WO2020022936A1

WO2020022936A1 - Heat energy storage device with regulated heat output at a constant temperature

Info

Publication number: WO2020022936A1
Application number: PCT/RU2019/000492
Authority: WO
Inventors: Сергей Игоревич БАРЦЕВ; Виктор Александрович ОХОНИН; Валерий Михайлович ПОДЛЕСНЫЙ; Александр Семенович ФЕДОРОВ
Original assignee: Общество с ограниченной ответственностью "Мекад"
Priority date: 2018-07-24
Filing date: 2019-07-10
Publication date: 2020-01-30
Also published as: RU2696183C1

Abstract

The invention relates to a physical method for storing heat energy at a high temperature. A heat energy storage device with regulated heat output at a constant temperature comprises a reservoir (1) having heat insulation (2) and being filled with a heat storage material (3), and also a main heat exchanger (4) and an external heat exchanger (6) with a heat transfer agent, which are connected to a source and to a consumer of heat energy (7). The main heat exchanger (4) is configured in the form of a helix which extends from a central axial part to the walls of the reservoir (1) and additionally periodically bends in the direction of the axis of the reservoir. The central part of the helix is connected to a hot heat transfer agent collector (5) which, for the output of heat at a constant temperature, is connected to the external heat exchanger (6) which is connected in turn to the peripheral part of the helix via a cold heat transfer agent collector (8). The invention makes it possible to carry out the regulated extraction of heat from the hot heat transfer agent collector at a constant high temperature, and also exhibits low heat losses.

Description

Thermal energy storage battery with adjustable heat dissipation at constant temperature

FIELD OF TECHNOLOGY

The invention relates to a physical method of accumulating thermal energy and can be used to generate electricity using a thermoelectric converter or a heat engine (Stirling engine, steam engine, steam turbine, etc.), as well as for hot water supply, heating, etc.

PREVIOUS LEVEL

Known thermal battery [Patent RU2027119, IPC F24H7 / 00, publ. 01/20/1995], which proposed a thermal storage of solar energy using cheap solid heat-storage materials (TM) based on rock, non-combustible solid waste, and overburden mining as a heat storage medium. This solves the problem of creating a thermal accumulator (TA), capable of transferring heat for a long time. This is achieved by the fact that in a TA containing a tank filled with scattered heat-accumulating material, a two-part heat exchanger is also used, where the charging side is connected to the solar collectors and the discharge side to the steam-powered part of the solar power station. According to the invention, the discharge side of the heat exchanger further comprises a heater located in the heat storage material, and a cavity in the ground is used as a reservoir.

The disadvantage of this TA is that in the process of heat transfer the temperature of the coolant at the outlet of the heat exchanger (on the discharge side) changes from the maximum temperature of the TM to the minimum, which reduces the efficiency of using the TA, as well as the fact that there are large heat losses on the walls of the battery due to their high temperature.

Known utility model [m RU 145327, IPC F24H7 / 00, publ. 09/20/2014, bull. N ° 26], in which the device comprises a housing filled with a phase transition substance with heat-conducting inclusions and a heat exchanger pipe, which has a cochlear shape from the coolant channels. The temperature constancy of the heated medium at the outlet of the battery-heat exchanger is achieved by the fact that only the outer pipe with the heated medium is in contact with the substance of the phase transition. Chilled pipe corrugated and has the form for intensifying heat transfer. At the inlet-outlet of the coolant pipe in the accumulator-heat exchanger, a flow control valve is located, which automatically regulates the flow flow without the use of electricity.

However, this heat accumulator has insufficient thermal energy storage capacity due to the use of TM, in which heat is stored only due to the heat of the phase transition.

Known battery of thermal energy [Patent RU 2626922, IPC F24H7 / 04, publ. 08/02/2017 Bull.Zh22], containing the reservoir, which is a cavity in the ground, filled with solid storage medium, as well as charging and discharge heat exchangers with a heat carrier, connected to the source and consumer of thermal energy, respectively, while the reservoir has thermal and hydraulic isolation from the external environment, and the inside the volume of the tank is divided by horizontal hydro- and heat-insulating partitions into separate sections, each of which has its own section of the charging and discharge circuit with a coolant, and discharge and The main circuits of each hydro- and thermally insulated section are connected to the discharge and charge collectors.

The disadvantage of this heat accumulator is that in the process of heat transfer, the temperature of the heat carrier at the outlet of the heat exchanger (in the discharge manifold) changes from the maximum temperature of the TM to the minimum, which reduces the efficiency of using TA, and also that it is designed for seasonal storage of thermal energy, with large TM volume and a small temperature difference during heat storage, which leads to a low specific thermal energy of this battery and to the inefficiency of using heat engines (Steer branding, etc.) to transform the stored heat into electricity.

