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Multi-cascaded phase change heat storage device with built-in fins, and enhanced heat transfer method

A phase change heat storage and multi-cascade technology, which is applied in heat transfer modification, heat storage equipment, indirect heat exchangers, etc. , to enhance the effect of heat transfer

Active Publication Date: 2021-02-26
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the thickness of the fins in the prior art gradually increases, after the experimental demonstration of the invention, the invention cannot meet the requirements of heat transfer speed, so a multi-cascade phase change heat storage device and its heat transfer method are urgently needed

Method used

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  • Multi-cascaded phase change heat storage device with built-in fins, and enhanced heat transfer method
  • Multi-cascaded phase change heat storage device with built-in fins, and enhanced heat transfer method
  • Multi-cascaded phase change heat storage device with built-in fins, and enhanced heat transfer method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] figure 1 and figure 2 The three-stage phase change heat storage system is shown. The three-stage phase change heat storage modules of the system are composed of three vertically placed shell-and-tube heat exchangers. The shell side of each heat exchanger is filled with a Phase change materials, phase change materials are arranged according to the phase change temperature from high to low, and the three-level phase change heat storage modules are named PCM1, PCM2 and PCM3 in sequence. Three different nitrate mixtures including solar salt (60wt.% NaNO 3 -40wt.% KNO 3 , phase transition temperature is 494.15 K), binary nitrate (46wt.%NaNO 3 -54wt.% LiNO 3 , phase transition temperature is 463.75 K) and Hitec salt (7wt.% NaNO 3 -40wt.% NaNO 2 -53wt.% KNO 3 , with a phase transition temperature of 415.59 K), which were successively selected as PCM1, PCM2, and PCM3. During the heating process, the heat transfer fluid flows through the tube side channels of PCM1, PCM2...

Embodiment 2

[0030]Fin arrangement: fins of the same size are used in the phase change heat storage units at all levels, the height of a single fin is 12 mm, and the thickness is 2 mm. Arrange the same number of fins at equal intervals. In the case of non-uniform number of fins, 4 fins are arranged at equal intervals in the first stage phase change heat storage unit, 8 fins are arranged at equal intervals in the second stage phase change heat storage unit, and 8 fins are arranged at equal intervals in the third stage phase change heat storage unit. No fins are arranged in the heat unit. The total number of fins is 12.

[0031] Figure 4 The change curve of the total time of charging and discharging of the system under uniform and non-uniform working conditions is shown. Since the total charging and discharging time of PCM2 is longer than that of PCM1 and PCM3, the total charging and discharging time of PCM2 is the total charging and discharging time of the system. It can be seen from t...

Embodiment 3

[0034] The specific design process of the built-in fins is as follows:

[0035] Step 1: Use ANSYS Fluent software to simulate the heat charging and discharging process of the three-cascade phase change heat storage device with 0, 2, 4, 6 or 8 fins arranged at equal intervals in each phase change heat storage unit, where the height of the fins is and the thickness are 12 mm and 2 mm respectively, record the charging and discharging time of the phase change heat storage units at all levels, and compare the charging and discharging times under the conditions of the five fin numbers, so as to determine that the total number of fins is 12.

[0036] Step 2: Use ANSYS Fluent software to simulate the heat charging and discharging process of the three-cascade phase change heat storage device with the fins of 8, 10, 12, 14 or 16 mm at equal intervals at all levels of phase change heat storage units. The number of fins in each stage is 4 mm. Record the charging and discharging time of th...

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Abstract

The invention discloses a multi-cascade phase change heat storage device with built-in fins, and an enhanced heat transfer method. The heat storage device comprises phase change materials, phase change heat storage units, heat-conducting fluid, a heat-conducting fluid channel and the fins. The heat-conducting fluid flows through the phase change heat storage units through the heat-conducting fluidchannel. The fins are arranged in the phase change material sides of the phase change heat storage units of each stage, and are close to the outer wall face of the heat-conducting fluid channel. Through the above way, according to the device provided by the invention, a large number of fins can be arranged for a phase-change material container with poor heat transfer and release performance according to different heat transfer and release performances of the phase change materials of each stage, and a small number of fins are arranged for a phase-change material container with good heat transfer and release performance; furthermore, the fins in the phase change containers are arranged at unequal intervals, unequal heights or unequal thicknesses according to the heat transfer and release processes of the phase change containers of each stage; and finally overall efficient enhanced heat transfer of the multi-cascade phase change heat storage device is achieved at the cost of less fins.

Description

technical field [0001] The invention relates to a multi-cascade phase change heat storage device with built-in fins and a method for enhancing heat transfer; it belongs to the application field of fin enhanced heat transfer technology and phase change heat storage systems. Background technique [0002] In recent decades, renewable energy has been considered as the most effective way to alleviate the rapidly increasing energy demand and the environmental problems brought about by traditional fossil energy. As a renewable energy with huge reserves and clean energy, solar energy is a very promising alternative energy source. Among the various technologies of solar energy utilization, concentrating solar thermal power generation technology has attracted extensive attention because of its renewable and dispatchable capabilities. Moreover, concentrating solar power plants are easy to integrate with thermal storage systems (TES), which greatly improves its flexibility. and competi...

Claims

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Application Information

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IPC IPC(8): F28D20/00F28F1/12F28F13/00F28F21/08
CPCF28D20/0034F28F1/12F28F13/00F28F21/083F28D2020/0047Y02E60/14
Inventor 廖志荣李朋达田紫芊徐超杜小泽
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)