Hydrogen refueling system

Abstract

The present invention is to provide a hydrogen refueling system capable to cool down the H2 pre-cooling heat exchanger fast enough when a FCV enters the HRS, so that there is no or very minimal waiting time for the customer before starting refueling. A hydrogen refueling system including a cryogenic fluid tank that stores a cryogenic fluid, a dispenser that supplies H2 to a vehicle, including a heat exchanger that cools H2 with the cold and/or cryogenic fluid provided from the cryogenic fluid tank, an inlet line that sends the cold and/or cryogenic fluid to the heat exchanger from the cryogenic fluid tank, an outlet line that collects the cryogenic fluid fed from the heat exchanger, and an injection valve that is provided in the inlet line.

Claims

1. A method for H.sub.2 refueling to vehicles comprising: (a) providing a hydrogen refueling system that comprises a cryogenic fluid tank that stores a cryogenic fluid, a dispenser that supplies H.sub.2 to a vehicle, a heat exchanger that cools H.sub.2 with the cryogenic fluid provided from the cryogenic fluid tank, an inlet line that sends the cryogenic fluid to the heat exchanger from the cryogenic fluid tank, an outlet line that collects the cryogenic fluid fed from the heat exchanger, and an injection valve that is provided in the inlet line; (b) detecting that a first vehicle to be refueled with H.sub.2 is entering said hydrogen refueling station; (c) opening said injection valve; (d) feeding the cryogenic fluid to said heat exchanger from said cryogenic fluid tank; (e) controlling a temperature of the heat exchanger to ensure the heat exchanger temperature is within a predetermined temperature range with the cryogenic fluid, a nominal operating temperature of the heat exchanger being within the predetermined temperature range; (f) refueling cold H.sub.2 cooled down by the heat exchanger to the first vehicle while maintaining the temperature of the heat exchanger within the predetermined temperature range; (g) after completion of said refueling, allowing the first vehicle to leave the hydrogen refueling station; (h) detecting that no vehicle to be refueled with H.sub.2 is entering the hydrogen refueling station and closing the injection valve based upon said lack of detection; (i) allowing the heat exchanger temperature to rise at least 7° C. above the nominal operating temperature; and (j) after said rise in temperature of heat exchanger to at least 7° C. above the nominal operating temperature, detecting that a second vehicle to be refueled with H.sub.2 is entering the hydrogen refueling station and performing the following steps, in order: said injection valve is opened, the cryogenic fluid is fed to said heat exchanger from said cryogenic fluid tank, the heat exchanger temperature of is controlled to ensure the heat exchanger temperature is within the predetermined temperature range with the fed cryogenic fluid, and the second vehicle is refueled with cold H.sub.2 cooled down by the heat exchanger while the temperature of the heat exchanger is maintained within the predetermined temperature range.

2. The method of claim 1, further comprising: measuring a temperature (t1) of the heat exchanger; outputting a ready-to-fill signal from a controller when said controller determines that the measured temperature (t1) is within the predetermined temperature range; and releasing a corresponding interlock condition on a H.sub.2 control valve and allowing performance of said step (e).

3. The method of claim 1, wherein said step of detecting that a vehicle to be refueled with H.sub.2 is entering a hydrogen refueling station and said step of detecting that no vehicle to be refueled with H.sub.2 is entering a hydrogen refueling station are performed using a vehicle detection system that detects whether a vehicle to be refueled with H.sub.2 is entering a hydrogen refueling station (HRS).

4. The method of claim 1, wherein said controller controls a flow of H.sub.2 to the vehicle during step (f).

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 illustrates an explanatory diagram showing a hydrogen refilling system according to Embodiment 1.

(2) FIG. 2 illustrates an explanatory flowchart showing a hydrogen refilling system according to Embodiment 1.

