Abstract: A heat exchanger for exchanging heat between first and second duct portions of a ventilation system includes first and second heat pipe portions in the first and second duct portions, respectively. Each heat pipe portion can be a heat pipe subassembly including one or more vertical heat pipes fluidly coupled to top and bottom headers, which are respectively connected to the top and bottom headers of the other subassembly to form a refrigerant loop. One or more flow restrictors can block air flow through a respective section of the first or second duct portion. The blocked section can be operatively aligned with a segment of the respective heat pipe portion along which there is a low probability of refrigerant phase change. Each flow restrictor can be an adjustable damper. The damper(s) can be selectively opened and closed as the ventilation system switches between heating and cooling modes.

Abstract: A heat exchanger for exchanging heat between first and second duct portions of a ventilation system includes first and second heat pipe portions in the first and second duct portions, respectively. Each heat pipe portion can be a heat pipe subassembly including one or more vertical heat pipes fluidly coupled to top and bottom headers, which are respectively connected to the top and bottom headers of the other subassembly to form a refrigerant loop. One or more flow restrictors can block air flow through a respective section of the first or second duct portion. The blocked section can be operatively aligned with a segment of the respective heat pipe portion along which there is a low probability of refrigerant phase change. Each flow restrictor can be an adjustable damper. The damper(s) can be selectively opened and closed as the ventilation system switches between heating and cooling modes.

Abstract: A heat pipe heat exchanger is used in combination with a damper assembly to selectively control an amount of heat exchange provided. A divider defines discrete heat pipe plenums and bypass plenums within a duct, and the heat pipe system is configured so that all of the coils of one portion of the heat pipe system are received in the heat pipe plenum(s), while the bypass plenum(s) are free of any coils. The damper assembly includes adjustable heat pipe dampers aligned with the heat pipe plenums and adjustable bypass dampers aligned with the bypass plenums.

Abstract: A heat exchanger for exchanging heat between first and second duct portions of a ventilation system includes first and second heat pipe portions in the first and second duct portions, respectively. Each heat pipe portion can be a heat pipe subassembly including one or more vertical heat pipes fluidly coupled to top and bottom headers, which are respectively connected to the top and bottom headers of the other subassembly to form a refrigerant loop. One or more flow restrictors can block air flow through a respective section of the first or second duct portion. The blocked section can be operatively aligned with a segment of the respective heat pipe portion along which there is a low probability of refrigerant phase change. Each flow restrictor can be an adjustable damper. The damper(s) can be selectively opened and closed as the ventilation system switches between heating and cooling modes.

Abstract: A heat pipe heat exchanger is provided in the form of a serpentine heat pipe that does not have the ends of the individual tubes manifolded to one another via a straight pipe or via any other common connector. Instead, it has been discovered that heat pipes connected via U-bends to form a continuous coil function adequately. The serpentine heat pipe may include integral condenser and evaporator portions separated by a divider to form a one-slab heat exchanger, or separate evaporator and condenser coils connected to one another by vapor and return lines to form a two-section heat pipe. The heat pipe heat exchanger may be formed in a continuous closed-loop pipe so that the heat exchanger can operate with or without the aid of gravitational effects.

Abstract: A heat pipe heat exchanger is provided in the form of a serpentine heat pipe that does not have the ends of the individual tubes manifolded to one another via a straight pipe or via any other common connector. Instead, it has been discovered that heat pipes connected via U-bends to form a continuous coil function adequately. The serpentine heat pipe may include integral condenser and evaporator portions separated by a divider to form a one-slab heat exchanger, or separate evaporator and condenser coils connected to one another by vapor and return lines to form a two-section heat pipe. A method of producing a serpentine heat pipe includes providing a plurality of U-shaped tubes which are interconnected to form a single serpentine heat pipe, one of the tubes having an open end, and inserting sufficient refrigerant in the one tube to allow each of the tubes to function as a separate heat pipe. The serpentine heat pipe heat exchanger may be used to increase the dehumidification capacity of an air conditioner.

Abstract: A bypass system is incorporated into a roof curb to permit selective partial or complete deactivation of at least one section of a heat pipe of an air conditioning system thereby 1) to permit optimization of the sensible heat ratio of the air conditioning system for prevailing environmental conditions and, 2) to prevent moisture from condensing onto the evaporator or cooling section of the heat pipe and subsequently dripping into the return ducts of the air conditioning system. The bypass system is characterized by a bypass duct located adjacent one of the sections of the heat pipe and a bypass device which selectively channels at least some of the air which would otherwise flow through the controlled section of the heat pipe through the bypass duct instead. In its simplest form, the bypass device may comprise a single damper or the like positioned within the bypass duct.

