A heating, ventilating, and air conditioning (HVAC) system includes a furnace having a primary heat exchanger and a secondary heat exchanger, where the primary heat exchanger and the secondary heat exchanger form a heat exchange relationship between an airflow and an exhaust gas, and where the primary heat exchanger is positioned upstream of the secondary heat exchanger, a burner configured to generate the exhaust gas, a sensor configured to monitor an ambient temperature, and a control system configured to receive feedback from the sensor, compare the feedback to a threshold, operate the furnace in a first mode when the ambient temperature exceeds the threshold, and operate the furnace in a second mode when the ambient temperature is at or below the threshold, where the furnace operates above a condensation temperature when in the second mode, such that the exhaust gas does not condense when operating in the second mode.

A heat exchanger includes flat cross-sectional shaped heat transfer tubes arranged with gaps between flat surfaces of the flat heat transfer tubes facing each other, and each having a flow passage in a vertical direction, and corrugated fins disposed between the flat surfaces facing each other. The corrugated fins each include an end portion in a direction in which air flows, and protruding from end portions of the flat surfaces, a drain hole provided adjacent to central regions of the flat surfaces in the direction in which the air flows, first louvers located upstream of the drain hole, and each including a slit and a slat that is inclined in the vertical direction, and second louvers located downstream of the drain hole, and each including a slit and a slat that is inclined in the vertical direction.

This disclosure provides a heat exchanger that can more efficiently remove the frost attached to the heat exchanger. A configuration of a heat exchanger according to the present invention includes a heat transfer member (e.g., a fin) that performs heat exchange with air, wherein the heat transfer member (e.g., the fin) includes, in a vicinity of an upstream-side edge in an air traveling direction, a plurality of linear protruding portions that are formed in parallel to the edge.

A heat exchanger includes tubes arranged in one direction, and a corrugated fin provided between the tubes. The corrugated fin includes joints joined to the tubes, and fin bodies that connect the joints which are located next to each other along the wave shape. The fin body includes a cut-raised portion that has a shape in which a part of the fin body is cut and raised for promotion of heat transfer. The cut-raised portion includes a cut-raised end on at least one end of the cut-raised portion in the one direction. The cut-raised end has recesses and projections on its surface that increase hydrophilicity of the surface of the cut-raised end.

A heat exchanger includes: a surface with a water-repellent coating. The surface has a surface structure that includes protrusions. Condensed water droplets, each having a droplet diameter that allows a subcooled state to be maintained even under a predetermined freezing condition, combine with one other on the surface and generate an energy. The surface structure uses the energy to remove the combined condensed water droplets from the surface.

A multiple tube bank heat exchanger includes a first tube bank including at least a first and a second flattened tube segments extending longitudinally in spaced parallel relationship and a second tube bank including at least a first and a second flattened tube segments extending longitudinally in spaced parallel relationship. The second tube bank is disposed behind the first tube bank with a leading edge of the second tube bank spaced from a trailing edge of the first tube bank. A continuous folded fin extends between the first and second flattened tube segments of both of said first tube bank and said second tube bank.

Arrangement for accumulation and evacuation of water such as defrosting and condensation water from refrigeration units, the system including a piping arrangement with a vertical pipe section extending from a water evacuation unit provided in conjunction with the respective refrigeration unit; discharge valves, one for each unit; one or more liquid reservoir for each unit; one or more vacuum pumps; air inlet nozzles; a control unit; one or more level switches and air conduit inlet opening for each vertical pipe. Each of the water evacuation units includes a docking station and a water collection tray preferably to be slideably provided within the docking station, whereby each unit is custom made to fit between the refrigeration unit and floor where the refrigeration units are placed.

A defrosting apparatus comprises a heater case comprising a heat pipe seating part formed to extend from one surface thereof in a recessed shape and a heater receiving part formed to extend to be parallel with the heat pipe seating part. The defrosting apparatus also includes a heater which is mounted in the heater receiving part so as to emit heat when power is applied thereto, a heat pipe which has a flow path through which a working fluid filled therein flows, which has a part seated on the heat pipe seating part, and which is disposed to be adjacent to a cooling pipe of an evaporator such that heat is radiated to the cooling pipe of the evaporator by means of the working fluid at a high temperature which is heated by the heater and then is transferred, and a holder which is detachably coupled to the heater case so as to cover the heat pipe seated on the heat pipe seating part.

The present invention discloses a device and method for generating high-purity hydrogen by biomass pyrolysis-chemical looping combustion. The device comprises a biomass pyrolysis unit, a chemical looping hydrogen generation unit and a waste heat recovery unit; the biomass pyrolysis unit comprises a vertical bin, a screw feeder, a rotary kiln pyrolysis reactor and a high temperature filter; the chemical looping hydrogen generation unit comprises a path switching system of intake gas end, at least one packed bed reactor and a path switching system of tail gas end, wherein the packed bed reactor is composed of three parallel packed bed reactors I, II and III, which are continuously subjected to fuel reduction-steam oxidation-air combustion stages (steam purging stage) successively; the waste heat recovery unit comprises a waste heat boiler, a cooler and a gas-liquid separator. According to the present invention, a process flow of generating hydrogen from biomass is short, high-purity hydrogen can be obtained by simple condensation and water removal of a hydrogen-containing product that is generated after entrance of a pyrolysis gas into the chemical looping hydrogen generation unit, no complex gas purification device is employed, and the costs for hydrogen generation are low.

A Heat Exchanger Unit comprising a venting unit, a shutter, a counter flow heat exchanger and a plurality of plenums. The venting unit pulls the outside air, or fresh/purer air, from outdoor through the shutter while it pushes the exhausted inside air through the counter flow heat exchanger and the plurality of plenums toward outside air.