Abstract: A screen valve (210) to control fluid flow comprising at least one multi-apertured valve plate (220) movable laterally relative to a multi-apertured valve seat (230) between a closed configuration whereby the apertures are not registered to prevent fluid flow, and an open configuration whereby the apertures are registered to permit fluid flow, wherein the valve plate is supported by a multi-apertured carrier plate (240) that moves laterally in synchrony with the valve plate (220) to maintain a predetermined lateral registration between their respective apertures as the valve plate moves between the open and closed configurations, the valve plate being movable relative to the carrier plate so as to be able to lift off and return into contact with the valve seat. The co-moving carrier plate shields the valve plate so as to minimize pressure locking. Aerodynamic features may be incorporated to urge the valve plate (220) towards or away from the carrier plate (240).

Abstract: A thermal energy store comprising a chamber having a gas inlet and a gas outlet and a plurality of successive, downstream, gas permeable thermal storage layers disposed between them, each layer comprising gas permeable thermal storage media, the store being configured for gas flow from the gas inlet to gas outlet through the layers for transfer of thermal energy to or from the thermal storage media, wherein at least one of the layers is a valved layer provided with at least one valve operable selectively to allow or prevent at least some gas flow through that layer via the valve so as to bypass the thermal storage media. A control system may selectively alter the flow path of the gas flowing from inlet to outlet in response to the progress of a thermal front, so as to bypass thermal storage layers upstream of the thermal front, where transfer is complete, or downstream thereof, where transfer is minimal.

Abstract: System (2) for carrying out a gas based thermodynamic cycle in which a gas is compressed in at least one compressor (8) in one part of the cycle and is expanded in at least one expander (10) operating simultaneously in an upstream or downstream part of the cycle, wherein the change in absolute internal power with gas mass flow rate differs as between the compressor and the expander and wherein the system comprises a control system configured to make selective adjustments so as individually to control, either directly or indirectly, the respective gas mass flow rates through each of the compressor and expander. The system may be an energy storage system including a pumped heat energy storage system configured to provide independent graduated control of system pressure and output power by selective adjustment of the respective gas mass flow rates through each half-engine.

Abstract: A heat storage system (400) comprising a system gas inlet (460), a system gas outlet (470), and at least two thermal stores (401, 402) connected together in series therebetween, wherein each store comprises a chamber having a gas inlet (461,462), a gas outlet (471,472), and a gas-permeable thermal storage media 431 disposed therebetween, the system further comprising flow controllers (451, 452, 453, 454, 457) operatively connected to bypass passageways and so configured that, during operation, the flow path of a gas flowing through the system (400) for transfer of thermal energy to or from the storage media (431) can be selectively altered in respect of which stores (401, 402) in the series are used in response to the progress of the thermal transfer.

Abstract: Heat storage apparatus comprising at least one thermal store (300) comprising a chamber (301) having a gas inlet (306), a gas outlet (307), and a gas-permeable thermal storage media (303) disposed therebetween, the apparatus being configured such that, during operation, the flow path of a gas flowing through the chamber (301) from inlet (306) to outlet (307) for transfer of thermal energy to or from the storage media (303) can be selectively altered in response to the progress of the thermal transfer, thereby enabling the flow path to bypass inactive upstream or downstream regions of the storage media where thermal transfer is complete or minimal, so as to minimize the pressure drop across the storage media. A baffle system (305) in a main flow passageway (312) may be used to control the gas flow path.

Abstract: A screen valve (210) to control fluid flow comprising at least one multi-apertured valve plate (220) movable laterally relative to a multi-apertured valve seat (230) between a closed configuration whereby the apertures are not registered to prevent fluid flow, and an open configuration whereby the apertures are registered to permit fluid flow, wherein the valve plate is supported by a multi-apertured carrier plate (240) that moves laterally in synchrony with the valve plate (220) to maintain a predetermined lateral registration between their respective apertures as the valve plate moves between the open and closed configurations, the valve plate being movable relative to the carrier plate so as to be able to lift off and return into contact with the valve seat. The co-moving carrier plate shields the valve plate so as to minimise pressure locking. Aerodynamic features may be incorporated to urge the valve plate (220) towards or away from the carrier plate (240).

