阅读说明：本技术 基于开式逆布雷顿循环的压缩空气储冷系统及控制方法 (Compressed air cold storage system based on open type reverse Brayton cycle and control method ) 是由 李丹童 何志龙 胡汪锋 张璐 邢子文 于 2021-09-16 设计创作，主要内容包括：基于开式逆布雷顿循环的压缩空气储冷系统及控制方法,系统包括压缩机、换热器、气罐、膨胀机、冷却塔、冷却水泵以及若干阀门；压缩机的气体入口通入常温常压的空气,压缩机的气体出口连接换热器的气体入口,换热器的气体出口经过第一阀门连接气罐的气体入口,气罐的气体出口经过第二阀门连接膨胀机的气体入口,膨胀机的气体出口连接用冷场所；所述换热器的工质入口经过冷却水泵连接冷却塔的冷水出口,所述换热器的工质出口连接冷却塔的热水入口；常温常压的空气经过压缩机压缩之后生成高压高温的空气,高压高温的空气在换热器中释放热量,形成高压常温的空气存储至气罐。本发明系统结构简单,耗电部件少,可切换运行模式,总体能量的利用率高。(The system comprises a compressor, a heat exchanger, a gas tank, an expander, a cooling tower, a cooling water pump and a plurality of valves; air at normal temperature and normal pressure is introduced into a gas inlet of the compressor, a gas outlet of the compressor is connected with a gas inlet of the heat exchanger, a gas outlet of the heat exchanger is connected with a gas inlet of the gas tank through a first valve, a gas outlet of the gas tank is connected with a gas inlet of the expander through a second valve, and a gas outlet of the expander is connected with a cold field; a working medium inlet of the heat exchanger is connected with a cold water outlet of the cooling tower through a cooling water pump, and a working medium outlet of the heat exchanger is connected with a hot water inlet of the cooling tower; the air at normal temperature and normal pressure generates high-pressure high-temperature air after being compressed by the compressor, and the high-pressure high-temperature air releases heat in the heat exchanger to form high-pressure normal-temperature air which is stored in the air tank. The system has the advantages of simple structure, less power consumption parts, switchable operation modes and high utilization rate of total energy.)

1. The utility model provides a compressed air cold storage system based on open contrary brayton cycle which characterized in that: the system comprises a compressor (1), a heat exchanger (2), a gas tank (3), an expander (4), a cooling tower (5), a cooling water pump (6) and a plurality of valves; air at normal temperature and normal pressure is introduced into a gas inlet of the compressor (1), a gas outlet of the compressor (1) is connected with a gas inlet of the heat exchanger (2), a gas outlet of the heat exchanger (2) is connected with a gas inlet of the gas tank (3) through a first valve (7), a gas outlet of the gas tank (3) is connected with a gas inlet of the expansion machine (4) through a second valve (8), and a gas outlet of the expansion machine (4) is connected with a cold field; a working medium inlet of the heat exchanger (2) is connected with a cold water outlet of the cooling tower (5) through a cooling water pump (6), and a working medium outlet of the heat exchanger (2) is connected with a hot water inlet of the cooling tower (5); the air at normal temperature and normal pressure is compressed by the compressor (1) to generate high-pressure high-temperature air, and the high-pressure high-temperature air releases heat in the heat exchanger (2) to form high-pressure normal-temperature air which is stored in the air tank (3).

2. The open inverted brayton cycle-based compressed air cold storage system of claim 1, wherein: the compressor (1) is connected with a driving motor (9), and the driving motor (9) is connected with a power supply (11) through a switch (10).

3. The open inverted brayton cycle-based compressed air cold storage system of claim 1, wherein: the expansion machine (4) is connected with and drives the generator (12) to work, and the generator (12) recovers energy in a power supply mode.

4. A control method of the compressed air cold storage system based on the open type inverted brayton cycle as claimed in any one of claims 1 to 3, characterized in that: correspondingly selecting a system working mode according to the peak period and the valley period of power utilization;

the system working modes comprise a compressed gas mode and an expansion refrigeration mode.