SUMMARY OF THE INVENTION

The technical problem of the invention is the creation of a reliable and stable thermal energy accumulator with a simple design, which allows for controlled heat removal from the hot heat collector at a constant high temperature and having low heat loss due to the low temperature of the external walls of the battery. The solution to this problem is achieved in that in a heat energy accumulator with controlled heat transfer at a constant temperature, containing a tank having thermal insulation filled with a solid storage medium, as well as main and external heat exchangers with a heat carrier, connected to a source and consumer of heat energy, respectively, according to the invention , the main heat exchanger is made in the form of a spiral diverging from the central axial part to the walls of the tank and additionally periodically curved in the direction and the axis of the tank, the central part of the spiral is connected to the collector of the hot coolant that returns to the heat at a constant temperature is connected to an external heat exchanger connected in turn with the periphery of the helix through the collector cold coolant. And also the fact that the coil of the heat exchanger can be made in the form of a multi-start spiral with the number of starts N> 1. And also the fact that between the turns of the main heat exchanger a heat-insulating screen (s) is installed in the form of a spiral with the number of entries N> 1.

The developed design of a thermal energy accumulator with adjustable heat transfer at a constant temperature allows for controlled heat removal in a hot coolant collector at a high constant temperature without the use of heat-storage material using phase transition heat, while ensuring simplicity of design, reliability and stability, high density of stored energy as well as low heat loss.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated by drawings:

figure 1 presents a schematic diagram of the proposed thermal battery;

in FIG. 2 is a plan view of a heat accumulator;

in FIG. 3 shows a top view of this heat accumulator for a heat exchanger in the form of a multi-start spiral with the number of starts N = 2;

in FIG. Figure 4 shows the dependence of the temperature of the TM on the radius in the working area of the heat accumulator.

Designations used in the drawings:

1- tank 2- mineral insulation

3- heat storage material (TM)

4- main heat exchanger

5- collector of hot heat carrier

6- external heat exchanger

7- thermal energy consumer

8- cold coolant collector

9- low voltage transformer

10- hot collector point

11- hot collector point

12- dielectric insert

13 - hot collector point

14- high temperature low flow pump

15- valves of locking equipment

16- control unit

17- outputs of temperature sensors

18- display

19- heat insulating screen.

BEST MODE FOR CARRYING OUT THE INVENTION

The thermal energy accumulator with adjustable heat transfer at a constant temperature (TA) consists of a cylindrical tank with double walls of the housing 1 (Fig. 1, 2), the space between which is filled with mineral insulation 2. Inside the tank is filled with powder or granular heat-accumulating material 3, which sand can be selected, and the closed main heat exchanger 4, which consists of a metal tube bent in the form of a spiral (Fig. 2), diverging from the central the axial part of the battery to its periphery - the walls of the tank 1 and additionally periodically bent in the direction of the axis of the tank, which leads to a complete and uniform coverage of the entire volume of the TM heat exchanger tubes. To reduce the diameter of the tubes of the main heat exchanger and accelerate heat exchange with it while maintaining the thermal power of the battery, the heat exchanger spiral can be made in the form of a multi-start spiral with the number of starts N> 1.

The central part of the heat exchanger is connected to the collector of the hot heat carrier 5, which is connected to an external heat exchanger 6, in which heat is transferred to the consumer of heat energy 7. The output of the external heat exchanger 6 with a cooled heat carrier is connected through valves 15 and the pump 14 to the peripheral part of the main heat exchanger 4 through a cold heat collector 8. The geometric parameters of the heat exchanger are calculated for each set of source materials depending on the thermal capacity of the battery. Copper is used as the material of the tubes of the heat exchanger due to its high thermal conductivity, low cost, as well as chemical inertness and resistance to alkali.

A liquid coolant circulates inside the heat exchanger, which can be used liquid caustic soda (NaOH) (operating temperature up to 1350 ° C), liquid sodium (melting point 98 ° C), which can be heated to a temperature of 850 ° C, mineral oil, ( operating temperature up to 300 ° С), the family of silicone high-temperature heat carriers Thermo lan (operating temperature up to 330 ° С), etc.

In the case of using a heat carrier, which may initially be in the solid phase (for the case of the heat carrier NaOH, Na), for heating it to the melting temperature, the spiral part of the heat exchanger is heated using ohmic heat generated by applying the required voltage to the tubes of the heat exchanger from the low-voltage transformer 9 between points of the hot collector 10 and the cold collector 8. To block this electric current through the pipe of the pump 14, the pipe of the hot collector is separated by a dielectric tion insert 12.

To accumulate heat by heating the hot collector in the central region of the heat exchanger and further transferring heat throughout the TM volume by forced circulation of the heated coolant in the heat exchanger, ohmic heating is applied by applying the necessary voltage from the low-voltage transformer 9 to the points 10 and 11 maximally spaced on the hot collector. 1 shows a low voltage transformer 9 and both heat exchanger heating circuits. To circulate the coolant along the TA circuit, an induction or other high-temperature low-flow pump 14 is used with the possibility of reverse flow.

The cycle of the device can be divided into three phases.

