Abstract: A system includes a gas turbine system, a thermal energy storage device, and a heat recovery system. The gas turbine system is powered by solar energy to generate a first amount of electric power. The thermal energy storage device is coupled to the gas turbine system. The thermal energy storage device is configured to selectively receive expanded exhaust gas from the gas turbine system and store heat of the expanded exhaust gas. The heat recovery system is coupled to the gas turbine system and the thermal energy storage device. The heat recovery system is selectively powered by at least one of the gas turbine system and the thermal energy storage device to generate a second amount of electric power.

Abstract: A method for storing and releasing heat by means of a phase change material. In said method, a phase change is caused in a first heat exchanging device (4) by supplying heat during a charging process in a storage medium comprising a phase change material in order to store the heat as latent heat in the storage medium, and a phase change is caused in the storage medium while heat is dissipated during a discharging process in the first or another heat exchanging device (2).

Abstract: An induction heatable server comprises a base element having top and bottom elements, said bottom element having a peripheral wall defining an upwardly opening cavity in which are disposed a heat retentive disc and a ring member which is bonded to the peripheral wall. A top element extends over the ring member and seals the cavity. The top element and ring member are bonded to the peripheral wall of the bottom element to preclude moisture penetration into the cavity.

Abstract: A device for the intermediate storage of thermal energy and to a system comprising a plurality of such devices is provided. The device has a solids store and a pipe system, which is formed of individual pipes and runs through the solids store and through which an energy carrier medium flows. In order to be able to quickly and uniformly charge the solids store with thermal energy or discharge thermal energy therefrom, heat conducting elements are provided, each forming heat transmission regions with the individual pipes and each extending into the regions of the solids store that are free of individual pipes. The heat conducting elements also have a higher heat conductivity than the solids store.

Abstract: Apparatus (1) for storing energy includes a high pressure storage vessel (10) for receiving high pressure gas, the high pressure storage vessel (10) including a high pressure heat store including a first chamber housing a first gas-permeable heat storage structure (14); and a low pressure storage vessel (11,12) for receiving low pressure gas, the low pressure storage vessel (11,12) including a low pressure heat store including a second chamber housing a second gas-permeable heat storage structure (16,18. The first heat storage structure (14) has a mean surface area per unit volume which is higher than a mean surface area per unit volume of the second heat storage structure (16,18).

Abstract: A latent heat storage material is formed of at least two plies of a compressible graphitic material in which graphite wafers are arranged substantially in layer planes lying one on the other and which is infiltrated with at least one phase change material. The surface of each ply is provided with a structuring reaching the outsides of the graphite material bundle. The evacuation and infiltration travel lengths in the layer planes, due to the structuring, amounts to a maximum of 200 mm.

Abstract: The present invention relates to a system of transfer and storage of thermal energy to and from the surrounding environment. In particular, this invention relates to a thermo-well (1) comprising at least a case (2) underground, at least one inlet pipe (10) of a heat carrier fluid and at least one outlet line (9) of said heat carrier fluid, wherein said case (2) is sealed, characterized in that said at least one case (2) contains within it an inert material (G) in granular form with which that heat carrier fluid is placed in contact to get an heat transfer between said heat carrier fluid and said inert material (G). Further objects of the invention are an heat transfer system and a storage of thermal or freezing energy and a cogeneration energy system comprising at least one thermo-well as defined above.

Abstract: In accordance with one aspect of the present invention, a cooking apparatus is provided. The cooking apparatus comprises a cooking surface, at least one grate, and a guard. The cooking surface includes at least one heat source and a control panel. The at least one grate is provided over a portion of the cooking surface. The guard is coupled to the at least one grate. The guard includes a first side and a second side. The first side of the guard is configured to deflect heat radiating from the at least one heat source. The second side of the guard corresponds with a sidewall of the cooking surface to form a channel between the guard and the sidewall. The channel is configured to create a thermal barrier between the at least one heat source and the control panel.

Abstract: A solar heating block, designed for use in assembling solar heating panels in the walls of buildings, has a first compartment and a second compartment within its interior volume. The first compartment contains a translucent insulating material, such as an aerogel. The second compartment, which is inward of the solar heating block from the first compartment, contains a heat-absorbing material. The translucent insulating material allows light to be transmitted through the solar heating block, but reduces heat loss to the exterior of the building from the heat-absorbing material.

