CN111306811A - An all-glass heat-pipe vacuum collector tube with a CPC concentrator - Google Patents

Abstract

The invention discloses an all-glass heat pipe type vacuum heat collector tube with a CPC concentrator, comprising a glass outer tube, a glass heat tube extending into the glass outer tube and seamlessly fixedly connected with the opening of the glass outer tube. The vacuum degree in the cavity between the glass outer tube and the glass heat pipe is less than 1×10-4Pa, and a support structure and a getter are placed therein. The glass heat pipe is equipped with a heat transfer medium, and the glass heat pipe is located in the glass outer tube. The part outside the glass outer tube becomes the heating section, the part outside the glass outer tube is inserted into the hot water tank to become the condensation section, the outer wall of the heating section is coated with an endothermic coating, and the glass outer tube and the glass heat pipe use the same Glass, a CPC concentrator is arranged between the glass outer tube and the glass heat pipe. The invention adopts an all-glass heat pipe type vacuum heat collector to solve the airtight connection problem of the metal-glass vacuum heat collector, and at the same time, a CPC concentrator is inserted into the vacuum area between the heat pipe and the outer pipe, which improves the thermal efficiency.

Description

An all-glass heat-pipe vacuum collector tube with a CPC concentrator

technical field

The invention relates to an all-glass heat pipe type vacuum heat collecting tube with a CPC concentrator, which is suitable for a solar concentrating heat collecting water heater of a non-tracking device system, and belongs to the technical field of solar heat collecting.

Background technique

As a clean, non-polluting renewable energy, the development and utilization of solar energy is considered to be an important part of the world's energy strategy, especially when dealing with challenging issues such as energy crisis and environmental pollution, its efficient development and utilization are even more important. important. According to the working range of solar collectors, it can be divided into three categories: low temperature collectors (<100℃), medium temperature collectors (100℃～250℃) and high temperature collectors (>250℃). Domestic hot water below 100°C is produced by low-temperature collectors. At present, low-temperature collectors are mainly divided into flat-plate collectors and vacuum tube collectors.

The flat plate collector has a simple structure and is convenient to use, but the efficiency is not high and the heat loss is large. The loss is mainly caused by radiation and convection heat transfer between the heat collector plate and the transparent cover. In order to reduce the heat loss of the collector, the heat loss can be reduced by evacuating the heat collector plate and the transparent cover plate, but this method cannot guarantee the sealing performance between large areas and the vacuum degree is difficult to maintain for a long time. However, vacuum can be maintained between the inner and outer tubes of the vacuum tube collector for a long time, which reduces the heat loss between the outer glass tube and the heat absorption tube and improves the thermal efficiency. Evacuated tube collectors are mainly divided into two categories, all-glass evacuated tube collectors and metal-glass evacuated tube collectors. Although the all-glass vacuum heat collector tube has many advantages, there are still many shortcomings. It is difficult to carry out convection heat transfer, the resistance is large, and the water at the bottom of the pipe is difficult to flow, which will affect the water quality in the pipe for a long time, and affect the quality of the hot water in the entire system; the pipe is made of glass, which is prone to accidental damage to the pipe in the open air. When the tube is damaged, it will directly affect the operation of the overall collector, and the water in the water tank will flow out from the damaged tube and cannot work normally. In order to further improve and improve its heat exchange efficiency, improvements are made on the basis of all-glass vacuum heat collectors, thereby leading to metal-glass vacuum heat collectors. There is no water in the metal-glass vacuum heat collector tube, and it will not be directly exchanged with the water in the water tank. The damage of one tube will not affect the normal operation of the system. It can be widely used in household solar water heaters. Due to the low quality of the working fluid in the heat pipe, the heat capacity is small. Therefore, the start-up is fast, and the introduction of heat pipes improves the heat transfer performance to a certain extent. However, due to the large difference in thermal expansion coefficients between metal and glass, there is a technical problem of hermetic connection between glass and metal. Research has been carried out, but no industrialized application has yet been formed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose an all-glass heat pipe type vacuum heat collector tube with a CPC concentrator (ie a compound parabolic concentrator) in view of the above-mentioned problems. The airtight connection of the vacuum heat collector is a problem. At the same time, a CPC concentrator is inserted in the vacuum area between the heat pipe and the outer pipe, which improves the thermal efficiency.

