COLD STORAGE SYSTEM AND METHOD OF OPERATING A MULTI-PACKED BED COLD STORAGE SYSTEM

Abstract

A Cold Storage System includes a chiller (B), a cold storage (C), a compressor (A), and a bypass control valve (K; L). The chiller (B) is for cooling the heat transfer fluid (HTF) to low or ultra-low temperature. The cold storage (C) is for storing coldness. The compressor (A) enables the circulation of the HTF. The bypass control valve (K; L) is applied in between an exit of chiller (B) and an exit of the cold storage (C) and is adapted to keep a temperature at an inlet of the compressor (A) at a predefined setpoint temperature.

Claims

1. A Cold Storage System comprising: a chiller (B) for cooling the heat transfer fluid (HTF) to low or ultra-low temperature; a cold storage (C) for storing coldness; a compressor (A) enabling the circulation of the HTF; and a bypass control valve (K; L) is applied in between an exit of chiller (B) and an exit of the cold storage (C) and adapted to keep a temperature at an inlet of the compressor (A) at a predefined setpoint temperature.

2. A Cold Storage System comprising: a cold storage (C) for storing coldness; a compressor (A) enabling the circulation of a heat transfer fluid (HTF); a heat exchanger coil (D) for delivering of coldness to a user, wherein the heat exchanger coil (D) is arranged between the compressor (A) and the cold storage; and a bypass line with a bypass control valve (L), wherein the bypass line connects an inlet and an outlet of the cold storage (C) and the bypass control valve (L) is adapted to control a bypass flow through the bypass line to keep a temperature at the outlet of the cold storage (C) at a predefined setpoint temperature.

3. A method for operating a pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources comprising a chiller as a cooling source (B) for cooling the heat transfer fluid (HTF) to low or ultra-low temperature, a multi-packed bed system as a cold storage (C) for storing coldness, the HTF compressor (A) enabling the circulation of the HTF in the closed circuit that operated under high-pressure and the heat exchanger coil for delivering of coldness to user (D) characterizing that, setpoints for temperatures and operation pressure which are: Charging setpoint temperature at the outlet of chiller as a Setpoint temperature for chiller, Setpoint temperature at the exit of every packed bed as a Setpoint temperature for bottom of each packed bed during charging mode, Setpoint temperature at the inlet of the HTF compressor, Setpoint pressure of the HTF compressor as a setpoint pressure, Setpoint temperature at the heat exchanger for delivering cooling to the user as a setpoint temperature of the heat exchanger for cooling purposes are set to the predetermined values before initiating the system; during charging phase, the heat transfer fluid is compressed by the HTF compressor (A); the pressurized HTF enters the chiller (B), where its temperature decreases to the setpoint temperature for chiller; the cold and pressurized HTF enters the multi-packed bed system (C) from the bottom and exit from the top; at the outlet (point (3)) of the multi-packed bed system, the HTF flows to the HTF compressor; the charging phase is stopped, when the temperature of the HTF at the top of the multi-packed bed system (point (3)) reaches the setpoint temperature at exit of packed bed; a bypass control valve (K) is applied in between the exit of chiller (B) and the exit of multi packed bed system (C) and the exit of HTF compressor (A) for keeping the HTF temperature at the inlet of HTF compressor (A) as setpoint temperature; and if no bypass is applied, the HTF temperature at the exit of the multi-packed bed system at point (3) is high at the start and declines over the course of the charging phase due the temperature decrease in the multi packed bed.

4. The method as claimed in claim 3, when more than one packed beds connected together are used; during charging the first packed bed (C1) (points 1, 2, 3, 4 to 5), the control valve between entries of first and second packed beds (CV1) and the control valve between entries of second and third packed beds (CV2) are closed; the control valves between exits of first and second packed beds (CV3) and between the exits of second and third packed beds (CV4) are opened; the HTF passes from first packed bed (C1) and flows via the points (1), (2), (3), (4) and (5); at this stage, the HTF temperature at the inlet (point (5)) of compressor (A) is controlled by the bypass control valve (K) to be at the setpoint temperature at the inlet of HTF compressor (A); when the HTF temperature at the exit (point (3)) of first packed bed (C1) reaches to the setpoint temperature at the exit of multi packed beds, the second packed bed starts charging with the first packed bed (C1 and C2) (points 1, 2, 3, 4, 5 to 6); at this stage, the control valve between entries of second and third packed beds (CV2) is closed; the valve between entries of first and second packed beds (CV1), the control valve between exits of first and second packed beds (CV3) and the control valve between exits of second and third packed beds (CV4) are opened; the HTF flows in the first and second packed beds (C1 and C2) via the points (1), (2), (3), (4), (5) and (6); the HTF temperature at the inlet (point (7)) of compressor (A) is controlled using the control valve between exits of first and second packed beds (CV3) and/or the bypass control valve (K) to be at the setpoint temperature; when the HTF temperature at the exit of second packed bed (C2) at point (5) reaches to the setpoint temperature at the exit of multi packed beds, the charging phase is stopped; in case of the connection of a third packed bed (C3); for charging the third packed bed (C3), the control valve between exits of first and second packed beds (CV3) is closed; the control valve between entries of first and second packed beds (CV1), the control valve between entries of second and third packed beds (CV2) and the control valve between exits of second and third packed beds (CV4) are opened; the HTF flows in the second and third packed beds (C2 and C3) via the points (1), (2), (3), (4), (6) and (7); the HTF temperature at the inlet (point (8)) of compressor (A) is controlled using the control valve between exits of second and third packed beds (CV4) and/or the bypass control valve (K) to be at the setpoint temperature; and in case of the connection of a further packed bed; for charging the last packed bed, the control valves of previous packed beds except last two are closed; the control valves of last two packed beds are opened; the HTF flows in the last packed bed and the one before last packed bed; the HTF temperature at the inlet of compressor (A) is controlled using the control valve installed at the outlet of the one before last packed bed and/or the bypass control valve (K) to be at the set point temperature.

5. The method as claimed in claim 3, which further comprises, when all packed beds connected together in parallel; Charging all packed beds (C1, C2 and C3) (points 1, 2, 3, 4, 5, 6, 7 to 8), while the bypass valve controls the temperature of the HTF at the inlet of the HTF compressor (A) to be at the setpoint temperature; at this stage, all control valves (CV1, CV2, CV3 and CV4) are opened; the HTF flows via the points (1), (2), (3), (4), (5), (6) and (7). The HTF temperature at the inlet of compressor (A) is controlled using the bypass control valve (K); and when the HTF temperature at point (7) reaches to the setpoint temperature at the exit of multi packed beds, the charging phase is stopped.