Abstract: The present invention relates to articles and heat storage devices for storage of thermal energy. The articles include a metal base sheet and a metal cover sheet, wherein the metal base sheet and the metal cover sheet are sealingly joined to form one or more sealed spaces. The articles include a thermal energy storage material that is contained within the sealed spaces. The sealed spaces preferably are substantially free of water or includes liquid water at a concentration of about 1 percent by volume or less at a temperature of about 25° C., based on the total volume of the sealed spaces. The articles include one or more of the following features: a) the pressure in a sealed space is about 700 Torr or less, when the temperature of the thermal energy storage material is about 25° C.

Abstract: A hot water solar heating system includes a solar collector assembly located outside a building, a hot water tank located inside the building and supply and return pipes connecting the tank to the solar collector assembly. Portions of the supply and return pipes are located outside the building and are subject to below freezing temperatures and ice blockages. The system includes resistance heating wires which melt ice blockages in the exterior portions of the supply and return pipes.

Abstract: A solar heating block, designed for use in assembling solar heating panels in the walls of buildings, has a first compartment and a second compartment within its interior volume. The first compartment contains a translucent insulating material, such as an aerogel. The second compartment, which is inward of the solar heating block from the first compartment, contains a heat-absorbing material. The translucent insulating material allows light to be transmitted through the solar heating block, but reduces heat loss to the exterior of the building from the heat-absorbing material.

Abstract: This claim is an improvement to existing and commercially available domestic heating systems which consist of an outdoor wood burning stove and boiler which recirculate hot water through radiators located inside an inhabited structure or domicile. The inventor proposes the efficiency and convenience of such ‘outdoor wood burning heating systems’ are substantially improved by the addition of a large storage tank for the heated water and an electronic control system. The claimed improvement allows the firebox to be stoked and ignited at a time convenient to the dwelling occupant. Heated water is stored in an insulated water tank until called upon for heating. Combustion is optimized for maximum efficiency and atmospheric emissions are substantially reduced.

Abstract: A two fluid thermal storage device that may allow for independent heating and cooling includes a plurality of plate members with a set of dividers brazed between two of them. The set of dividers, which may define a series of passageways therein, may include a first sub-series of alternate passageways filled with a phase change material, and a second sub-series of remaining passageways that transports a fluid, the remaining passageways alternating between transporting a cooling fluid through a first fluid circuit and transporting a heating fluid through a second and independent fluid circuit. The remaining passageways that transport the cooling fluid through the first fluid circuit are defined by a first subset of dividers and the remaining passageways that transport the heating fluid through the second fluid circuit are defined by a second subset of dividers.

Abstract: A thermocline storage tank is presented, which includes a barrier member that floats between the two fluids stored at different temperatures, physically separating and insulating them. The floating barrier includes a number of design features that broaden its application scope, enabling it for use in fields like thermal storage systems of solar power plants.

Abstract: An active thermal energy storage system is disclosed which uses an energy storage material that is stable at atmospheric pressure and temperature and has a melting point higher than 32 degrees F. This energy storage material is held within a storage tank and used as an energy storage source, from which a heat transfer system (e.g., a heat pump) can draw to provide heating of residential or commercial buildings and associated hot water. The energy storage material may also accept waste heat from a conventional air conditioning loop, and may store such heat until needed. The system may be supplemented by a solar panel system that can be used to collect energy during daylight hours, storing the collected energy in the energy storage material. The stored energy may then be used during the evening hours to heat recirculation air for a building in which the system is installed.

Abstract: A system and method is provided for converting electrical energy input provided by a renewable prime energy into efficient thermo-dynamic energy for cogeneration purposes, activated by the main infrared radiation means and an energy density increasing means functioning synergistically. A closely approximated ideal blackbody condition therein, is utilized to heat the (TES,) resulting in a highly stable total kinetic energy (TES) mass. Another section provides an energy density increasing means. Steam generates power and then heats residential or commercial buildings. Service hot-water and air conditioning is also provided. The system can be an auxiliary system for other power plants increasing efficiency. In the second embodiment, higher capacity low cost electricity generation enables efficient power cogeneration.

