RELATED APPLICATIONS

[0001] This international application claims the benefit of Chinese Patent Application Serial No. 201911069705.8, filed November 5, 2019, and to Chinese Patent Application Serial No. 202011059510.8, filed September 30, 2020. The entireties of Chinese Patent Application Serial No. 201911069705.8 and Chinese Patent Application Serial No. 202011059510.8 are expressly incorporated herein by reference.

FIELD OF THE DISCLOSURE

[0002] The present application relates to a sintering apparatus, in particular to a sintering apparatus for use in the field of solar cell manufacturing.

BACKGROUND

[0003] In the course of production of photovoltaic devices such as crystalline silicon solar cell wafers, a sintering furnace needs to be used to sinter the photovoltaic device. The sintering furnace generally comprises a drying section, a sintering section, a cooling section and a light treatment section. The photovoltaic device is conveyed by a conveyor belt through the drying section, sintering section, cooling section and light treatment section in sequence. In each section, the temperature of the photovoltaic device must be controlled to be within a certain range, to guarantee the effectiveness of photovoltaic device sintering.

BRIEF SUMMARY OF THE DISCLOSURE

[0004] The present application provides a sintering apparatus, comprising: a sintering section, for sintering a photovoltaic device; a light treatment section, for subjecting the sintered photovoltaic device to light treatment; a cooling section, the cooling section being disposed between the sintering section and the light treatment section, the cooling section comprising a first cooling subzone and a second cooling subzone, wherein the first cooling subzone is connected to the sintering section, the first cooling subzone is configured to cool the photovoltaic device by radiative cooling, the second cooling subzone is configured to cool the photovoltaic device by convective cooling, the first cooling subzone cools the photovoltaic device to a first temperature range, and the second cooling subzone cools the photovoltaic device to a second temperature range.

[0005] According to the sintering apparatus described above, the second temperature range is 180°C-250°C.

[0006] According to the sintering apparatus described above, the first temperature range is 280°C-350°C.

[0007] According to the sintering apparatus described above, the first cooling subzone comprises at least one radiative cooling module, the radiative cooling module comprising a first upper heat exchanger and a first lower heat exchanger, a gap allowing passage of the photovoltaic device is provided between the first upper heat exchanger and first lower heat exchanger, and surfaces of the first upper heat exchanger and first lower heat exchanger are a black color.

[0008] According to the sintering apparatus described above, the black color of the surfaces of the first upper heat exchanger and first lower heat exchanger is formed by an aluminum oxidation process or formed by application of a coating.

[0009] According to the sintering apparatus described above, the first upper heat exchanger and first lower heat exchanger are finned tube heat exchangers, the finned tube heat exchangers comprising a coiled tube and multiple fins arranged in sequence, with a gap being provided between adjacent said fins, and the coiled tube passing through the fins.

[0010] According to the sintering apparatus described above, the second cooling subzone comprises at least one convective cooling module, the convective cooling module comprising a second upper heat exchanger and a second lower heat exchanger, a gap allowing passage of the photovoltaic device is provided between the second upper heat exchanger and second lower heat exchanger, and at least one fan is provided above the second upper heat exchanger, the at least one fan being configured to enable an airflow to flow from the second upper heat exchanger toward the second lower heat exchanger; a gap between the bottom of the fan and the top of the second upper heat exchanger is not less than 25 cm.

[0011] According to the sintering apparatus described above, the second upper heat exchanger and second lower heat exchanger are finned tube heat exchangers, the finned tube heat exchangers comprising a coiled tube and multiple fins arranged in sequence, with a gap being provided between adjacent said fins, and the coiled tube passing through the fins.

[0012] According to the sintering apparatus described above, the at least one fan is multiple fans, the multiple fans being distributed uniformly above the second upper heat exchanger, and the power of the multiple fans being adjustable; the second cooling subzone comprises a fan support, with the multiple fans being mounted on the fan support.

[0013] According to the sintering apparatus described above, the distance between the second cooling subzone and the sintering section is not less than 0.85 m.

