Flow paths and boundary layer restart features are provided. For example, a flow path comprises a flow path wall defining an inner flow path surface and an asymmetric notch defined in the flow path wall. The asymmetric notch comprises a first surface and a second surface and is asymmetric about a first line extending through an intersection of the first and second surfaces. Further, a flow boundary layer restart feature comprises a first surface extending inward with respect to a flow path surface of a flow path and a second surface extending inward with respect to the flow path surface. The second surface is asymmetric with respect to the first surface such that the first and second surfaces define an asymmetric notch. Additionally, a flow path wall may comprise an asymmetric notch that includes a flow expansion angle and a flow contraction angle that are unequal.

A heat exchanger includes a hollow heat exchanger main body that is enclosed in a radiant tube, and a heat conductor that is disposed on outer periphery of the heat exchanger main body. The heat exchanger performs heat exchange between a first gas flowing in between the radiant tube and the heat exchanger main body and a second gas flowing in hollow interior of the heat exchanger main body, and the heat exchanger comprises a turbulence flow generation promoting unit configured to promote generation of a turbulence flow from the first gas flowing in between the radiant tube and the heat exchanger main body, the turbulence flow generation promoting unit being disposed on the outer periphery of the heat exchanger main body without welding.

A method for producing ribbed pipes, in which a first pipe base body is ribbed on its outer side, in particular helically, with a first band, to which end the first band is secured to the first pipe base body using a first laser beam. While the first band is being secured to the first pipe base body using the first laser beam, a second pipe base body is ribbed on its outer side with a second band, to which end the second band is secured to the second pipe base body using a second laser beam, wherein the first and second laser beams come from the same laser source.

A method for producing ribbed pipes, in which a first pipe base body is ribbed on its outer side, in particular helically, with a first band, to which end the first band is secured to the first pipe base body using a first laser beam. While the first band is being secured to the first pipe base body using the first laser beam, a second pipe base body is ribbed on its outer side with a second band, to which end the second band is secured to the second pipe base body using a second laser beam, wherein the first and second laser beams come from the same laser source.

A heat dissipation device includes a first pipeline and a second pipeline. The first pipeline is configured to circulate a first fluid. The second pipeline is configured to circulate a second fluid. The second pipeline has a sleeve portion. The sleeve portion is sleeved with a part of the first pipeline to form a circulation tunnel therebetween. One of the sleeve portions and the part of the first pipeline has a first surface and a second surface. The first surface contacts the first fluid. The second surface contacts the second fluid. The second surface has a plurality of protruding strips.

A finned tube (e.g., for use in a flooded and falling film evaporator) is provided. The finned tube includes a tube body with an interior surface and an exterior surface. The finned tube may include a plurality of adjacent helical fins (e.g., continuously or intermittently) protruding circumferentially around the exterior surface of the tube body. At least one channel is disposed between the plurality of adjacent helical fins. Each respective helical fin includes at least one sidewall and a fin top. Each channel includes at least one channel enhancement impressed radially into and transversely through at intervals around the circumference of the exterior surface of the tube body. The finned tube may also include at least one top enhancement and/or sidewall enhancement impressed radially into and transversely through at intervals around the circumference of the exterior surface of the tube body.

A finned tube (e.g., for use in a flooded and falling film evaporator) is provided. The finned tube includes a tube body with an interior surface and an exterior surface. The finned tube may include a plurality of adjacent helical fins (e.g., continuously or intermittently) protruding circumferentially around the exterior surface of the tube body. At least one channel is disposed between the plurality of adjacent helical fins. Each respective helical fin includes at least one sidewall and a fin top. Each channel includes at least one channel enhancement impressed radially into and transversely through at intervals around the circumference of the exterior surface of the tube body. The finned tube may also include at least one top enhancement and/or sidewall enhancement impressed radially into and transversely through at intervals around the circumference of the exterior surface of the tube body.

The subject of present invention is a hood with a condenser for a commercial oven, particularly a combination steam-convection oven, comprising a housing, an air inlet for supplying cooling air from the outside, a fan drawing in the cooling air through the air inlet, a cooling air outlet for expelling the air drawn in by the fan, a steam condenser in the form of a heat exchanger with a coil having at least one inlet opening for supplying steam from the inside of a commercial oven to the coil and at least one outlet opening for draining the condensate coming out of the coil, characterised in that it comprises a radial fan (3) that blows cooling air radially onto the at least one coil (5) surrounding the fan (3), wherein the at least one coil (5) surrounding the fan having an external finning (6).

The subject of present invention is a hood with a condenser for a commercial oven, particularly a combination steam-convection oven, comprising a housing, an air inlet for supplying cooling air from the outside, a fan drawing in the cooling air through the air inlet, a cooling air outlet for expelling the air drawn in by the fan, a steam condenser in the form of a heat exchanger with a coil having at least one inlet opening for supplying steam from the inside of a commercial oven to the coil and at least one outlet opening for draining the condensate coming out of the coil, characterised in that it comprises a radial fan (3) that blows cooling air radially onto the at least one coil (5) surrounding the fan (3), wherein the at least one coil (5) surrounding the fan having an external finning (6).

A heat utilization system according to the invention includes: a sealed container into which a hydrogen-based gas is supplied; a heat generating structure that is accommodated in the sealed container and includes a heat generating element that is configured to generate heat by occluding and discharging hydrogen contained in the hydrogen-based gas; and a heat utilization device that utilizes, as a heat source, a heat medium heated by the heat of the heat generating element. The heat generating element includes a base made of a hydrogen storage metal, a hydrogen storage alloy, or a proton conductor, and a multilayer film provided on the base. The multilayer film has a first layer made of a hydrogen storage metal or a hydrogen storage alloy and having a thickness of less than 1000 nm and a second layer made of a hydrogen storage metal or a hydrogen storage alloy, which is different from that of the first layer, or ceramics and having a thickness of less than 1000 nm.