The object of the present invention is achieved through the following technical solutions:

An all-glass heat pipe type vacuum heat collector tube with a CPC concentrator, comprising a glass outer tube, a glass heat pipe extending into the glass outer tube and seamlessly fixedly connected with the opening of the glass outer tube, the glass outer tube The vacuum degree in the cavity between the glass heat pipe and the glass heat pipe is less than 1×10-4Pa, and the supporting structure and the getter are placed in it. The part outside the glass outer tube is inserted into the hot water tank to become the condensation section, the outer wall of the heating section is coated with an endothermic coating, the glass outer tube and the glass heat pipe are made of the same glass, and the A CPC concentrator is arranged between the glass outer tube and the glass heat pipe.

The all-glass heat pipe type vacuum heat collector tube with a CPC concentrator, the CPC concentrator includes a CPC-type structure, and the CPC-type structure and the glass outer tube have the same material and are integrally formed, so that the The glass outer tube becomes a structure with a CPC type and a semicircle in section, the outer or inner layer of the CPC type structure is coated with a reflective coating, and the section profile of the CPC type structure is an involute and a transition platform in the middle, The base circle of the involute is the cross-sectional circle of the heating section of the glass heat pipe. Let the radius of the base circle be r, the equation of the involute is:

where L is the arc length of the involute angle β, and L:

The involute is symmetrically distributed. The involute starts from the bottom end of the base circle and ends when both sides are flush with the center of the base circle. The distance between the transition platform in the middle and the bottom end of the base circle is H, and H is 3-5mm;

The semicircular structure of the glass outer tube integrated with the CPC type structure is concentric with the heating section of the glass heat pipe, and the radius R of the semicircular part is:

The all-glass heat pipe type vacuum heat collector tube with a CPC concentrator, the CPC concentrator includes a reflector with a CPC structure, and the CPC reflector is inserted into the glass outer tube and the glass In the cavity between the heat pipes, the section profile of the CPC type reflector is an involute and a transition platform in the middle, and the base circle of the involute is the cross-sectional circle of the heating section of the glass heat pipe. If the radius is r, the equation of the involute is:

where L is the arc length of the involute angle β, and L:

The involute is symmetrically distributed. The involute starts from the bottom end of the base circle and ends when both sides are flush with the center of the base circle. The distance between the transition platform in the middle and the bottom end of the base circle is H, and H is 3-5mm.

In the all-glass heat-pipe vacuum heat-collecting tube with a CPC concentrator, the glass outer tube and the glass heat tube are made of the same high borosilicate glass, and the thermal expansion coefficient is (3.3±0.1)×10 ^-6 /K. Wall thickness 2-3mm.

In the all-glass heat pipe type vacuum heat collector tube with a CPC concentrator, the length of the heating section is greater than the length of the condensation section, and the ratio is between 4:1 and 5:1.

In the all-glass heat pipe type vacuum heat collector tube with CPC concentrator, the support structure is fixed at the end of the heating section of the glass heat pipe.

For the all-glass heat pipe type vacuum heat collecting tube with CPC concentrator, the heat transfer working medium is selected from one or more combinations of antifreeze, water, acetone and ethanol, and the mass is greater than 0.00896kg.

In the all-glass heat-pipe vacuum heat-collecting tube with a CPC concentrator, the absorption coating is a multi-layer graded aluminum-nitrogen-aluminum (Al-N/Al).

Beneficial effects:

The invention adopts the glass heat pipe to solve the problem of different material expansion coefficients, and at the same time, compared with the metal heat pipe type vacuum heat collector, the manufacturing cost is reduced, and the integrated production and market promotion are convenient, and the glass material has very good light transmittance, chemical Stability and tightness improve the service life of the collector tube.

The present invention improves the efficiency through the CPC concentrator, thereby reducing the cost.

The collector in this paper is a gravity heat pipe, without a liquid absorbing core, with a simple structure, convenient manufacture, low cost, and a heat transfer capacity and working limit far greater than that of an ordinary cored heat pipe.

Description of drawings

FIG. 1 is a schematic structural diagram of an all-glass heat-pipe vacuum heat-collecting tube with a CPC concentrator of the present invention.

FIG. 2 is a cross-sectional view of the all-glass heat-pipe vacuum heat-collecting tube with a CPC concentrator according to Embodiment 1 of the present invention.

