阅读说明：本技术 一种具有圆锥螺旋盘管结构的管壳式相变蓄热装置 (Shell-and-tube phase-change heat storage device with conical spiral coil pipe structure ) 是由 胡定华 林肯 林伯 于 2021-06-11 设计创作，主要内容包括：本发明公开了一种具有圆锥螺旋盘管结构的管壳式相变蓄热装置,包括换热管组、相变蓄热材料及蓄热装置外壳；换热管组包括进口总管、出口总管与圆锥螺旋盘管；圆锥螺旋盘管是一种管中心线在圆锥面上自外向内逐圈旋转的盘管结构；多组圆锥螺旋盘管等间距且同轴地布置在一起；每组螺旋盘管的进口在螺旋外侧,出口在螺旋内侧；这些螺旋盘管的进口与出口分别连接在上而形成了换热管组；该换热管组浸没在相变蓄热材料中,并由蓄热装置外壳包裹,形成了具有圆锥螺旋盘管结构的相变蓄热装置。该装置利用流体旋转过程促进了蓄热过程的进行,具有结构紧凑、蓄热效率高的优点。(The invention discloses a shell-and-tube phase-change heat storage device with a conical spiral coil pipe structure, which comprises a heat exchange pipe set, a phase-change heat storage material and a heat storage device shell; the heat exchange tube group comprises an inlet main pipe, an outlet main pipe and a conical spiral coil; the conical spiral coil is a coil structure in which the central line of the pipe rotates from outside to inside one by one on a conical surface; the multiple groups of conical spiral coil pipes are arranged together in an equidistant and coaxial manner; the inlet of each group of spiral coil pipes is arranged at the outer side of the spiral, and the outlet is arranged at the inner side of the spiral; the inlet and the outlet of the spiral coils are respectively connected to form a heat exchange tube set; the heat exchange tube group is immersed in the phase change heat storage material and is wrapped by the heat storage device shell to form the phase change heat storage device with the conical spiral coil structure. The device utilizes the rotatory process of fluid to promote going on of heat accumulation process, has compact structure, the efficient advantage of heat accumulation.)

1. A shell-and-tube phase-change heat storage device with a conical spiral coil structure comprises a phase-change heat storage device shell, a heat exchange tube set and a phase-change heat storage material, wherein the heat exchange tube set is arranged in the phase-change heat storage device shell; it is characterized in that the preparation method is characterized in that,

the heat exchange tube group comprises a group of inlet main pipes, a group of outlet main pipes and a plurality of groups of conical spiral coil pipes; the conical spiral coil is of a coil structure with a pipe center line rotating on a conical surface from outside to inside circle by circle, and the conical spiral coils are coaxially arranged at equal intervals; the bending radius of the conical spiral coil is gradually reduced to improve the turbulence of the fluid.

2. A shell-and-tube phase-change thermal storage device with a conical spiral coil structure according to claim 1, characterized in that the heat exchange tube set and the phase-change thermal storage device shell are aluminum, copper or stainless steel.

3. A shell-and-tube phase-change thermal storage device with a conical spiral coil structure according to claim 1, characterized in that the phase-change thermal storage material is paraffin, fatty acid or molten salt.

4. A shell-and-tube phase-change thermal storage device with a conical helical coil structure according to claim 1, characterized in that the multiple sets of conical helical coil structures are in a nested relationship.

5. A shell-and-tube phase-change thermal storage device with a conical spiral coil structure according to claim 1, characterized in that the lengths l (r) of the different bending radius coils of the conical spiral coil satisfy the following formula:

wherein the heat transfer coefficient

h_liq、h_pip、h_PCMRespectively representing the heat transfer coefficient of the fluid, the heat transfer coefficient of the heat exchange tube wall and the heat transfer coefficient of the phase change heat storage material; r is the bending radius of the coil; n is a coil correction coefficient; q is the heat storage power, and dT is the temperature difference between the input fluid and the phase change heat storage material.

