Low-melting-point alloy electric heating tube type constant-temperature heating plate for laminating machine

Abstract

A low-melting-point alloy electric heating tube type constant-temperature heating plate for a laminating machine is characterized in that a plurality of low-melting-point alloy electric heating tubes are connected in series, in parallel or in series and in parallel in a composite manner, and the heating tubes are tightly connected and densely arranged to form the constant-temperature heating plate which is large in area and high in heating power and is used for directly contacting and heating a solar component in the laminating machine; the mode of heating a solar cell module by the heating tube type constant-temperature heating plate using the low-melting-point alloy as the resistance heating body for the laminating machine is a composite mode of a direct contact heat conduction mode and an infrared radiation heating mode. The infrared radiation heating mode comprises infrared radiation heating of the tube wall of the composite material insulator tube mixed with high infrared radiation composite oxide powder on the solar cell module and infrared radiation heating of high infrared radiation composite oxide particles in the low-melting-point alloy-based composite material on the solar cell module; the infrared absorption coefficient of the EVA film is high, and infrared radiation directly heats the EVA film through the glass, so that the heating efficiency of the EVA film is improved.

Description

Technical Field

[0001] A low-melting-point alloy electric heating tube constant-temperature heating plate for laminators relates to the field of photovoltaic solar module packaging equipment technology. Background Technology

[0002] A laminator is a device used for encapsulating solar cell modules. The core process in solar module encapsulation is the uniform heating and melting of the EVA film. A solar module consists of five layers: two outer layers of high-transmittance glass, a central layer of solar cell silicon wafers, and an EVA film bonding between the silicon wafers and the glass. Under vacuum conditions, the EVA film is heated and melted, bonding the solar module together and sealing the silicon wafers between the two glass layers. In the laminator, the solar module lies flat against the laminator's worktable. A 0.3mm~0.5mm thick Teflon high-temperature resistant film acts as a mechanical buffer between the laminator worktable and the solar module. A 30mm~50mm thick steel plate at the bottom of the laminator worktable is heated to a certain temperature, and heat is transferred layer by layer through contact heat conduction. The process of heating the entire solar module to melt the EVA film for encapsulation is complex. Because the steel plate is thick and has a large heat capacity, heating it to the required temperature for the solar module requires high energy and takes a long time. The slow response speed of temperature control hinders precise temperature control. Teflon has a thermal conductivity of approximately 20 W / mK, glass has a thermal conductivity of 0.76 W / mK and a specific heat capacity of 0.966 kJ / kg·K, silicon wafers have a thermal conductivity of 150-200 W / mK, and EVA film has a thermal conductivity of 0.2-0.4 W / mK. Glass accounts for over 90% of the weight of a solar module, while EVA film accounts for less than 2%. Therefore, the energy consumption for heating and encapsulation of solar modules is mainly concentrated in heating the glass, rather than in melting the core of the encapsulation process—the EVA film. This results in high energy consumption and low encapsulation efficiency.

[0003] This invention discloses a heating tube with an insulated tube sheathed and a low-melting-point alloy as the resistive heating element, which effectively avoids the drawbacks of general low-temperature heating tubes. The low-melting-point alloy is inserted into an insulated tube of a certain length and diameter, giving the alloy a specific resistance value. Metal electrodes are inserted into both ends of the insulated tube to contact the low-melting-point alloy. The insulated tube is sealed with one end of the metal electrode in contact with the alloy and the other end extending out of the tube, forming a heating tube with an insulated tube sheathed and a low-melting-point alloy as the resistive heating element. When the metal electrodes are energized, the solid low-melting-point alloy is heated to melting, acting as a resistor. A solid-liquid phase change occurs, storing heat. Temperature control maintains the low-melting-point alloy at its melting point, allowing for direct contact heating of solar cell modules. Multiple heating tubes with insulated tube sheathed and a low-melting-point alloy as the resistive heating element can be connected in series, parallel, or a combination of series and parallel connections to form a large-area heating plate.

