Abstract: A system and method for thermoelectric energy storage are disclosed. A thermoelectric energy storage system can include a heat exchanger which contains a thermal storage medium, and a working fluid circuit for circulating a working fluid through the heat exchanger for heat transfer with the thermal storage medium. The working fluid undergoes transcritical cooling during the charging and transcritical heating during the discharging cycle as it exchanges heat with the thermal storage medium. Improved roundtrip efficiency can be achieved through minimizing the maximum temperature difference (?Tmax) between the working fluid and the thermal storage medium during operating cycles.

Abstract: A system and method are provided for thermoelectric energy storage. A thermoelectric energy storage system having at least one hot storage unit is provided. In an exemplary embodiment, each hot storage unit includes a hot tank and a cold tank connected via a heat exchanger and containing a thermal storage medium. The thermoelectric energy storage system also includes a working fluid circuit for circulating working fluid through each heat exchanger for heat transfer with the thermal storage medium. Improved roundtrip efficiency is achieved by minimizing the temperature difference between the working fluid and the thermal storage medium in each heat exchanger during heat transfer. Exemplary embodiments realize this improved roundtrip efficiency through modification of thermal storage media parameters.

Abstract: Because the efficiency of the thermal energy storage technology is inherently restricted, its beneficial use is limited to very particular economic boundary conditions, i.e. a large difference between the value of electricity going into the unit and the value of electricity coming out of the unit. With the reduction in wind power equipment prices and the cost of fossil fuels and/or their combustion products this is occasionally the case for wind power. Wind is a free fuel and the value of wind power when there is too little load demand is essentially zero, and the value of wind power when there is demand is considerable indeed. Under these circumstances, a combination of electrothermal energy storage and combustion of (fossil) fuels as an auxiliary heat source provides for a cost efficient system for storing energy and an economical way of generating electricity.

Abstract: The cable connector for making an electrical contact with a cable (1) having a cable conductor (2), comprises a guiding means (4) for receiving one end (1a) of the cable (1) in an initial state (O), a contact element (6) for electrically contacting the cable conductor (2) in a final state, and a holding means (18) for holding the cable (1) in electrical contact with the contact element (6) in the final state, wherein the guiding means (4) and the contact element (6) are moveable relative to each other, allowing for movements between the initial state (O) and the final state. A spring device (7) is provided, which is arranged such that it exerts a force against the movement from the initial state (O) to the final state, and which moves the cable (1) towards the initial state (O) if the cable is not in the final state. A contact ensuring mechanism (8) can be provided, which in the final state reduces the force exerted by the spring device (7) against the movement from the initial state (O) to the final state.

Abstract: The present invention provides a fluid-to-fluid through-the-wall heat exchanger for condensation of a vapour in a primary fluid stream, wherein a flow path (5) of the primary fluid stream is defined by an inner cylinder (1), an outer cylinder (2) arranged concentrically to and surrounding the inner cylinder, and a helical space holder (3) arranged between the inner and the outer cylinder. Additionally, the cylinder surfaces delimiting the primary flow path are made of or coated with corrosion resistant material in order to reduce a contamination of the primary fluid. Compared to other condensers with identical ratings, this heat exchanger shows a smaller flow resistance, resulting in a smaller power demand of the blower or pumps, It is therefore particularly suitable for fuel cell systems where the condensed water has to be recirculated in the system and where purity demands are high and parasitic blower power should be minimal.

Abstract: The cable connector for making an electrical contact with a cable (1) having a cable conductor (2), comprises a guiding means (4) for receiving one end (1a) of the cable (1) in an initial state (O), a contact element (6) for electrically contacting the cable conductor (2) in a final state, and a holding means (18) for holding the cable (1) in electrical contact with the contact element (6) in the final state, wherein the guiding means (4) and the contact element (6) are moveable relative to each other, allowing for movements between the initial state (O) and the final state. A spring device (7) is provided, which is arranged such that it exerts a force against the movement from the initial state (O) to the final state, and which moves the cable (1) towards the initial state (O) if the cable is not in the final state. A contact ensuring mechanism (8) can be provided, which in the final state reduces the force exerted by the spring device (7) against the movement from the initial state (O) to the final state.

Abstract: The invention relates to a direct methanol fuel cell and to a method for controlling the methanol concentration without requiring the provision of additional methanol concentration sensors (47). Instead, the current-voltage characteristic curves of the fuel cell (40) are sampled using small variations of the system variables current I and methanol concentration M, and information used for controlling is obtained therefrom. In systems possessing an electrical buffer (49), a connected consumer is supplied without interruption despite the abandonment, as described by the invention, of the optimal operating point of the fuel cell.

Abstract: The capacitor according to the invention is wound from at least one film (1) comprising a carrier film (3)—serving as dielectric—with at least one conductor layer (4). It has an internal series circuit. The latter is brought about by the conductor layer (4) applied on the dielectric or the conductor layers being divided into sectors (4.1, 4.2) which are mutually arranged and, if appropriate, connected to one another in such a way that a plurality of series-connected elementary capacitors are formed. It is distinguished essentially by the fact that a current path structure is formed on the sectors, the conductor layer (4) having a high sheet resistance for the purpose of reducing breakdown-governed capacitance losses and the current paths (5, 6) of the current path structure having a significantly reduced sheet resistance for the purpose of reducing the total sheet resistance.

Abstract: A method is disclosed for measuring the concentration of a low molecular weight alcohol, such as methanol, in an aqueous solution. The method uses a fuel cell sensor that includes an anode chamber for electrochemical oxidation of the methanol, a cathode chamber for electrochemical reduction of oxygen; a proton conducting membrane arranged between the anode and cathode; and a voltmeter operatively connected to the anode and cathode chambers. An aqueous solution of the methanol is fed to the anode chamber while the fuel cell sensor is operated at an open circuit state, thereby allowing the methanol to crossover to the cathode where it is oxidized. The open circuit voltage across the anode and the cathode is measured using the voltmeter and the concentration of the methanol is determined from the open circuit voltage.

Abstract: Film capacitors have a thin carrier film (1) as dielectric. The surfaces of the carrier films are provided with conductor layers (2)—serving as electrodes—made of metal or made of a nonmetallic conductor. If the capacitor is charged during operation, electric fields with large field strengths can arise at the edges of the conductor layers (2), which can lead to breakdowns. The invention is essentially distinguished by the fact that an edge zone coating (3) is present at the edges of the electrode-forming conductor layer (2), which edge zone coating is only partly charged in the time periods—for example of the alternating-current period—which are critical for changes in the applied voltage. To that end, the edge zone coating of the film must have a surface conductivity which is less than the surface conductivity of the conductor layer.

Abstract: The capacitor according to the invention is wound from at least one film (1) comprising a carrier film (3)—serving as dielectric—with at least one conductor layer (4). It has an internal series circuit. The latter is brought about by the conductor layer (4) applied on the dielectric or the conductor layers being divided into sectors (4.1, 4.2) which are mutually arranged and, if appropriate, connected to one another in such a way that a plurality of series-connected elementary capacitors are formed. It is distinguished essentially by the fact that a current path structure is formed on the sectors, the conductor layer (4) having a high sheet resistance for the purpose of reducing breakdown-governed capacitance losses and the current paths (5, 6) of the current path structure having a significantly reduced sheet resistance for the purpose of reducing the total sheet resistance.