5. The control method according to claim 4, characterized in that: in the compressed gas mode, the compressor (1) is put into operation, the first valve (7) is opened, the second valve (8) is closed, and the cooling water pump (6) is started; air at normal temperature and normal pressure is introduced into the compressor (1), the air at normal temperature and normal pressure is compressed into high-temperature and high-pressure air through the compressor (1), and the high-temperature and high-pressure air is released heat through the heat exchanger (2) to become high-pressure and normal-temperature air which is stored in the air tank (3).

6. The control method according to claim 4, characterized in that: under the expansion refrigeration mode, the compressor (1) stops working, the first valve (7) is closed, the second valve (8) is opened, and the cooling water pump (6) is closed; the high-pressure air in the air tank (3) is expanded by the expander (4) to become normal-pressure low-temperature air, and the normal-pressure low-temperature air is conveyed to a cooling place for refrigeration.

7. The control method according to claim 6, characterized in that: the expansion machine (4) transmits the generated expansion work to the generator (12), and the energy is recovered by the generator (12) in a power supply mode.

8. The control method according to claim 6, characterized in that: the electricity consumption peak time is day time, and the electricity consumption valley time is night time; the system adopts the expansion refrigeration mode during the peak period of electricity utilization, and the system adopts the compressed gas mode during the peak period of electricity utilization.

Technical Field

The invention belongs to the field of mechanical engineering design, and particularly relates to a compressed air cold storage system based on an open type inverse Brayton cycle and a control method.

Background

Air refrigeration technology has long been known, and in 1844, american j.corrie produced the first air refrigerator applied to the field of refrigeration and air conditioning, but since its refrigeration efficiency was lower than that of a vapor compression refrigerator, it was only applied to a small range of aircraft air conditioning and the like. With the continuous development of turbomachines, the air refrigerator which is silent for many years is used as a generator, the historical stage is re-built in the common refrigeration field, and when the temperature is lower, particularly below-80 ℃, the air refrigerator has economic superiority incomparable with other refrigeration cycles, and has good development prospect. In addition, the air which is non-toxic, harmless and inexhaustible is used as the refrigeration working medium, and the environment is not polluted. In recent years, the air conditioner has attracted attention again from the world science and technology, and the application range of the air conditioner is gradually expanded from the airplane air conditioner to various vehicle-mounted air conditioners, food cold processing devices and large-scale low-temperature environment simulation rooms. The inverse Brayton cycle air refrigerator can obtain larger temperature drop by utilizing gas expansion refrigeration, has the potential of being widely applied to the field of industrial energy conservation, and the most main energy consumption component in the refrigerator is a compressor.

In recent years, the energy storage technology has become a key technology for solving the problems of peak clipping and valley filling of the conventional power system and improving the efficiency and safety of the regional energy system. The demand side energy storage technology can allocate and utilize electric power according to real-time electricity price, effectively saves operation cost, and simultaneously realizes peak clipping and valley filling of the electric power. The typical application scenario is that during the power off-peak period at night, the power is used to produce material data required in the day and the material data is stored in other forms for the production and application in the day, so that the effect of peak clipping and valley filling of the power can be realized while the overall cost is saved.

For large-scale cold enterprises, the compressor in the air refrigerating machine is a main energy consumption part, electricity is used at night to produce cold energy and store the cold energy, the cold energy is used for production in the daytime, and the method has important significance for peak clipping and valley filling for saving cost and electric power.

Disclosure of Invention

The present invention is directed to solve the above problems in the prior art, and an object of the present invention is to provide a compressed air cold storage system and a control method based on an open type inverted brayton cycle, which can switch between two modes according to electricity price, thereby achieving the effect of saving energy and cost.

