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 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.

An air-cooled heat exchanger includes a plenum having an intake and a discharge, a cooling tube assembly inside the plenum, a fan assembly that has a fan, an engine positioned outside the plenum, and an internal drive assembly. The internal drive assembly is configured to transfer torque from the engine to the fan. The internal drive assembly is contained inside the plenum.

An air-cooled heat exchanger includes a plenum having an intake and a discharge, a cooling tube assembly inside the plenum, a fan assembly that has a fan, an engine positioned outside the plenum, and an internal drive assembly. The internal drive assembly is configured to transfer torque from the engine to the fan. The internal drive assembly is contained inside the plenum.

Disclosed is a corrosion-resistant air preheater capable of slowing down dust deposit. The air preheater comprises a shell, an air inlet is fixedly formed in the side wall of the shell, an air outlet is fixedly formed in the side, away from the air inlet, of the shell, a flue gas through pipe is fixedly arranged on the inner side wall of the shell, rotating assemblies are arranged on the outer side wall of the flue gas through pipe, a flue gas inlet box is fixedly arranged at the top of the shell. According to the corrosion-resistant air preheater, an air pressure plate is pushed through the flue gas pressure intensity, and then the air pressure plate can descend. After the air pressure plate descends, rotating blades can rotate under the flowing effect of flue gas, then a movable rod rotates, and a scraping plate is further enabled to rotate.

A shell-and-plate heat exchanger includes: a shell that forms an internal space and includes a refrigerant outlet at a top of the shell; and a plate stack disposed in the internal space and that includes heat transfer plates that are stacked and joined together. The shell-and-plate heat exchanger is configured to allow a refrigerant that has flowed into the internal space to evaporate. The refrigerant outlet emits a gas refrigerant out of the internal space through the refrigerant outlet. The plate stack forms: refrigerant channels that communicate with the internal space and through which a refrigerant flows; and heating medium channels that are blocked from the internal space and through which a heating medium flows. Each of the refrigerant channels is adjacent to an associated one of the heating medium channels with one of the heat transfer plates interposed therebetween.

A heat exchanger includes a shell, a coiled tube, and a swirler. The shell has an inlet and an outlet and forms a cavity. A first of a liquid refrigerant and a vapor refrigerant enters the inlet of the shell. The coiled tube is positioned within the cavity and is connected to an inlet tube from outside the shell and an outlet tube to outside the shell. A second of the liquid refrigerant and the vapor refrigerant enters the inlet tube of the coiled tube. The swirler is arranged adjacent the inlet of the shell and is dimensioned to distribute the first of the liquid refrigerant and the vapor refrigerant across the coiled tube.

A heat exchanger includes a metal fiber structure (20) formed from metal fibers, and a housing body (for example, a pipe (10)) in which the metal fiber structure (20) is housed, and a gap is formed at least partially between the metal fiber structure (20) housed in the housing body and an inner surface of the housing body.

A heat exchanger includes a metal fiber structure (20) formed from metal fibers, and a housing body (for example, a pipe (10)) in which the metal fiber structure (20) is housed, and a gap is formed at least partially between the metal fiber structure (20) housed in the housing body and an inner surface of the housing body.

Embodiments of the present invention relate to a heat dissipation apparatus and relates to the field of heat dissipation technologies, so as to solve a problem that heat dissipation efficiency of heat dissipation fins of an existing heat dissipation apparatus is low. In embodiments of the present invention, the heat dissipation apparatus includes a base plate, where multiple main fins are disposed on the base plate, and multiple auxiliary fins are disposed on the main fins; a gap exists between the auxiliary fins and the base plate; and a blocking structure is disposed and fastened on the base plate and/or the main fins, and the blocking structure can make cooling airflow first flow along the auxiliary fins and then flow along gaps between adjacent main fins and flow out. The present invention is mainly used in the field of communication accessories.