6. A method for determining key parameters of a shell-and-tube phase-change heat storage device with a conical spiral coil structure is characterized by comprising the following steps:

step 1, calculating heat transfer coefficient h of fluid in phase change heat storage device_liqHeat transfer coefficient h of heat exchange tube wall_pipAnd heat transfer coefficient h of phase change heat storage material_PCM；

Step 2, calculating heat transfer coefficients h (r) of coils with different bending radii:

wherein r is the coil bend radius; n is a coil correction coefficient;

step 3, establishing the following equation based on the heat storage power requirement and the conical spiral shape requirement to determine the lengths l (r) of the coils with different bending radii and establish corresponding conical spiral coil structures;

wherein q is the heat storage power, dT is the temperature difference between the input fluid and the phase change heat storage material, and d₂Is the outer diameter of the heat exchange tube.

7. Method for determining a key parameter according to claim 5, characterised in that step 1 the fluid heat transfer coefficient h_liqHeat transfer coefficient h of heat exchange tube wall_pipAnd heat transfer coefficient h of phase change heat storage material_PCMRespectively as follows:

wherein d is₁E is the inner diameter of the heat exchange tube and the thickness of the phase change heat storage material layer respectively; mu.s_liq、c_liq、v_liq、ρ_liqHydrodynamic viscosity, isobaric specific heat capacity, linear flow rate and density; lambda [ alpha ]_liq、λ_pip、λ_PCMThe heat conductivity coefficients of the fluid, the heat exchange tube and the phase change heat storage material are respectively.

Technical Field

The invention belongs to the field of phase change heat storage, and particularly relates to a shell-and-tube phase change heat storage device with a conical spiral coil structure.

Background

The solar power generation technology is a clean and pollution-free energy technology, but because the solar energy is periodically fluctuated in the daytime in the collection process, the stable operation of the power generation process is influenced, and the solar power generation technology is not suitable for directly using the solar energy for power generation. To solve this problem, a phase change heat storage device is often used to store the collected solar energy in the form of thermal energy and stably supply it to a power generation device.

The shell-and-tube phase-change heat storage device is a classic phase-change heat storage device and has mature processing and manufacturing experience. Conventional phase change thermal storage devices, such as the phase change thermal storage device of patent No. 201010119607.3, use heat exchange tube bundles that spread out on a flat surface to store heat. Along with the progress of heat accumulation process, the temperature of the fluid flowing in the phase-change heat accumulation device is gradually reduced, the heat accumulation effect of the heat exchange tube bundle in the phase-change heat accumulation device is gradually reduced, and a large amount of phase-change heat accumulation materials at the tail end of the heat exchange tube bundle can not participate in the heat accumulation process.

In order to solve the problem, patent No. 201621087825.2 proposes a pitch-gradient spiral coil heat accumulator, which reduces the thickness of a phase-change heat accumulation layer at the end of a heat exchange tube bundle, promotes the melting of a phase-change heat accumulation material, but correspondingly increases the length of the heat exchange tube bundle and consumes more metal materials.

Disclosure of Invention

The invention aims to provide a shell-and-tube phase-change heat storage device with a conical spiral coil structure, so as to achieve the purpose of reducing consumption of heat-conducting metal materials and phase-change heat storage materials on the premise of meeting the phase-change heat storage requirements.

The technical solution for realizing the purpose of the invention is as follows:

a shell-and-tube phase-change heat storage device with a conical spiral coil structure comprises a phase-change heat storage device shell, a heat exchange tube set and a phase-change heat storage material, wherein the heat exchange tube set is arranged in the phase-change heat storage device shell;

the heat exchange tube group comprises a group of inlet main pipes, a group of outlet main pipes and a plurality of groups of conical spiral coil pipes; the conical spiral coil is of a coil structure with a pipe center line rotating on a conical surface from outside to inside circle by circle, and the conical spiral coils are coaxially arranged at equal intervals; the bending radius of the conical spiral coil is gradually reduced to improve the turbulence of the fluid.

A method for determining key parameters of a shell-and-tube phase-change heat storage device with a conical spiral coil structure comprises the following steps:

step 1, calculating heat transfer coefficient h of fluid in phase change heat storage device_liqHeat transfer coefficient h of heat exchange tube wall_pipAnd heat transfer coefficient h of phase change heat storage material_PCM；

Step 2, calculating heat transfer coefficients h (r) of coils with different bending radii:

wherein r is the coil bend radius; n is a coil correction coefficient;

step 3, establishing the following equation based on the heat storage power requirement and the conical spiral shape requirement to determine the lengths l (r) of the coils with different bending radii and establish corresponding conical spiral coil structures;

wherein q is the heat storage power, dT is the temperature difference between the input fluid and the phase change heat storage material, and d₂Is the outer diameter of the heat exchange tube.