Abstract: The invention comprises a Thermal Energy Module comprising a tank adapted to hold water or other heat transfer medium (such as water), a water loop for introducing the heat transfer medium and removing the heat transfer medium, and a refrigeration loop comprising a heat exchanger further comprised of an inlet manifold, a heat transfer structure (such as a micro channel or pipe-in-plate panel) and an outlet manifold wherein the heat exchanger is adapted to transfer thermal energy between the heat transfer structure and the heat transfer medium. The Thermal energy Module may be utilized as a component of a heating and cooling system. Such a Thermal Energy Module may be used to store thermal energy during the day and return it during the evening. Additionally, such a Thermal Energy Module may be implemented as an array of such modules and such array of modules may be adapted to fit within the walls of a building or structure.

Abstract: A containment vessel for a thermal energy storage system comprising a bottom wall joined to a surrounding containment side wall, and a liner comprising a liner bottom disposed upon the bottom wall of the vessel, the liner bottom having an outer perimeter and comprising an array of plates, each of the plates joined at a portion of its perimeter to a portion of the perimeter of an adjacent plate by a flexible joint; and a liner side wall joined to the outer perimeter of the liner bottom and disposed within the containment side wall. A thermal energy storage system comprising the containment vessel and an array of heat exchangers is also disclosed. The heat exchangers are disposed in the vessel, and are each supported by a support frame joined to one of the plates of the array of plates of the liner.

Abstract: The invention relates to a drying cylinder which is used to dry a paper, cardboard, tissue or other web of fibrous material in a machine for the production and/or for the transformation thereof. The drying cylinder includes a support body and an external cover layer which is heated by a hot fluid. The thermal flow passing through the external cover layer is increased such that at least one cavity is provided between the support body and the external cover layer through which the fluid flows. The external cover layer is predominately so thin that the ratio formed by the thermal conductivity of the material and the thickness of the external cover layer is greater than a threshold value of 3.2 kW/m2K for steel, 30 kW/m2K for aluminum, 18 kW/m2K for bronze alloys, 3.4 kW/m2K for copper and 6.1 kW/m2K for magnesium.

Abstract: A heat storage apparatus includes heat storage panels having primary fluid passages formed therein; passage plates having secondary fluid passages formed therein; and heat reservoirs. The heat storage panels and the passage plates are layered alternately, and the heat reservoirs are interposed between the heat storage panels and the passage plates in such a manner that the heat reservoirs, the heat storage panels and the passage plates are adhered to one another. Protrusions are formed on surfaces of the heat storage panels in such a manner that the heat reservoirs are supported by the protrusions.

Abstract: A thermal energy storage (“TES”) device including a vessel housing a continuous volume of a TES media, an input portion, an output portion, and a plurality of thermal energy transport members connected to the input portion and/or the output portion. The input portion receives thermal energy from a thermal energy source. The received thermal energy is transported by one or more of the thermal energy transport members to the output portion and/or the TES media for storage. One or more of the thermal energy transport members connected to the output portion transport stored thermal energy from the TES media to the output portion. The output portion is coupled to an external device, such as a Stirling engine, and configured to transfer thermal energy the external device. Optionally, selected ones of the thermal energy transport members connected to both the input and output portions may be insulated from the TES media.

Abstract: A phase change material (PCM) is used as thermal storage for lighting systems. The PCM is placed in a thermally conductive container in close contact with the lighting system. As the PCM absorbs heat, it changes from a solid to a liquid state, but the temperature of the PCM is clamped at its melting point temperature. For LED-based systems, the PCM is selected to have a melting point such that the junction temperatures of the LEDs in the system are maintained at approximately their optimum operating temperature inside the lighting system housing. Because the thermal conductivity of the molten PCM is poor, a low thermal resistance heat flow path is provided from the PCM to the container.

Abstract: An improved system and methods useful for the cooking of one or more food items by the application of a non-ambient temperature developed within a temperature retentive element. The temperature retentive element can be sized and shaped to form a cooking box in which cooking at a temperature relative to the non-ambient temperature may proceed and from which the food item, when fully cooked, may be served.

Abstract: The present invention relates to an improved container, which is applicable to heating an object to be heated inside the container by radiation or conduction of thermal energy. The container has an outside surface on which at least one heat collector is provided and the heat collector is made of a material having excellent thermal conductivity, whereby the overall heat absorbing surface area of the heat absorbing section of the container is increased.

Abstract: The present invention is directed to an energy storage system comprised of a heat block having a relatively high specific energy capacity. The heat block can be used, for example, with a regenerative braking system for gas turbine powered vehicles to improve fuel efficiency.