In order to achieve the purpose, the invention has the following technical scheme:

a compressed air cold storage system based on an open type reverse Brayton cycle comprises a compressor, a heat exchanger, a gas tank, an expander, a cooling tower, a cooling water pump and a plurality of valves; air at normal temperature and normal pressure is introduced into a gas inlet of the compressor, a gas outlet of the compressor is connected with a gas inlet of the heat exchanger, a gas outlet of the heat exchanger is connected with a gas inlet of the gas tank through a first valve, a gas outlet of the gas tank is connected with a gas inlet of the expander through a second valve, and a gas outlet of the expander is connected with a cold field; a working medium inlet of the heat exchanger is connected with a cold water outlet of the cooling tower through a cooling water pump, and a working medium outlet of the heat exchanger is connected with a hot water inlet of the cooling tower; the air at normal temperature and normal pressure generates high-pressure high-temperature air after being compressed by the compressor, and the high-pressure high-temperature air releases heat in the heat exchanger to form high-pressure normal-temperature air which is stored in the air tank.

As a preferable scheme of the compressed air cold storage system of the invention, the compressor is connected with a driving motor, and the driving motor is connected with a power supply through a switch.

As a preferable scheme of the compressed air cold storage system of the present invention, the expander is connected to and drives the generator to operate, and the generator performs energy recovery in a power supply manner.

The invention also provides a control method of the compressed air cold storage system based on the open type inverse Brayton cycle, which comprises the following steps:

correspondingly selecting a system working mode according to the peak period and the valley period of power utilization;

the system working modes comprise a compressed gas mode and an expansion refrigeration mode.

As a preferable scheme of the control method of the invention, in the compressed gas mode, the compressor is put into operation, the first valve is opened, the second valve is closed, and the cooling water pump is started; air at normal temperature and normal pressure is introduced into the compressor, the air at normal temperature and normal pressure is compressed into high-temperature high-pressure air through the compressor, and the high-temperature high-pressure air is released heat through the heat exchanger to become high-pressure normal-temperature air which is stored in the air tank.

As a preferable scheme of the control method of the present invention, in the expansion refrigeration mode, the compressor stops working, the first valve is closed, the second valve is opened, and the cooling water pump is closed; the high-pressure air in the air tank is expanded by the expander to become normal-pressure low-temperature air, and the normal-pressure low-temperature air is conveyed to a cold field for refrigeration.

In a preferred embodiment of the control method of the present invention, the expander transmits the generated expansion work to the generator, and the generator supplies power to the generator to recover energy.

As a preferred scheme of the control method of the invention, the electricity consumption peak time is day time, and the electricity consumption valley time is night time; the system adopts the expansion refrigeration mode during the peak period of electricity utilization, and the system adopts the compressed gas mode during the peak period of electricity utilization.

Compared with the prior art, the invention has the following beneficial effects:

because the working medium used by the compressed air cold storage system is air which is an inexhaustible, nontoxic, tasteless and pollution-free natural working medium, the cold air generated by the system can be used in various occasions such as a worker workshop, an air-conditioning room, a meat, vegetable and vegetable freezing room and the like, and the cold air is not required to be recycled. The system of the invention has two working modes, wherein the compressed high-pressure gas is stored by adopting a compressed gas mode at night, and the high-pressure gas is expanded by adopting an expansion refrigeration mode in the daytime to obtain cold energy and expansion power, which is equivalent to that the circulation of the whole system is divided into two parts to run at night and in the daytime respectively. This has two benefits over direct compression of the gas and expansion refrigeration during the day: firstly, the system is in a power utilization valley at night, is in a power utilization peak at daytime, and has lower electricity price at night than at daytime, so that power consumption parts such as a compressor, a cooling water pump and the like are operated at night, and the cost is saved; and secondly, the ambient temperature at night is lower than that at daytime, the same cold quantity is obtained under the same other conditions according to the inverse Brayton cycle theory, and the energy consumption for operating the system compressor and other components at night is lower, so that the system is more energy-saving. In addition, the refrigeration system can recover the expansion work generated by the expander by using the generator when the electricity price is higher in the daytime, and the expansion work can be used as the power supply of other electrical appliances, which is equivalent to recovering part of the power consumption of parts such as a compressor and the like at night. Generally, the system has simple structure and less power consumption parts, and the whole system has low power consumption, low energy consumption and high utilization rate of the total energy through two operation modes.