FIG. 3 is a cross-sectional view of the all-glass heat-pipe vacuum heat-collecting tube with a CPC concentrator according to Embodiment 2 of the present invention.

Detailed ways

The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

Embodiment 1, as shown in Figures 1-2, the all-glass heat pipe type vacuum heat collector tube with a CPC concentrator in this embodiment includes a glass outer tube 1, which extends into the glass outer tube and is connected to the opening of the glass outer tube. The glass heat pipe 2 is seamlessly fixed and connected together, the vacuum degree in the cavity between the glass outer pipe and the glass heat pipe is less than 1×10-4Pa, and the support structure 6 and the getter are placed in it, and the glass heat pipe is equipped with Heat transfer medium 4, the part of the glass heat pipe located in the glass outer pipe becomes the heating section 2-1, the part located outside the glass outer pipe is inserted into the hot water tank to become the condensation section 2-2, the outer wall of the heating section is coated with Covered with an endothermic coating 3, the glass outer tube and the glass heat pipe are made of the same glass, and a CPC concentrator 5 is arranged between the glass outer tube and the glass heat pipe.

In this embodiment, the CPC concentrator includes a CPC-type structure. The CPC-type structure and the glass outer tube have the same material and are integrally formed, so that the glass outer tube has a CPC-type and semi-circular-shaped structure in one section. , the outer or inner layer of the CPC-type structure is coated with a reflective coating. The reflective coating in this embodiment is sprayed with a reflective silver film through the production process of magnetron sputtering. The reflective film is silver, aluminum and paint in turn, silver and The thickness of aluminum is 0.2mm, and the thickness of paint is 0.5mm. The section profile of the CPC type structure is an involute and a transition platform in the middle. The base circle of the involute is the cross-sectional circle of the heating section of the glass heat pipe. Let the radius of the base circle be r, then the involute is The equation is:

where L is the arc length of the involute angle β, and L:

The involute is symmetrically distributed. The involute starts from the bottom end of the base circle and ends when both sides are flush with the center of the base circle. The distance between the transition platform in the middle and the bottom end of the base circle is H, and H is 3-5mm;

The semicircular structure of the glass outer tube integrated with the CPC type structure is concentric with the heating section of the glass heat pipe, and the radius R of the semicircular part is:

In this embodiment, the diameter of the semicircular portion of the glass outer tube (1) is 58 mm, and the diameter of the glass heat pipe (2) is 47 mm. The radius of the base circle is r=23.5mm, the angle β when the involute is parallel to the base circle is 70.3°, the length of the involute L is 51.4mm, the radius of the outer circle of the glass is 56.5mm, and the starting position of the involute is far from the base. The distance H from the lowest end of the circle is 4mm.

In the all-glass heat-pipe vacuum heat-collecting tube with a CPC concentrator, the glass outer tube and the glass heat tube are made of the same high borosilicate glass, and the thermal expansion coefficient is (3.3±0.1)×10 ^-6 /K. Wall thickness 2-3mm.

In the all-glass heat pipe type vacuum heat collector tube with a CPC concentrator, the length of the heating section is greater than the length of the condensation section, and the ratio is between 4:1 and 5:1. The total length of the glass heat pipe in this embodiment is 1800 mm.

In the all-glass heat pipe type vacuum heat collector tube with CPC concentrator, the support structure is fixed at the end of the heating section of the glass heat pipe.

For the all-glass heat pipe type vacuum heat collecting tube with CPC concentrator, the heat transfer working medium is selected from one or more combinations of antifreeze, water, acetone and ethanol, and the mass is greater than 0.00896kg.

In the all-glass heat-pipe vacuum heat-collecting tube with a CPC concentrator, the absorption coating is a multi-layer graded aluminum-nitrogen-aluminum (Al-N/Al).

Compared with the traditional all-glass evacuated tube heat collector, the all-glass heat-pipe type evacuated heat collector with a CPC concentrator in this embodiment improves the efficiency by 6.5% and the response speed by 20%.

Example 2:

The difference between this embodiment and Embodiment 1 is that the all-glass heat pipe type vacuum heat collector tube with a CPC concentrator described in this embodiment, the CPC concentrator includes a reflector with a CPC type structure, The CPC-type reflector is inserted into the cavity between the glass outer tube and the glass heat pipe. The cross-section profile of the CPC-type reflector is an involute and an intermediate transition platform. The base circle of is the cross-sectional circle of the heating section of the glass heat pipe, and let the radius of the base circle be r, the equation of the involute is:

where L is the arc length of the involute angle β, and L:

The involute is symmetrically distributed. The involute starts from the bottom end of the base circle and ends when both sides are flush with the center of the base circle. The distance between the transition platform in the middle and the bottom end of the base circle is H, and H is 3-5mm.

