Composite phase change heat storage tank

Abstract

The invention relates to the technical field of energy storage, in particular to a composite phase change heat storage box. The composite phase change heat storage box comprises a box body, the box body is filled with a composite phase change material, a heat exchange pipe is embedded in the composite phase change material, and an inlet and an outlet of the heat exchange pipe extend out of the box body; the composite phase change material is an EG (at) PW composite phase change material or an EG (at) SA composite phase change material; the EG (at) PW composite phase change material is formed by taking paraffin as a phase change material and compounding the paraffin with expanded graphite according to a certain proportion; the EG (at) SA composite phase change material is formed by taking stearyl alcohol as a phase change material and compounding the stearyl alcohol with expanded graphite according to a certain proportion. According to the invention, the composite phase change material with high energy storage performance and high heat conduction performance is utilized, and waste heat in reclaimed water is stored in the material in a latent heat manner through the heat exchange tube, so that energy in wastewater can be intensively stored and transferred to a specific scene.

Description

Technical Field

[0001] The invention relates to the technical field of energy storage, and in particular to a composite phase-change heat storage box. Background Art

[0002] In industrial production, the treated industrial waste gas and wastewater (recycled water) contain a lot of heat. Since there is no mature technology to make good use of the heat, it leads to huge energy waste, which is not only not conducive to the sustainable development of industrial production, but also causes a certain waste of financial and material resources of enterprises. Summary of the invention

[0003] The purpose of the present invention is to address the above-mentioned deficiencies of the prior art and propose a composite phase-change heat storage tank, which extracts the waste heat from industrial recycled water, stores it, and transfers it, and then uses it as an energy source to heat domestic water, thereby achieving high energy utilization.

[0004] A composite phase-change heat storage box of the present invention comprises a box body, wherein the box body is filled with a composite phase-change material, a heat exchange tube is buried in the composite phase-change material, and the inlet and outlet of the heat exchange tube extend to the outside of the box body;

[0005] The composite phase change material is an EG@PW composite phase change material or an EG@SA composite phase change material;

[0006] The EG@PW composite phase change material uses paraffin as the phase change material and is compounded with expanded graphite in a certain ratio;

[0007] The EG@SA composite phase change material uses stearyl alcohol as a phase change material, and is compounded with expanded graphite in a certain ratio.

[0008] Furthermore, the heat exchange tube is a U-tube or a plate-type hollow tube.

[0009] Furthermore, the box body includes a stainless steel box and a foam box arranged inside the stainless steel box, and an acrylic plate is adhered to the inner wall of the foam box.

[0010] Furthermore, a plurality of temperature sensors are arranged at intervals on the inner wall of the box.

[0011] Furthermore, the mass ratio of paraffin wax to expanded graphite is 18:1-3.

[0012] Furthermore, the mass ratio of stearyl alcohol to expanded graphite is 18:1-3.

[0013] Furthermore, the specific preparation process of the EG@PW composite phase change material is as follows: a certain amount of paraffin is melted and poured into a vacuum emulsifier together with expanded graphite, and then vacuum stirred and impregnated for a period of time to obtain the composite phase change material.

[0014] Furthermore, the specific preparation process of the EG@SA composite phase change material is as follows: a certain amount of stearyl alcohol is melted and poured into a vacuum emulsifier together with expanded graphite, and then vacuum stirred and immersed for a period of time to obtain a composite phase change material.

[0015] The present invention utilizes EG@PW composite phase change material or EG@SA composite phase change material with high energy storage performance and high thermal conductivity, and stores the waste heat in the recycled water in the material in the form of latent heat through heat exchange tubes. Therefore, the energy in the wastewater can be centrally stored and transferred to a specific scene, and then the stored energy can be released to realize the reuse of waste heat of industrial recycled water. The use of the energy storage box reduces energy waste, thereby improving energy utilization, reducing costs for industrial production, and is conducive to the sustainable development of enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1-3 It is a structural schematic diagram of the return U-tube of the embodiment;

[0017] Figure 4 It is a structural schematic diagram of a plate-type hollow tube;

[0018] Figure 5 and 6 This is a real photo of the heat storage box of the present invention;

[0019] Figure 7 The temperature-time curve of heat storage in the vacuum plate heat exchanger heat storage tank at a 70°C hot water source flow rate of 500ml / min;

[0020] Figure 8 It is the self-heating process of the circular U-tube heat storage box;

[0021] Fig. 9 It is the self-heating process of the vacuum plate heat storage box. DETAILED DESCRIPTION

[0022] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0023] (1) Preparation of composite phase change materials

[0024] Weigh 18 kg of paraffin wax (PW) and 2 kg of expanded graphite (EG) respectively, place PW in an oven at 80°C to melt it, and then pour it and EG into a vacuum emulsifier. Figure 1 As shown in the figure, at 75 °C, 40 rpm, vacuum stirring and impregnation for 2 h, a composite phase change material EG@90%PW with a PW loading rate of 90% was obtained. EG@90%PW has a peak power of 176.9 J g -1The phase change enthalpy and 2.94W m -1 k -1 Thermal conductivity.

