Patent Application
20080149310
Heat exchangers or heat transfer devices are known, particularly those used in refrigeration appliances.
U.S. Pat. No. 5,157,941 discloses an evaporator which has a trapezoid shaped fin structure to result in a trapezoid shaped tube coil structure which causes air flow through the evaporator to accelerate as the cross sectional area of the air flow path decreases from the air inlet to the air outlet. A trapezoidal shaped tube and fin evaporator is also disclosed in U.S. Pat. No. 5,826,442.
Other types of heat exchangers include plate type refrigerant evaporators such as those disclosed in U.S. Pat. Nos. 5,172,759, 5,099,913 and 5,137,082 in which a wall is provided in the interior of the refrigerant plate to allow refrigerant flowing through the plate to expand or compress between an inlet and an outlet.
It would be an improvement in the art if there were provided a fluid heat transfer device that provided for the acceleration of one of the fluids through the heat transfer device, yet would not require a specially shaped arrangement of the tubes of the heat transfer device and which could be incorporated into presently existing heat exchangers.
The present invention provides a heat transfer device or heat exchanger which, in some embodiments, may be used in a refrigeration appliance, such as part of an evaporator or part of a condenser, and which can be incorporated into existing heat exchangers.
In an embodiment of the invention, the heat transfer device includes a tube having a first fluid inlet and a first fluid outlet, the tube arranged to form a plurality of generally parallel elongated segments of the tube. An enclosure encloses the tube to define at least a part of a flow path for a second fluid over an exterior surface of the tube from a second fluid inlet to a second fluid outlet. A wall interior of the enclosure defines a first section of the flow path for the second fluid in the enclosure which first section leads from the second fluid inlet and extends across at least a first portion of a length of substantially all of the elongated segments of the tube. The wall further defines a second section of the flow path for the second fluid in the enclosure which second section extends across at least a second portion of the length of substantially all of the elongated segments of the tube and leads to the second fluid outlet. The interior wall is shaped and arranged in the enclosure such that a cross sectional area of the flow path for the second fluid in the enclosure changes along its length from the second fluid inlet to the second fluid outlet.
In an embodiment, the tube has a substantially constant cross sectional area along a length of the tube from the first fluid inlet to the first fluid outlet.
In an embodiment, the elongated segments of the tube are connected to each other in series in a serpentine path.
In an embodiment, an interior of the enclosure is substantially rectangular with a generally constant cross-sectional area along its height and long its length.
In an embodiment, the elongated segments of the tube are generally straight.
In an embodiment, the first section of the flow path for the second fluid extends in a first direction substantially perpendicular to the length of the elongated segments and the second section of the flow path for the second fluid extends in a second, opposite direction also substantially perpendicular to the length of the elongated segments.
In an embodiment, the wall is substantially planar and is arranged at an acute angle to the length of the elongated segments of the tube.
In an embodiment, the wall has a zig-zag shape with an alternating series of sections parallel and perpendicular to the length of the straight segments of the tube.
In an embodiment, the heat transfer device further includes a plurality of fins arranged in engagement with the exterior surface of the tube, the fins arranged to guide the second fluid flowing over the exterior surface of the tube to effect a heat transfer from one of the fluids to the other via thermal conduction through the fins and tube.
In an embodiment, each fin lies in a plane generally perpendicular to the length of the elongated segments of the tube.
In an embodiment, the first section of the flow path for the second fluid has a downstream end at one end of the wall with a cross sectional area substantially identical to a cross sectional area of the second section of the flow path for the second fluid at an upstream end at the same end of the wall.
In an embodiment, the cross sectional area of the flow path for the second fluid in the enclosure decreases along its length from the second fluid inlet to the second fluid outlet.