Abstract: A solar thermal collection cabinet is disclosed that includes a thermal mass comprising concrete mix and metallic pieces. The cabinet includes a corrugated metallic surface with a black finish that faces solar radiation. A plurality of metallic bolts attaches the black corrugated surface to the thermal mass, to enable good heat conduction to the thermal mass. Channels through the thermal mass enable heat transfer fluid to circulate through the thermal mass, the heat transfer fluid exchange heat for direct utilization, or to transfer heat to a thermal storage reservoir through suitable heat exchanger means. Alternatively, the thermal storage reservoir continuously receives and returns heat exchange fluid whereby over extended periods of time the system approaches a thermal steady state.

Abstract: Improved thermal energy storage materials, devices and systems employing the same and related methods. The thermal energy storage materials may include a phase change material that includes a metal-containing compound. This invention is directed at methods of encapsulating thermal energy storage materials, devices containing encapsulated thermal energy storage materials, and capsular structures for encapsulating thermal energy storage materials.

Abstract: A firewood retainer assembly and a fireplace incorporating the same are provided. The assembly includes a grate for supporting firewood at a level above a floor of a fireplace combustion chamber. The grate includes a first end opposite a second end such that a width of said grate is defined between these ends. The assembly also includes a deflector positioned adjacent the grate for deflecting air entering said combustion chamber below the level. A method of burning firewood is also provided which results in reduced particulate emissions. The method requires the deflection of air used for combustion below the firewood, heating the air with embers located below the firewood, and using the heated air for combustion.

Abstract: A disposable enclosure or sealed envelope packet configured to be used for the purpose of warming objects and utensils intended for use in conjunction with prepared food products. The warming packet incorporates organic material and is shaped and sized to be positioned next to a food container and to thereby keep the container warm as well as the food within or on the container. The organic material contained within the packet is susceptible to warming by microwave ovens and retains such heat energy for a period of time to assist in the maintenance of warmth in the food products. In a preferred embodiment, flat circular shaped packets are designed to incorporate organic materials such as a starch (rice grains or the like) as well as a heat retention material (such as crystalline salt). The packets are heated in a microwave oven, individually or collectively in a stack, and then placed in between empty plates for the purposes of maintaining the plates in a warm condition prior to being used to serve food.

Abstract: An active thermal energy storage system is disclosed which uses an energy storage material that is stable at atmospheric pressure and temperature and has a melting point higher than 32 degrees F. This energy storage material is held within a storage tank and used as an energy storage source, from which a heat transfer system (e.g., a heat pump) can draw to provide heating of residential or commercial buildings and associated hot water. The energy storage material may also accept waste heat from a conventional air conditioning loop, and may store such heat until needed. The system may be supplemented by a solar panel system that can be used to collect energy during daylight hours, storing the collected energy in the energy storage material. The stored energy may then be used during the evening hours to heat recirculation air for a building in which the system is installed.

Abstract: A thermal energy storage apparatus is disclosed. The thermal energy storage apparatus has a phase change medium. The thermal energy storage apparatus also has an inner manifold area having at least one inner feed port. The thermal energy storage apparatus also has an outer manifold area having at least one outer feed port and fluidically coupled to the inner manifold area. The inner manifold area and the outer manifold area are configured to be substantially immersed in the phase change medium. Methods of constructing and controlling embodiments of related thermal energy storage apparati are also disclosed, as well as embodiments of related heat exchangers.

Abstract: An active thermal energy storage system is disclosed which uses an energy storage material that is stable at atmospheric pressure and temperature and has a melting point higher than 32 degrees F. This energy storage material is held within a storage tank and used as an energy storage source, from which a heat transfer system (e.g., a heat pump) can draw to provide heating of residential or commercial buildings and associated hot water. The energy storage material may also accept waste heat from a conventional air conditioning loop, and may store such heat until needed. The system may be supplemented by a solar panel system that can be used to collect energy during daylight hours, storing the collected energy in the energy storage material. The stored energy may then be used during the evening hours to heat recirculation air for a building in which the system is installed.

Abstract: A heat accumulator has a heat accumulator structure with at least two accumulator elements through which a medium flows for charging and that thus each forms a hot end and a cold end by temperature layering and having a medium rinse device. In a rinse operation the heat accumulator produces at least one cold medium rinse flow and introduces it into the cold end of at least one of the accumulator elements. The hot medium rinse flow exiting from the hot end of the accumulator element enters the hot end that is in the charged state via at least one rinse path.