6. The method as claimed in claim 3, wherein all packed beds may be connected together in serial order instead of parallel order; in this case, additional connection pipes that connecting the exit of first packed bed to the entry of second packed bed as well as the exit of second packed bed to the entry of third packed bed is used; the HTF temperature at the inlet of compressor (A) (point (8)) is controlled using the bypass control valve (K).

7. The method as claimed in claim 3, wherein the charging process can either be from top to bottom or from bottom to top.

8. The method as claimed in claim 3, wherein: during discharging phase, the heat transfer fluid is compressed by the HTF compressor (A) (point (1)); part of the pressurized HTF enters the packed bed system from the top and exits from the bottom (point (2)), while the remaining part of the pressurized HTF is bypassed to point (3); the bypassed mass flow rate of the HTF through the bypass control valve (L) is controlled, so that the temperature of the HTF at the inlet of the heat exchanger coil is maintained to the setpoint temperature of the heat exchanger for cooling purposes; a fan blows air with ambient temperature; at the outlet of the heat exchanger coil, the temperature of the HTF (point (4)) is similar to ambient temperature; when the temperature of the HTF at the outlet of the packed bed system (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes, the discharge phase is stopped.

9. The method as claimed in claim 3, wherein, when more than one packed beds connected together are used; during discharging the third packed bed (C3) (points 1, 2 to 3), the bypass control valve (L) controls the temperature of the HTF at the inlet of the heat exchanger coil; the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of second packed bed (C2) (DCV2), between the inlets of first and second packed beds (C1 and C2) (DCV4) and between the inlets of second and third packed beds (C2 and C3) (DCV5) are closed; the discharge control valve at the exit of third packed bed (C3) (DCV3) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened; the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1), (2) and (3); during discharging the third packed bed (C3), the temperature at point (3) is kept constant to the setpoint temperature of the heat exchanger for cooling purposes using the bypass control valve (L); when the HTF temperature at the outlet of third packed bed (C3) (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes, the discharging of the third packed is stopped and the discharging of the second packed bed starts; during discharging the second packed bed (points 1, 2 to 3), the bypass valve (L) controls the temperature of the HTF at the inlet of the heat exchanger coil to be to the setpoint temperature of the heat exchanger for cooling purposes; the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of third packed bed (C3) (DCV3) and between the inlets of first and second packed beds (C1 and C2) (DCV4) are closed; the discharge control valves at the exit of second packed bed (C2) (DCV2), between the inlets of second and third packed beds (C2 and C3) (DCV5) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened; the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1), (2) and (3); during discharging the second packed bed (C2), the temperature at point (3) is kept constant to be the setpoint temperature of the heat exchanger for cooling purposes using the bypass control valve (L); when the HTF temperature at the outlet of second packed bed (C2) (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes, the discharging of the second packed is stopped; and in order to discharge the first packed bed (C1), the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of second packed bed (C2) (DCV2) and at the exit of third packed bed (C3) (DCV3) are closed; the discharge control valves between the inlets of first and second packed beds (C1 and C2) (DCV4), between the inlets of second and third packed beds (C2 and C3) (DCV5) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened; the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1) and (2); during discharging the first packed bed (C1), the temperature at point (2) is kept constant to be the setpoint temperature of the heat exchanger for cooling purposes using the bypass control valve (L); when the HTF temperature at the outlet of first packed bed (C1) (point (2)) reaches to be the setpoint temperature of the heat exchanger for cooling purposes (here it is 16° C.), the discharging of the first packed is stopped.

10. The method as claimed in claim 3, wherein the discharging can be from bottom to top or from top to bottom.

11. The method as claimed in claim 3, wherein each packed bed is randomly filled with filling materials as monodisperse and/or polydisperse solid particles.

12. The method as claimed in claim 3, wherein the filling materials may be made of aluminum oxide, steel or ceramic or other solid particles that include fluid inside such as phase change material (PCM) and/or small objects like Raschig rings.

13. The method as claimed in claim 3, wherein the filling materials may be mixture of two or more of aluminum oxide, steel or ceramic or other solid particles that include fluid inside such as phase change material (PCM) and/or small objects like Raschig rings.

14. The method as claimed in claim 3, wherein the multi-packed bed system may be placed outside of the buildings vertically or horizontally and/or in the ground or underground and/or may also be movable.

15. The method as claimed in claim 3, wherein the HTF fluid may be carbon dioxide, nitrogen, dried air or other suitable gases.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0026] The figures used for better describing the pressurised, low temperature, single or multi-packed bed cold storage and distribution system developed by the invention and descriptions of said figures are provided below:

[0027] FIG. 1: Schematic representation of process components

[0028] FIG. 2: Simplified process layout of the system

[0029] FIG. 3: Schematic view of charging process (in general) without bypass

[0030] FIG. 3.1: Temperature change at point (0) and (1) during charging without bypass

[0031] FIG. 4: Schematic view of charging process (in general) with bypass

[0032] FIG. 4.1: Temperature change at point (0) and (1) during charging with bypass

[0033] FIG. 5: Schematic view of charging phase sequences in case of three packed beds connected together in parallel

[0034] FIG. 5.a: Schematic view of charging phase sequences in case of three packed beds connected together in parallel (charging first packed bed)

[0035] FIG. 5.b: Schematic view of charging phase sequences in case of three packed beds connected together in parallel (charging first and second packed beds)

[0036] FIG. 5.c: Schematic view of charging phase sequences in case of three packed beds connected together in parallel (charging second and third packed beds)

[0037] FIG. 6: Schematic view of charging sequences in case of all packed beds connected together in parallel

[0038] FIG. 7: Schematic view of discharging process (in general) with bypass

[0039] FIG. 7.1: Temperature change at point (0) and (1) during charging with and without bypass

[0040] FIG. 8: Schematic view of sequence of discharging phase (in general)

[0041] FIG. 8.a: Schematic view of discharging phase sequences in case of three packed beds connected together in parallel (discharging third packed bed)

[0042] FIG. 8.b: Schematic view of discharging phase sequences in case of three packed beds connected together in parallel (discharging second packed bed)

[0043] FIG. 8.c: Schematic view of discharging phase sequences in case of three packed beds connected together in parallel (discharging first packed bed)