[0025] 18 kg of hard alcohol (SA) and 2 kg of expanded graphite (EG) were weighed separately, and SA was placed in an oven at 80 ° C to melt it. Then, it was poured into a vacuum emulsifier together with EG, and vacuum stirred and impregnated for 2 h at 75 ° C and 40 rpm to obtain a composite phase change material EG@90%SA with an SA loading rate of 90%. EG@90%SA has a thermal conductivity of 217.4 J g -1 The phase change enthalpy and 3.06W m - 1 k -1 Thermal conductivity.

[0026] (2) Design of heat exchange tubes

[0027] The present invention designs and manufactures two types of heat exchange tubes made of red copper, namely, a return-shaped U-tube and a plate-type hollow tube.

[0028] U-tube Figure 1-3 As shown, high thermal conductivity copper is used as the raw material and arranged in a matrix of 7 rows and 7 columns. The inner diameter of the tube is 4mm, the outer diameter is 6mm, the total length is 13.34m, and the total volume is 0.38dm 3 , heat exchange area 0.252m 2 .

[0029] Plate type hollow tube Figure 4 As shown, four 220mm*220mm*6mm rectangular plates are arranged in parallel at a spacing of 60mm and connected by a tube with an inner diameter of 4mm, an outer diameter of 6mm and a length of 60mm. The total volume is 1.23dm 3 , heat exchange area 0.413m 2 .

[0030] (3) Fabrication of heat storage tank

[0031] The present invention uses a foam box with an outer volume of 390mm*390mm*390mm and an inner volume of 330mm*330mm*330mm as the body of the heat storage box, and sticks an acrylic plate on the inner wall of the foam box to place the composite phase change material in direct contact with the foam box to cause corrosion. The foam box is then placed in a customized stainless steel box to prevent the foam box from being damaged during daily use.

[0032] Then, the heat exchange tube is placed in the box, and the composite phase change material and temperature sensor are placed. The temperature sensor uses Capeson's ultra-fine T-type thermocouple, which is placed in the lower, middle, upper, front, back, left and right positions in the box to observe in real time whether the temperature change of the composite phase change material is uniform during the heat storage box charging and discharging process. Figure 5 and6 shown.

[0033] Two heat storage tanks were made. The first one uses EG@90%PW as the heat storage material and the U-tube as the heat exchanger. The second one uses EG@90%SA as the heat storage material and the plate hollow tube as the heat exchanger. The first heat storage tank can achieve 83682kJ m -3 The heat storage density of the second type of thermal storage tank is 0.84kwh; the second type of thermal storage tank can achieve 108890kJ m -3 The heat storage density is 1.09kwh.

[0034] (4) Test system construction

[0035] The present invention extracts and stores the waste heat of industrial recycled water, and uses it as a heat source to heat domestic water. Therefore, according to actual applications, a test system simulating the actual situation is built in the laboratory, and water is heated by an intelligent temperature control heater to simulate industrial recycled water containing waste heat. Through a peristaltic pump that can intelligently adjust the water flow rate, the hot water source passes through the port of the heat exchange tube extending out of the box to enter the box. When the hot water flows through the box, the heat is transferred to the composite phase change material through the heat exchange tube and stored. Through the temperature sensor placed in the box, the temperature change of the composite phase change material at different positions inside the box can be detected in real time on the computer, and the temperature-time curve can be obtained.

[0036] Example 1

[0037] Investigate the effect of flow rate of 500ml / min on the heat storage performance of the return U-tube heat storage box:

[0038] EG@90%PW, U-tube and 7 temperature sensors are placed in a foam box with an outer volume of 390mm*390mm*390mm and an inner volume of 330mm*330mm*330mm with an acrylic plate on the inner wall and compacted, and then the foam box is placed in a customized stainless steel box. Both ends of the heat exchange tube extend out of the box as water inlet and outlet. A peristaltic pump with intelligent water flow rate adjustment is used to introduce hot water at a constant temperature of 70℃ into the heat exchange tube at a flow rate of 500ml / min. When the hot water flows through the box, the heat is transferred to the composite phase change material through the heat exchange tube and stored. The temperature changes of the composite phase change material at different positions inside the box are detected in real time on the computer through the 7 temperature sensors placed in the box, and the temperature-time curve is obtained.