Abstract: System (2) for carrying out a gas based thermodynamic cycle in which a gas is compressed in at least one compressor (8) in one part of the cycle and is expanded in at least one expander (10) operating simultaneously in an upstream or downstream part of the cycle, wherein the change in absolute internal power with gas mass flow rate differs as between the compressor and the expander and wherein the system comprises a control system configured to make selective adjustments so as individually to control, either directly or indirectly, the respective gas mass flow rates through each of the compressor and expander. The system may be an energy storage system including a pumped heat energy storage system configured to provide independent graduated control of system pressure and output power by selective adjustment of the respective gas mass flow rates through each half-engine.

Abstract: A thermal energy store comprising a chamber having a gas inlet and a gas outlet and a plurality of successive, downstream, gas permeable thermal storage layers disposed between them, each layer comprising gas permeable thermal storage media, the store being configured for gas flow from the gas inlet to gas outlet through the layers for transfer of thermal energy to or from the thermal storage media, wherein at least one of the layers is a valved layer provided with at least one valve operable selectively to allow or prevent at least some gas flow through that layer via the valve so as to bypass the thermal storage media. A control system may selectively alter the flow path of the gas flowing from inlet to outlet in response to the progress of a thermal front, so as to bypass thermal storage layers upstream of the thermal front, where transfer is complete, or downstream thereof, where transfer is minimal.

Abstract: Heat storage apparatus comprising at least one thermal store (300) comprising a chamber (301) having a gas inlet (306), a gas outlet (307), and a gas-permeable thermal storage media (303) disposed therebetween, the apparatus being configured such that, during operation, the flow path of a gas flowing through the chamber (301) from inlet (306) to outlet (307) for transfer of thermal energy to or from the storage media (303) can be selectively altered in response to the progress of the thermal transfer, thereby enabling the flow path to bypass inactive upstream or downstream regions of the storage media where thermal transfer is complete or minimal, so as to minimise the pressure drop across the storage media. A baffle system (305) in a main flow passageway (312) may be used to control the gas flow path.

Abstract: A heat storage system (400) comprising a system gas inlet (460), a system gas outlet (470), and at least two thermal stores (401, 402) connected together in series therebetween, wherein each store comprises a chamber having a gas inlet (461,462), a gas outlet (471,472), and a gas-permeable thermal storage media 431 disposed therebetween, the system further comprising flow controllers (451, 452, 453, 454, 457) operatively connected to bypass passageways and so configured that, during operation, the flow path of a gas flowing through the system (400) for transfer of thermal energy to or from the storage media (431) can be selectively altered in respect of which stores (401, 402) in the series are used in response to the progress of the thermal transfer.

Abstract: In a communications network, a count is maintained of the number of calls made to a selected number. The number may be that of an answering center or of any other destination which has the capacity to handle a multiplicity of calls simultaneously. The count is automatically updated when calls are admitted to the number and when they are terminated. If a new call would take the number of calls in progress above a stored value for the maximum capacity of the number, then the call is rejected. In one implementation, resources are allocated dynamically on an Overload Control Server to a particular destination number only when congestion occurs. The stored value for the capacity may be amended automatically depending on the response of the network to admitted calls. The value for the capacity may initially be estimated as a function of the holding times for calls to the destination number.

Abstract: A telecommunications network includes a processor controlled switch and a network intelligence platform overload control function runs in the network intelligence layer. The overload control function measures the period of time taken to handle a call switching request and if the time taken exceeds a pre-determined quality of service threshold, it implements a call gapping function. The call gapping function modifies the gapping period such that requests to effect calls to particular destinations are spaced and any call arriving at a switching point prior to expiration of the gap period is automatically rejected by the local control processor. As the overload control function runs in a plurality of nodes, which may be file servers of the intelligence layer, the gapping period returned to the switch is dependent upon the perceived overload at the particular node.