Method and system for storing energy by positive and reverse organic Rankine cycles

Abstract

The invention discloses a system for storing energy by positive and reverse organic Rankine cycles. The system comprises a low-pressure and high-pressure work medium storage tanks coated with heat-insulating material layers and low-temperature and high-temperature phase change materials which are respectively arranged at the low-pressure work medium storage tank and the high-pressure work medium storage tank; an air heat exchanger is arranged in the low-pressure work medium storage tank and is communicated with the outside; and the upper end of the low-pressure work medium storage tank is divided into two paths, wherein one path is sequentially connected with a compressor and the high-pressure work medium storage tank through a program control valve and the other path is sequentially connected with an expander and the high-pressure work medium storage tank through another program control valve. The energy storage process of the system is as follows: the compressor is opened for reverse Rankine cycle, a work medium in the low-pressure work medium storage tank is compressed to the high-pressure work medium storage tank and condensed heat of input work and low-temperature phase change work medium in the low-pressure work medium storage tank is stored into dissolution heat of the high-temperature phase change work medium in the high-pressure work medium storage tank; the power generation process is as follows: the expander is opened for positive organic Rankine cycle, the work medium does work in the high-pressure work medium storage tank and then enters the low-pressure work medium storage tank and is condensed by a low-temperature phase change work medium and air in the low-pressure work medium storage tank; and meanwhile, the high-temperature phase change work medium in the high-pressure work medium storage tank discharges heat and is condensed. According to the system disclosed by the invention, the energy is stored by using phase change, energy storage density is great and the storage and the release of electric energy can be realized stably and continuously.

Description

technical field [0001] The invention belongs to an energy storage method and system, in particular to a forward and reverse organic Rankine cycle energy storage method and system, which is an energy storage and power generation method and system using phase change materials and organic working fluids as energy storage media. Background technique [0002] In recent years, the world's electricity production and use have continued to grow, and the construction of power facilities has developed rapidly. In addition to traditional thermal power plants, the power generation of renewable resources such as hydropower, wind energy, and solar energy has also achieved rapid growth. However, the power generation of this type of renewable energy is limited by natural conditions, and has the characteristics of instability and intermittent. On the other hand, the power consumption of users has obvious periodicity. The power consumption in the daytime is mainly in the industry, and the powe...

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Problems solved by technology

Generally, the compressed air energy storage system needs to compress the air to 7Mpa~10Mpa. Due to the huge technical difficulty and cost required to manufacture large-volume high-pressure storage tanks, special terrain conditions such as caves and mines are usually required to realize air storage. This greatly limits the development of compressed air energy storage; on the other hand, the pressure of compressed air decreases continuously during the release process. In order to ensure the stable operation of the expander, it is necessary to throttle the high-pressure air through a pressure stabilizing device and then use it after depressurization. This process wastes a lot of compression energy

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