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A multi-cascade phase change heat storage device with built-in fins and a method for enhancing heat transfer

A phase-change heat storage, multi-cascade technology, applied in heat transfer modification, heat storage equipment, indirect heat exchangers, etc. Enhanced heat transfer effect

Active Publication Date: 2022-04-22
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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  • A multi-cascade phase change heat storage device with built-in fins and a method for enhancing heat transfer
  • A multi-cascade phase change heat storage device with built-in fins and a method for enhancing heat transfer
  • A multi-cascade phase change heat storage device with built-in fins and a method for enhancing heat transfer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] figure 1 with 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, PCM...

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 a method for enhancing heat transfer. The multi-cascade phase-change heat storage device includes: a phase-change material, a phase-change heat storage unit, a heat transfer fluid, and a heat transfer fluid Channels and fins; the heat transfer fluid flows through the phase change heat storage units at all levels through the heat transfer fluid channels; the fins are built in the phase change material side of the phase change heat storage units at all levels and are close to the outer wall of the heat transfer fluid channel. Through the above method, the device of the present invention can arrange a large number of fins for phase change material containers with poor heat charging and discharging performance according to the difference in charging and discharging performance of phase change materials at different levels, and arrange a large number of fins for phase change material containers with better charging and discharging performance. The phase change material container is arranged with a small number of fins, and the internal fins are arranged with non-equal spacing, non-equal height or non-equal thickness according to the charging and discharging process of the phase change container at all levels, and finally with fewer fins At the cost of the multi-cascade phase change heat storage device, the overall efficient enhanced heat transfer is realized.

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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Patent Type & Authority Patents(China)
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)