DESCRIPTIONS OF THE COMPONENTS/SECTIONS/PARTS FORMING THE INVENTION

[0044] In order to better describe the pressurised, low temperature, single or multi-packed bed cold storage and distribution system developed by this invention, reference numbers are individually assigned to the parts and components in the figures and description of each of these numbers are provided below: [0045] A—Heat Transfer Fluid (HTF) Compressor [0046] B— Chiller [0047] C— Multi-packed bed system [0048] C1—First packed bed [0049] C2—Second packed bed [0050] C3—Third packed bed [0051] D—Heat Exchanger Coil [0052] E—User [0053] F— Fan for Heat Exchanger [0054] G—Evaporator [0055] H— Compressor for Chiller [0056] I— Condenser [0057] J—Expansion Valve [0058] K— Bypass control valve (charging) [0059] L—Bypass control valve (discharging) [0060] 0—The point at the inlet of HTF Compressor (FIG. 3) [0061] 1—The point between HTF Compressor and Chiller by charging (FIG. 3) [0062] 2—Entry of first packed bed by charging (FIG. 3) [0063] 3—Exit of first packed bed by charging (FIG. 3) [0064] CV1: Control Valve between entries of first and second packed beds (FIG. 5 in charging) [0065] CV2: Control Valve between entries of second and third packed beds (FIG. 5 in charging) [0066] CV3: Control Valve between exits of first and second packed beds (FIG. 5 in charging) [0067] CV4: Control Valve between exits of second and third packed beds (FIG. 5 in charging) [0068] DCV1: Discharge Control Valve at the exit of first packed bed (C1) (FIG. 8 in discharging) [0069] DCV2: Discharge Control Valve at the exit of second packed bed (C2) (FIG. 8 in discharging) [0070] DCV3: Discharge Control Valve at the exit of third packed bed (C3) (FIG. 8 in discharging) [0071] DCV4: Discharge Control Valve in between the inlets of first and second packed beds (C1 and C2) (FIG. 8 in discharging) [0072] DCV5: Discharge Control Valve in between the inlets of second and third packed beds (C2 and C3) (FIG. 8 in discharging) [0073] DCV6: Discharge Control Valve between exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (FIG. 8 in discharging)

Process Components

[0074] The process consists of a multi-packed bed system, a chiller, a heat exchanger coil and a HTF compressor (see FIG. 1). [0075] 1) Multi-packed bed system: This system comprises at least one packed bed or more connected to each other for storing coldness. Each packed bed is randomly filled with filling materials. Filling materials may be monodisperse and/or polydisperse solid particles. The filling material may be made of e.g. aluminium oxide, steel or ceramic or other solid particles that include fluid inside such as phase change material (PCM) and/or small objects like Raschig rings and/or anything else that can be designed as filling material. The filling material may be mixture of two or more of these materials. The multi-packed bed system may be placed outside of the buildings vertically or horizontally and/or in the ground (underground) and/or may also be movable. [0076] 2) Chiller: It cools the heat transfer fluid (HTF) to low or ultra-low temperature. [0077] 3) Heat exchanger coil: It delivers cooling to the end users. [0078] 4) HTF compressor: The compressor enables the circulation of the HTF (e.g. carbon dioxide, nitrogen, dried air or other suitable gases) in the closed circuit that operated under high-pressure.

Process Description

[0079] FIG. 2 shows a simplified process layout of the pressurised, low/ultra-low temperature, multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources. Four components are required for this process: the chiller (cooling source) (B), the multi-packed bed system (cold storage) (C), the HTF compressor (pressure drop compensation) (A) and the heat exchanger coil (delivering of coldness to user) (D).

[0080] Chiller (B) comprises, Evaporator (G), Compressor for Chiller (H), Condenser (I) and Expansion Valve 0). It is well-known technology.

[0081] In the process of the invention, some setpoints (for temperatures and operation pressure) must be defined according the design conditions and user requirements. These are: [0082] Charging setpoint temperature at the outlet of chiller (Setpoint temperature for chiller), [0083] Setpoint temperature at the exit of every packed bed (Setpoint temperature for bottom of each packed bed during charging mode), [0084] Setpoint temperature at the inlet of the HTF compressor, [0085] Setpoint operation pressure of the HTF Compressor (setpoint pressure), [0086] Setpoint temperature at the heat exchanger for delivering cooling to the user (Setpoint temperature of the heat exchanger for cooling purposes).

[0087] These temperature and pressure setpoints are set to predetermined values before initiating the system.

[0088] During charging phase, illustrated in FIG. 3, the heat transfer fluid is compressed by the HTF compressor (A) (point (1)). The pressurized HTF enters the chiller (B), where its temperature decreases to about −50° C. (temperature of the HTF could be higher or lower—here the setpoint temperature for chiller is assumed as −50° C.) (point (2)). Then, the cold and pressurized HTF enters the multi-packed bed system (C) from the bottom and exit from the top. At the outlet of the multi-packed bed systems (point (3)), the HTF flows to the HTF compressor. The charging phase is stopped, when the temperature of the HTF at the top of the multi-packed bed system (point (3)) reaches a certain value (here is −5° C., but could be higher or lower—here the setpoint temperature at exit of every packed bed is assumed as −5° C.). It should be mentioned that the exit HTF temperature at point (3) is at the start is high and declines over the course of the charging phase due the temperature decrease in the cold storage system. This means, the HTF compressor and the chiller will work under different performances by the reason of different HTF temperatures at the inlet of compressor (A). In FIG. 3.1, it can be noticed that the temperature of HTF fluid will decrease at the points (0) and (1) during charging phase.

[0089] The exit HTF temperature can be maintained at a constant value (here is 10° C., but could be higher or lower) during charging phase, if part of the mass flow rate at point (1+2) is bypassed to point (4) (see FIG. 4). A control circuit is required in order to adjust the mass flow rate through the bypass control valve (K). In FIG. 4.1, it is seen that the temperature of the HTF fluid will be kept constant at the points (0) and (1) using the bypass control valve (K).

[0090] The pressure drop during the charging phase is related mostly to the pressure losses in the multi-packed bed system. In order to reduce the pressure losses, it is favourable to increase the operation pressure (setpoint pressure) (here, the operation pressure is 15 bar, but it could be higher or lower). If higher operation pressure is applied, then the pressure losses in the multi-packed bed system will be low. Increasing the operation pressure will result in increasing the wall thickness of the multi-packed bed system and all related components. The HTF mass flow rate during charging phase depends on the chiller capacity to achieve the charging temperature (here is −50° C.) and to compensate the pressure losses in the system.

