A cold-chain medical heat preservation box with continuous and accurate temperature control, a thermoelectric material, a vacuum heat insulation plate material and a preparation method thereof

Abstract

The application discloses a cold-chain medical heat preservation box with continuous and accurate temperature control, a thermoelectric material, a vacuum heat insulation plate material and a preparation method thereof. The cold-chain medical heat preservation box comprises an outer box heat preservation layer, an ice block, an inner box heat preservation layer, a semiconductor thermoelectric element installed on the inner box heat preservation layer, a power supply, a temperature sensor, a control panel and a temperature control switch. The hot end and the cold end of the semiconductor thermoelectric element are respectively connected with a heat dissipation fin and a cold lead. The temperature sensor is arranged on the inner side of the inner box heat preservation layer to detect the temperature of the inner box in real time. The lithium battery, the control panel and the temperature control switch are arranged on the outer box heat preservation layer. The semiconductor thermoelectric element and the phase change material are combined, the power required by the thermoelectric cooling can be reduced by providing a lower ambient temperature for the hot end of the semiconductor thermoelectric element, the refrigeration efficiency is improved, and the power consumption is reduced. The temperature of the inner box can be changed by the thermoelectric element, and the purpose of one box with multiple uses is achieved.

Description

Technical Field

[0001] This invention relates to the field of medical insulation box technology, and in particular to a cold chain medical insulation box with continuous and precise temperature control, as well as thermoelectric materials and vacuum insulation plate materials and their preparation methods. Background Technology

[0002] The pharmaceutical industry has always been a vital sector related to people's livelihoods, especially with the global spread of COVID-19, which has led to a surge in demand for the refrigerated storage and transportation of vaccines and medicines. Medicines and vaccines have strict temperature requirements during transportation; currently, the most commonly used temperature ranges on the market are -20℃, 2-8℃, 0-5℃, and 15-20℃. Currently, passive cold chain pharmaceutical insulated boxes generally use phase change materials to fill the insulation layer. However, limited by the phase change temperature point of these materials, using the same type of ice pack can only achieve one ideal insulation temperature range. To achieve an insulated box that can use different temperature ranges according to different needs, a phase change cold storage dual-temperature zone insulated box, as proposed in Chinese patent CN210527362U, can be used. While this allows for two temperature zones simultaneously, it reduces the actual usable volume of each individual insulation zone. Chinese patent CN211876475U mentions using a combination of thermoelectric elements and phase change refrigeration to extend the refrigeration and heat preservation time. However, the efficiency of a single thermoelectric element in the design is very low, the cooling capacity is limited, and the temperature inside the heat preservation box cannot be accurately controlled.

[0003] The application of thermoelectric devices is currently limited by the insufficient conversion efficiency of thermoelectric materials. The conversion efficiency of thermoelectric materials is usually measured by the dimensionless figure of merit zT, zT = S^2σT / κ, where S is the Seebeck coefficient (V / K), σ is the electrical conductivity (S / cm), T is the absolute temperature (K), and κ is the thermal conductivity (W / mK). Therefore, to achieve a higher zT, materials typically need to possess a high Seebeck coefficient, high electrical conductivity, and low thermal conductivity. However, this is limited by the influence of the carrier concentration n.

[0004] σ = n eμ;

[0005] κ=κl+κe;

[0006] Ke = n eμL0 T;

[0007] The thermal conductivity of a material consists of two parts: lattice thermal conductivity κl and κe electronic thermal conductivity.

[0008] Where μ is the carrier mobility, e is the electron charge, L0 is the Lorentz number, and T is the absolute temperature.

[0009] This shows that when n increases, both σ and κe increase; conversely, when n decreases, both σ and κe decrease. Due to the inherent influencing factors among the variables, it is difficult to optimize each variable simultaneously, increasing the difficulty of optimizing the zT value. However, the lattice thermal conductivity κl is relatively independent; its value is unrelated to the carrier concentration n and is mainly related to the material's crystal structure. More complex crystal structures increase phonon scattering, which can effectively reduce the lattice thermal conductivity. This invention provides an effective way to optimize the zT value of thermoelectric materials by introducing incommensurable structures to reduce the lattice thermal conductivity.

