US20090241586A1

US20090241586A1 - Inlet orifice of blower fan of fan coil unit

Info

Publication number: US20090241586A1
Application number: US12/405,467
Authority: US
Inventors: Yu Wang
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2008-03-26
Filing date: 2009-03-17
Publication date: 2009-10-01

Abstract

A blower fan of a fan coil unit includes a fan wheel including a first end ring, a second end ring, and a plurality of blades that extend between the first end ring and the second end ring. The plurality of blades define a wheel inner diameter, and each of the first end ring and the second end ring define an end ring inner diameter. The blower fan also includes a housing including an inlet orifice having an orifice diameter. The fan wheel is located within the housing. The orifice diameter is substantially equal to the end ring inner diameter and greater than the wheel inner diameter.

Description

REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No. 61/039,513 filed Mar. 26, 2008.

BACKGROUND OF THE INVENTION

This invention relates generally to a blower fan of a fan coil unit including a housing having an inlet orifice with a diameter that is substantially equal to an inner diameter of an end ring of a fan wheel received in the housing.
A fan coil unit includes a blower fan and a coil. Refrigerant flows through the coil, and the blower fan draws air over the coil. Heat is exchanged between the air drawn over the coil and the refrigerant flowing through the coil.
One example blower fan includes a fan wheel located in a housing. The fan wheel includes a plurality of blades that extend between two end rings and that define an inner diameter and an outer diameter of the fan wheel. The housing includes an inlet orifice having an orifice diameter, and air is drawn into the housing through the inlet orifice. In one example, the diameter of the inlet orifice is approximately equal to the inner diameter of fan wheel. Therefore, the housing covers the ends of the blades, hindering the flow of the air entering the blades.
Another example blower fan includes a fan wheel including a plurality of blades that extend between an end ring and an endplate. The end ring has an inner diameter that defines a central opening. The endplate includes a hub that receives a shaft. The endplate is only defined by the outer diameter and does not have an inner diameter that defines a central opening once the shaft is received in the hub.

SUMMARY OF THE INVENTION

A blower fan of a fan coil unit includes a fan wheel including a first end ring, a second end ring, and a plurality of blades that extend between the first end ring and the second end ring. The plurality of blades define a wheel inner diameter, and each of the first end ring and the second end ring define an end ring inner diameter. The blower fan also includes a housing including an inlet orifice having an orifice diameter. The fan wheel is located within the housing. The orifice diameter is substantially equal to the end ring inner diameter and greater than the wheel inner diameter.
Another aspect provides a fan coil unit including a coil through which refrigerant flows and a blower fan that draws air over the coil. The blower fan includes a first end ring, a second end ring, and a plurality of blades that extend between the first end ring and the second end ring. The plurality of blades define a wheel inner diameter, and each of the first end ring and the second end ring define an end ring inner diameter. The blower fan also includes a housing including an inlet orifice having an orifice diameter. The fan wheel is located within the housing. The orifice diameter is substantially equal to the end ring inner diameter and greater than the wheel inner diameter.
Another aspect provides a refrigeration system including a compressor for compressing a refrigerant, a condenser for cooling the refrigerant, an expansion device for expanding the refrigerant, and a fan coil unit including an evaporator coil and a blower fan. The refrigerant flows through the evaporator coil, and the blower fan draws air over the evaporator coil to reject heat to the refrigerant. The blower fan includes a first end ring, a second end ring, and a plurality of blades that extend between the first end ring and the second end ring. The plurality of blades define a wheel inner diameter, and each of the first end ring and the second end ring define an end ring inner diameter. The blower fan also includes a housing including an inlet orifice having an orifice diameter. The fan wheel is located within the housing. The orifice diameter is substantially equal to the end ring inner diameter and greater than the wheel inner diameter.
These and other features of the present invention will be best understood from the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:

FIG. 1A illustrates a refrigeration system operating in a cooling cycle including a fan coil unit;

FIG. 1B illustrates a refrigeration system operating in a heating cycle including the fan coil unit;

FIG. 2 illustrates an example fan coil unit;

FIG. 3 illustrates a perspective view of a blower fan of the fan coil unit including a housing and a fan wheel;

FIG. 4 illustrates a perspective view of an enlarged view of a portion of the blower fan of FIG. 3; and