[0091] FIG. 5 shows the charging phase sequences in case of three packed beds connected together in parallel: [0092] Charging the first packed bed (C1) (points 1, 2, 3, 4 to 5), while the bypass valve controls the setpoint temperature of the HTF at the inlet of the HTF compressor as constant (here it is 10° C.). At this stage (FIG. 5.a), the control valve between entries of first and second packed beds (CV1) and the control valve between entries of second and third packed beds (CV2) are closed. The control valves between exits of first and second packed beds (CV3) and between the exits of second and third packed beds (CV4) are opened. Therefore, the HTF flows via the points (1), (2), (3), (4) and (5). The HTF temperature (setpoint temperature) at the inlet of compressor (A) (point (5)) is controlled using the bypass control valve (K) (FIG. 5.a). [0093] When the HTF temperature at the exit of first packed bed (C1) (point (3)) reaches to the setpoint temperature at the exit of multi packed beds (here it is −5° C.), the second packed bed starts charging together with the first packed bed (C1 and C2) (points 1, 2, 3, 4, 5 to 6), while the bypass control valve (K) controls the temperature of the HTF at the inlet of the HTF compressor at the setpoint temperature (here it is 10° C.). At this stage (See FIG. 5.b), the control valve between entries of second and third packed beds (CV2) is closed. The valve between entries of first and second packed beds (CV1), the control valve between exits of first and second packed beds (CV3) and the control valve between exits of second and third packed beds (CV4) are opened. Therefore, the HTF flows via the points (1), (2), (3), (4), (5) and (6). The HTF temperature at the inlet of compressor (A) (point (7)) is controlled using the bypass control valve (K) to be at the setpoint temperature (FIG. 5.b). [0094] When the HTF temperature at the exit of second packed bed (C2) at point (5) reaches to the setpoint temperature at the exit of multi packed beds (here it is −5° C.), the third packed bed starts charging together with the second packed bed (C2 and C3). FIG. 5.c shows the charging phase of third packed bed (C3). [0095] In order to charge the third packed bed (C3), the control valve between exits of first and second packed beds (CV3) is closed. The control valve between entries of first and second packed beds (CV1), the control valve between entries of second and third packed beds (CV2) and the control valve between exits of second and third packed beds (CV4) are opened. Therefore, the HTF flows via the points (1), (2), (3), (4), (6) and (7). The HTF temperature at the inlet of compressor (A) (point (8)) is controlled using the bypass control valve (K) (FIG. 5.c). Compressor inlet temperature may be set to 10° C., lower or higher depending on the purpose. [0096] Similar procedure applies in case of the connection of fourth (not shown in the figures) or additional packed beds. [0097] Charging process can either be from top to bottom or from bottom to top.

[0098] FIG. 6 shows the charging sequences in case of all packed beds connected together in parallel: [0099] Charging all packed beds (C1, C2 and C3) (points 1, 2, 3, 4, 5, 6, 7 to 8), while the bypass valve controls the temperature of the HTF at the inlet of the HTF compressor to 10° C. At this stage, all control valves (CV1, CV2, CV3 and CV4) are opened. Therefore, the HTF flows via the points (1), (2), (3), (4), (5), (6), (7) and (8). The HTF temperature at the inlet of compressor (A) is controlled using the bypass control valve (K) (FIG. 6). [0100] When the HTF temperature at point (7) reaches to the setpoint temperature at the exit of multi packed beds (here it is −5° C.), the charging phase is stopped. [0101] Charging sequences in case of all packed beds connected together in parallel shown in FIG. 6 can also be in serial order (points 1, 2, 5, 3, 6, 4, 7, 8) instead of parallel order. In this case, additional connection pipes are required (i.e. the exit of first packed bed to the entry of second packed bed as well as the exit of second packed bed to the entry of third packed bed). The HTF temperature at the inlet of compressor (A) (point (8)) is controlled using the bypass control valve (K). It should be mentioned here that the charging phase in series (C1, C2 and C3) will result in higher pressure losses in the system.

[0102] During discharging phase, illustrated in FIG. 7, the heat transfer fluid is compressed by the HTF compressor (A) (point (1)). FIG. 7.1 shows that the exit HTF temperature at point (3) without the bypass system is very low at the start and increases over the course of the discharging phase due the temperature increases in the cold storage system. Using the bypass control valve (L), the exit HTF temperature at point (3) is kept constant at the setpoint temperature of the heat exchanger for cooling purposes. Here, part of the pressurized HTF enters the packed bed system from the top and exits from the bottom (point (2)), while the remaining part of the pressurized HTF is bypassed to point (3). The bypassed mass flow rate of the HTF through the bypass control valve (L) is controlled, so that the temperature of the HTF at the inlet of the heat exchanger coil is maintained to the setpoint temperature of the heat exchanger for cooling purposes (here it is 16° C.) during discharging phase (this setpoint temperature can be selected higher or lower according to user). A fan blows air with ambient temperature of 50° C. over the coils to deliver cooling to the end user (the ambient temperature can be lower or higher). At the outlet of the heat exchanger coil, the temperature of the HTF (point (4)) is similar to ambient temperature. When the temperature of the HTF at the outlet of the packed bed system (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes (here it is 16° C.), the discharge phase is stopped. The HTF mass flow rate during the discharging phase depends on the HTF compressor and the pressure losses raised in the system. Generally, the system can be discharged with much higher mass flow rates of the HTF compared to charging phase. This is of high relevance to provide high quantity of cold air during peak hours.