[0010] In classical crystallography, atomic arrangements are considered complete and periodically repeating. However, subsequent observations have revealed materials with non-periodic repeating atomic arrangements, such as incommensurable structural materials and quasicrystals. Incommensurable structural materials are further categorized into incommensurable modulated structures and incommensurable composite structures. The structural complexity of incommensurable structures can effectively increase the phonon scattering effect within the material, reduce the lattice thermal conductivity, thereby increasing the zT value of the material and improving the thermoelectric conversion efficiency of devices. Summary of the Invention

[0011] To address the problems existing in the prior art, this invention provides a cold chain medical insulated box with continuous and precise temperature control, as well as thermoelectric materials, vacuum insulation board materials, and their preparation methods.

[0012] To achieve the above objectives:

[0013] First, the present invention provides a cold chain medical insulated box with continuous and precise temperature control, comprising: an outer box insulation layer, an ice pack, an inner box insulation layer, and a semiconductor thermoelectric element, a power supply, a temperature sensor, a control panel, and a temperature control switch installed on the inner box insulation layer. The hot end and cold end of the semiconductor thermoelectric element are respectively connected to a heat sink and a cold conductive plate. The temperature sensor is placed inside the inner box insulation layer to detect the inner box temperature in real time. The lithium battery, control panel, and temperature control switch are all located on the outer box insulation layer.

[0014] Preferably, the control panel is equipped with a microcontroller, and the corresponding terminals of the microcontroller are electrically connected to the corresponding terminals of the power supply, temperature sensor, and temperature control switch; the corresponding terminal of the semiconductor thermoelectric element is also electrically connected to the corresponding terminal of the temperature control switch.

[0015] Preferably, both the outer casing insulation layer and the inner casing insulation layer are equipped with vacuum insulation panels.

[0016] This invention also provides a thermoelectric material for a semiconductor thermoelectric device, which employs a nano-layered non-commensurate structure (Bi2Te3). m (X) n Thermoelectric material, wherein X is selected from any one of Bi, Sb, Sb2Te3, SbO2, and BiO2, and m / n is an irrational number.

[0017] This invention also provides a method for preparing thermoelectric materials for semiconductor thermoelectric devices, comprising the following steps:

[0018] Step 1: In a vacuum glove box, take bismuth, tellurium, and the required element X according to the stoichiometric ratio.

[0019] Step 2: Vacuum melt at 700-900℃, then quickly quench (not limited to ice water, dry ice, or liquid nitrogen and other low temperature media) and quickly solidify to form a block;

[0020] Step 3: Then anneal the block at 200-400℃ for 2-10 hours;

[0021] Step 4: Further reduce the particle size through grinding;

[0022] Step 5: Finally, sheet-like samples are obtained through hot pressing sintering and extrusion hot deformation.

[0023] The present invention also provides a vacuum insulation panel material, the material comprising by weight percentage: 50%-60% atmospheric silica, 5%-10% glass fiber, 10%-20% opacifier, and 15%-30% micro / nano cellulose crystals.

[0024] Preferably, the emulsifier is selected from one or more of silicon carbide, titanium dioxide, carbon black, and coal ash.

[0025] Preferably, the extraction method of the micro / nano cellulose crystals includes the following steps:

[0026] Step 1: Select suitable plant fiber, which includes 60-70% cellulose and 0.5%-10% lignin;

[0027] Step 2: After crushing the plant fiber with a content of 3%-6%, treat it with 1%-5% NaOH solution and transfer it to a high-pressure reactor of 10-20 psi. React for 30-60 minutes and then release the pressure quickly.

[0028] Step 3: The obtained reaction mixture is subjected to ultrasonic treatment to further decompose cellulose;

[0029] Step 4: Then apply mechanical stirring at 3000-5000 rpm for several hours, then wash and dry the extracted cellulose;

[0030] Step 5: Add 8%-20% sodium hypochlorite solution to an alkaline medium to bleach the prepared nanocellulose crystals to remove residual lignin;

[0031] Step 6: After bleaching, add 2%-5% NaOH solution for continuous washing until pH=5-9, then ball mill to further reduce the nanoscale size of cellulose.