[0004] The insulating tube is a polytetrafluoroethylene composite tube and a silicone composite tube with high infrared emissivity. The low-temperature molten salt is a low-temperature molten salt doped with composite oxide particles with high infrared emissivity. Therefore, when the constant temperature heating plate formed by the heating tubes with low-temperature molten salt as the resistive heating element is directly in contact with the solar cell, the heat transfer mode is contact heat conduction and infrared radiation heat transfer. Infrared rays can pass through the glass to directly heat the EVA film with high infrared absorption, thereby improving the heating efficiency. Summary of the Invention

[0005] A low-melting-point alloy electric heating tube type constant temperature heating plate for laminators is characterized by: multiple low-melting-point alloy electric heating tubes connected in series, parallel, or a combination of series and parallel, forming a large-area, high-heating-power constant temperature heating plate for direct contact heating of solar modules in laminators. The low-melting-point alloy electric heating tube type constant temperature heating plate for laminators heats solar modules through a combination of direct contact heat conduction and infrared radiation heating. The infrared radiation heating method involves infrared radiation heating of the solar module by the wall of the composite material insulator tube incorporating high infrared radiation composite oxide powder, and infrared radiation heating of the solar module by the high infrared radiation composite oxide particles in the low-melting-point alloy-based composite material. The EVA film has a high infrared absorption coefficient, and infrared radiation passes through the glass to directly heat the EVA film, thereby improving the heating efficiency of the EVA film.

[0006] The low-melting-point alloy heating tube is an insulated tube armored heating tube with a low-melting-point alloy as the resistive heating element. The low-melting-point alloy is loaded into an insulated tube of a certain length and cross-sectional size so that the low-melting-point alloy in the insulated tube has a certain resistance value. Metal electrodes are inserted into both ends of the insulated tube to contact the low-melting-point alloy. The two ends of the insulated tube are sealed with one end of the metal electrode in contact with the low-melting-point alloy and the other end extending out of the insulated tube to form an insulated tube armored heating tube. When the metal electrodes are energized, the solid low-melting-point alloy is heated to melt as a resistive element. The solid-liquid phase change stores heat, and the temperature of the low-melting-point alloy is kept at the melting point temperature of the low-melting-point alloy by temperature control.

[0007] The insulating tube is either a polytetrafluoroethylene (PTFE) tube or a silicone tube. The maximum operating temperature of the PTFE tube is below 270°C, and the maximum operating temperature of the silicone tube is 280°C. The cross-sectional shape of the insulating tube is circular or rectangular.

[0008] The aforementioned insulating tube is formed by mixing 5% to 25% by volume of composite oxide powders of ferric oxide, manganese dioxide, copper oxide, chromium trioxide, and cobalt oxide with high infrared emissivity and an average particle size of less than 2 micrometers during the molding process. This mixture forms polytetrafluoroethylene (PTFE) composite material and silicone composite material, which are then extruded to form PTFE composite tubes and silicone composite tubes with high infrared emissivity. This improves the infrared radiation heating efficiency of the heating tube with insulator-clad low-temperature molten salt as the resistance heating element.

[0009] The composite oxide powder used for mixing polytetrafluoroethylene composite materials and silicone composite materials is a mixture of oxides with the following weight fractions: 10%~30% ferric oxide, 50%~70% manganese dioxide, 7.5%~12.5% ​​copper oxide, 2.5%~5% chromium trioxide, and 7.5%~12.5% ​​cobalt oxide. The oxides are ground to an average particle size of less than 2 micrometers, then calcined at 1000℃~1200℃, crushed, ground again to an average particle size of less than 2 micrometers, and dried before being used for mixing polytetrafluoroethylene composite materials and silicone composite materials.

[0010] The low-melting-point alloy is a low-melting-point alloy composed of two, three, or four metals selected from Bi, Pb, Sn, and Cd, with a melting point of 145℃~200℃. The composition of the low-melting-point alloy is designed based on the binary, ternary, or quaternary phase diagrams of Bi, Pb, Sn, and Cd, according to the constant-temperature heating temperature required for the solar cell module. The melting point of the low-melting-point alloy is controlled, and its melting point temperature is the controlled constant-temperature temperature of the heating element. Typical low-melting-point alloys include: Pb 32% Sn 50% Cd 8% (melting point: 145℃), Bi 50% Pb 50% (melting point: 160℃), Pb 38% Sn 62% (melting point: 183℃), and Bi 20% Sn 80% (melting point: 200℃).