Abstract: The present invention provides a kind of solar-architectural materials which receive solar radiation and transfer it into heat energy and at the same time works as building finishing and decoration material, and thereof a system of building integrative solar heat utilization in which comprise a kind of heat-energy-conflux-device via metal matching surface impinging on each other without leakage possibility of liquid as heat transfer medium in the system.

Abstract: A warming device (30) for warming the lens portion (2) of an optical instrument (1), such as a laparoscope, to a temperature above ambient to prevent lens fogging comprising: a double walled cylindrical tube (3) having an internal wall (3b), and an external wall (3a), an upper surface and an open distal portion (7) with a central cavity (4) therebetween; a protrusion (9) extending from said upper surface, sized and shaped to receive the lens portion; a circular cap (5) sized to attach to said distal portion of said double walled cylindrical tube; and, a heating element (15) enclosed within said central cavity and thermally coupled to said insulation layer

Abstract: An active thermal energy storage system is disclosed which uses an energy storage material that is stable at atmospheric pressure and temperature and has a melting point higher than 32 degrees F. This energy storage material is held within a storage tank and used as an energy storage source, from which a heat transfer system (e.g., a heat pump) can draw to provide heating of residential or commercial buildings and associated hot water. The energy storage material may also accept waste heat from a conventional air conditioning loop, and may store such heat until needed. The system may be supplemented by a solar panel system that can be used to collect energy during daylight hours, storing the collected energy in the energy storage material. The stored energy may then be used during the evening hours to heat recirculation air for a building in which the system is installed.

Abstract: A compact heat battery (CHB) may comprise a casing, a tube containment sheath, a bundle of hermetically sealed phase change material (PCM) encapsulation tubes, and encapsulation tube inserts. An insulation envelope and insulation shield may be positioned radially outward from the casing. As an alternative the casing, insulation, and insulation shield can be integrated into a double-walled vacuum cylinder. The cylindrical containment sheath can open and close along a split-seam in response to radial expansion of the tubes. The natural packing of the encapsulation tubes within the containment sheath can distribute a heat transfer fluid through the interstitial spaces between the encapsulation tubes. Floating baffle plates provide for axial containment and expansion of the encapsulation tube bundle. The CHB of the present invention can allow for increased tube density, providing increased heat absorption and decreased CHB dimensions.

Abstract: It is not possible to store heat of a domestic hot water supply level at a high density. If thermal storage temperature is T, variation in enthalpy in a chemical reaction is &Dgr;H, variation in entropy is &Dgr;S, and variation in free energy is &Dgr;G, a thermal storage material satisfying a relationship of T&Dgr;S≧&Dgr;G is used under a condition of &Dgr;H>0 so as to promote a reaction for putting the thermal storage material in a thermal storage reaction portion in an energy storing state by having supplemental energy added by an electrode portion when putting the thermal storage material in the energy storing state by decomposing or separating it.

Abstract: A thermal food container comprises a receptacle having an upwardly disposed opening and a bottom and side walls; and a lid coextensive with the opening. The bottom wall includes a first pocket with a first cover operable outside the receptacle, the first pocket being adapted to receive a first thermal storage device. The lid includes a second pocket with a second cover operable outside the receptacle when the lid is secured to the receptacle, the second pocket being adapted to receive a second thermal storage device.

Abstract: The installation stores thermal energy, i.e., heat energy and/or cold energy. A plurality of conduits are laid underground. Several regions that are arranged one inside the other and contain energy-saving material and conduits respectively are provided. The conduits that are arranged in the individual areas can be connected to users having different temperature levels. The innermost region is maintained at a highest temperature differential relative to the outside of the installation and the innermost region can be connected, inter alia, to drive an electrical generator.

Abstract: An induction heatable body (22) that quickly heats to a desired temperature, retains heat long enough to be used in almost any application, and develops no “hot spots” even when heated by a heating source having an uneven magnetic field distribution. The induction-heatable body (22) achieves the foregoing while remaining relatively lightweight, inexpensive and easy to manufacture. The induction-heatable body (22) includes a plurality of induction-heatable layers (32a, b, c) each sandwiched between alternating layers of heat retentive material (34a, b, c). The induction-heatable layers (32a, b, c) consist of sheets of graphite material that can be inductively heated at magnetic field frequencies between 20 and 50 kHz. The heat-retentive layers (34a, b, c) consist of solid-to-solid phase change material such as radiation cross-linked polyethylene.