[0103] FIG. 8 shows the sequence of discharging phase as follows: [0104] Discharging the third packed bed (C3) (points 1, 2 to 3), while the bypass control valve (L) controls the temperature of the HTF at the inlet of the heat exchanger coil of 16° C. In order to discharge the third packed bed (C3), the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of second packed bed (C2) (DCV2), between the inlets of first and second packed beds (C1 and C2) (DCV4) and between the inlets of second and third packed beds (C2 and C3) (DCV5) are closed. The discharge control valve at the exit of third packed bed (C3) (DCV3) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened. Therefore, the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1), (2) and (3). During discharging the third packed bed (C3), the temperature at point (3) is kept constant to the setpoint temperature of the heat exchanger for cooling purposes using the bypass control valve (L) (FIG. 8.a). Here, the exit temperature at point (3) is 16° C., but it may be higher or lower according to the implementing conditions. When the HTF temperature at the outlet of third packed bed (C3) (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes (16° C.), the discharging of the third packed is stopped and the discharging of the second packed bed starts. [0105] Discharging the second packed bed (points 1, 2 to 3), while the bypass valve (L) controls the temperature of the HTF at the inlet of the heat exchanger coil to be to the setpoint temperature of the heat exchanger for cooling purposes (here it is 16° C.). In order to discharge the second packed bed (C2), the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of third packed bed (C3) (DCV3) and between the inlets of first and second packed beds (C1 and C2) (DCV4) are closed. The discharge control valves at the exit of second packed bed (C2) (DCV2), between the inlets of second and third packed beds (C2 and C3) (DCV5) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened. Therefore, the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1), (2) and (3). During discharging the second packed bed (C2), the temperature at point (3) is kept constant to be the setpoint temperature of the heat exchanger for cooling purposes (here it is 16° C., but may be higher or lower according to the implementing conditions) using the bypass control valve (L) (FIG. 8.b). When the HTF temperature at the outlet of second packed bed (C2) (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes (16° C.), the discharging of the second packed is stopped. [0106] In order to discharge the first packed bed (C1), the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of second packed bed (C2) (DCV2) and at the exit of third packed bed (C3) (DCV3) are closed. The discharge control valves between the inlets of first and second packed beds (C1 and C2) (DCV4), between the inlets of second and third packed beds (C2 and C3) (DCV5) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened. Therefore, the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1) and (2). During discharging the first packed bed (C1), the temperature at point (2) is kept constant to be the setpoint temperature of the heat exchanger for cooling purposes (here it is 16° C.), may be higher or lower according to the implementing conditions) using the bypass control valve (L) (FIG. 8.c). When the HTF temperature at the outlet of first packed bed (C1) (point (2)) reaches to be the setpoint temperature of the heat exchanger for cooling purposes (16° C.), the discharging of the first packed is stopped. [0107] Similar procedure applies to additional packed beds. [0108] Discharging can either be from bottom to top or from top to bottom.

General Explanation of the Invention

[0109] The pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources comprises a chiller (cooling source) (B) for cooling the heat transfer fluid (HTF) to low or ultra-low temperature, a multi-packed bed system (cold storage) (C) for storing coldness, the HTF compressor (A) enabling the circulation of the HTF in the closed circuit that operated under high-pressure and the heat exchanger coil (delivering of coldness to user) (D) (FIG. 2).

[0110] At the starting phase (before initiating the system) the setpoints (for temperatures and operation pressure) which are: [0111] Charging setpoint temperature at the outlet of chiller (Setpoint temperature for chiller), [0112] Setpoint temperature at the exit of every packed bed (Setpoint temperature for bottom of each packed bed during charging mode), [0113] Setpoint temperature at the inlet of the HTF compressor, [0114] Setpoint pressure of the HTF compressor (setpoint pressure), [0115] Setpoint temperature at the heat exchanger for delivering cooling to the user (Setpoint temperature of the heat exchanger for cooling purposes) [0116] are set to the predetermined values.

[0117] During charging phase, the heat transfer fluid is compressed by the HTF compressor (A) (point (1)); the pressurized HTF enters the chiller (B), where its temperature decreases to the setpoint temperature for chiller (point (2)); the cold and pressurized HTF enters the multi-packed bed system (C) from the bottom and exit from the top; at the outlet of the multi-packed bed system (point (3)), the HTF flows to the HTF compressor; the charging phase is stopped, when the temperature of the HTF at the top of the multi-packed bed system (point (3)) reaches the setpoint temperature at exit of packed bed; if no bypass is applied, the HTF temperature at the exit of the multi-packed bed system at point (3) is high at the start and declines over the course of the charging phase due the temperature decrease in the multi packed bed. (FIG. 3)

[0118] During charging phase, when bypass control valve (K) is applied in between the exit of chiller (B) and the exit of multi packed bed system (C) and the exit of HTF compressor (A) for keeping the HTF temperature at the inlet of HTF compressor (A) as setpoint temperature. (FIG. 4)

[0119] When more than one packed beds connected together are used; in charging of the packed beds; [0120] The first packed bed (C1) is charged between (points 1, 2, 3, 4 to 5) (FIG. 5.a) as below; [0121] the control valve between entries of first and second packed beds (CV1) and the control valve between entries of second and third packed beds (CV2) are closed; the control valves between exits of first and second packed beds (CV3) and between the exits of second and third packed beds (CV4) are opened; (FIG. 5.a) [0122] the HTF passes from first packed bed (C1) and flows via the points (1), (2), (3), (4) and (5); (FIG. 5.a) [0123] at this stage, the HTF temperature at the inlet of compressor (A) (point (5)) is controlled by the bypass control valve (K) to be at the setpoint temperature at the inlet of HTF compressor (A) (FIG. 5.a); [0124] When the HTF temperature at the exit of first packed bed (C1) (point (3)) reaches to the setpoint temperature at the exit of multi packed beds, the second packed bed starts charging with the first packed bed (C1 and C2) (points 1, 2, 3, 4, 5 to 6) (FIG. 5.b); [0125] at this stage, the control valve between entries of second and third packed beds (CV2) is closed; the valve between entries of first and second packed beds (CV1), the control valve between exits of first and second packed beds (CV3) and the control valve between exits of second and third packed beds (CV4) are opened; the HTF flows in the first and second packed beds (C1 and C2) via the points (1), (2), (3), (4), (5) and (6); the HTF temperature at the inlet of compressor (A) (point (7)) is controlled using the bypass control valve (K) to be at the setpoint temperature; when the HTF temperature at the exit of second packed bed (C2) at point (5) reaches to the setpoint temperature at the exit of multi packed beds, the charging phase is stopped (FIG. 5.b). [0126] In case of the connection of a third packed bed (C3); for charging the third packed bed (C3), the control valve between exits of first and second packed beds (CV3) is closed; the control valve between entries of first and second packed beds (CV1), the control valve between entries of second and third packed beds (CV2) and the control valve between exits of second and third packed beds (CV4) are opened; the HTF flows in the second and third packed beds (C2 and C3) via the points (1), (2), (3), (4), (6) and (7); the HTF temperature at the inlet of compressor (A) (point (8)) is controlled using the bypass control valve (K) to be at the set point temperature (FIG. 5.c). [0127] In case of the connection of a further packed bed; for charging the last packed bed, the control valves of previous packed beds except last two are closed; the control valves of last two packed beds are opened; the HTF flows in the last packed bed and the one before last packed bed; the HTF temperature at the inlet of compressor (A) is controlled using the bypass control valve (K) to be at the set point temperature.