[0014] The cooling section provided in the present application comprises two cooling subzones, which employ radiative cooling and convective cooling respectively; the combination thereof can achieve a good cooling effect, and the cooling section is thereby able to effectively lower the temperature to an ideal range. The combination of the two types of cooling enables the cooling section to have a small volume and save space while guaranteeing the cooling effect.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Fig. 1 is a three-dimensional drawing of a sintering furnace in the present application.

[0016] Fig. 2A is a three-dimensional drawing of the cooling section 103 of the sintering apparatus 100 in fig. 1.

[0017] Fig. 2B is a three-dimensional drawing of the cooling section 103 in fig. 2A with a front cover plate removed.

[0018] Fig. 3A is a three-dimensional drawing of the cooling assembly 201 in the cooling section 103 in fig. 2B.

[0019] Fig. 3B is a sectional view, taken along line A-A, of the cooling assembly 201 in fig. 3A.

[0020] Fig. 4A is a three-dimensional drawing of the radiative cooling assembly 221 in fig. 3A.

[0021] Fig. 4B is an exploded view of the radiative cooling assembly 221 in fig. 4A. [0022] Fig. 5 is a three-dimensional drawing of the heat exchanger support of the radiative cooling assembly 221 in fig. 4A.

[0023] Fig. 6A is a three-dimensional drawing of the convective cooling assembly 222 in fig. 3A.

[0024] Fig. 6B is an exploded view of the convective cooling assembly 222 in fig. 6A.

[0025] Fig. 7 is a sectional view, taken along line B-B, of the convective cooling assembly 222 in fig. 6A.

DETAILED DESCRIPTION

[0026] Various particular embodiments of the present application are described below with reference to the accompanying drawings, which form part of this Description. It should be understood that although terms indicating direction, such as “front”, “rear”, “up”, “down”, “left” and “right”, etc. are used in the present application to describe various demonstrative structural parts and elements of the present application, these terms are used here purely in order to facilitate explanation, and are determined on the basis of demonstrative orientations shown in the drawings. Since the embodiments disclosed in the present application may be arranged in accordance with different directions, these terms indicating direction are purely illustrative, and should not be regarded as limiting.

[0027] Fig. 1 is a three-dimensional drawing of a sintering apparatus 100 in the present application; as shown in fig. 1 , the sintering apparatus 100 comprises a drying section 101 , a sintering section 102, a cooling section 103, a light treatment section 104 and a recooling section 105. A photovoltaic device to be processed (not shown in the figure) is conveyed by a conveyor belt, passing through the drying section 101 , sintering section 102, cooling section 103, light treatment section 104 and recooling section 105 in sequence in the direction indicated by the arrows 108, to complete sintering. A heating means is provided in the drying section 101 ; this is configured to heat the temperature of the photovoltaic device to a drying temperature (e.g. 200°C- 300°C), such that an organic solvent on the photovoltaic device volatilizes. The dried photovoltaic device enters the sintering section 102; a heating means is provided in the sintering section 102, and this is configured to heat the temperature of the photovoltaic device to a sintering temperature (e.g. 700°C-900°C), such that the photovoltaic device is sintered at a high temperature. The sintered photovoltaic device enters the cooling section 103; a cooling means is provided in the cooling section 103, and this is configured to cool the photovoltaic device to a cooling temperature (e.g. 200°C-250°C), to suit the temperature requirements of the light treatment section 104. The light treatment section 104 subjects the photovoltaic device to illumination treatment, such that the light attenuation of the photovoltaic device attains an equilibrium state. A heating means is provided in the light treatment section 104, and this is configured to keep the temperature within the range of 180°C-250°C in the light treatment section 104. The recooling section 105 cools the photovoltaic device that has been processed in the light treatment section 104 to a low temperature (e.g. 20°C- 70°C).