[0032] Preferably, the length of the plant fiber pulverized in step two is less than 0.5 cm; and in step six, the nanoscale size of cellulose is further reduced to 100 nm-10 μm.

[0033] The present invention also provides a method for preparing a vacuum insulation panel material, comprising the following steps: mixing atmospheric silica, glass fiber, opacifier, and micro / nano cellulose crystals and filling them into a mold, then compacting them using a hydraulic press and heating them in a furnace to 50°C-150°C.

[0034] The technical solution of this invention has the following beneficial effects: The combination of semiconductor thermoelectric elements and phase change materials in this invention can reduce the power required for thermoelectric cooling by providing a lower ambient temperature to the hot end of the semiconductor thermoelectric element, thereby improving cooling efficiency and reducing power consumption; the temperature of the inner box can be changed by the thermoelectric element, achieving the purpose of multiple uses for one box, and the traditional 2-8℃ range can be extended to -20℃ to 20℃; when the required temperature is still 2-8℃, the thermoelectric element can extend the heat preservation time of the insulated box by assisting in cooling, thereby achieving a longer transportation range.

[0035] The present invention provides a thermoelectric material with a non-commensurable structure, which can significantly reduce the lattice thermal conductivity of bismuth telluride materials. Without reducing the electrical conductivity and Seebeck coefficient, the thermal conductivity of the material is reduced, further improving the thermoelectric figure of merit zT and achieving macroscopic performance improvement of the thermoelectric material.

[0036] This invention utilizes cellulose, a natural polymer, to develop a vacuum insulation panel, which can effectively reduce the thermal conductivity of the insulation layer, improve the overall insulation performance of the insulation box, is more environmentally friendly, and can also reduce the price of the vacuum insulation panel. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of the present invention;

[0038] Figure 2 This is a schematic diagram of the installation of the semiconductor thermoelectric element of the present invention;

[0039] Figure 3 This is an electrical connection diagram of the thermoelectric material of the present invention. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0041] Reference Figures 1 to 3The present invention provides a cold chain medical insulated box with continuous and precise temperature control, comprising: an outer box insulation layer 1, an ice pack 2, an inner box insulation layer 3, and a semiconductor thermoelectric element 4, a power supply 7, a temperature sensor 8, a control panel 9, and a temperature control switch 10 installed on the inner box insulation layer. The hot end and cold end of the semiconductor thermoelectric element 4 are respectively connected to a heat sink 6 and a cold conductive sheet 5.

[0042] The temperature sensor 8 is placed inside the inner insulation layer 3 of the inner box and is used to detect the temperature of the inner box in real time. The power supply 7, control panel 9, and temperature control switch 10 are all located on the outer insulation layer 1.

[0043] The control panel 9 is equipped with a microcontroller, whose corresponding terminals are electrically connected to the power supply 7, temperature sensor 8, and temperature control switch 10, respectively. The corresponding terminal of the thermoelectric semiconductor device 4 is also electrically connected to the corresponding terminal of the temperature control switch 10. The power supply 7 is a lithium battery. The thermoelectric semiconductor device 4 includes a thermoelectric temperature control device. When the temperature set on the control panel 9 does not match the inner chamber temperature detected by the temperature sensor 8, the temperature control switch 10 is activated, and the thermoelectric temperature control device starts working. When the set temperature is reached, the thermoelectric temperature control device stops working. The cooling fins 5 and fins 6 are mainly used to increase the heat dissipation or cooling area, improve the temperature uniformity inside the inner chamber and the ice pack chamber, and effectively transfer the heat of the thermoelectric semiconductor device 4 to the ice pack 2, reduce the hot end temperature of the thermoelectric semiconductor device 4, improve the working efficiency and cooling efficiency of the thermoelectric device 4, and reduce power consumption. The lithium battery provides DC power to the thermoelectric semiconductor temperature control device. The temperature sensor 8 is mainly used to detect the real-time temperature of the inner chamber. The control panel 9 is mainly used to set the temperature and display the real-time temperature inside the chamber.