In an embodiment of the invention, the heat transfer device includes a tube arranged in a serpentine path of elongated straight segments joined by u-shaped returns to form a plurality of parallel straight segments of the tube to carry a first fluid from a first fluid inlet to a first fluid outlet. A plurality of fins are arranged in engagement with an exterior surface of the tube, each fin lying in a plane generally perpendicular to a length of the straight segments of the tube. The fins are arranged to guide a second fluid flowing over the exterior surface of the tube to effect a heat transfer from one of the fluids to the other via thermal conduction through the fins and tube. An enclosure encloses the tube and fins to define at least a part of a flow path for the second fluid in a region of the tube and fins from a second fluid inlet to a second fluid outlet. A wall interior of the enclosure defines a first section of the flow path for the second fluid in the enclosure. This first section leads from the second fluid inlet and extends in a first direction substantially perpendicular to a length of the elongated segments of the tube. The wall further defines a second section of the flow path for the second fluid in the enclosure. This second section extends in an opposite direction from the first section substantially perpendicular to the length of the elongated segments of the tube and leads to the second fluid outlet. The interior wall is shaped and arranged in the enclosure such that a cross sectional area of the flow path for the second fluid in the enclosure changes along its length from the second fluid inlet to the second fluid outlet.
In an embodiment, the first section of the flow path for the second fluid has a downstream end at one end of the wall with a cross sectional area substantially identical to a cross sectional area of the second section of the flow path for the second fluid at an upstream end at the same end of the wall.
In an embodiment, the cross sectional area of the flow path for the second fluid in the enclosure decreases along its length from the second fluid inlet to the second fluid outlet.
In an embodiment, the first section of the flow path for the second fluid extends across at least a portion of the length of substantially all of the elongated segments of the tube and the second section of the flow path for the second fluid extends across at least a portion of the length of substantially all of the elongated segments of the tube.
In an embodiment of the invention, a method of transferring heat from one fluid to another is provided which includes the steps of flowing a first fluid through a tube from a first fluid inlet to a first fluid outlet, the tube arranged to form a plurality of generally parallel elongated segments of the tube, flowing a second fluid within an enclosure along a first section of a flow path from a second fluid inlet across an exterior surface of at least a first portion of a length of substantially all of the elongated segments of the tube, and along a second section of the flow path across the exterior surface of at least a second portion of the length of substantially all of the elongated segments of the tube and to the second fluid outlet, and successively changing a cross sectional area within the enclosure of the flow path of the second fluid causing a velocity of the second fluid to change as it flows along the flow path.
In an embodiment, the second fluid from the second fluid inlet is guided in a first direction substantially perpendicular to the length of the elongated segments of the tube, and then is caused to reverse direction and is guided in a second, opposite direction also substantially perpendicular to the length of the elongated segments of the tubes to the second fluid outlet.
In an embodiment, the cross sectional area of the flow path of the second fluid in the enclosure is successively decreased from the second fluid inlet to the second fluid outlet.
The inclusion and arrangement of the interior wall, and reconnection of the second fluid inlet or outlet, would permit the present invention to be used in an existing tube and fin style heat exchanger without modification of the tubes or fins.
The present invention provides a heat transfer device or heat exchanger 20. As an example of an environment in which the heat transfer device 20 may be used,
The refrigerator 22 of
The refrigerant and cooling air circuits are also located within the housing of refrigerator 22. The refrigerant circuit includes a compressor 32, the condenser 26, the evaporator 24 and a sealed refrigerant system including tubes 34 for connecting these elements. The tubes 34 contain the refrigerant fluid. The portion of the refrigerator housing containing the condenser 26 may also include a condenser fan 36. Except as set forth herein these elements are normally found in refrigerators and are well understood by those skilled in the art.
Similarly, cooling air circuits are normally found in refrigerators. In general, previous cooling air circuits have fostered air flow from the evaporator 24 through vents 38 into the compartment 28 for frozen items. A relatively small portion of the cooling air then typically gets diverted through an air duct 40 to enter the refrigerator compartment 30. The freezer portion of the cooling air returns to the evaporator 24 through vents 42. Cooling air in the refrigerator compartment 30 returns to the evaporator 24 through vents 44.