[0028] In the embodiment shown in fig. 1 , the cooling section 103 is provided with a first cooling subzone 112 and a second cooling subzone 113. A heat exchanger is provided in the first cooling subzone 112, and this is configured to cool the photovoltaic device by radiative cooling, i.e. the heat exchanger directly absorbs heat that is radiatively emitted by the photovoltaic device into the air. A heat exchanger is also provided in the second cooling subzone 113, and this is configured to cool the photovoltaic device by convective cooling, i.e. the heat exchanger absorbs heat which air convection causes the photovoltaic device to emit, thereby cooling the photovoltaic device. According to an embodiment of the present application, when the photovoltaic device enters the first cooling subzone 112 from the sintering section 102, the temperature of the photovoltaic device is 700°C-900°C; when the photovoltaic device leaves the first cooling subzone 112, the temperature of the photovoltaic device close to an outlet of the first cooling subzone 112 is reduced to around 300°C (300°C-350°C). When the photovoltaic device enters the second cooling subzone 113 from the first cooling subzone 112, the temperature of the photovoltaic device is around 300°C (300°C-350°C); when the photovoltaic device leaves the second cooling subzone 113, the temperature of the photovoltaic device is reduced to around 200°C (200°C-250°C). The temperature range of the photovoltaic device leaving the second cooling subzone 113 is matched to the temperature required for the light treatment section 104.

[0029] In an existing sintering apparatus, a first cooling subzone 112 that cools by radiative cooling is provided in a cooling section 103 thereof, but a second cooling subzone 1 13 that cools by convective cooling is not provided; thus, the cooling section of the existing sintering apparatus cools the temperature of a photovoltaic device entering the cooling section from a sintering section 102 from 800°C-900°C to around 300°C (300°C-350°C). The photovoltaic device manufactured using the existing sintering apparatus can meet existing requirements for use, but in the manufacturing process using the existing sintering apparatus, parameters of the photovoltaic device will still have room for improvement. For example, the illumination treatment time needed for the photovoltaic device will be extended; if the illumination treatment time is insufficient, the finished photovoltaic device product will not have attained light attenuation equilibrium, in which case, if the newly manufactured finished photovoltaic device product is used immediately, the light conversion efficiency of the finished photovoltaic device product will be affected. Through observation, testing and use of photovoltaic devices, the applicant has realized that when the photovoltaic device is subjected to illumination treatment in the light treatment section 104, the fact that the temperature of the photovoltaic device is around 300°C (300°C-350°C) is the reason why the finished photovoltaic device product needs a long illumination treatment time. Thus, in the embodiment shown in fig. 1 , the present application adds the second cooling subzone 113, for the purpose of reducing the temperature of the photovoltaic device outputted from the second cooling subzone 113 from around 300°C (300°C- 350°C) to around 200°C (200°C-250°C). By reducing the temperature of the photovoltaic device from around 300°C (300°C-350°C) to around 200°C (200°C-250°C) and then subjecting the photovoltaic device to illumination treatment in the light treatment section 104, the light treatment time needed for the photovoltaic device to attain light attenuation equilibrium can be shortened.

[0030] Fig. 2A is a three-dimensional drawing of the cooling section 103 of the sintering apparatus 100 in fig. 1 ; fig. 2B is a three-dimensional drawing of the cooling section 103 in fig. 2A with a front plate hidden in order to show the internal structure of the cooling section 103. As shown in figs. 2A and 2B, the cooling section 103 comprises a housing 202 and a cooling assembly 201. The housing 202 is substantially a box having an opening in a lower region, and has an upper plate 211 , a front plate 212, a rear plate 213, a left plate 214 and a right plate 215. That side of the housing 202 which is close to the left plate 214 is connected to the sintering section 103, and that side which is close to the right plate 215 is connected to the light treatment section 104. An opening 218 is provided in an upper region of the left plate 214 and of the right plate 215, for the purpose of allowing the passage of a conveyor belt. The cooling assembly 201 is disposed in an upper region of the housing 202, and arranged close to the conveyor belt. The cooling assembly 201 comprises a radiative cooling assembly 221 and a convective cooling assembly 222; the radiative cooling assembly 221 is located in the first cooling subzone 112, and the convective cooling assembly 222 is located in the second cooling subzone 113. The bottom of the housing 202 is provided with a support or rollers 271 , so that the opening in the lower region is separated from the ground by a certain gap, and the opening in the lower region is thereby in communication with the outside.