Compared with the prior art, the invention has the following remarkable advantages:

(1) by the conical spiral coil pipe structure, the invention consumes less metal heat conduction materials and phase change heat storage materials on the premise of meeting the phase change heat storage requirement, and has a more compact structure.

(2) Through the structure of the conical spiral coil pipe, the length of the central low-bending-radius part of the spiral coil pipe is effectively improved. And the heat transfer coefficient of the central low-bending radius part of the spiral coil is higher, so that the heat storage efficiency of the phase change heat storage device is effectively improved by prolonging the part.

Drawings

Fig. 1 is an assembly view of a phase change thermal storage device.

Fig. 2(a-c) are schematic isometric, side and top views, respectively, of a conical helical coil structure.

Fig. 3 is a structural view of a heat exchange tube group.

FIG. 4 is a plot of coil correction coefficients for a 20 ℃ heat transfer differential.

Detailed Description

The invention is further described with reference to the following figures and embodiments.

Referring to fig. 1, fig. 2(a-c) and fig. 3, the shell-and-tube phase-change heat storage device with a conical spiral coil structure according to the present invention includes a heat exchange tube set 1, a phase-change heat storage material 2 and a phase-change heat storage device housing 3.

The heat exchange tube set 1 comprises an inlet header pipe 4, an outlet header pipe 5 and a plurality of sets of conical spiral coils (in this embodiment, two types of conical spiral coils 6 and 7 are adopted). The conical spiral coils 6 and 7 are a coil structure (as shown in fig. 2) in which the central line of the pipe rotates from outside to inside on the conical surface one by one, and the bending radius of the coil structure is gradually reduced to be consistent with the outer diameter of the pipe. The surfaces of the inlet manifold 4 and the outlet manifold 5 are provided with openings, and the conical spiral coils 6 and 7 are inserted into the openings on the surfaces of the inlet manifold 4 and the outlet manifold 5 and are tightly connected. The inlet header pipe 4 and the outlet header pipe 5 are connected with the conical spiral coils 6 and 7 to form the heat exchange group 1 (as shown in figure 3). The inlet of each set of spiral coils is arranged at the outer side of the spiral, and the outlet is arranged at the inner side of the spiral. The heat exchange tube group is immersed in the phase change heat storage material and is wrapped by the heat storage device shell to form the phase change heat storage device with the conical spiral coil structure. The phase change heat storage device shell 3 is a cylindrical barrel, and a heat exchange tube group hole 8 is formed in the top of the barrel. The conical spiral coil pipes 6 and 7 are nested in structure, and the conical top of the conical spiral coil pipe 7 is coincided with the conical bottom of the conical spiral coil pipe 6.

Further, after the heat exchange tube group 1 is verified to have good tightness through a water pressure test, the heat exchange tube group 1 is placed in the phase change heat storage device shell 3 and fixed, and the phase change heat storage material which is melted into a liquid state is filled in the phase change heat storage device shell 3 until the phase change heat storage material passes through the conical spiral coils 6 and 7. The shell 3 of the closed phase-change heat storage device forms a shell-and-tube phase-change heat storage device with a conical spiral coil structure.

The heat exchange tube set 1 is made of aluminum, copper or stainless steel. The bottom of the phase change heat storage device shell is provided with a heat exchange tube bundle positioning and supporting structure, the top of the phase change heat storage device shell is provided with a heat exchange tube bundle opening, and the phase change heat storage device shell is made of aluminum, copper or stainless steel. The phase-change heat storage material 2 is paraffin, fatty acid or molten salt, or corresponding materials are selected according to the phase-change temperature requirement.

The phase change heat storage function of the device is mainly realized by the heat exchange tube group 1 and the phase change heat storage material together. The hot fluid is input into the device from the inlet of the heat exchange tube group 1 and is in heat transfer with the phase change heat storage material with lower temperature in the device, so that the heat is stored in the form of latent heat of the phase change heat storage material.