[0011] The low-melting-point alloy is a low-melting-point alloy-based composite material. This composite material is a mixture of the low-melting-point alloy and composite oxide particles (iron oxide, manganese dioxide, copper oxide, chromium oxide, and cobalt oxide) with high infrared emissivity and a particle size of 0.2 mm to 1 mm, comprising 40% to 65% of the volume of the insulating tube. After melting, the low-melting-point alloy fills the gaps between the composite oxide particles. The non-conductivity and volume percentage of the composite oxide particles are used to adjust and control the resistance value of the low-melting-point alloy inside the insulating tube armored heating tube, thereby controlling the heating power under constant voltage and improving the infrared radiation heating efficiency of the insulating tube heating tube.

[0012] The composite oxide particles used in the low-melting-point alloy-based composite material are a mixture of oxides with the following weight fractions: 10%~30% ferric oxide, 50%~70% manganese dioxide, 7.5%~12.5% ​​copper oxide, 2.5%~5% chromium trioxide, and 7.5%~12.5% ​​cobalt oxide. The mixture is ground to an average particle size of less than 2 micrometers, then calcined at 1000℃~1200℃, crushed and pulverized to a particle size of 0.2mm~1mm, and dried before being used in the manufacture of the low-melting-point alloy-based composite material.

[0013] The low-melting-point alloy is cast or extruded into a circular or rectangular cylinder with a diameter slightly smaller than the internal geometric dimensions of the insulator tube and a length 1 to 2 times its geometric dimensions. The circular or rectangular cylinders are placed one by one into the insulator tube to the designed length. The electrodes are vacuum-sealed and placed in a heating furnace and heated until the low-melting-point alloy is completely melted and in contact with the conductive metal electrodes. The insulator-armored heating tube with the low-melting-point alloy completely melted is placed in a mold and cooled to form an insulator-armored heating tube with the low-melting-point alloy as the resistive heating element.

[0014] The alloy powder of the melting point alloy is mixed evenly with a certain proportion of the composite oxide particles, and then pressed into a press mold to form a circular or rectangular cylinder with a diameter slightly smaller than the internal geometric dimensions of the insulator tube and a length 1 to 2 times its geometric dimensions. The circular or rectangular cylinders are placed one by one into the insulator tube to the designed length. The metal electrodes are vacuum sealed and placed in a heating furnace and heated until the low melting point alloy is completely melted and fills the gaps between the composite oxide particles, and the low melting point alloy contacts and conducts to the metal electrodes. The insulator armored heating tube with the low melting point alloy completely melted is placed in a mold and cooled to form an insulator tube armored heating tube with the low melting point alloy as the resistive heating element.

Claims

1. A low-melting-point alloy electric heating tube type constant temperature heating plate for a laminator, characterized in that: multiple low-melting-point alloy electric heating tubes are connected in series, parallel, or a combination of series and parallel, and the heating tubes are closely connected and densely arranged to form a large-area, high-heating-power constant temperature heating plate for direct contact heating of solar modules in the laminator; the low-melting-point alloy electric heating tube type constant temperature heating plate for heating solar modules in the laminator heats solar modules by a combination of direct contact heat conduction and infrared radiation heating, wherein the infrared radiation heating is achieved by the infrared radiation heating of the solar module by the composite material insulating tube wall mixed with high infrared radiation composite oxide powder, and by the infrared radiation heating of the solar module by the high infrared radiation composite oxide particles in the low-melting-point alloy-based composite material, wherein the EVA film has a high infrared absorption coefficient, and the infrared radiation passes through the glass to directly heat the EVA film, thereby improving the heating efficiency of the EVA film.

2. According to claim 1, the low-melting-point alloy heating tube is an insulated tube armored heating tube with a low-melting-point alloy as the resistive heating element. The low-melting-point alloy is loaded into an insulated tube of a certain length and a certain cross-sectional geometry so that the low-melting-point alloy in the insulated tube has a certain resistance value. Metal electrodes are inserted into both ends of the insulated tube to contact the low-melting-point alloy. The two ends of the insulated tube are sealed with one end of the metal electrode in contact with the low-melting-point alloy and the other end extending out of the insulated tube to form an insulated tube armored heating tube. When the metal electrode is energized, the solid low-melting-point alloy is heated to melt as a resistive element, and the solid-liquid phase change stores heat. The temperature of the low-melting-point alloy is kept at the melting point temperature of the low-melting-point alloy by temperature control.

3. According to claim 1, the insulating tube is: a polytetrafluoroethylene tube or a silicone tube; the cross-sectional shape of the insulating tube is circular or rectangular.