[0128] When all packed beds connected together in parallel (FIG. 6); [0129] Charging all packed beds (C1, C2 and C3) (points 1, 2, 3, 4, 5, 6, 7 to 8), while the bypass valve controls the temperature of the HTF at the inlet of the HTF compressor (A) to be at the setpoint temperature; at this stage, all control valves (CV1, CV2, CV3 and CV4) are opened; the HTF flows via the points (1), (2), (3), (4), (5), (6) and (7). The HTF temperature at the inlet of compressor (A) is controlled using the bypass control valve (K) (FIG. 6); [0130] When the HTF temperature at point (7) reaches to the setpoint temperature at the exit of multi packed beds, the charging phase is stopped (FIG. 6).

[0131] When all packed beds are connected together in serial order instead of parallel order; in this case, additional connection pipes that connecting the exit of first packed bed to the entry of second packed bed as well as the exit of second packed bed to the entry of third packed bed is used. The HTF temperature at the inlet of compressor (A) (point (8)) is controlled using the bypass control valve (K).

[0132] The charging process can either be from top to bottom or from bottom to top for the single or multi-packed bed cold storage system developed in this invention.

[0133] During discharging phase (FIG. 7).

[0134] the heat transfer fluid is compressed by the HTF compressor (A) (point (1));

[0135] part of the pressurized HTF enters the packed bed system from the top and exits from the bottom (point (2)), while the remaining part of the pressurized HTF is bypassed to point (3);

[0136] the bypassed mass flow rate of the HTF through the bypass control valve (L) is controlled, so that the temperature of the HTF at the inlet of the heat exchanger coil is maintained to the setpoint temperature of the heat exchanger for cooling purposes;

[0137] a fan blows air with ambient temperature; at the outlet of the heat exchanger coil, the temperature of the HTF (point (4)) is similar to ambient temperature;

[0138] when the temperature of the HTF at the outlet of the packed bed system (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes, the discharge phase is stopped (FIG. 7).

[0139] When more than one packed beds connected together are used (FIG. 8); [0140] During discharging the third packed bed (C3) (points 1, 2 to 3) (FIG. 8.a), [0141] the bypass control valve (L) controls the temperature of the HTF at the inlet of the heat exchanger coil; [0142] the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of second packed bed (C2) (DCV2), between the inlets of first and second packed beds (C1 and C2) (DCV4) and between the inlets of second and third packed beds (C2 and C3) (DCV5) are closed; [0143] the discharge control valve at the exit of third packed bed (C3) (DCV3) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened; [0144] the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1), (2) and (3); during discharging the third packed bed (C3), the temperature at point (3) is kept constant to the setpoint temperature of the heat exchanger for cooling purposes using the bypass control valve (L); [0145] when the HTF temperature at the outlet of third packed bed (C3) (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes, the discharging of the third packed is stopped and the discharging of the second packed bed starts. [0146] During discharging the second packed bed (points 1, 2 to 3) (FIG. 8.b), [0147] the bypass valve (L) controls the temperature of the HTF at the inlet of the heat exchanger coil to be to the setpoint temperature of the heat exchanger for cooling purposes; [0148] the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of third packed bed (C3) (DCV3) and between the inlets of first and second packed beds (C1 and C2) (DCV4) are closed; [0149] the discharge control valves at the exit of second packed bed (C2) (DCV2), between the inlets of second and third packed beds (C2 and C3) (DCV5) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened; [0150] the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1), (2) and (3); [0151] during discharging the second packed bed (C2), the temperature at point (3) is kept constant to be the setpoint temperature of the heat exchanger for cooling purposes using the bypass control valve (L); [0152] when the HTF temperature at the outlet of second packed bed (C2) (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes, the discharging of the second packed is stopped. [0153] In order to discharge the first packed bed (C1) (FIG. 8.c), [0154] the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of second packed bed (C2) (DCV2) and at the exit of third packed bed (C3) (DCV3) are closed; [0155] the discharge control valves between the inlets of first and second packed beds (C1 and C2) (DCV4), between the inlets of second and third packed beds (C2 and C3) (DCVS) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened; [0156] the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1) and (2); [0157] during discharging the first packed bed (C1), the temperature at point (2) is kept constant to be the setpoint temperature of the heat exchanger for cooling purposes using the bypass control valve (L); [0158] when the HTF temperature at the outlet of first packed bed (C1) (point (2)) reaches to be the setpoint temperature of the heat exchanger for cooling purposes (here it is 16° C.), the discharging of the first packed is stopped.

[0159] The discharging process can either be from top to bottom or from bottom to top for the single or multi-packed bed cold storage system developed in this invention.

[0160] Each packed bed of the single or multi-packed bed cold storage system developed in this invention is randomly filled with filling materials as monodisperse and/or polydisperse solid particles.

[0161] The filling materials of each packed bed of the single or multi-packed bed cold storage system developed in this invention may be made of aluminium oxide, steel or ceramic or other solid particles that include fluid inside such as phase change material (PCM) and/or small objects like Raschig rings.

[0162] The filling materials of each packed bed of the single or multi-packed bed cold storage system developed in this invention may be mixture of two or more of aluminum oxide, steel or ceramic or other solid particles that include fluid inside such as phase change material [PCM] and/or small objects like Raschig rings.

[0163] The single or multi-packed bed system developed in this invention may be placed outside of the buildings vertically or horizontally and/or in the ground (underground) and/or may also be movable.

[0164] The HTF fluid of the single or multi-packed bed system developed in this invention may be carbon dioxide, nitrogen, dried air or other suitable gases.

[0165] Further embodiments of the present inventions relate to the following examples:

[0166] 1. A pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources comprising a chiller (cooling source) (B) for cooling the heat transfer fluid (HTF) to low or ultra-low temperature, a multi-packed bed system (cold storage) (C) for storing coldness, the HTF compressor (A) enabling the circulation of the HTF in the closed circuit that operated under high-pressure and the heat exchanger coil (delivering of coldness to user) (D) characterizing that,

[0167] Setpoints (for temperatures and operation pressure) which are: [0168] Charging setpoint temperature at the outlet of chiller (Setpoint temperature for chiller), [0169] Setpoint temperature at the exit of every packed bed (Setpoint temperature for bottom of each packed bed during charging mode), [0170] Setpoint temperature at the inlet of the HTF compressor, [0171] Setpoint pressure of the HTF compressor (setpoint pressure), [0172] Setpoint temperature at the heat exchanger for delivering cooling to the user (Setpoint temperature of the heat exchanger for cooling purposes)

[0173] are set to the predetermined values before initiating the system.

