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 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 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. The damper assembly can include a single actuator that simultaneously opens the heat pipe dampers and closes the bypass dampers and simultaneously closes the heat pipe dampers and opens the bypass dampers.

Abstract: A heat exchanger for exchanging heat between an inside airstream flowing within an interior of a building structure and an outdoor airstream flowing outside of the interior of the building structure includes a heat pipe system comprising a refrigerant. A first heat pipe assembly is installed within the interior of the building structure such that heat is transferrable between the first heat pipe assembly and the inside airstream flowing within the interior of the building structure. A second heat pipe assembly is installed outside of the interior of the building structure such that heat is transferrable between the second heat pipe assembly and the outside airstream flowing outside of the interior of the building structure. The heat pipe system is configured such that the inside airstream remains within the interior of the building structure and the outside airstream remains outside of the interior of the building structure.

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. The damper assembly can include a single actuator that simultaneously opens the heat pipe dampers and closes the bypass dampers and simultaneously closes the heat pipe dampers and opens the bypass dampers.

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 air streams in two horizontally spaced ducts of a ventilation system. The heat exchanger includes a plurality of single-loop heat pipes, each with top and bottom legs extending along a heat pipe axis. A frame permanently mounts the heat pipes in the ventilation system so that sections of the legs are received in each duct and the legs are inclined with respect to a horizontal axis. The frame can define a non-rectangular interior. Heat pipe mounting features spaced apart along a width of the frame that can be offset along the height of the frame. A top or bottom of the frame can have an inclined inner side. In use, the frame is arranged in the ducts so that the inclined heat pipes provide whole-year heat recovery in cooling and heating modes.