(3) FIG. 3 illustrates an explanatory diagram showing prior art of a hydrogen refilling system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) Several embodiments of the present invention will be explained below. The embodiments explained below are to explain one example of the present invention. The present invention is not limited to the following embodiments at all and includes various types of modifications carried out within a scope where the gist of the present invention is not changed. All of the configurations explained below are not necessarily essential configurations of the present invention.

Embodiment 1

(5) The hydrogen refueling system 100 of the first embodiment is explained by referring FIGS. 1 and 2. The hydrogen refueling system 100 includes a liquid nitrogen (LN.sub.2) tank 110 and Dispenser 120. LN.sub.2 tank 110 stores the liquid nitrogen (LN.sub.2).

(6) First, Dispenser 120 is explained below.

(7) Dispenser 120 supplies H.sub.2 to a vehicle. Dispenser 120 includes the heat exchanger 121 that cools H.sub.2 with LN.sub.2 provided from the LN.sub.2 tank 110. Dispenser 120 includes the dispenser hose and the refueling nozzle for refueling H.sub.2 to a vehicle.

(8) In this embodiment, the temperature control unit 151 measures the temperature (t1) of the heat exchanger metal mass. The temperature control unit 151 may measures the temperature at a wall of the heat exchanger 121, at a channel of the outlet line 132 within the heat exchanger 121. In this embodiment, the temperature control unit 151 includes both function of a temperature measuring unit and a valve control unit.

(9) In other embodiment, the temperature control unit 151 may measures the temperature of LN.sub.2 at outlet of the heat exchanger 121 in the outlet line 132.

(10) In other embodiment, instead of the temperature control unit 151, the temperature measuring unit may measures the temperature (t1) of the heat exchanger 121. The temperature measuring unit may be provided at a wall of the heat exchanger 121, at a channel of the outlet line 132 within the heat exchanger 121 or within the heat exchanger metal mass.

(11) The inlet line 130 is a line for sending LN.sub.2 to the heat exchanger 121 from LN.sub.2 tank 110. The outlet line 132 is a line for collecting LN.sub.2 from the heat exchanger 121. The inlet line 130 or the outlet line 132 is configured may be usual pipe or an insulated pipe.

(12) The injection valve 131 is provided at an inlet side of the heat exchanger 121 at the inlet line 130 but the injection valve 131 may be located at any point of the inlet line 130.

(13) The vehicle detection system 140 detects that a vehicle to be refueled with H.sub.2 is entering the HRS(Hydrogen Refueling Station). The vehicle detection system 140 is for example of a camera with image treatment system, IR detector, pressure detector on the ground, magnetic loop in the ground or a combination of several detectors and/or techniques.

(14) Next, the controller 150 is explained below. The controller 50 may be configured by combination between hardware and software program, firmware, dedicated circuit or combination of thereof, the controller 150 includes one or more function unit (it is so called function module).

(15) The controller 150 controls opening the injection valve 131 on the basis of a detection result of the vehicle detection system 140 and on the basis of specific control strategy. More specifically, the controller 150 is constituted by the following elements.

(16) The temperature control unit 151 can adjust the opening ratio of the injection valve 131 depending on measured temperature (t1) so that the temperature (151) measured by the temperature control unit 151 is maintained within a predetermined temperature range (or close to the target temperature). By adjusting the opening ratio of the injection valve 131, the heat exchanger 121 is cooled quickly down to a predetermined target temperature and the temperature of H.sub.2 during refueling can be kept within the desired temperature range after reaching the predetermined temperature range.

(17) The temperature comparison unit 152 determines whether the temperature (t1) measured by the temperature control unit 151 is maintained within the predetermined temperature range (or close enough to the target temperature).

(18) The output unit 153 outputs a ready-to-fill signal when the temperature comparison unit 152 determined that the measured temperature (t1) is within the predetermined temperature range (or close enough to the target temperature).

(19) In this embodiment, the predetermined temperature range for the heat exchanger temperature (t1) may be for example −45° C. to −35° C., with a target temperature lying in between.