[0174] During charging phase, the heat transfer fluid is compressed by the HTF compressor (A) (point (1)); the pressurized HTF enters the chiller (B), where its temperature decreases to the setpoint temperature for chiller (point (2)); the cold and pressurized HTF enters the multi-packed bed system (C) from the bottom and exit from the top; at the outlet of the multi-packed bed system (point (3)), the HTF flows to the HTF compressor; the charging phase is stopped, when the temperature of the HTF at the top of the multi-packed bed system (point (3)) reaches the setpoint temperature at exit of packed bed; if no bypass is applied, the HTF temperature at the exit of the multi-packed bed system at point (3) is high at the start and declines over the course of the charging phase due the temperature decrease in the multi packed bed.

[0175] 2. A pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in example 1, when bypass control valve (K) is applied in between the exit of chiller (B) and the exit of multi packed bed system (C) and the exit of HTF compressor (A) for keeping the HTF temperature at the inlet of HTF compressor (A) as setpoint temperature.

[0176] 3. A pressurised, low/ultra-low temperature, multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in example 1 or 2, when more than one packed beds connected together are used; [0177] During charging the first packed bed (C1) (points 1, 2, 3, 4 to 5), the control valve between entries of first and second packed beds (CV1) and the control valve between entries of second and third packed beds (CV2) are closed; the control valves between exits of first and second packed beds (CV3) and between the exits of second and third packed beds (CV4) are opened; the HTF passes from first packed bed (C1) and flows via the points (1), (2), (3), (4) and (5); at this stage, the HTF temperature at the inlet of compressor (A) (point (5)) is controlled by the bypass control valve (K) to be at the setpoint temperature at the inlet of HTF compressor (A); [0178] When the HTF temperature at the exit of first packed bed (C1) (point (3)) reaches to the setpoint temperature at the exit of multi packed beds, the second packed bed starts charging with the first packed bed (C1 and C2) (points 1, 2, 3, 4, 5 to 6); at this stage, the control valve between entries of second and third packed beds (CV2) is closed; the valve between entries of first and second packed beds (CV1), the control valve between exits of first and second packed beds (CV3) and the control valve between exits of second and third packed beds (CV4) are opened; the HTF flows in the first and second packed beds (C1 and C2) via the points (1), (2), (3), (4), (5) and (6); the HTF temperature at the inlet of compressor (A) (point (7)) is controlled using the bypass control valve (K) to be at the setpoint temperature; when the HTF temperature at the exit of second packed bed (C2) at point (5) reaches to the setpoint temperature at the exit of multi packed beds, the charging phase is stopped. [0179] In case of the connection of a third packed bed (C3); for charging the third packed bed (C3), the control valve between exits of first and second packed beds (CV3) is closed; the control valve between entries of first and second packed beds (CV1), the control valve between entries of second and third packed beds (CV2) and the control valve between exits of second and third packed beds (CV4) are opened; the HTF flows in the second and third packed beds (C2 and C3) via the points (1), (2), (3), (4), (6) and (7); the HTF temperature at the inlet of compressor (A) (point (8)) is controlled using the bypass control valve (K) to be at the set point temperature. [0180] In case of the connection of a further packed bed; for charging the last packed bed, the control valves of previous packed beds except last two are closed; the control valves of last two packed beds are opened; the HTF flows in the last packed bed and the one before last packed bed; the HTF temperature at the inlet of compressor (A) is controlled using the bypass control valve (K) to be at the set point temperature.

[0181] Optionally, the HTF temperature at the inlet of compressor (A) (point (7)) is controlled using the control valve CV3 and, if it is necessary, also the bypass control valve (K) to be at the setpoint temperature. Similarly, the HTF temperature at the inlet of compressor (A) (point (8)) may be controlled using the control valve CV4 and, if it is necessary, also the bypass control valve (K) to be at the setpoint temperature. Finally, the HTF temperature at the inlet of compressor (A) may be controlled using the control valve installed at the outlet of the one before last packed bed and, if it is necessary, also the bypass control valve (K) to be at the set point temperature.

[0182] This is for the following reason advantageous: During the charging phase of C1 and C2, the HTF temperature at the inlet of compressor can be controlled by dividing the mass flow rate between C1 and C2. At the beginning of the charging phase, the outlet temperature of the C1 is low, while the outlet temperature of the C2 is high. High amount of the HTF will flow in the C1 and fewer amount of the HTF will flow in the C2, so that the mixture temperature is constant (the setpoint of HTF temperature at the inlet of compressor). After a while, the outlet temperature of C2 becomes lower. Therefore, higher amount of HTF will flow through C2 and the remaining part through C1, so that the mixture temperature is constant (the setpoint of HTF temperature at the inlet of compressor).

[0183] 4. A pressurised, low/ultra-low temperature, multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in a previous example, when all packed beds connected together in parallel; [0184] Charging all packed beds (C1, C2 and C3) (points 1, 2, 3, 4, 5, 6, 7 to 8), while the bypass valve controls the temperature of the HTF at the inlet of the HTF compressor (A) to be at the setpoint temperature; at this stage, all control valves (CV1, CV2, CV3 and CV4) are opened; the HTF flows via the points (1), (2), (3), (4), (5), (6) and (7). The HTF temperature at the inlet of compressor (A) is controlled using the bypass control valve (K); [0185] When the HTF temperature at point (7) reaches to the setpoint temperature at the exit of multi packed beds, the charging phase is stopped.

[0186] 5. A pressurised, low/ultra-low temperature, multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in the previous examples, all packed beds may be connected together in serial order instead of parallel order; in this case, additional connection pipes that connecting the exit of first packed bed to the entry of second packed bed as well as the exit of second packed bed to the entry of third packed bed is used; the HTF temperature at the inlet of compressor (A) (point (8)) is controlled using the bypass control valve (K).

[0187] 6. A pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as any one of the previous examples, the charging process can either be from top to bottom or from bottom to top.

[0188] 7. A pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in any one of the previous examples;

[0189] During discharging phase, the heat transfer fluid is compressed by the HTF compressor (A) (point (1)); part of the pressurized HTF enters the packed bed system from the top and exits from the bottom (point (2)), while the remaining part of the pressurized HTF is bypassed to point (3); the bypassed mass flow rate of the HTF through the bypass control valve (L) is controlled, so that the temperature of the HTF at the inlet of the heat exchanger coil is maintained to the setpoint temperature of the heat exchanger for cooling purposes; a fan blows air with ambient temperature; at the outlet of the heat exchanger coil, the temperature of the HTF (point (4)) is similar to ambient temperature; when the temperature of the HTF at the outlet of the packed bed system (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes, the discharge phase is stopped.