[0031] Fig. 3A is a three-dimensional drawing of the cooling assembly 201 in fig. 2B; fig. 3B is a sectional view, taken along line A-A, of the cooling assembly 201 in fig. 3A. As shown in figs. 3A and 3B, the radiative cooling assembly 221 and convective cooling assembly 222 in the cooling assembly 201 are connected by means of a connecting member 305. The radiative cooling assembly 221 comprises two identical radiative cooling modules 311.1 and 311.2; the convective cooling assembly 222 comprises two identical convective cooling modules 312.1 and 312.2. Conveying spaces 315.1 and 315.2 are provided in the radiative cooling modules 311.1 and 311.2; conveying spaces 316.1 and 316.2 are provided in the convective cooling modules 312.1 and 312.2. The conveying space 315.1 and conveying space 316.1 are aligned to form a first conveying channel; the conveying space 315.2 and conveying space 316.2 are aligned to form a second conveying channel. The first conveying channel and second conveying channel are independent of each other, with a conveyor belt being provided in the interior of each conveying channel, to form two photovoltaic device processing lines. In other embodiments, only one radiative cooling module and one convective cooling module may be provided to form one processing line, or multiple radiative cooling modules and convective cooling modules in one-to- one correspondence may be provided to form multiple processing lines. The radiative cooling assembly 221 is close to the sintering section 102; the convective cooling assembly 222 is close to the light treatment section 104.

[0032] Fig. 4A is a three-dimensional drawing of the radiative cooling assembly 221 in fig. 3A; fig. 4B is an exploded view of the radiative cooling assembly 221 in fig. 4A. As shown in figs. 4A and 4B, besides the two radiative cooling modules 311.1 and 311 .2, the radiative cooling assembly 221 further comprises a heat exchanger support 405. The specific structure of the two radiative cooling modules is described below, taking as an example the radiative cooling module 311 .2 located at the front of the pictures. The radiative cooling module 311.2 comprises a first upper heat exchanger

401 and a first lower heat exchanger 402. The first upper heat exchanger 401 and first lower heat exchanger 402 are mounted at two opposite sides of the heat exchanger support 405, and the first upper heat exchanger 401 and first lower heat exchanger

402 are separated by a certain gap, to form the conveying space 315.1. The first upper heat exchanger 401 and first lower heat exchanger 402 are both finned tube heat exchangers, respectively comprising multiple fins 432 and 433 disposed side by side, and a coiled tube 435 passing through the fins 432 and 433. The coiled tube 435 has a cooling water inlet and a cooling water outlet, the cooling water inlet being in communication with cooling water; after the cooling water entering the coiled tube 435 has undergone heat exchange, the cooling water flows out through the cooling water outlet. Surfaces of the fins 432 and 433 form heat exchange surfaces, which undergo heat exchange with air.

[0033] The coiled tubes 435 of the first upper heat exchanger 401 and first lower heat exchanger 402 in each heat exchanger module are in communication via a coiled tube connecting section 436. Cooling water flows into the coiled tube 435 of the first upper heat exchanger 401 through a cooling water inlet of the first upper heat exchanger 401 located in an upper region, then flows into the coiled tube 435 of the first lower heat exchanger 402 located in a lower region via the coiled tube connecting section 436, and flows out through a cooling water outlet of the first lower heat exchanger 402 located in the lower region. The flow direction of the cooling water is arranged to enable more effective heat exchange. Specifically, due to the fact that hot air flows upward, comparatively speaking, there is a greater amount of heat in air close to the first upper heat exchanger 401 than close to the first lower heat exchanger 402. Since the cooling water enters the first upper heat exchanger 401 first and then enters the first lower heat exchanger 402, the temperature of the cooling water is lower in the first upper heat exchanger 401 , thus facilitating heat exchange with air having a greater amount of heat close to the first upper heat exchanger 401 .