Abstract: The heat exchange efficiency of a finned tube heat exchanger is increased by providing secondary heat exchange surfaces which are dimensioned and configured to maximize heat exchange with the surrounding fluid. These secondary heat exchange surfaces, formed from materials which would normally be wasted when blanks are removed from the fins to form apertures for receiving the tubes, are formed by bending the preserved materials into star-shaped structures which increase the surface area in contact with the surrounding fluid. The secondary heat exchange surfaces increase the surface area of the fin which is available for heat exchange, and provide this increased surface area at a location maximizing heat transfer capability to the surrounding fluid and to the tubes. The heat exchanger can be constructed in a simple and inexpensive process while preventing fin presses or related machinery from being jammed by removed materials.

Abstract: A metalworking tool is capable of making internally grooved and externally finned heat exchanger coils from ordinary tubes in a single operation in which the tubes are expanded into bonding mechanical contact with external fins at the same time that grooves are formed in the inner surfaces of the tubes. The process is performed by a tool head having both expanding and groove forming tools mounted thereon. The expanding tool preferably comprises a hardened expansion ball which mechanically expands the tube with or without hydraulic or pneumatic assist. The groove forming tool may comprise a cutting point which scribes the tube, a roller which forges a groove, or any other suitable scribing or forging device. The groove forming tool may rotate or oscillate to produce nonlinear grooves and may form grooves during the in-going and/or out-going strokes of the tool.

Abstract: An air conditioning system uses heat-pipes in combination with a cooling coil to increase either the dehumidification capacity or the efficiency and capacity of an air-conditioning system. In the dehumidification mode, the secondary cooling coil is inactive, and the heat pipes operate as a heat-exchanger between the warm return air and the cold supply air of the air conditioning system to precool the return air and reheat the supply air, increasing the latent capacity of the main cooling coil. In the efficiency and capacity boosting mode, the secondary cooling coil is activated by introducing a portion of the cooling fluid from the air-conditioning system. This results in a neutralization of the effect of the heat pipes as well as an increase in effective heat-exchange area between the cooling fluid and the air, therefore produces an increase in the capacity of the system.

Abstract: A single assembly heat transfer device installed in an environmental control apparatus having a primary evaporator, a two-section heat pipe having an evaporator section and a condenser section, and an end plate. The primary evaporator, the evaporator section and the condenser section are mounted on the end plate, thereby forming a single assembly.

Abstract: A heat dissipator for an electric motor includes an impeller having an internal heat transfer mechanism. The heat transfer mechanism provides efficient heat transfer from the motor armature to the surrounding environment without forcing cooling fluids into the motor and without transferring heat through the motor housing. The motor can therefore be encased in sealed, light-weight plastic motor housing having relatively poor heat transfer characteristics without danger of overheating. The impeller is preferably designed to displace fluids without turbulence, thereby reducing noise and increasing efficiency. To this end, the impeller employs annular disks stacked on a shaft which may be rotatably mounted in a specially shaped housing and which preferably is formed from an extension of the motor drive shaft. The disks and a complementary surface cooperate so as to use a combination of surface friction, centrifugal forces, and a venturi effect to propel fluids without turbulence.

Abstract: An impeller displaces fluids without turbulence, thereby reducing noise and increasing efficiency. The impeller employs annular disks stacked on a shaft which may be rotatably mounted in a specially shaped housing. The disks cooperate with a complementary surface formed, e.g., by the interior of the impeller housing or by another impeller, so as to use a combination of surface friction, centrifugal forces, and a venturi effect to propel fluids tangentially without turbulence. The impeller is well suited for use with a heat exchange device because the flat disks present a large surface area providing good heat exchange with fluids flowing past the disks. A heat pipe or other suitable heat transfer mechanism may be provided in the shaft of the impeller to form a heat transfer system integral with the impeller for heating or cooling purposes.

Abstract: An air conditioning system uses heat-pipes in combination with a cooling coil to increase either the dehumidification capacity or the efficiency and capacity of an air-conditioning system. In the dehumidification mode, the secondary cooling coil is inactive, and the heat pipes operate as a heat exchanger between the warm return air and the cold supply air of the air conditioning system to precool the return air and reheat the supply air, increasing the latent capacity of the main cooling coil. In the efficiency and capacity boosting mode, the secondary cooling coil is activated by introducing a portion of the cooling fluid from the air-conditioning system. This results in a neutralization of the effect of the heat pipes as well as an increase in effective heat-exchange area between the cooling fluid and the air, therefore produces an increase in the capacity of the system.

Abstract: A passive defrost system uses a heat-exchanger/storage defrost module containing a thermal storage material such as a phase change material to capture and store low grade, waste heat contained in the liquid refrigerant line of a refrigeration system. The waste heat is stored during normal operation. Upon shut down of the refrigeration system, the stored heat in the defrost module is released by an automatic device for defrosting the evaporator. The preferred embodiment of this passive defrost system includes the defrost module and some device to transfer heat from the defrost module to the evaporator, preferably in the configuration of a gravity heat pipe. Since waste heat is taken out of the liquid refrigerant line, the efficiency of the refrigeration system is improved, and no additional energy is needed for the defrost operation.