[0190] 8. A pressurised, low/ultra-low temperature, multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in example 1 or 2, when more than one packed beds connected together are used; [0191] During discharging the third packed bed (C3) (points 1, 2 to 3), the bypass control valve (L) controls the temperature of the HTF at the inlet of the heat exchanger coil; the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of second packed bed (C2) (DCV2), between the inlets of first and second packed beds (C1 and C2) (DCV4) and between the inlets of second and third packed beds (C2 and C3) (DCV5) are closed; the discharge control valve at the exit of third packed bed (C3) (DCV3) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened; the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1), (2) and (3); during discharging the third packed bed (C3), the temperature at point (3) is kept constant to the setpoint temperature of the heat exchanger for cooling purposes using the bypass control valve (L); when the HTF temperature at the outlet of third packed bed (C3) (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes, the discharging of the third packed is stopped and the discharging of the second packed bed starts. [0192] During discharging the second packed bed (points 1, 2 to 3), the bypass valve (L) controls the temperature of the HTF at the inlet of the heat exchanger coil to be to the setpoint temperature of the heat exchanger for cooling purposes; the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of third packed bed (C3) (DCV3) and between the inlets of first and second packed beds (C1 and C2) (DCV4) are closed; the discharge control valves at the exit of second packed bed (C2) (DCV2), between the inlets of second and third packed beds (C2 and C3) (DCVS) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened; the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1), (2) and (3); during discharging the second packed bed (C2), the temperature at point (3) is kept constant to be the setpoint temperature of the heat exchanger for cooling purposes using the bypass control valve (L); when the HTF temperature at the outlet of second packed bed (C2) (point (2)) reaches to the setpoint temperature of the heat exchanger for cooling purposes, the discharging of the second packed is stopped. [0193] In order to discharge the first packed bed (C1), the discharge control valves at the exit of first packed bed (C1) (DCV1), at the exit of second packed bed (C2) (DCVZ) and at the exit of third packed bed (C3) (DCV3) are closed; the discharge control valves between the inlets of first and second packed beds (C1 and C2) (DCV4), between the inlets of second and third packed beds (C2 and C3) (DCV5) and the valve between the exits of packed beds (C1, C2 and C3) and heat exchanger coil (D) (DCV6) are opened; the HTF flows from the HTF compressor (A) to heat exchanger coil (D) via the points (1) and (2); during discharging the first packed bed (C1), the temperature at point (2) is kept constant to be the setpoint temperature of the heat exchanger for cooling purposes using the bypass control valve (L); when the HTF temperature at the outlet of first packed bed (C1) (point (2)) reaches to be the setpoint temperature of the heat exchanger for cooling purposes (here it is 16° C.), the discharging of the first packed is stopped.

[0194] 9. A pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in any one of the previous examples, discharging can be from bottom to top or from top to bottom.

[0195] 10. A pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in any one of the previous examples, each packed bed is randomly filled with filling materials as monodisperse and/or polydisperse solid particles.

[0196] 11. A pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in any one of the previous examples, the filling materials may be made of aluminum oxide, steel or ceramic or other solid particles that 5 include fluid inside such as phase change material (PCM) and/or small objects like Raschig rings.

[0197] 12. A pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in any one of the previous examples, the filling materials may be mixture of two or more of aluminum oxide, steel or ceramic or other solid particles that include fluid inside such as phase change material (PCM) and/or small objects like Raschig rings.

[0198] 13. A pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in any one of the previous examples, the multi-packed bed system may be placed outside of the buildings vertically or horizontally and/or in the ground (underground) and/or may also be movable.

[0199] 14. A pressurised, low/ultra-low temperature, single or multi-packed bed cold storage system for central air conditioning, other cooling requirements or as energy storage system for renewable energy sources as in any of the previous examples the HTF fluid may be carbon dioxide, nitrogen, dried air or other suitable gases.

[0200] 15. A Cold Storage System (see FIGS. 4 and 6) comprising: a chiller (B) for cooling the heat transfer fluid (HTF) to low or ultra-low temperature; a compressor (A) enabling the circulation of the HTF; a cold storage (C) for storing coldness, wherein the chiller (B) is arranged between the compressor (A) and the cold storage (C); and a bypass line with a bypass control valve (K), wherein the bypass line connects an inlet and an outlet of the cold storage (C) and the bypass control valve (K) is adapted to control a bypass flow through the bypass line to keep a temperature at the outlet of the cold storage (C) (and hence at an inlet of the compressor (A)) at a predefined setpoint temperature. Optionally, a further bypass line may be provided to connect an outlet of the compressor (A) with the outlet of the cold storage (C). This further bypass line may be controlled also by the bypass control valve (K) (e.g. by using a 3-way valve) or by an additional bypass control valve.

[0201] 16. A Cold Storage System (see FIG. 7) comprising: a cold storage (C) for storing coldness; a compressor (A) enabling the circulation of a heat transfer fluid (HTF); a heat exchanger coil (D) for delivering of coldness to a user, wherein the heat exchanger coil (D) is arranged between the compressor (A) and the cold storage; and a bypass line with a bypass control valve (L), wherein the bypass line connects an inlet and an outlet of the cold storage (C) and the bypass control valve (L) is adapted to control a bypass flow through the bypass line to keep a temperature at the outlet of the cold storage (C) (and hence at an inlet of the heat exchanger coil (D)) at a predefined setpoint temperature.

[0202] It is understood that the compressor may not just be a pump, but provides a compression of the HTF and thus relates to temperature drop/jump across the compressor. It is further understood that both cold storage systems (example 15 and 16) may be combined. For this, the chiller B and the heat exchange coil D may be arranged in parallel fluid lines, but couple to the same cold storage and compressor. According to further embodiments, only the cold storage is jointly used and all other components couple to the inlet/outlet of the cold storage. It is further understood that the terms inlet/outlet may be defined dependent on the usage or flow direction. For example, the inlet in one operation (charging the cold storage) may become outlet in the other operation (discharging the cold storage).

[0203] The temperature at the outlet of the cold storage may vary significantly. This will result in a degradation of the system. For example, the compressor or the heat exchange coil operate best for a particular temperature range at the inlet. In addition, thermal stress or an excess of condensation water can be avoided by maintaining predefined temperatures. Embodiments achieve this be using the bypass valves. For this, a control unit may be provided that controls the bypass control valve(s) K, L to setup any appropriate temperature and keep this temperature.

[0204] It is further of advantage that the bypass control valves K, L control only the bypass line (i.e. the fluid volume therethrough) and not the output (or input) of the cold storage. Since the bypass valves K, L are not provided in the flow path from and to the cold storage C, the HTF can flow freely. This increases the reliability, because even if the bypass control valves K, L fail (e.g. are blocking), the system still operates.