[0034] Each fin 433 extends in a vertical direction, with a gap between adjacent fins 433. The fins 433 can increase the heat exchange area. An outer surface of the fins 433 is black, being made by an aluminum oxidation process, or made by applying a black material such as Teflon. The black surface will facilitate absorption of heat by the heat exchanger, thus increasing the heat exchange efficiency. An outer surface of the coiled tube 435 may also be configured to be black. In other embodiments, the first upper heat exchanger 401 and first lower heat exchanger 402 may also be configured as plate-type heat exchangers, wherein heat exchange surfaces of the plate-type heat exchangers are flat plates. The heat exchange area of the flat plates in the plate-type heat exchangers is smaller than the heat exchange area of the fins in the finned tube heat exchangers; thus, in order to obtain a heat exchange capacity similar or identical to that of the finned heat exchangers, the length of the cooling section 103 using the plate-type heat exchangers may be configured to be greater than the length of the cooling section 103 using the finned tube exchangers.

[0035] Fig. 5 is a three-dimensional drawing of the heat exchanger support of the radiative cooling assembly 221 in fig. 4B; as shown in fig. 5, two hollow parts 508.1 and 508.2 are provided in the heat exchanger support 405, with the radiative cooling modules 311.1 and 311.2 being disposed in the hollow parts 508.1 and 508.2 respectively, such that the radiative cooling modules 311.1 and 311 .2 can easily come into direct contact with air, and will not be blocked by the heat exchanger support 405. The heat exchanger support 405 has a pair of first lateral openings 415.1 and 415.2 and a pair of second lateral openings 416.1 and 416.2 at two opposite sides respectively of the radiative cooling modules 311.1 and 311.2. The first lateral opening

415.1 and second lateral opening 416.1 are aligned with the conveying space 315.1 of the radiative cooling module 311.1 , for the purpose of forming the first conveying channel; the first lateral opening 415.2 and second lateral opening 416.2 are aligned with the conveying space 315.2 of the radiative cooling module 311 .2, for the purpose of forming the second conveying channel.

[0036] Fig. 6A is a three-dimensional drawing of the convective cooling assembly 222 in fig. 3A; fig. 6B is an exploded view of the convective cooling assembly 222 in fig. 6A. As shown in figs. 6A and 6B, in the two convective cooling modules 312.1 and

312.2 of the convective cooling assembly 222, each convective cooling module comprises a fan assembly 603, a second upper heat exchanger 601 and a second lower heat exchanger 602. The specific structure of the two convective cooling modules is described below, taking as an example the convective cooling module 312.2. Besides the two convective cooling modules 312.1 and 312.2, the convective cooling assembly 222 further comprises a heat exchanger support 617 for supporting the two convective cooling modules 312.1 and 312.2. The heat exchanger support 617 and and heat exchangers in the convective cooling assembly 222 are structurally similar or identical to the heat exchanger support and heat exchangers in the radiative cooling assembly 221 , so are not described superfluously here.

[0037] A conveying space is provided between the second upper heat exchanger 601 and second lower heat exchanger 602; a conveyor belt is disposed between the second upper heat exchanger 601 and second lower heat exchanger 602. The fan assembly 603 is disposed above the second upper heat exchanger 601. The fan assembly 603 comprises a fan support 609 and three fans 605. The fan support 609 comprises a support plate 713 and connecting plates 714 extending downward from the periphery of the support plate 713. The support plate 713 is provided with three fan mounting holes, for mounting the three fans 605. The connecting plates 714 are used for connecting the fan support 609 to the heat exchanger support 617 or the second upper heat exchanger 601 . A fluid space is formed between the bottom of the three fans 605 and the second upper heat exchanger 601 ; a fluid can circulate in the fluid space. The second upper heat exchanger 601 and second lower heat exchanger 602 are each finned tube heat exchangers. The second upper heat exchanger 601 and second lower heat exchanger 602 have multiple fins 632 and 633 respectively; the fins 632 and 633 are arranged side by side in a horizontal direction, each fin extending in a vertical direction. The three fans 605 are disposed above the second upper heat exchanger 601 , and blow air downward, so that an airflow close to the conveyor belt flows downward. The downward flow of the airflow close the conveyor belt can avoid movement of the lightweight photovoltaic device to be processed on the conveyor belt due to the effects of lateral and upward airflows. The downward airflow provided by the fans 605 passes through the gaps between the fins 632 of the second upper heat exchanger 601 and the fins 633 of the second lower heat exchanger 602, such that the flow speed of air is increased. In an embodiment of the present application, the three fans 605 distributed uniformly above the second upper heat exchanger 601 enable a more uniform distribution of the airflow between the heat exchangers. In other embodiments, the quantity and power of the fans above the second upper heat exchanger 601 may be configured according to actual needs.