The above embodiments are only used to illustrate the design ideas and features of the present invention, and the purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications made according to the principles and design ideas disclosed in the present invention fall within the protection scope of the present invention.

Claims (8)

1. an all-glass heat pipe type vacuum heat collector tube with a CPC concentrator, comprising a glass outer tube, a glass heat pipe extending into the glass outer tube and seamlessly fixedly connected to the opening of the glass outer tube, the glass The vacuum degree in the cavity between the outer tube and the glass heat pipe is less than 1×10-4Pa, and the supporting structure and getter are placed in it. The glass heat pipe is equipped with a heat transfer medium, and the glass heat pipe is located in the part of the glass outer tube. It becomes a heating section, the part outside the glass outer tube is inserted into the hot water tank to become a condensation section, and the outer wall of the heating section is coated with an endothermic coating, characterized in that the glass outer tube and the glass heat pipe are made of For the same glass, a CPC concentrator is arranged between the glass outer tube and the glass heat pipe. 2 . The all-glass heat pipe type vacuum heat collector tube with a CPC concentrator according to claim 1 , wherein the CPC concentrator comprises a CPC type structure, and the CPC type structure is connected to the outer glass surface. 3 . The tube has the same material and is integrally formed, so that the glass outer tube has a structure with a CPC type and a semi-circular section. The outer or inner layer of the CPC type structure is coated with a reflective coating. is the involute and the transition platform in the middle. The base circle of the involute is the cross-sectional circle of the heating section of the glass heat pipe. Let the radius of the base circle be r, the equation of the involute is:

where L is the arc length of the involute angle β, and L:

The involute is symmetrically distributed. The involute starts from the bottom end of the base circle and ends when both sides are flush with the center of the base circle. The distance between the transition platform in the middle and the bottom end of the base circle is H, and H is 3-5mm; The semicircular structure of the glass outer tube integrated with the CPC type structure is concentric with the heating section of the glass heat pipe, and the radius R of the semicircular part is:

3. The all-glass heat pipe type vacuum heat collector tube with a CPC concentrator according to claim 1, wherein the CPC concentrator comprises a reflector of a CPC type structure, and the reflector of the CPC type Insert into the cavity between the glass outer tube and the glass heat pipe, the section profile of the CPC type reflector is an involute and a transition platform in the middle, and the base circle of the involute is heated by the glass heat pipe The cross-sectional circle of the segment, let the radius of the base circle be r, then the equation of the involute is:

where L is the arc length of the involute angle β, and L:

The involute is symmetrically distributed. The involute starts from the bottom end of the base circle and ends when both sides are flush with the center of the base circle. The distance between the transition platform in the middle and the bottom end of the base circle is H, and H is 3-5mm. 4. The all-glass heat pipe type vacuum heat collector tube with a CPC concentrator according to claim 1, 2 or 3, wherein the glass outer tube and the glass heat pipe are made of the same high borosilicate glass, and the thermal expansion coefficient is the same. It is (3.3±0.1)×10 ^-6 /K, and the thickness of the pipe wall is 2-3mm. 5. The all-glass heat pipe type vacuum heat collecting tube with a CPC concentrator according to claim 1 or 2 or 3, wherein the length of the heating section is greater than the length of the condensation section, and the ratio is 4:1 -5:1. 6 . The all-glass heat pipe type vacuum heat collector tube with a CPC concentrator according to claim 1 , wherein the support structure is fixed at the end of the heating section of the glass heat pipe. 7 . 7. The all-glass heat pipe type vacuum heat collecting tube with CPC concentrator according to claim 1 or 2 or 3, wherein the heat transfer working medium is selected from antifreeze, water, acetone, and one of ethanol. One or more combinations, and the mass is greater than 0.00896kg. 8. The all-glass heat pipe type vacuum heat collector tube with a CPC concentrator according to claim 1, 2 or 3, wherein the absorption coating is a multi-layer graded aluminum nitride aluminum (Al-N/Al ).

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