Described herein is an apparatus and method for avoiding frost and ice buildup in and on vent pipes that transport a stream of gas from the inside to the outside of a building. The apparatus and method comprise a heat-conducting path that extracts heat energy from the stream of gas exiting the vent pipe, and transfers this energy to the frost and ice condensing surfaces at or near the terminus of the vent pipe. The heat-conducting path comprises a heat pipe. In one embodiment the heat-conducting path further comprises a heat exchanger. The passive transfer of heat energy via the heat-conducting path, from the stream of gas to the condensing surfaces of the vent pipe, avoids frost and ice buildup in or around the terminus of the vent pipe.

Disclosed is an air-conditioning apparatus using a heat pipe. The state of the outside air is compared with the state of set supply air. The heat exchange and mixed supply of outside air and ventilation air are effectively performed by changing the passage of the ventilation air and the outside air through the selective opening/shutting of dampers, cooling the outside air through latent heat by spraying mist, and by controlling supply air in a set state through the cooling and humidification of the supply air. Accordingly, energy efficiency can be improved and the energy necessary for the air-conditioning apparatus can be reduced using the evaporation latent heat of water. Furthermore, operation costs can be reduced and financial gains can be obtained because an efficient operation can be performed in response to the state of a measured outside air.

A heat exchanger (100) comprises: a first header tube (1) and two second header tubes (3); a first heat exchange tube (51) in fluid communication with one of the two second header tubes (3) and a second chamber (B) of the first header tube (1); a first runner tube (61) in fluid communication with the one of two second header tubes (3) and a first chamber (A) of the first header tube (1); a second heat exchange tube (52) in fluid communication with the other of the two second header tubes (3) and the first chamber (A) of the first header tube (1); and a second runner tube (62) in fluid communication with the other of the two second header tubes (3) and the second chamber (B) of the first header tube (1). The heat exchanger (100) bends at a first bending portion (71) between the other of the two second header tubes (3) and the first header tube (1), so as to enable the other of the two second header tubes (3) to be higher or lower than the first header tube (1).

Systems and methods for controlling conditions in an enclosed space, such as a data center, or for providing cooling to a device, can include using a Liquid-to-Air Membrane Energy Exchanger (LAMEE) as an evaporative cooler. The LAMEE or exchanger can cool water to the outdoor air wet bulb temperature in a cooling system disposed outside of the enclosed space or device. The reduced-temperature water can be delivered to the enclosed space or device or can cool a coolant that is delivered to the enclosed space or device. The air in the enclosed space, or one or more components in the enclosed space, can be cooled by delivering the reduced-temperature water or coolant to the enclosed space, rather than moving the supply air from the enclosed space to the cooling system. In an example, the cooling system can include one or more cooling coils, upstream or downstream of the LAMEE.

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.

Embodiments of the present disclosure are directed toward a heat exchanger that includes an evaporator coil section disposed at least partially within a first flow structure configured to direct a first flow of air across the evaporator coil section, a condenser coil section fluidly coupled with the evaporator coil section and disposed at least partially within a second flow structure configured to direct a second flow of air across the condenser coil section, and an auxiliary heat exchanger fluidly coupled with the evaporator coil section, where the auxiliary heat exchanger is external to the first flow structure.

Elongated, smaller-diameter tube heat pipes have an airflow arrangement that allows for short distances between evaporating and condensing sections of the heat pipe. The heat pipe is exposed to multiple alternate hot and cold zones adjacent to each other. Each evaporator zone accepts input heat to cause evaporation of the working fluid in the wick of the immediate vicinity. The vapor produced moves to either side by local pressure differences to condense in the two adjacent condenser zones where it is absorbed by the wick as a liquid and flows in the wick back to adjacent evaporator zones at each side. Each evaporator zone creates two fluid loops whereby evaporated working fluid splits up left and right, condenses in adjacent condenser zones and flows back to the evaporator zone as a liquid within the wick. Therefore, the overall tube length can be increased indefinitely, without traditional degradation of performance.

A dehumidifying system includes an enclosure having at least one opening disposed at a first end and at least one opening disposed at a second end. A plurality of air paths that extend through the enclosure and are separated from one another by partitions along at least a portion of the enclosure. A dehumidifier evaporator is disposed within the enclosure and configured such that at least one of the air paths is disposed to flow through the dehumidifier evaporator. The dehumidifier evaporator includes a dehumidifying coil and a heat pipe assembly at least partially wrapping around the dehumidification coil.

A heat exchanger (100) comprises: a first header tube (1) and two second header tubes (3); a first heat exchange tube (51) in fluid communication with one of the two second header tubes (3) and a second chamber (B) of the first header tube (1); a first runner tube (61) in fluid communication with the one of two second header tubes (3) and a first chamber (A) of the first header tube (1); a second heat exchange tube (52) in fluid communication with the other of the two second header tubes (3) and the first chamber (A) of the first header tube (1); and a second runner tube (62) in fluid communication with the other of the two second header tubes (3) and the second chamber (B) of the first header tube (1). The heat exchanger (100) bends at a first bending portion (71) between the other of the two second header tubes (3) and the first header tube (1), so as to enable the other of the two second header tubes (3) to be higher or lower than the first header tube (1).

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.