-I Q- [0038] Fig. 7 is a sectional view, taken along line B-B, of the convective cooling assembly 222 in fig. 6A; as shown in fig. 7, due to the fan support 609, the fans 605 are separated from the top of the second upper heat exchanger 601 by a certain gap, so as to form an air flow space. The gap is for example more than 25 cm, and in one embodiment is 30 cm. The gap between the fans 605 and the top of the second upper heat exchanger 601 enables the airflow blown out by the fans 605 to diffuse uniformly, in the air flow space formed by the gap, to a region above the fins of the second upper heat exchanger 601 , such that the airflow can pass through the fins of the second upper heat exchanger 601 uniformly. If the distance between the fans 605 and the top of the second upper heat exchanger 601 is too small, most of the airflow blown out from the fans 605 will pass through the fins of the second upper heat exchanger 601 directly below the fans 605 before it has had time to diffuse, with the result that the second upper heat exchanger 601 is heated unevenly. Outer surfaces of the heat exchanger fins and coiled tube of the convective cooling assembly 222 may be processed so as to be black, but may also be unprocessed.

[0039] According to the present application, in the first cooling subzone 112, the heat exchanger directly absorbs heat that is radiatively emitted into the air by the photovoltaic device, thereby cooling the photovoltaic device; in the second cooling subzone 113, the heat exchanger absorbs heat which air convection causes the photovoltaic device to emit, thereby cooling the photovoltaic device. In both the first cooling subzone 112 and the second cooling subzone 113, cooling is performed by heat exchange between the heat exchanger and air around the photovoltaic device; the difference is that the air flow situations are different in the first cooling subzone 112 and second cooling subzone 113. Air does not flow or only flows to a very small extent in the first cooling subzone, whereas air flows to a very large extent in the second cooling subzone 113.

[0040] In the embodiments shown in figs. 1 - 7, the present application does not employ the method of increasing the total heat exchange capacity of the heat exchanger of the first cooling subzone 112 (e.g. increasing the cooling water flow rate, lowering the cooling water temperature) to increase the effect of the first cooling subzone 112 on the photovoltaic device. In the first cooling subzone 112, the heat exchanger lowers the temperature of the photovoltaic device by absorbing the energy that is radiatively emitted by the photovoltaic device. In an existing design, if the cooling water flow rate is further increased to enhance the cooling effect on the photovoltaic device, this will be of little help in further cooling the photovoltaic device. This is because, in the first cooling subzone 112, the temperature of cooling water at the heat exchanger cooling water inlet is the same as the ambient temperature, and in the heat exchanger, the temperature of heat exchange surfaces of the heat exchanger is lowered by heat transfer between the cooling water and the heat exchange surfaces. During heat exchanger operation, the heat exchange surfaces of the heat exchanger have a heat exchange surface temperature, and the air around the heat exchange surfaces of the heat exchanger has an air temperature. The heat exchange surface temperature is affected by the cooling water temperature; the air temperature is affected by heat emitted by thermal radiation by the photovoltaic device. The heat exchange surface temperature is quite close to the air temperature, so after heat exchange has taken place between the heat exchanger and the air around the heat exchange surfaces of the heat exchanger, the temperatures of the cooling water inlet and outlet of the heat exchanger do not differ to a great extent; if the cooling water flow rate is further increased, this will be of little help in further absorbing the heat generated by the photovoltaic device, and thus of little help in further lowering the temperature of the photovoltaic device, and the temperature of the photovoltaic device cannot be further lowered to around 200°C (200°C-250°C). If the temperature of the cooling water is lowered to enhance the cooling effect on the photovoltaic device, then the temperature of the photovoltaic device can be further lowered; however, the cooling water must be cooled first, in a complex process and at a high cost, and cooling water at a lower temperature easily causes condensation on cooling water pipeline surfaces, affecting the service life of the heat exchanger.

