Heat recovery ventilator

A heat recovery wheel for a heat exchanger includes a wheel rim defining an outer perimeter of the heat recovery wheel, and a plurality of wheel passages located between the wheel rim and the wheel axis. The plurality of wheel passages are arranged in a plurality of radial layers relative to a wheel central axis. Each layer is defined by a first shaped material having a first cross-sectional shape and a second shaped material assembled to the first shaped material, the second shaped material having a second cross-sectional shape. Radially adjacent layers of the plurality of layers are secured directly to one another, and the plurality of wheel passages are configured for flow of a first airflow and a second airflow therethrough for thermal energy exchange between the first airflow and the second airflow.

BACKGROUND

Exemplary embodiments pertain to the art of heat exchangers, and more particularly to rotary wheel heat recovery ventilators.

Heat exchangers are utilized in ventilation systems installed in, for example, residential, commercial and industrial spaces to extract and remove heat and/or moisture from one airstream and transfer that heat energy and/or moisture to a second airstream. In particular, rotary wheel heat exchangers, or heat recovery ventilators, are known wherein a wheel rotates in a housing through countervailing streams of exhaust and fresh air, in the winter extracting heat and moisture from the exhaust stream and transferring it to the fresh air stream. In the summer rotary wheel heat exchangers extract heat and moisture from the fresh air stream and transfer it to the exhaust stream, preserving building air conditioning while providing desired ventilation.

Heat transfer enhanced heat recovery wheels present an opportunity for the development of significantly more compact designs of ventilation systems, reducing material and fabrication cost. However, a number of challenges exist for the application of new designs: Wheel effectiveness, pressure drop, material cost and design complexity are some of the key challenges.

BRIEF DESCRIPTION

In one embodiment, a heat recovery wheel for a heat exchanger includes a wheel rim defining an outer perimeter of the heat recovery wheel, and a plurality of wheel passages located between the wheel rim and the wheel axis. The plurality of wheel passages are arranged in a plurality of radial layers relative to a wheel central axis. Each layer is defined by a first shaped material having a first cross-sectional shape and a second shaped material assembled to the first shaped material, the second shaped material having a second cross-sectional shape. Radially adjacent layers of the plurality of layers are secured directly to one another, and the plurality of wheel passages are configured for flow of a first airflow and a second airflow therethrough for thermal energy exchange between the first airflow and the second airflow.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is the same as the second cross-sectional shape.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is different from the second cross-sectional shape.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is a first chevron pattern.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is a first trapezoidal pattern.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape has a first angular alignment relative to the wheel central axis and the second cross-sectional shape has a second angular alignment different from the first angular alignment.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is circumferentially angularly offset from the second cross-sectional shape.

Additionally or alternatively, in this or other embodiments the heat recovery wheel includes a plurality of axially stacked layers of wheel passages relative to the wheel central axis, wherein the wheel passages of axially adjacent layers are circumferentially offset.

In another embodiment, a heat exchanger includes a housing. The housing defines a first airflow chamber through which a first airflow is directed and a second airflow chamber through which a second airflow is directed. A heat recovery wheel is positioned in the housing and is rotatable about a wheel axis. The heat recovery wheel includes a wheel rim defining an outer perimeter of the heat recovery wheel and a plurality of wheel passages located between the wheel rim and the wheel axis. The plurality of wheel passages are arranged in a plurality of radial layers relative to a wheel central axis. Each layer is defined by a first shaped material having a first cross-sectional shape and a second shaped material assembled to the first shaped material. The second shaped material has a second cross-sectional shape. Radially adjacent layers of the plurality of layers are secured directly to one another and the plurality of wheel passages are configured for flow of a first airflow and a second airflow therethrough for thermal energy exchange between the first airflow and the second airflow.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is the same as the second cross-sectional shape.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is different from the second cross-sectional shape.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is a first chevron pattern.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is a first trapezoidal pattern.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape has a first angular alignment relative to the wheel central axis and the second cross-sectional shape has a second angular alignment different from the first angular alignment.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is circumferentially angularly offset from the second cross-sectional shape.

Additionally or alternatively, in this or other embodiments a plurality layers of wheel passages are axially stacked relative to the wheel central axis. The wheel passages of axially adjacent layers are circumferentially offset.

In another embodiment, a method of forming a heat recovery wheel includes forming a first cross-sectional shape in a first material layer, forming a second cross-sectional shape in a second material layer, assembling the first material layer directly to the second material layer thereby defining a passage layer having a plurality of wheel passages, and winding the passage layer about a central wheel axis, with radially adjacent passage layers directly abutting.

Additionally or alternatively, in this or other embodiments the first material layer is angularly offset from the second material layer.

Additionally or alternatively, in this or other embodiments radially adjacent passage layers are circumferentially offset.

Additionally or alternatively, in this or other embodiments the first cross-sectional shape is different from the second cross-sectional shape.

