators, the close attachment design of the furnace core 2 and the evaporator 106 improves the heat exchange efficiency and the cooling speed, and the phase-change latent heat of the mixed working medium ensures stable cold energy output.

[0031] Further, the uniform temperature block 3 is located in the first deep well 204 at the top center of the furnace core main body 201, and a cylindrical second deep well 301 is formed at the top of the uniform temperature block 3, which is used to install the temperature measuring thermometer 302. The central position of the uniform temperature block 3 can fully absorb the heat of the furnace core main body 201 and conduct uniformly, and the second deep well 301 at the top provides installation space for the temperature measuring thermometer 302: when the temperature measuring thermometer 302 is inserted into the second deep well 301, it can directly contact the uniform temperature block 3, ensuring that the temperature measured by the temperature measuring thermometer 302 is consistent with the temperature of the furnace core main body 201, avoiding temperature deviation caused by installation position, thereby ensuring the accuracy and reliability in the process of thermometer calibration.

[0032] Furthermore, the portable low-temperature dry block furnace of the present invention also includes a heat insulation layer 4, which is made of a foaming agent and is tightly coupled to the regenerator 104, the evaporator 106, and the furnace core 2. The heat insulation layer 4 uses a foaming agent material, and its internal porous structure forms good heat insulation performance, effectively blocking the transfer of external heat to the furnace core 2; at the same time, the tight coupling design of the heat insulation layer 4 with the regenerator 104, the evaporator 106, and the furnace core 2 ensures that the three form an integrated heat insulation system, reducing the loss of cold energy during the refrigeration process.

[0033] The portability of this invention is achieved through the following structural design: a foaming agent insulation layer is used to tightly couple the spiral regenerator 104, evaporator 106 and furnace core 2 into a single module, eliminating the redundancy of the traditional split structure; the regenerator 104 is coiled into a spiral shape and the furnace core 12 and evaporator 106 are wrapped in the center to form a centripetal layout, thereby achieving radial space compression, thus achieving overall compactness and portability of the equipment.

[0034] Furthermore, the aforementioned control system 5 includes a control program, a PLC module, a display screen, a power regulator, a temperature measurement module, and a fuse. The control program, as the core logic of the system, coordinates the operation of each module through a preset algorithm. The PLC module receives the temperature signal from the platinum resistance thermometer 203, processes it, and outputs control commands to the power regulator to adjust the power of the heating rod 202 and the parameters of the refrigeration system 1. The display screen shows the temperature and operating status of the furnace core 2 in real time for user convenience. The power regulator adjusts the input voltage according to the PLC commands to control the heating power of the heating rod 202 and the operating status of the compressor 101. The temperature measurement module collects the temperature data of the furnace core 2 in real time and transmits it to the PLC module, forming a closed-loop control. The fuse automatically blows in case of circuit overload, protecting the electrical safety of the control system 5 and the refrigeration system 1 and ensuring stable equipment operation.

[0035] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A portable low-temperature dry body furnace, characterized in that, include: A furnace core, a multi-component mixed refrigerant refrigeration system acting on the furnace core, and a control system for controlling the furnace core temperature; wherein, the multi-component mixed refrigerant refrigeration system includes a compressor, a condenser, a gas-liquid separator, a regenerator, a first throttling element, and an evaporator arranged around the furnace core. The evaporator is in contact with the furnace core surface. The compressor outlet is connected to the condenser inlet, the condenser outlet is connected to the gas-liquid separator inlet, the gas phase outlet of the gas-liquid separator is connected to the hot fluid inlet of the regenerator, the liquid phase outlet of the gas-liquid separator is connected to the compressor inlet, the hot fluid outlet of the regenerator is connected to one end of the first throttling element, the other end of the first throttling element is connected to the evaporator inlet, the evaporator outlet is connected to the cold fluid inlet of the regenerator, and the cold fluid outlet of the regenerator is connected to the compressor inlet; The multi-component working fluid includes methane, ethane, ethylene, propane, isobutane, and isopentane.

2. The portable low-temperature dry body furnace according to claim 1, characterized in that, It also includes multiple semi-circular grooves on the surface of the furnace core, with the groove surfaces fitting against the surface of the copper tubes of the evaporator.

3. The portable low-temperature dry body furnace according to claim 2, characterized in that, The furnace core is cylindrical, and the regenerator is coiled into a spiral shape. The furnace core and evaporator are placed at the center of the spiral regenerator.

4. The portable low-temperature dry body furnace according to claim 2, characterized in that, The furnace core includes a furnace core body, heating rods and a platinum resistance thermometer disposed inside the furnace core body.

5. The portable low-temperature dry block furnace according to claim 3, characterized in that, It also includes a temperature equalization block set inside the furnace core body. The furnace core body is cylindrical, and multiple cylindrical first deep wells are opened at the top of the furnace core body. The temperature equalization block, heating rod and platinum resistance thermometer are all installed in the first deep wells.

6. The portable low-temperature dry body furnace according to claim 4, characterized in that, The temperature equalization block is located in the first deep well at the top center of the furnace core body. A cylindrical second deep well is opened on the top of the temperature equalization block, which is used to install the thermometer to be measured.

7. The portable low-temperature dry-body furnace according to claim 1, characterized in that, It also includes a second throttling element, with the liquid phase outlet of the gas-liquid separator connected to one end of the second throttling element and the other end of the second throttling element connected to the compressor inlet.

8. The portable low-temperature dry block furnace according to claim 1, characterized in that, It also includes an insulation layer, which is made of foaming agent and is tightly coupled with the regenerator, evaporator and furnace core.

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