A fan 46 is, for example, employed to serve as an impeller to cause movement of the cooling air within this circuit. The passageways 48 between the evaporator 24 and the vents of the cooling air circuit can be located and dimensioned according to the specific configuration desired for the refrigerator 22. To avoid unnecessary complication the drawings of this application illustrate the passageways for the cooling air flow only in the vicinity of the evaporator.
An embodiment of the heat transfer device 20 incorporating the present invention is shown in isolation in
This tube 50, when in a refrigeration circuit would communicate with the refrigeration tubes 34. The tube 50 is arranged to form a plurality of generally parallel elongated segments 56 of the tube. In the illustrated embodiment, the elongated segments 56 of the tube 50 are connected to each other in series by u-shaped returns 57 in a serpentine path. In other embodiments, the elongated segments 56 might be connected in parallel with manifolds at each end of the segments to which the segments connect in common. Also, in the embodiment shown, the elongated segments 56 of the tube 50 are generally straight, although in other embodiments they might be bent or curved.
An enclosure 58 encloses the tube 50 to define at least a part of a flow path 60 for a second fluid over an exterior surface 62 of the tube from a second fluid inlet 64 to a second fluid outlet 66. The enclosure 58 may be formed of a separate housing, or may be formed from the walls of various disparate components. In an embodiment, an interior 67 of the enclosure 58 is substantially rectangular with a generally constant cross-sectional area along its height and long its length. Typically, the tube 50 extends exteriorly of the enclosure 58 such that the first fluid inlet 52 and the first fluid outlet 54 are positioned outside of the enclosure.
A wall 68 interior of the enclosure 58 defines a first section 70 of the flow path 60 for the second fluid in the enclosure. This first section 70 leads from the second fluid inlet 64 and extends across at least a first portion 72 of a length of substantially all of the elongated segments 56 of the tube 50. The wall 68 further defines a second section 74 of the flow path 60 for the second fluid in the enclosure 58. This second section 74 extends across at least a second portion 76 of the length of substantially all of the elongated segments 56 of the tube 50 and leads to the second fluid outlet 66. The interior wall 68 is shaped and arranged in the enclosure 58 such that a cross sectional area of the flow path 60 for the second fluid in the enclosure 58 changes along its length from the second fluid inlet 64 to the second fluid outlet 66. As shown in the arrangement of
In the example of
A shown in the embodiment of the heat transfer device 20 in
As also shown in the embodiment of
Thus, in accordance with the embodiments shown in
In an embodiment, the first section 70 of the flow path 60 for the second fluid extends across at least the portion 72 of the length of substantially all of the elongated segments 56 of the tube 50 and the second section 74 of the flow path for the second fluid extends across at least the portion 76 of the length of substantially all of the elongated segments of the tube.
In an embodiment of the invention, a method of transferring heat from one fluid to another is provided which includes the steps of flowing the first fluid through the tube 50 from the first fluid inlet 52 to the first fluid outlet 54, the tube 50 arranged to form the plurality of generally parallel elongated segments 56 of the tube, flowing the second fluid within the enclosure 58 along the first section 70 of the flow path 60 from the second fluid inlet 64 across the exterior surface 62 of at least the first portion 72 of the length of substantially all of the elongated segments 56 of the tube 50, and along the second section 74 of the flow path 60 across the exterior surface 62 of at least the second portion 76 of the length of substantially all of the elongated segments 56 of the tube 50 and to the second fluid outlet 66, and successively changing a cross sectional area within the enclosure 58 of the flow path 60 of the second fluid causing a velocity of the second fluid to change as it flows along the flow path.
The second fluid from the second fluid inlet 64 may further be guided in the first direction 78 substantially perpendicular to the length of the elongated segments 56 of the tube 50, and then is caused to reverse direction and may be guided in the second, opposite direction 80 also substantially perpendicular to the length of the elongated segments 56 of the tube 50 to the second fluid outlet 66.
Various features of the heat transfer device 20 have been described which may be incorporated singly or in various combinations into a desired system.
As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.