(20) The desired temperature range of H.sub.2 at dispenser outlet during refueling may be for example −40° C. to −33° C.

(21) The output unit 153 sends releasing ready-to-fill signal to a refueling control unit 154.

(22) The refueling control unit 154 controls H.sub.2 refueling flow to vehicles by Dispenser 120. During H.sub.2 refueling, the refueling control unit 154 controls the opening ratio of a H.sub.2 control valve 123 on a dispenser H.sub.2 line 125 that connects one high pressure H.sub.2 source 126, so as to feed H.sub.2 into the heat exchanger 121 from H.sub.2 source 126.

(23) The refueling control unit 154 has interlocking logic and/or sequence logic with transition conditions. Typically, H.sub.2 control valve 123 cannot be opened or is closed by the function of the interlocking logic and/or sequence logic. H.sub.2 can be refueled by releasing relevant interlocks and/or affecting H.sub.2 refueling sequence transition conditions.

(24) In this embodiment, after receiving the ready-to-fill signal from the output unit 153, the refueling control unit 154 releases the corresponding interlock condition on H.sub.2 control valve 123 and/or affect the status of transition conditions of H.sub.2 refueling sequence. Subsequently, when all other conditions and/or interlocks prohibiting to start H.sub.2 refueling to vehicle are released, and upon manual command by operator or customer, the refueling control unit starts refueling and opens the H.sub.2 control valve 123.

(25) The refueling control unit 154 displays information about the status of heat exchanger temperature condition to start H.sub.2 refueling to vehicle. When all conditions and/or interlocks prohibiting to start H.sub.2 refueling to vehicle are released, the refueling control unit 154 send signal to display an information that H.sub.2 refueling to vehicle can be started and/or to inform by audio device.

(26) The refueling control unit 154 sends a signal of end of refueling. The signal of end of refueling is for example a signal for indicating (informing) that filling termination conditions have been reached and that H.sub.2 control valve 123 has been closed.

(27) In this embodiment, the vehicle queuing calculation unit 155 calculates a signal indicating that no vehicle is waiting for refueling by using the detection signal(s) from the vehicle detection system 140. The vehicle queuing calculation unit 155 may include a possibility of manual input by the operator that no vehicle is waiting for refueling. The vehicle queuing calculation unit 155 may use the end of refueling signal to calculate the signal indicating that no vehicle is waiting for refueling. In this embodiment, the temperature control unit 151 may control to close the injection valve 131 only after receiving signal from the vehicle queuing calculation unit 155 that no vehicle is waiting for refueling.

(28) Next flowchart of FIG. 2 is explained below.

(29) In the HRS idle time, the injection valve 131 is closed, the system 100 come back to ambient temperature (step S11).

(30) As another embodiment instead that the system 100 comes back to ambient temperature, the controller 150 may control opening of the injection valve 131 in such a way that during part of the idle time of the system 100, the heat exchanger 121 that cools H.sub.2 with LN.sub.2 provided from the tank 110 heats up more than 7° C. above its nominal temperature during FCV refueling, and that it is cooled down upon arrival of a vehicle to be refilled.

(31) The vehicle detection system 140 detects that a vehicle to be refueled with H.sub.2 is entering the HRS (transition T11).

(32) The controller 150 controls opening of the injection valve 131 and cold and/or liquid nitrogen is fed into the heat exchanger 121 through the inlet line 130 from the tank 110 (step S12). The temperature within the heat exchanger 121 cools down rapidly. LN.sub.2 which is possibly mixture in liquid and/or gaseous phase is sent to the vent or the recycling process through the outlet line 132 from the heat exchanger 121.

(33) The temperature control unit 151 controls the injection valve 131 on a fixed high opening ratio upon detection of FCV entering the HRS, thus providing high cooling power.

(34) The temperature of heat exchanger 121 is measured by the temperature control unit 151. The temperature comparison unit 152 determines whether the temperature (t1) measured by the temperature control unit 151 is maintained within the predetermined temperature range or close enough to the target temperature.