DETAILED DESCRIPTION

Referring now toFIG.1, illustrated is a schematic view of an embodiment of a heat recovery ventilator10. The heat recovery ventilator10includes a housing12having a first airflow chamber14and a second airflow chamber16. In some embodiments, the first airflow chamber14and the second airflow chamber16are separated by an internal housing wall18. The first airflow chamber14includes a first inlet port20and a first outlet port22, through which a first airflow24is directed through the first airflow chamber14. Similarly, the second airflow chamber16includes a second inlet port26and a second outlet port28, through which a second airflow30is directed through the second airflow chamber16. In some embodiments, the first airflow24is, for example, a return airflow from a conditioned or ventilated space, while the second airflow30is, for example, a fresh airflow. In the embodiment ofFIG.1, the first airflow24and the second airflow30are directed through the first airflow chamber14and the second airflow chamber16, respectively, in opposite directions, while in another embodiment, such as schematically illustrated inFIG.2, the first airflow14and the second airflow16are directed through the first airflow chamber14and the second airflow chamber16, respectively, in the same direction.

Referring again toFIG.1, a heat recovery wheel32is located in the housing12and is configured to rotate about a wheel axis34. The heat recovery wheel32rotates continuously about the wheel axis34, and in some embodiments is driven by a wheel motor36operably connected to the heat recovery wheel32by, for example, a shaft or belt. With the heat recovery wheel32rotating, the first airflow24and the second airflow30flow through a plurality of wheel passages38(shown inFIG.3) in the heat recovery wheel32. Thermal energy is transferred between the first airflow24and the second airflow30via the heat recovery wheel32structure.

Referring to the cross-sectional view ofFIG.3, the heat recovery wheel32includes a wheel outer rim40defining an outer perimeter of the heat recovery wheel32. The plurality of wheel passages38are formed in one or more passage layers42arranged radially about the wheel axis34. The passage layers42may be formed by generally circular elements, or may be formed in a spiral configuration about the wheel axis34. The wheel passages38of the same passage layers42are separated by passage fins46.

Referring now toFIG.4, a view of a forming process of a heat recovery wheel32is shown. A first layer material48is fed into a first set of forming rollers50or other forming tools at which a first shaped material52having, for example, a first chevron pattern as shown inFIG.5. Referring again toFIG.4, a second layer material54is fed into a second set of forming rollers56or other forming tools at which a second shaped material58having, for example, a second chevron pattern as shown inFIG.5. In some embodiments the first chevron pattern is the same as the second chevron pattern, while in other embodiments the second chevron pattern of the second shaped material58is different or opposite to the first chevron pattern of the first shaped material52. In some embodiments, the first chevron pattern is aligned along a first axis60and the second chevron pattern is aligned along a second axis62offset from the first axis60. In one embodiment, the second axis62is offset from the first axis60by 90 degrees.

The first shaped material52and the second shaped material58are assembled directly to each other at an assembly section64(shown inFIG.4) to form an assembled sheet66, as shown inFIG.6. The assembled sheet66has the plurality of wheel passages38formed therein by the first chevron pattern and the second chevron pattern. The assembled sheet66is wound to produce the heat recovery wheel32comprising radially adjacent passage layers42directly abutting each other, without a parting element, for example, a parting sheet between the passage layers42.

In another embodiment, shown inFIG.7, the first shaped material52and the second shaped material58may be formed of other shapes to define the wheel passages38when formed into the assembled sheet66. In the embodiment ofFIG.7, the first shaped material52has a first trapezoidal-shaped pattern70formed therein, while the second shaped material58has a second trapezoidal-shaped pattern72formed therein. Each trapezoidal shape has an open end74and a closed end76opposite the open end74. In some embodiments, the closed end76has a closed end width greater than an open end width of the open end74.

When assembled at the assembly section64, the first shaped material52and the second shaped material58are offset such that when wound or rolled to for the heat recovery wheel32, the first trapezoidal-shaped pattern70is angularly offset from the second trapezoidal-shaped pattern72. Referring now toFIG.8, in some embodiments, two or more assembled sheets66are stacked along the wheel axis34. In such embodiments, a first assembled sheet66ais angularly offset from a second assembled sheet66b.

In some embodiments, the first shaped material52and/or the second shaped material58may be textured to further enhance heat transfer, and/or may be coated with an adsorbent material for moisture control in the heat recovery ventilator10. Additionally, the first shaped material52and the second shaped material58may be coated with a hydrophobic and/or hydrophilic coatings to enhance moisture removal. The first shaped material52and the second shaped material58may be formed from a metallic material, or alternatively may be formed from a polymer or a composite material.

The first shaped material52and the second shaped material58and heat recovery wheel32of the present disclosure provides a solution to improve heat transfer of the heat recovery wheel32while maintaining a compact structure of the heat recovery wheel32by not including a parting sheet of a typical heat recovery wheel32, and not increasing the length of the heat recovery wheel32to increase the performance.