[0039] Example 2

[0040] Investigate the effect of flow rate of 1000ml / min on the heat storage performance of the return U-tube heat storage tank:

[0041] EG@90%PW, U-tube and 7 temperature sensors are placed in a foam box with an outer volume of 390mm*390mm*390mm and an inner volume of 330mm*330mm*330mm with an acrylic plate on the inner wall and compacted, and then the foam box is placed in a customized stainless steel box. Both ends of the heat exchange tube extend out of the box as water inlet and outlet. A peristaltic pump with intelligent water flow rate adjustment is used to introduce hot water at a constant temperature of 70℃ into the heat exchange tube at a flow rate of 1000ml / min. When the hot water flows through the box, the heat is transferred to the composite phase change material through the heat exchange tube and stored. The temperature changes of the composite phase change material at different positions inside the box are detected in real time on the computer through the 7 temperature sensors placed in the box, and the temperature-time curve is obtained.

[0042] Example 3

[0043] Investigate the effect of flow rate of 1500ml / min on the heat storage performance of the return U-tube heat storage tank:

[0044] EG@90%PW, U-tube and 7 temperature sensors are placed in a foam box with an outer volume of 390mm*390mm*390mm and an inner volume of 330mm*330mm*330mm with an acrylic plate on the inner wall and compacted, and then the foam box is placed in a customized stainless steel box. Both ends of the heat exchange tube extend out of the box as water inlet and outlet. A peristaltic pump with intelligent water flow rate adjustment is used to introduce hot water at a constant temperature of 70℃ into the heat exchange tube at a flow rate of 1500ml / min. When the hot water flows through the box, the heat is transferred to the composite phase change material through the heat exchange tube and stored. The temperature changes of the composite phase change material at different positions inside the box are detected in real time on the computer through the 7 temperature sensors placed in the box, and the temperature-time curve is obtained.

[0045] Example 4

[0046] Investigate the effect of flow rate of 500ml / min on the heat storage performance of plate-type hollow tube heat storage box:

[0047] EG@90%SA, plate-type hollow tubes and 7 temperature sensors were placed in a foam box with an outer volume of 390mm*390mm*390mm and an inner volume of 330mm*330mm*330mm with an acrylic plate on the inner wall and compacted, and then the foam box was placed in a customized stainless steel box. Both ends of the heat exchange tube extend out of the box as water inlets and outlets. A peristaltic pump with intelligent water flow rate adjustment is used to introduce hot water at a constant temperature of 70°C into the heat exchange tube at a flow rate of 500ml / min. When the hot water flows through the box, the heat is transferred to the composite phase change material through the heat exchange tube and stored. The temperature changes of the composite phase change material at different positions inside the box are detected in real time on the computer through the 7 temperature sensors placed in the box, and the temperature-time curve is obtained.

[0048] Example 5

[0049] Investigate the effect of flow rate of 1000ml / min on the thermal storage performance of plate-type hollow tube thermal storage box:

[0050] EG@90%SA, plate-type hollow tubes and 7 temperature sensors were placed in a foam box with an outer volume of 390mm*390mm*390mm and an inner volume of 330mm*330mm*330mm with an acrylic plate on the inner wall and compacted, and then the foam box was placed in a customized stainless steel box. Both ends of the heat exchange tube extend out of the box as water inlets and outlets. A peristaltic pump with intelligent water flow rate regulation is used to introduce hot water at a constant temperature of 70°C into the heat exchange tube at a flow rate of 1000ml / min. When the hot water flows through the box, the heat is transferred to the composite phase change material through the heat exchange tube and stored. The temperature changes of the composite phase change material at different positions inside the box are detected in real time on the computer through the 7 temperature sensors placed in the box, and the temperature-time curve is obtained.

[0051] Example 6

[0052] Investigate the effect of flow rate of 1500ml / min on the heat storage performance of plate-type hollow tube heat storage box:

[0053] EG@90%SA, plate-type hollow tubes and 7 temperature sensors are placed in a foam box with an outer volume of 390mm*390mm*390mm and an inner volume of 330mm*330mm*330mm, with an acrylic plate on the inner wall, and compacted. The foam box is then placed in a customized stainless steel box. Both ends of the heat exchange tube extend out of the box as water inlets and outlets. A peristaltic pump with intelligent water flow rate regulation is used to introduce hot water at a constant temperature of 70°C into the heat exchange tube at a flow rate of 1500ml / min. When the hot water flows through the box, the heat is transferred to the composite phase change material through the heat exchange tube and stored. The temperature changes of the composite phase change material at different positions inside the box are detected in real time on the computer through the 7 temperature sensors placed in the box, and the temperature-time curve is obtained.