Drawings

FIG. 1 is a schematic diagram of a compressed air cooling system based on an open inverted Brayton cycle according to the present invention;

FIG. 2 is a temperature-entropy diagram of a working cycle of a compressed air cold storage system based on an open type inverted Brayton cycle;

FIG. 3 is a schematic diagram of a control method for the compressed air cooling storage system based on the open type inverted Brayton cycle according to the present invention;

FIG. 4 is a schematic diagram showing a comparison of temperature entropy diagrams of a working cycle under different environmental temperatures of the system of the present invention;

in the drawings: 1-a compressor; 2-a heat exchanger; 3-a gas tank; 4-an expander; 5-a cooling tower; 6-cooling water pump; 7-a first valve; 8-a second valve; 9-driving a motor; 10-a switch; 11-a power supply; 12-a generator.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Referring to fig. 1, the compressed air cold storage system based on the open type inverted brayton cycle of the embodiment of the present invention includes a compressor 1, a heat exchanger 2, a gas tank 3, an expander 4, a cooling tower 5, a cooling water pump 6, and a plurality of valves; air at normal temperature and normal pressure is introduced into a gas inlet of the compressor 1, a gas outlet of the compressor 1 is connected with a gas inlet of the heat exchanger 2, a gas outlet of the heat exchanger 2 is connected with a gas inlet of the gas tank 3 through the first valve 7, a gas outlet of the gas tank 3 is connected with a gas inlet of the expander 4 through the second valve 8, and a gas outlet of the expander 4 is connected with a cold field; a working medium inlet of the heat exchanger 2 is connected with a cold water outlet of the cooling tower 5 through a cooling water pump 6, and a working medium outlet of the heat exchanger 2 is connected with a hot water inlet of the cooling tower 5; the air at normal temperature and normal pressure generates high-pressure high-temperature air after being compressed by the compressor 1, the high-pressure high-temperature air releases heat in the heat exchanger 2, and the high-pressure normal-temperature air is formed and stored in the air tank 3. The compressor 1 is connected with a driving motor 9, and the driving motor 9 is connected with a power supply 11 through a switch 10. The expander 4 is connected with and drives the generator 12 to work, and the generator 12 performs energy recovery in a power supply mode.

A compressed air cold storage system control method based on an open type reverse Brayton cycle comprises the following steps: correspondingly selecting a system working mode according to the peak period and the valley period of power utilization; the system operating modes include a compressed gas mode and an expansion refrigeration mode.

And a compressed gas mode in which air at normal temperature and pressure is sucked through an air inlet of the compressor 1, compressed into air at high pressure and high temperature, and then passes through the heat exchanger 2 to release heat to cooling water cooled by the cooling tower 5, so that the air is changed into air at high pressure and normal temperature, and finally stored in the air tank 3. The other is an expansion refrigeration mode, in which high-pressure normal-temperature gas stored in the gas tank 3 is expanded by the expander 4 to become low-temperature air at normal pressure, the released cold air can be directly refrigerated and sent to a place needing refrigeration, and meanwhile, a part of expansion work generated by the expander 4 can be connected with the generator 12 to recover energy in a power supply mode. As shown in fig. 2, the refrigeration system of the present invention employs an open inverted brayton cycle in which a temperature-entropy diagram (T-s diagram) of air as a working fluid is shown, in which points a to b to c represent a compressed gas mode, and points c to d represent an expansion refrigeration mode. As shown in fig. 3, the method for controlling a compressed air cold storage system according to the present invention controls the operation modes of a refrigeration system according to the peak and the valley of power consumption, wherein a compressor 1 is a main power consuming component of the system, and the price of electricity is low at the valley of power consumption and high at the peak of power consumption, so the control principle of the system is to turn on the compressor 1 at the valley of power consumption and stop at the peak of power consumption. As shown in fig. 4, since the ambient temperature during the day is higher than that during the night, the temperature entropy diagrams of the theoretical cycle of the refrigeration system of the present invention are different when the refrigeration system is operated during the day and at night, and it can be seen from the diagrams that the system is operated in the compressed gas mode at night, and compared with the operation during the day, the temperature of the high-pressure normal-temperature gas obtained is lower, that is, the temperature at the point c is lower, and the temperature of the cold air obtained after the expansion of the expander 4 is also lower.