In traditional shell-and-tube phase change heat storage device, along with the fluid flows from the input to the output, the difference in temperature between fluid and the phase change heat storage material reduces gradually for phase change heat storage device's heat accumulation effect weakens gradually from the input to the output. In the shell-and-tube phase-change heat storage device with the conical spiral coil pipe structure, the bending radius of the pipeline is gradually reduced from the input end to the output end, the turbulence degree of the fluid is gradually improved, and the heat exchange process between the fluid and the phase-change heat storage material is promoted. Because the influence of the reduction of the heat transfer temperature difference and the improvement of the fluid turbulence degree is simultaneously received, the heat storage effect of the phase change heat storage device is not greatly changed from the input end to the output end, and the compactness of the phase change heat storage device is favorably improved.

A method for determining key parameters of a shell-and-tube phase-change heat storage device with a conical spiral coil structure comprises the following steps:

step 1, calculating heat transfer coefficients h of all parts in the phase change heat storage device_liq，h_pipAnd h_PCM：

Wherein h is_liq、h_pip、h_PCMRespectively representing the heat transfer coefficient of the fluid, the heat transfer coefficient of the heat exchange tube wall and the heat transfer coefficient of the phase change heat storage material; d₁、d₂E is the inner diameter and the outer diameter of the heat exchange tube and the thickness of the phase change heat storage material layer respectively; mu.s_liq、c_liq、v_liq、ρ_liqHydrodynamic viscosity, isobaric specific heat capacity, linear flow rate and density; lambda [ alpha ]_liq、λ_pip、λ_PCMThe heat conductivity coefficients of the fluid, the heat exchange tube and the phase change heat storage material are respectively.

Step 2, calculating heat transfer coefficients h (r) of coils with different bending radii:

wherein r is the coil bend radius; n is coil correction coefficient, which is composed of coil bending radius r and coil external diameter d₂The ratio determination can be obtained through numerical simulation or experimental calculation.

Step 3, determining the lengths l (r) of the coils with different bending radii according to the following equation and establishing corresponding conical spiral coil structures;

wherein q is the heat storage power, and dT is the temperature difference between the input fluid and the phase change heat storage material. The two equations of the equation respectively and correspondingly meet the requirements of heat storage power and conical spiral shape.

And 4, adjusting the outer diameter of the heat exchange tube, recalculating l (r) and establishing a conical spiral structure. And comparing conical spiral structures with different heat exchange tube outer diameters, and selecting the lowest quality of the device as a final design result.

Examples

The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

Step 1, calculating the heat transfer coefficients of all parts respectively:

a copper tube with the outer diameter of 6mm and the inner diameter of 5mm is selected as a heat exchange tube, and the heat transfer coefficient is 728 kW/(m)²K); deionized water as fluid working medium, input temperature of 80 deg.C, input flow rate of 0.8m/s, and heat transfer coefficient of 73.9W/(m)²K); no. 58 refined paraffin is a phase change heat storage material, the thickness is 5mm, and the heat transfer coefficient is 52.4W/(m)²·K)。

And 2, obtaining a coil correction coefficient n shown in the following figure 4 through numerical simulation.

And 3, calculating to obtain the maximum bending radius of the conical spiral coil pipe of 50mm, the minimum bending radius of 20mm, the spiral stage interval of 10mm, the whole conical spiral comprises 4 revolutions, and the distance between the conical spiral coil pipes is 40 mm.

Step 4, in order to meet the requirements of the conical spiral coil, the radius of the shell of the phase change heat storage device is designed to be 60mm, the height of the shell is 160mm, the wall thickness of the shell is 1mm, and the shell is made of aluminum; designing the inlet main pipe and the outlet main pipe to be red copper heat exchange pipes with the diameter of 8mm, and welding and sealing the bottoms of the pipes; the minimum filling height of the phase change heat storage material is designed to be 130mm so as to ensure that the phase change heat storage material is completely immersed in the conical spiral coil; the maximum filling height is 150mm to prevent the phase change heat storage material from overflowing during melting.

The total weight of the phase change heat storage device is about 2.2kg, the volume is about 1.8L, after continuous heat storage for 1800s, the number 58 refined paraffin filled in the device as the phase change heat storage material is melted by more than 60%, and the heat storage capacity can reach 150 kJ.