4. According to claim 1, the insulator tube is made by mixing 5% to 25% by volume of composite oxide powders of ferric oxide, manganese dioxide, copper oxide, chromium trioxide, and cobalt oxide with high infrared radiation coefficients and average particle sizes of less than 2 micrometers during the molding process of the insulator tube to form polytetrafluoroethylene composite material and silicone composite material, which are then extruded to form polytetrafluoroethylene composite material tubes and silicone composite material tubes with high infrared emissivity, so as to improve the infrared radiation heating efficiency of the insulator tube armored heating tube with low temperature molten salt as the resistance heating element.

5. According to claim 1, the composite oxide powder is a mixture of oxides with the following weight fractions: 10%~30% ferric oxide, 50%~70% manganese dioxide, 7.5%~12.5% ​​copper oxide, 2.5%~5% chromium trioxide, and 7.5%~12.5% ​​cobalt oxide. The mixture is ground to an average particle size of less than 2 micrometers, then calcined at 1000℃~1200℃, crushed, ground again to an average particle size of less than 2 micrometers, and dried before being used in the mixing of the polytetrafluoroethylene composite material and the silicone composite material.

6. According to claim 1, the low-melting-point alloy is a low-melting-point alloy composed of two, three, or four metals selected from Bi, Pb, Sn, and Cd, with a melting point of 145℃~200℃. The composition of the low-melting-point alloy is designed based on the constant-temperature heating temperature required for the solar cell module and the binary, ternary, or quaternary phase diagrams of Bi, Pb, Sn, and Cd. The melting point of the low-melting-point alloy is controlled, and the melting point temperature of the low-melting-point alloy is the controlled constant-temperature temperature of the heating tube.

7. According to claim 1, the low-melting-point alloy is a low-melting-point alloy-based composite material, wherein the low-melting-point alloy-based composite material is a mixture of the low-melting-point alloy and composite oxide particles of ferric oxide, manganese dioxide, copper oxide, chromium trioxide, and cobalt oxide with high infrared emissivity and a particle size of 0.2 mm to 1 mm, comprising 40% to 65% of the volume of the insulating tube. After melting, the low-melting-point alloy fills the gaps between the composite oxide particles. The non-conductivity and volume percentage of the composite oxide particles are used to adjust and control the resistance value of the low-melting-point alloy inside the insulating tube armored heating tube, i.e., the heating power under constant voltage and to improve the infrared radiation heating efficiency of the insulating tube armored heating tube.

8. According to claim 1, the composite oxide particles are a mixture of oxides with a weight fraction of 10%~30% ferric oxide, 50%~70% manganese dioxide, 7.5%~12.5% ​​copper oxide, 2.5%~5% chromium trioxide, and 7.5%~12.5% ​​cobalt oxide, which are ground to an average particle size of less than 2 micrometers, calcined at 1000℃~1200℃, crushed and pulverized to a particle size of 0.2mm~1mm, and dried before being used in the manufacture of the low melting point alloy composite material.

9. According to claim 1, the low-melting-point alloy is cast or extruded into a cylinder or rectangular prism with a diameter slightly smaller than the internal geometric dimensions of the insulator tube and a length 1 to 2 times its geometric dimensions. The cylinders or rectangular prisms are placed one by one into the insulator tube to the designed length. The electrodes are vacuum-sealed and placed in a heating furnace and heated until the low-melting-point alloy is completely melted and the low-melting-point alloy contacts the conductive metal electrode. The insulator-armored heating tube with the low-melting-point alloy completely melted is placed in a mold and cooled to form an insulator-armored heating tube with the low-melting-point alloy as the resistive heating element.

10. According to claim 1, the alloy powder of the low melting point alloy is mixed evenly with a certain proportion of the composite oxide particles, and then pressed into a cylinder or rectangular column with a diameter slightly smaller than the internal geometric dimensions of the insulator tube and a length 1 to 2 times its geometric dimensions in a press mold. The cylinders or rectangular columns are placed one by one into the insulator tube to the designed length. The metal electrodes are vacuum-sealed and placed in a heating furnace and heated until the low melting point alloy is completely melted and fills the gaps between the composite oxide particles, and the low melting point alloy contacts and conducts to the metal electrodes. The insulator armored heating tube with the low melting point alloy completely melted is placed in a mold and cooled to form an insulator tube armored heating tube with the low melting point alloy as the resistive heating element.