As shown in fig. 1, thereby the start of switch 10 control driving motor 9 stops the start of control compressor 1 and stops, compressor 1 plays the effect of compressed gas, heat exchanger 2 provides the place of heat transfer between air and the cooling water, cooling tower 5 cools the high temperature cooling water that comes out in heat exchanger 2 to ambient temperature, cooling water pump 6 draws low temperature cooling water from cooling tower 5 and delivers to heat exchanger 2, gas pitcher 3 is responsible for storing high-pressure gas, expander 4 plays the refrigerated effect of gaseous expansion, generator 12 is responsible for converting the work of expansion into the electric energy, the break-make of gaseous in first valve 7 and the second valve 8 control pipeline. In the compressed gas mode, the switch 10 is closed, the first valve 7 is opened, the second valve 8 is closed, the cooling water pump 6 is opened, the driving motor 9 and the compressor 1 are in a working state at the moment, and the air at normal temperature and normal pressure is compressed into high-temperature and high-pressure air through the compressor 1, then is subjected to heat release through the heat exchanger 2 to become high-pressure and normal-temperature air, and is stored in the air tank 3. In the expansion refrigeration mode, the switch 10 is switched off, the first valve 7 is closed, the second valve 8 is opened, the cooling water pump 6 is closed, the driving motor 9 does not work at the moment, the expander 4 and the generator 12 work, no power consumption working part exists in the mode, high-pressure air in the air tank 3 is expanded by the expander 4 to become normal-pressure low-temperature air, the cold air can be directly used for refrigeration, and expansion work generated by the expander 4 is supplied with power by the generator 12.

As shown in FIG. 2, point a is air at normal temperature and pressure, and point b is the outlet of the compressor 1The state, point c, is the state of the outlet of the heat exchanger 2, and point d, is the state of the expander 4. Ideally, the compression from point a to point b is isentropic, in which the entropy of the air is constant and the pressure and temperature increase. The constant pressure heat release is carried out from the point b to the point c, the pressure of the air is unchanged in the process, the temperature is reduced, and if the heat exchange is sufficient, the temperature can be reduced to the ambient temperature T at most_CI.e. the temperature at point a. The point c to the point d are isentropic expansion, the entropy of the air is unchanged in the process, the pressure and the temperature are reduced, and the temperature is reduced to be lower than the ambient temperature, so that the air can be used for refrigeration. The compressed gas mode is represented by points a to b to c, and the expansion refrigeration mode is represented by points c to d.

As shown in fig. 3, the peak of electricity consumption refers to the time period with the highest electricity price, generally daytime, and the valley of electricity consumption refers to the time period with the lowest electricity price, generally night. Considering that the compressor is the main electricity consumption component in the system, the control method of the system is as follows:

the system adopts the expansion refrigeration mode during the peak of power consumption, and the system adopts the compressed gas mode during the valley of power consumption.

In the compressed gas mode, the switch 10 is closed, the first valve 7 is opened and the second valve 8 is closed. In the expansion cooling mode, the switch 10 is turned off, the first valve 7 is closed, and the second valve 8 is opened.

As shown in FIG. 4, the ambient temperature T at night_C1Ambient temperature T of daytime_C2According to the open type inverse Brayton cycle, the system can obtain high-pressure air with lower temperature at the point c when operated at night under the same other conditions, and the temperature of cold air obtained after isentropic expansion is lower. That is, the compressor of the system consumes less power and the system consumes less power when the system is operated at night under the condition of obtaining cold air with the same temperature (point d).

Therefore, the compressed air cold storage system based on the open type reverse Brayton cycle and the control method can obtain larger temperature drop and provide certain refrigerating capacity. The system is simple, the power consumption parts are few, the two modes can be switched according to the electricity price, and the effects of saving energy and cost are finally achieved.

The above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the technical solution of the present invention, and it should be understood by those skilled in the art that the technical solution can be modified and replaced by a plurality of simple modifications and replacements without departing from the spirit and principle of the present invention, and the modifications and replacements also fall into the protection scope covered by the claims.