[0041] Furthermore, in the embodiments shown in fig. 1 - 7, the present application also does not employ the method of increasing the length of the first cooling subzone 112 (i.e. adding more heat exchangers in the first cooling subzone) to lower the temperature of the photovoltaic device in the first cooling subzone 112 to around 200°C (200°C-250°C), for a similar reason to that given above; when the cooling water inlet temperature is the same as the ambient temperature, the temperatures of the cooling water inlet and outlet of the heat exchanger of the first cooling subzone 112 do not differ to a great extent, and if the length of the first cooling subzone 112 is further increased, this will be of little help in further absorbing heat. If the method of increasing the length of the first cooling subzone 112 is employed to continue cooling the photovoltaic device, then it might be necessary to add a longer first cooling subzone 112, e.g. several times the length of the original first cooling subzone 112, in order to lower the temperature of the photovoltaic device to around 200°C (200°C-250°C). Such a design will increase the volume of the sintering furnace excessively, and adds a large cost.

[0042] Furthermore, in the embodiments shown in figs. 1 - 7, the present application also does not arrange convective cooling in the first cooling subzone 112; this is because the first cooling subzone 112 is immediately adjacent to the sintering section 102, and air fluctuation generated by convective cooling might interfere with the operation of the sintering section 102.

[0043] In the embodiments shown in figs. 1 - 7, the present application uses the first cooling subzone 112, which employs radiative cooling, to cool the photovoltaic device therein from 800°C-900°C to around 300°C (300°C-350°C). The power of heat radiatively emitted by an object is directly proportional to the fourth power of the absolute temperature of the object; in a higher temperature range, the power of radiative emission of heat by the object is greater, whereas in a lower temperature range, the power of radiative emission of heat by the object is smaller. In the present application, the power of radiative emission of heat by the photovoltaic device is greater in the range of 800°C-900°C to around 300°C. The first cooling subzone 112, which employs radiative cooling, can absorb this portion of heat, thereby cooling the photovoltaic device from 800°C-900°C to around 300°C (300°C-350°C). The power of radiative emission of heat by the photovoltaic device is smaller in the range of around 300°C to around 200°C, and the present application uses the convective cooling of the second cooling subzone 113 to increase the circulation of air close to the photovoltaic device, increasing the speed of heat dissipation from the photovoltaic device and increasing the power of heat emission by the photovoltaic device; the heat exchanger in the second cooling subzone 113 can absorb the heat emitted by the photovoltaic device, such that the photovoltaic device can be quickly cooled from around 300°C (300°C- 350°C) to around 200°C (200°C-250°C).