Abstract: Heat insulations in houses having card-board lattice arranged behind a glass pane yield, in practice, a heat flow which is dependent on insolation. Said heat flow is lower at night and during weak insolation and begins to increase when the lattice is solar heated. The inventive solar cell (1) comprises a lattice (5) which is situated behind a rear-ventilated glass pane (2) and which exhibits durable storage properties. The solar cells characterize a solar energy yield (v′) by an arrangement which selects for an angle of incidence. Said solar energy yield does not lead to overheating in the room interior (R) also when the sun is at a high position. A thermal time constant is obtained by means of heat insulations (11, 12, 13) which are connected in succession. Said time constant guarantees comfortable temperatures in the interior (R) of the house also in the case of low supplementary heating.

Abstract: The present invention is directed to a water heater which includes a phase change material having a freezing/melting temperature from about 30° C. to about 90° C. The water heater include a source of water, a heating element for heating the water, a heat exchange unit which contains the material, and a plurality of heat exchange tubes positioned in the heat exchange unit, which tubes are in heat transfer relation to the phase change material so that heat stored in the material can be transferred to the water. The phase change material is preferably heated from the top down to accommodate the changes in volume during thermocycling.

Abstract: A delivery apparatus comprising a container and a heater is provided for holding an article in thermally conductive contact with the heater. The heater includes a heating grid constructed to provide a output watt density of greater than 2.5 watts per square inch. A heat sink is provided in thermally conductive contact with the heating grid for receiving and storing heat energy from the heating grid. The heater also includes a cover and a power cord. In another embodiment a delivery apparatus includes a controller. The controller provides information to the user about the status of the delivery apparatus by changing the state of a light source.

Abstract: The present invention is directed to a water heater which includes a material having a thermal energy capacity of at least about 25 cal/g and having a freezing/melting temperature from about 20° C. to about 100° C. The water heater include a source of water, a heating element for heating the water, a heat exchange unit which contains the material, and a plurality of heat exchange tubes positioned in the heat exchange unit, which tubes are in heat transfer relation to the material so that heat stored in the material can be transferred to the water.

Abstract: A pizza oven that has an air curtain or air wash along the bottom of the cooking stones that reduces heat transfer from the burners to the stones during idle modes to thereby prevent over heating and burning of pizza bottoms during an ensuing cooking mode. The heating stones are situated on a plurality of bosses that extend from a base plate disposed between the burner flame and the stones. The air curtain extends along a gap between the bottom surface of the stones and the upper surface of the base plate.

Abstract: A delivery apparatus comprising a container and a heater is provided. The container is provided for holding an article in thermally conductive contact with the heater. The heater includes a heating grid constructed to provide a output watt density of greater than 2.5 watts per square inch. A heat sink is provided in thermally conductive contact with the heating grid for receiving and storing heat energy from the heating grid. The heater also includes a cover and a power cord. In another embodiment a delivery apparatus includes a controller. The controller provides information to the user about the status of the delivery apparatus by changing the state of a light source. A method of delivering food is also provided.

Abstract: A carrying case for protecting heat sensitive materials includes a first portion, a second portion, and a closure device. The closure device seals the first portion to the second portion. Each portion includes a retainer which contains a phase change material. The retainer is covered on an outside with an insulation layer. The insulation layer and retainer are preferably covered with a fabric layer. A second embodiment of a carrying case for protecting heat sensitive materials includes a cover, a container, and a closure device. The walls of the container and cover preferably include a retainer which contains phase change material, an insulation layer, an outer fabric layer, and an inner fabric layer. A third embodiment of a carrying case for protecting heat sensitive materials includes a pouch which is sealable with a closure device. The wall of the pouch preferably includes a fabric outer layer, a flexible foam outer layer, a phase change layer, a flexible foam inner layer, and a fabric inner layer.

Abstract: A heat exchanger for a phase change material including a container holding the phase change material, a tube surrounding the container to define an annular space therebetween, and preferably divider walls within that annular space to create a circuitous path for heat exchange fluid to be routed in multiple passes along the length of the container when passing from the top of the annular space to the bottom of the annular space. When the heat exchanger is operated in a melt cycle, multiple heat energy transfer elements positioned within the lower portion of the container and extending through the phase change material are heatable to a sufficiently high temperature to initiate melting of the phase change material. The heat energy transfer elements are preferably electrical resistance heated rods or coils, or tubes through which is routed high temperature fluid.