Device for cooling a gas

Abstract

A device for cooling a gas and a hydrogen filling station, comprising at least one device according to the invention, are described. The device comprises the following: a piston chamber (2); a liquid piston (3) arranged in the piston chamber (2); a supply line (1) associated with the first end (9) of the piston chamber (2) and having an inlet valve (b); a discharge line (10) associated with the first end (9) of the piston chamber (2) and having an outlet valve (b); a piston (4) associated with the second end of the piston chamber (2); a damping system associated with the piston (4); a control unit (8) that is operatively connected to the damping system and dynamically regulates the pressure to be applied to the piston (4); and means for dissipating heat from the piston chamber (2) and / or damping system.

Description

[0001] The invention relates to a device for cooling a gas and a hydrogen filling station with such a device.

[0002] Hydrogen refueling stations (HRS) for the gaseous refueling of hydrogen-powered vehicles are based on the principle of pressure equalization between the source storage, i.e., the (pressure) storage tank(s) of the hydrogen refueling station, and the sink storage, i.e., the vehicle's fuel tank being filled. The source storage is usually cascaded to ensure a sufficiently rapid hydrogen flow as the sink pressure increases, thus complying with the respective refueling standard (e.g., SAE J2601, CEP, JPEC, or similar). Due to these refueling standards, the pressure ramps must be controlled accordingly. To enable this, the state of the art requires the use of a so-called pressure ramp regulator, which is typically a pneumatically or magnetically actuated proportional valve.The heat generated during the expansion of the hydrogen is in most cases cooled away or removed using a compression chiller, resulting in increased costs and reduced energy efficiency.

[0003] The expansion occurring at the proportional valve or pressure ramp regulator is comparatively strongly isenthalpic, which is why a significant amount of heat is released during refueling. Vehicle tanks are generally approved for a maximum permissible gas temperature of 85 °C. Without pre-cooling, these temperatures are not achievable under current refueling standards, which is why an additional chiller is usually required. This, however, increases the electrical energy consumption of the hydrogen refueling station, negatively impacting its environmental footprint as well as its installation and operating costs.

[0004] The object of the present invention is to provide a device for cooling a gas and a hydrogen filling station with such a device which requires less equipment and process engineering effort for pre-cooling the hydrogen to be transferred, or in the best case makes this pre-cooling obsolete.

[0005] To solve this problem, a generic device for cooling a gas is proposed, comprising a piston chamber, a liquid piston arranged in the piston chamber, a supply line associated with the first end of the piston chamber and having an inlet valve, a discharge line associated with the first end of the piston chamber and having an outlet valve, a piston associated with the second end of the piston chamber, a damping system associated with the piston, a control unit that is operatively connected to the damping system and dynamically regulates the pressure to be applied to the piston, and means for removing heat from the piston chamber and / or damping system.

[0006] Furthermore, a hydrogen filling station is proposed which has at least one device according to the invention.

[0007] Advantageous embodiments and further developments of the device according to the invention for cooling a gas are characterized in that the liquid piston is formed by an ionic liquid and / or a liquid with a solubility for gaseous hydrogen of 0.0003 to 0.0005 g hydrogen per g liquid at a hydrogen partial pressure of 256 bar, the damping system is designed as a spring-damper system, an electromechanical damping system or a gas storage damping system, the control unit is designed as a hydraulic control unit, and / or a magnetic field can be generated in the area of ​​the piston chamber.

[0008] The functioning of the device according to the invention for cooling a gas, preferably hydrogen, is based on the principle of so-called isentropic expansion, in which work is taken away from the gas in order to cool it down.

[0009] Based on the in the FigureThe illustrated embodiment of the device according to the invention for cooling a gas, in particular hydrogen, as well as further advantageous embodiments of this device, are described below.

[0010] The hydrogen, preferably originating from a pressure storage tank of a hydrogen filling station (not shown in the figure), flows intermittently into the first end 9 of the piston chamber 2 via line 1, in which an inlet valve a is arranged. A discharge line 10, having an outlet valve b, is also associated with this first end 9 of the piston chamber 2. Due to the pressure increase in the piston chamber 2, the hydrogen flowing in during an opening stroke of the inlet valve 1 displaces the liquid piston 3 located therein. This piston is preferably formed by an ionic liquid and / or a liquid with a solubility for gaseous hydrogen of 0.0003 to 0.0005 g of hydrogen per g of liquid at a hydrogen partial pressure of 256 bar. A piston 4 is arranged in the second and preferably opposite end of the piston chamber 2. This piston is displaced by the liquid column 3.The piston 4, in turn, performs mechanical work against a damping system. This damping system is preferably designed as a spring-damper system, an electromechanical damping system, or a gas-accumulated damping system. The figure shows a spring-damper system consisting of a spring 5 and a hydraulic damper 6. Furthermore, a control unit 8 is provided, which is operatively connected to the damping system and dynamically regulates the pressure to be applied to the piston 4 by means of the damping system.