[0044] Both the outer casing insulation layer 1 and the inner casing insulation layer are equipped with vacuum insulation panels. The outer casing insulation layer 1 is mainly used to insulate the external ambient temperature and ensure the low temperature environment of the ice pack 2 and the inner casing. The ice pack 2 is filled with phase change material to provide a basic low temperature for the inner casing. The inner casing insulation layer 3 is mainly used to insulate the temperature of the ice pack chamber and ensure that the inner casing can reach a lower or higher temperature.

[0045] The semiconductor thermoelectric element 4 is mainly used to lower or raise the temperature of the inner box. The heat absorbed by it in the inner box will be dissipated in the ice pack chamber, so that the inner box reaches a lower temperature than the ice pack chamber; or it can absorb heat in the ice pack chamber as needed and dissipate the heat in the inner box to raise the temperature and extend the use time of the ice pack.

[0046] In this scheme, the semiconductor thermoelectric device 4 is composed of three-stage tower-shaped thermoelectric devices. Each stage of the tower-shaped thermoelectric device has a hot end and a cold end. The three-stage tower-shaped thermoelectric device includes a first-stage thermoelectric device 4a, a second-stage thermoelectric device 4b, and a third-stage thermoelectric device 4c. The hot end of the third-stage thermoelectric device 4c dissipates heat to the cold end of the second-stage thermoelectric device 4b, and the hot end of the second-stage thermoelectric device 4b dissipates heat to the cold end of the first-stage thermoelectric device 4a. The heat from the hot end of the third-stage thermoelectric device 4c is directly discharged to the ice pack, which is filled with phase change material (PCM). The tower-shaped semiconductor thermoelectric device can reduce the temperature to a lower level, reaching -70°C.

[0047] The cooling pad 5 is located on the upper side of the inner insulation layer 3, and the heat sink 6 is located in the ice pack chamber. When the insulation box needs to be below the temperature of the phase change material, the semiconductor thermoelectric element 4 can be activated to cool and reach the required temperature. When the current direction is changed, the hot and cold ends of the semiconductor thermoelectric element 4 are interchanged, that is, the section inside the box is the hot end, and the section in the ice pack chamber is the cold end. Thus, when the insulation box needs to be above the temperature of the phase change material, the semiconductor thermoelectric element 4 can be activated to heat and reach the required temperature. In this way, the insulation box can use the same phase change material to achieve a wider temperature range and achieve precise temperature control, solving the technical problem of not being able to use one box for multiple purposes in the market. Furthermore, through the design of this patent, using a specific phase change material, the traditional method of using air cooling to dissipate heat from the hot end of the semiconductor thermoelectric element can be replaced, improving heat dissipation efficiency and thus improving the cooling efficiency of the semiconductor thermoelectric element. This can significantly reduce the battery capacity required for the box, and reduce the weight and transportation cost of the passive medical cold chain box.

[0048] The present invention also provides a thermoelectric material for a semiconductor thermoelectric device, which employs a nano-layered non-commensurate structure (Bi2Te3). m (X) n Thermoelectric material, wherein X is selected from any one of Bi, Sb, Sb2Te3, SbO2, and BiO2; m / n is an irrational number.

[0049] This invention also provides a method for preparing thermoelectric materials for semiconductor thermoelectric devices, comprising the following steps:

[0050] Step 1: In a vacuum glove box, take bismuth, tellurium, and the required element X according to the stoichiometric ratio.

[0051] Step 2: Vacuum melt at 700-900℃, then quickly quench (not limited to ice water, dry ice, or liquid nitrogen and other low temperature media) and quickly solidify to form a block;

[0052] Step 3: Then anneal the block at 200-400℃ for 2-10 hours;

[0053] Step 4: Further reduce the particle size to 100nm-100μm by grinding. This step is not limited to dry or wet grinding.

[0054] Step 5: Finally, sheet-like samples are obtained through hot pressing sintering and extrusion hot deformation.