[0044] In the embodiments shown in figs. 1 - 7, two cooling subzones operating in different ways are provided, specifically the first cooling subzone 112 and the second cooling subzone 113: the first cooling subzone 112 lowers the temperature of the photovoltaic device mainly through direct absorption, by the heat exchanger, of heat radiatively emitted by the photovoltaic device; the second cooling subzone 113 enhances the flow of air close to the photovoltaic device by convection, and the second cooling subzone 113 lowers the temperature of the photovoltaic device mainly by absorbing heat close to the photovoltaic device that is emitted due to air convection. In the first cooling subzone 112, the temperature of the photovoltaic device is higher, and the power of radiative heat dissipation from the photovoltaic device is greater, so radiative cooling is a relatively efficient method of cooling. In the second cooling subzone 113, the temperature of the photovoltaic device has been lowered, and the power of radiative heat dissipation from the photovoltaic device is reduced; convection can increase the power of heat dissipation from the photovoltaic device, so convective cooling is a relatively efficient method of cooling. The combination of the first cooling subzone 112 and second cooling subzone 113 can meet the cooling requirements of the photovoltaic device, cooling the photovoltaic device to a rational temperature range, in order to suit the temperature required for the light treatment section 104. Furthermore, besides the fact that the combination of the first cooling subzone 112 and second cooling subzone 113 enables the photovoltaic device to be cooled to an ideal temperature range, the cooling section 103 has a short length, a small volume and a low manufacturing cost.

[0045] The inventor has learned through observation and experiment that when the temperature of the light treatment section 104 is higher, this will weaken the effectiveness of illumination treatment, such that a longer light treatment time is needed to attain a light attenuation equilibrium state. Thus, the photovoltaic device entering the light treatment section 104 must attain an ideal temperature range, to reduce the light treatment time. The use of the combination of the convective cooling assembly 222 and radiative cooling assembly 221 enables the cooling section 103 to lower the temperature to the temperature required for the light treatment section 104. Thus, the photovoltaic device that has undergone light treatment in the light treatment section 104 attains light attenuation equilibrium.

[0046] In the present application, there is a large temperature difference between the sintering section 102 and the cooling section 103; a certain temperature must be guaranteed inside the sintering section 102, to prevent temperature fluctuations from affecting sintering quality, so air in the cooling section 103 should be prevented from entering the sintering section 102. The distance between the second cooling subzone 113 and the sintering section 102 is not less than 0.85 m, to prevent the airflow generated by the fans from entering the sintering section 102, lowering the temperature close to a sintering zone outlet, causing significant fluctuation in the maximum temperature of the photovoltaic device, and thereby affecting the sintering result. The temperature of the light treatment section 104 is close to the temperature of an outlet of the convective cooling assembly 222, so even if the airflow were to enter the light treatment section 104, the temperature of the light treatment section 104 would not be affected. That is to say, the second cooling subzone 113 employing convective cooling may be arranged immediately adjacent to the light treatment section 104, but cannot be arranged immediately adjacent to the sintering section 102. The first cooling subzone 112 separates the second cooling subzone 113 from the sintering section 102, preventing the airflow from affecting the sintering section 102.

[0047] In the present application, the conveying speed of the conveyor belt is 6 - 10 m/min, and the total length of the first cooling subzone 112 and second cooling subzone 113 is about 1 .5 - 2 m. The first cooling subzone 112 is arranged immediately adjacent to the sintering section 102, so that the photovoltaic device that has been sintered in the sintering section 102 can rapidly enter the first cooling subzone 112 for cooling, to guarantee the light conversion efficiency of the finished photovoltaic device product. If the speed of cooling of the sintered photovoltaic device is too slow, the light conversion efficiency of the finished photovoltaic device product will be affected.

[0048] In the present application, with regard to the heat exchangers arranged in the first cooling subzone 112 and second cooling subzone 113, during use, the heat exchanger in the first cooling subzone 112 generally operates at the maximum design heat exchange power, in order to rapidly lower the temperature of the photovoltaic device. The heat exchanger power and fan power in the second cooling subzone 113 will be adjusted according to the circumstances of use, to cool the photovoltaic device to a suitable temperature range, avoiding too low a photovoltaic device temperature which would affect subsequent illumination treatment. The heat exchanger power can be adjusted by adjusting the flow speed of water in the heat exchange coiled tube. The fan power can be adjusted by adjusting the rotation speed of the fans.

[0049] Although only some features of the present application have been shown and described herein, many improvements and changes could be made by those skilled in the art. Thus, it should be understood that the attached claims are intended to encompass all of the abovementioned improvements and changes which fall within the scope of the essential spirit of the present application.