(35) In the meantime the vehicle to be refueled is positioned in front of the dispenser. Then, operator or customer connects the FCV receptacle to the dispenser using dispenser hose and nozzle.

(36) The output unit 153 outputs a ready-to-fill signal when the temperature comparison unit 152 determined that the measured temperature (t1) is within the predetermined temperature range or close enough to the target temperature. After receiving the ready-to-fill signal from the output unit 153, the refueling control unit 154 releases the corresponding interlock condition on H.sub.2 control valve 123 and/or affect the status of transition conditions of H.sub.2 refueling sequence.

(37) After receiving the ready-to-fill signal from the output unit 153, the temperature control unit 151 changes strategy to adjust opening ratio of the injection valve 131, depending on the heat exchanger measured temperature (t1), so that it is within the predetermined temperature range or close enough to the target temperature.

(38) Subsequently, when other ready-to-fill conditions are fulfilled (e.g. detection that dispenser nozzle has been connected to FCV receptacle), the system is goes to step S13 (transition T12).

(39) HRS is in ready-to-fill status and cold/liquid nitrogen continues to circulate, in order to maintain the heat exchanger within a predetermined temperature range or close to the target temperature (step S13). The temperature control unit 151 continues to use the same strategy to maintain the heat exchanger temperature (t1) within a predetermined temperature range.

(40) The refueling control unit 154 displays information about the status of heat exchanger temperature condition to start H.sub.2 refueling to vehicle. The refueling control unit 154 send signal to display an information that H.sub.2 refueling to vehicle can be started and/or to inform by audio device.

(41) The operator or customer gives start command of H.sub.2 refueling to the vehicle (transition T13).

(42) Following filling protocol, the refueling control unit 154 controls H.sub.2 control valve 123, in order to transfer hydrogen from the hydrogen high pressure source 126 to the tank of FCV; and cold/liquid nitrogen continues to circulate, in order to maintain the heat exchanger within a predetermined temperature range or close to the target temperature (step S14). The temperature control unit 151 continues to use the same strategy to maintain the heat exchanger temperature (t1) within a predetermined temperature range.

(43) The refueling control unit 154 sends a signal of end of refueling indicating (informing) that filling termination conditions have been reached and that H.sub.2 control valve 123 has been closed (transition T14).

(44) If the vehicle queuing calculation unit 155 sends signal that no other vehicle is waiting for refueling, the system goes to step S11, which is already described above.

(45) If the vehicle queuing calculation unit 155 sends signal that another vehicle is waiting for refueling, the system goes to step S15, which is described below.

(46) The next vehicle to be refueled is positioned in front of the dispenser. Then, operator or customer connects the FCV receptacle to the dispenser using dispenser hose and nozzle (step S15). The temperature control unit 151 continues to use the same strategy to maintain the heat exchanger temperature (t1) within a predetermined temperature range.

(47) Subsequently, when other ready-to-fill conditions are fulfilled (e.g. detection that dispenser nozzle has been connected to FCV receptacle), the system goes to step S13, which is already described above (transition T12).

Example 1

(48) Currently, the weight of compact stainless steel diffusion bonded heat exchangers used in H.sub.2 dispensers can be around 150 kg. Around 5000 kJ are necessary to cool down the mass of the heat exchanger from 30° C. to −40° C.

(49) This could be achieved within 3 minutes with around 30 kW frigorific power. Such power is achievable by injection of ˜500 l/h of liquid nitrogen.

(50) While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.

(51) The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.

(52) “Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing i.e. anything else may be additionally included and remain within the scope of “comprising.” “Comprising” is defined herein as necessarily encompassing the more limited transitional terms “consisting essentially of” and “consisting of”; “comprising” may therefore be replaced by “consisting essentially of” or “consisting of” and remain within the expressly defined scope of “comprising”.

(53) “Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.

(54) Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.

(55) Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.

(56) All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.