[0055] The thermoelectric material with incommensurable structure grown by this step can significantly reduce the lattice thermal conductivity of bismuth telluride material. Without reducing the electrical conductivity and Seebeck coefficient, the thermal conductivity of the material is reduced, further improving the thermoelectric figure of merit zT and achieving macroscopic performance improvement of the thermoelectric material.

[0056] The present invention also provides a vacuum insulation panel material, the material comprising by weight percentage: 50%-60% atmospheric silica, 5%-10% glass fiber, 10%-20% opacifier, and 15%-30% micro / nano cellulose crystals.

[0057] The emulsifier is selected from one or more of silicon carbide, titanium dioxide, carbon black, and coal ash.

[0058] The extraction method for the micro / nano cellulose crystals includes the following steps:

[0059] Step 1: Select suitable plant fiber, which includes 60%-70% cellulose and 0.5%-10% lignin;

[0060] Step 2: After crushing the plant fiber with a content of 3%-6%, treat it with 1%-5% NaOH solution and transfer it to a high-pressure reactor with a pressure of 10psi-20psi. React for 30min-60min and then release the pressure quickly.

[0061] Step 3: The obtained reaction mixture is subjected to ultrasonic treatment to further break down the cellulose into smaller fragments;

[0062] Step 4: Then apply mechanical stirring at 3000-5000 rpm for several hours, then wash and dry the extracted cellulose;

[0063] Step 5: Add 8%-20% sodium hypochlorite solution to an alkaline medium to bleach the prepared nanocellulose crystals to remove residual lignin;

[0064] Step 6: After bleaching, add 2%-5% NaOH solution for continuous washing until pH=5-9, then ball mill to further reduce the nanoscale size of cellulose.

[0065] The length of the plant fiber shredded in step two is less than 0.5 cm.

[0066] In step six, the nanoscale size of cellulose is further reduced to 100 nm-10 μm.

[0067] The present invention also provides a method for preparing a vacuum insulation panel material, comprising the following steps: mixing atmospheric silica, glass fiber, opacifier, and micro / nano cellulose crystals and filling them into a mold, then compacting them using a hydraulic press and heating them in a furnace to 50-150°C.

[0068] The thermoelectric material of the semiconductor thermoelectric element in the medical insulated box of the present invention preferably adopts the thermoelectric material of the semiconductor thermoelectric element described above; the vacuum insulation plate in the medical insulated box of the present invention preferably adopts the vacuum insulation plate material described above.

[0069] Thermal Insulation Material - Vacuum Insulation Panel: Cellulose is a natural and abundant renewable material, and wood fiber waste is rich in cellulose, xylose, and hemicellulose. This invention utilizes cellulose, a natural polymer, to develop a vacuum insulation panel, which can effectively reduce the thermal conductivity of the insulation layer and improve the overall thermal insulation performance of the insulated box.

[0070] Vacuum insulation panels are vacuum porous composite materials covered with multiple layers of film to achieve heat insulation. Currently, fumed silica is widely used as its core material. However, fumed silica is expensive, thus increasing the price of vacuum insulation panels. Cellulose is an abundant and renewable natural material. Using it in the development of super insulation materials for vacuum insulation panels is not only more environmentally friendly and allows for waste recycling, but it can also reduce the price of vacuum insulation panels.

[0071] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A thermoelectric material for a semiconductor thermoelectric element, characterized in that, This thermoelectric material employs a nanoscale misaligned non-commensurate structure (Bi2Te3). m (X) n Thermoelectric material, wherein X is selected from any one of Bi, Sb, Sb2Te3, SbO2, and BiO2, and m / n is an irrational number; The method for preparing the thermoelectric material of the semiconductor thermoelectric device is characterized by comprising the following steps: Step 1: In a vacuum glove box, take bismuth, tellurium, and the required element X according to the stoichiometric ratio. Step 2: Vacuum melt at 700-900℃, then quickly quench and solidify to form a block; Step 3: Then anneal the block at 200-400℃ for 2-10 hours; Step 4: Further reduce the particle size through grinding; Step 5: Finally, sheet-like samples are obtained through hot pressing sintering and extrusion hot deformation.

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