[0011] When valve a is closed and valve b is opened simultaneously, piston 4 is moved downwards by the spring-damper system 5 / 6. This causes the liquid column 3 to push the gas volume 9 through the discharge line 10 into the vehicle tank (not shown in the figure). The gas transported is therefore cooler than at the beginning of the process. The pressure ramp required to transfer the gas into the vehicle tank according to a common refueling standard such as SAE J2601 is intermittently controlled by the dynamically changing counterforce applied to piston 4 by the (spring-)damper system. This dynamic control is achieved by a control unit 8, preferably hydraulic, which dynamically adjusts or varies the pressure of the damper 6. The heat generated during this damping process is dissipated from the piston chamber 2 and / or the damper system by suitable heat dissipation means.As shown in the figure, the heat can be released to the atmosphere, particularly via cooling fins 7.

[0012] According to an advantageous embodiment of the device according to the invention, the cooled gas flowing through the discharge line 10 can also be used to supply cooling to, in particular, a further cooling circuit not shown in the figure. The pressure fluctuations occurring during the transfer of the gas or hydrogen into the vehicle tank due to the intermittent control can be buffered using conventional storage cylinders. According to a further embodiment of the invention, the gas drawn off through the discharge line 10 is mixed with at least one other gas stream to achieve the required or desired refueling conditions.

[0013] As already mentioned, the liquid piston 3 is formed by an ionic liquid and / or a liquid with a solubility for gaseous hydrogen of 0.0003 to 0.0005 g of hydrogen per g of liquid at a hydrogen partial pressure of 256 bar. According to an advantageous embodiment, means can be provided that generate a magnetic field in the region of the piston chamber 2. This allows the liquid piston 3, or the liquid used, to be stabilized so that little to no aerosols of this liquid enter the gas or gas mixture. In addition to or alternatively from such a magnetic field, a separation device can be provided.

[0014] It should be emphasized that the device according to the invention for cooling a gas can be operated with any gases and gas mixtures.

[0015] By using the device according to the invention for cooling a gas in a hydrogen filling station, the previously required pressure ramp regulator can be completely or at least partially replaced. Furthermore, a chiller for cooling the hydrogen to be dispensed can be partially or completely dispensed with. The invention enables a significant saving in cooling capacity in the range of 50 to 100%, depending on the refueling protocol, while simultaneously offering a cost-effective and wear-resistant design compared to other expansion machines.

[0016] The hydraulic control of the required gas-side pressure ramps can be achieved by sealing with an ionic liquid or a similar fluid, which improves the sealing performance, including in terms of long-term resistance. Furthermore, in a configuration with an electromechanical brake, electrical energy can be generated.

Claims

1. Device for cooling a gas, comprising: - a piston chamber (2), - a liquid piston (3) arranged in the piston chamber (2), - a supply line (1) having an inlet valve (b) associated with the first end (9) of the piston chamber (2), - a discharge line (10) having an outlet valve (b) associated with the first end (9) of the piston chamber (2), - a piston (4) associated with the second end of the piston chamber (2), - a damping system associated with the piston (4), - a control unit (8) which is operatively connected with the damping system and dynamically controls the pressure to be applied to the piston (4), and - means for removing heat from the piston chamber (2) and / or damping system.

2. Device for cooling a gas according to claim 1, characterized by the fact thatthe liquid piston (3) is formed by an ionic liquid and / or a liquid with a solubility for gaseous hydrogen of 0.0003 to 0.0005 g of hydrogen per g of liquid at a hydrogen partial pressure of 256 bar.

3. Device for cooling a gas according to claim 1 or 2, characterized by the fact that the damping system is designed as a spring damping system (4, 5, 6), an electromechanical damping system or a gas storage damping system.

4. Device for cooling a gas according to one of the preceding claims, characterized by the fact that the control unit (8) is designed as a hydraulic control unit.

5. Device for cooling a gas according to one of the preceding claims, characterized by the fact that a magnetic field can be generated in the area of ​​the piston chamber (2).

6. Hydrogen filling station, characterized by the fact that it has at least one device for cooling a gas according to one of the preceding claims.

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