[0054] By designing and trial-producing two types of heat storage tanks, the effects of heat exchanger type, composite phase change material selection, and water flow rate on the heat storage and heat release performance of the heat storage tank were explored. -1 ) and thermal conductivity (3.06W m -1 k -1 ) are higher than EG@90%PW(176.9J g -1 ,2.94Wm -1 k -1 ). The heat storage density of the first thermal storage tank (0.84kwh) is also lower than that of the second one (1.09kwh).

[0055] For the two types of heat storage tanks, the three processes of heat storage, self-heat release and heat release are studied respectively. That is, during the heat storage process, how long does it take for hot water with different flow rates to complete the heat storage; during the self-heat release process, how long does the heat storage tank that has completed the heat storage be left still before the heat is completely lost, in order to explore the thermal insulation performance of the heat storage tank; during the heat release process, how long does cold water with different flow rates flow through the tank to heat the cold water?

[0056] Figure 7 The heat storage tank of the vacuum plate heat exchanger is stored with 70℃ hot water at a flow rate of 500ml / min. After charging for about 2h, the composite phase change material reaches the phase change temperature and begins to change phase, and the temperature change tends to be gentle. The phase change is completed in about 10h, and then the temperature rises to 65℃ in a sensible heat manner. The 7 different colors in the figure represent the data of temperature sensors at different positions.

[0057] Figure 8 It is the self-heating process of the circular U-tube heat storage box. The composite phase change material drops from 65°C to the phase change temperature after 8 hours, and then a reverse phase change process occurs, and the temperature changes relatively slowly. The phase change process is completed in about 40 hours, and then the temperature continues to drop to room temperature.

[0058] Fig. 9 It is the self-heating process of the vacuum plate heat storage box. The composite phase change material drops from 65°C to the phase change temperature after 4 hours, and then a reverse phase change process occurs, and the temperature changes relatively slowly. The phase change process is completed in about 30 hours, and then the temperature continues to drop to room temperature.

[0059] For matters not mentioned above, the prior art applies.

[0060] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art to which the present invention belongs may make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but they will not deviate from the direction of the present invention or exceed the scope defined by the attached claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite phase change thermal storage box, characterized in that: It comprises a box body, the box body is filled with a composite phase change material, a heat exchange tube is buried in the composite phase change material, and the inlet and outlet of the heat exchange tube extend to the outside of the box body; The composite phase change material is an EG@PW composite phase change material or an EG@SA composite phase change material; The EG@PW composite phase change material uses paraffin as the phase change material and is compounded with expanded graphite in a certain ratio; The EG@SA composite phase change material uses stearyl alcohol as a phase change material, and is compounded with expanded graphite in a certain ratio.

2. The composite phase change thermal storage box according to claim 1, characterized in that: The heat exchange tube is a return-type U-tube or a plate-type hollow tube.

3. The composite phase change thermal storage box according to claim 1, characterized in that: The box body comprises a stainless steel box and a foam box which is sleeved in the stainless steel box, and an acrylic plate is adhered to the inner wall of the foam box.

4. The composite phase change thermal storage box according to claim 1, characterized in that: A plurality of temperature sensors are arranged at intervals on the inner wall of the box.

5. The composite phase change thermal storage box according to claim 1, characterized in that: The mass ratio of paraffin wax to expanded graphite is 18:1-3.

6. The composite phase change thermal storage box according to claim 1, characterized in that: The mass ratio of stearyl alcohol to expanded graphite is 18:1-3.

7. The composite phase change thermal storage box according to claim 1, characterized in that: The specific preparation process of the EG@PW composite phase change material is as follows: a certain amount of paraffin is melted and poured into a vacuum emulsifier together with expanded graphite, and then vacuum stirred and immersed for a period of time to obtain the composite phase change material.

8. The composite phase change thermal storage box according to claim 1, characterized in that: The specific preparation process of the EG@SA composite phase change material is as follows: a certain amount of stearyl alcohol is melted and poured into a vacuum emulsifier together with expanded graphite, and then vacuum stirred and immersed for a period of time to obtain the composite phase change material.

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