During the first phase of heat storage, the coolant is heated to a high temperature T1 by ohmic heating of the hot collector heat carrier 5. The coolant heated to a temperature T1 by means of a pump 14 starts to be pumped from the central part of the TA from the hot collector 5 to the periphery of the TA. The heat exchange material is heated, transferring heat to the surrounding TM and warming it to temperature T1.

This TA charging technology is fundamentally important in the case of using an energy source with a borehole operating mode during the TA charging period, since It allows storing thermal energy in the TM at a stable high temperature T1.

When temperature T1 is reached in the entire volume of the heat-accumulating material, the heating ceases, and the heat transfer unit either passes into the second phase of thermal energy storage, or switches to the third phase, the discharge phase of the thermal energy. In the second phase, the valves of the shutoff valves 15 are locked, blocking the heat flux through the movement of the coolant in the pipes.

The external heat exchanger 6, due to the low heat capacity, quickly cools to ambient temperature TK, thereby not transferring heat to the consumer of thermal energy 7. The presence of thermal insulation in the form of mineral insulation 2 reduces the heat loss of TA.

During the third phase, thermal energy is transferred to the external consumer 7. For this, the valves of the shutoff valves 15 open, the coolant is pumped back through the pump 14 at the required speed from the cold coolant collector 8 to the hot coolant collector 5. The heat stored in the heated coolant to a temperature T1, it is given to an external consumer of thermal energy 7 by means of its thermal contact through an external heat exchanger 6. A coolant cooled to a temperature T2 from external heat exchanger 6 is transferred to the peripheral zone of the heat accumulator, displacing the coolant heated to a temperature T1 closer to the central zone of the accumulator. Thus, the movement of the heat carrier from the collector of the hot heat carrier 5 to the collector of the cold heat carrier 8 through an external heat exchanger 6 provides the relative stability of the temperature of the heat carrier T1 at the outlet of the TA to the heat-consuming equipment. When taking heat from TA, the temperature distribution gradient from time to time sharply changes from T2 in the peripheral region to T1 in the central region, Fig. 4. Moreover, in addition to the stability of the high temperature T1 at the outlet of the TA, the low temperature T2 will remain on the walls of the tank 1, significantly reducing the heat loss of the TA. To maintain this stability of the temperature of the coolant at the outlet, the heat accumulator is equipped with a control unit 16, which controls the shut-off valves 15 and the speed of movement of the coolant inside the tubes by controlling the power of the pump 14 and the direction of flow of the coolant. For this, the inputs of the device 16 are connected to the outputs of the temperature sensors 17, detecting the distribution of temperature values along the radius inside the TM volume, with the pump control unit 16 and shut-off valves 15.

For visual control of the stored and supplied heat energy, as well as operating modes, the control unit 16 is equipped with a display 18.

In the mode of operation of the TA, characterized by low heat transfer and a sufficiently high heat conductivity of the TM to reduce heat loss through the walls of the housing 1 and the insulation layer 2 inside the tank between the turns of the heat exchanger 4 can be installed insulating screen (s) 19 (Fig. 2 and 3) in the form of a spiral with the number of visits equal to or greater than 1, which (e) slows down the process of movement of heat from the central hot region with the 5 TA collector to the cold walls of the housing 1 through direct thermal conductivity of the TM.

In the proposed TA, heat losses on the walls of the battery are reduced due to their low temperature due to a sharp jump in temperature inside the TM (figure 4).

INDUSTRIAL APPLICABILITY

The claimed battery of thermal energy with adjustable heat transfer at a constant temperature has a high efficiency due to the possibility of using high-temperature operation up to 1000 ° C, depending on the selected type of coolant.

The invention may be carried out in other embodiments, not going beyond the scope of the invention defined by the patent claims. So, for example, the coil of the heat exchanger can be made in the form of a multi-start spiral with the number of starts N> 1 and between the turns of the main heat exchanger can be installed heat-insulating screen (s) in the form of a spiral with the number of starts N> 1.

Claims

FORMULA

1. A thermal energy accumulator with controlled heat transfer at a constant temperature, containing a tank having thermal insulation filled with a solid storage medium, as well as main and external heat exchangers with a heat carrier, connected to a source and consumer of thermal energy, respectively, DIFFERENT in that the main heat exchanger (4 ) is made in the form of a spiral diverging from the central axial part to the walls of the tank and additionally periodically curved in the direction of the axis of the tank (1), while spiral part is connected to the collector of the hot water heater (5), which returns to the heat at a constant temperature is connected to the external heat exchanger (6) connected in turn with the periphery of the spiral coolant through the cold collector (8).

2. The thermal energy accumulator according to claim 1, characterized in that the coil of the heat exchanger can be made in the form of a multi-start spiral with the number of starts N> 1.

3. The thermal energy accumulator according to claim 1, characterized in that between the turns of the main heat exchanger is installed heat-insulating screen (s) in the form of a spiral with the number of entries N> 1.