FIG. 5 illustrates a perspective view of the fan wheel of the blower fan.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A illustrates a refrigeration system 20 operating in a cooling mode. Refrigerant flows through the closed circuit refrigeration system 20. The refrigeration system 20 includes a fan coil unit 21 located inside 17 a building and an outdoor unit 23 located outside 15 the building. The inside 17 of the building and the outside 15 of the building can be separated by a wall 19.
Refrigerant exits a compressor 22 in the outdoor unit 23 at a high pressure and a high enthalpy. A reversing valve 25 directs the refrigerant through a first heat exchanger 24, which operates as a condenser. In the first heat exchanger 24, the refrigerant flows through a coil 26 and rejects heat to air that is drawn over the coil 26 by a fan 29. In one example, the fan 29 is a propeller fan. In the first heat exchanger 24, the refrigerant is condensed into a liquid that exits the first heat exchanger 24 at a low enthalpy and a high pressure.
The refrigerant bypasses an outdoor expansion device 26 b (described below) and travels to the fan coil unit 21 through tubing 37. In the fan coil unit 21, the cooled refrigerant then passes through an indoor expansion device 26 a, expanding the refrigerant to a low pressure. After expansion, the refrigerant flows through a second heat exchanger 28, which operates as an evaporator. A blower fan 30 draws air through the second heat exchanger 28 and over a coil 27. The refrigerant flowing through the coil 27 accepts heat from air, exiting the second heat exchanger 28 at a high enthalpy and a low pressure.
The refrigerant then flows back to the outdoor unit 23 through tubing 39. The refrigerant can flow through an accumulator 31, which regulates the amount of refrigerant flowing through the refrigeration system 20. The refrigerant then flows to the compressor 22, completing the cycle.
FIG. 1B illustrates the refrigeration system 20 operating in a heating mode. Refrigerant exits the compressor 22 in the outdoor unit 23 at a high pressure and a high enthalpy. The reversing valve 25 directs the refrigerant to the fan coil unit 21 through the tubing 39.
In the fan coil unit 21, the refrigerant flows through the second heat exchanger 28, which operates as a condenser. A blower fan 30 draws air through the second heat exchanger 28 and over the coil 27. In the second heat exchanger 28, the refrigerant flows through the coil 27 and rejects heat to air and is condensed into a liquid, exiting the second heat exchanger 28 at a low enthalpy and a high pressure. The refrigerant exits the coil 27 and bypasses the indoor expansion device 26 a.
The refrigerant exits the fan coil unit 21 and flows through the tubing 37 towards the outdoor unit 23, where the refrigerant is expanded to a low pressure in the outdoor expansion device 26 b. After expansion, the refrigerant flows through the first heat exchanger 24, which operates as an evaporator. In the first heat exchanger 24, the refrigerant flows through the coil 26 and accepts heat from air that is drawn over the coil 26 by the fan 29, exiting the first heat exchanger 24 at a high enthalpy and a low pressure. The refrigerant can flow through the accumulator 31. The refrigerant then flows to the compressor 22, completing the cycle.
FIG. 2 illustrates the fan coil unit 21. The fan coil unit 21 includes a housing 41 that contains the blower fan 30 that draws the air over the coil 26. A motor 58 rotates the blower fan 30 about an axis of rotation 70. Air enters the blower fan 30 through an inlet orifice 60 and exits the blower fan 30 through an outlet 68.
As shown in FIGS. 3 and 4, the blower fan 30 includes a fan wheel 32 and a housing 34. In one example, the housing 34 is metal. The fan wheel 32 rotates about the axis of rotation 70. As further shown in FIG. 5, the fan wheel 32 includes a first end ring 36 and a second end ring 38. The end rings 36 and 38 are substantially the same size and shape. In one example, the end rings 36 and 38 are substantially circular in shape. The end rings 36 and 38 define an end ring inner diameter 66.
The fan wheel 32 also includes a plurality of blades 40 each having a first end 42 and a second end 44. The plurality of blades 40 are equally spaced and define a space 46 between each of the plurality of blades 40. The plurality of blades 40 are substantially parallel to each other and substantially perpendicular to the end rings 36 and 38. The plurality of blades 40 define a wheel inner diameter 64.
The ends 42 and 44 of the blades 40 are each connected to a base portion (not shown), and each of the end rings 36 and 38 are attached to one of the base portions. In one example, the end rings 36 and 38 are attached to the base portions by crimping. In one example, the fan wheel 32 is substantially cylindrical in shape. A cross-section of each of the plurality of blades 40 taken substantially perpendicularly to a length 48 of the blades 40 is substantially arc-shaped.
A wheel disc 50 is attached to the plurality of blades 40 at a location 52 along the length 48 of the blades 40 that is substantially equidistant from each of the ends 42 and 44. The wheel disc 50 includes a hub 51 that receives a shaft 54 of the motor 58, and a setup screw 53 mounts the wheel disc 50 to the shaft 54. As the motor 58 rotates the shaft 54, the fan wheel 32 rotates about the axis of rotation 70 to draw air into the fan wheel 32.
The housing 34 includes the inlet orifice 60 and the outlet 68. In one example, the inlet orifice 60 is substantially circular and has an orifice diameter 62. The fan wheel 32 is installed in the housing 34 such that the axis of rotation 70 of the fan wheel 32 is substantially centered within the inlet orifice 60. In one example, the housing 34 includes a planar surface 61, and the inlet orifice 60 is defined in the plane of the planar surface 61.
As the fan wheel 32 rotates about the axis of rotation 70, air is drawn into the inlet orifice 60 of the housing 34 and through the spaces 46 between the blades 40 of the fan wheel 32. The air is directed in an outwardly direction relative to the axis of rotation 70 of the fan wheel 32 and through the outlet 68 of the housing 34. The blower fan 30 draws air over the coil 27, the air exchanging heat with the refrigerant flowing through the coil 27.
As stated above, the second heat exchanger 28 can be an evaporator or a condenser. If the second heat exchanger 28 is an evaporator, the air rejects heat to the refrigerant flowing through the coil 27. If the second heat exchanger 28 is a condenser, the air accepts heat from the refrigerant flowing through the coil 27.
The size and shape of the inlet orifice 60 affects the flow of air into the fan wheel 32, and therefore efficiency. The orifice diameter 62 of the inlet orifice 60 of the housing 34 is approximately equal to or greater than the end ring inner diameter 66 of the end rings 36 and 38 of the fan wheel 32. The orifice diameter 62 of the inlet orifice 60 is therefore greater than the wheel inner diameter 64 (defined by the innermost portion of the blades 40), and the ends 42 and 44 of the blades 40 are partially exposed by the housing 34. In another example, the ends 42 and 44 of the blades 40 are entirely exposed by the housing 34. The air can be directly drawn into the fan wheel 32, and the rotation of the fan wheel 32 helps the air evenly flow over the fan wheel 32. The air is not required to make abrupt turns from the inlet orifice 60 to blade regions near the ends 42 and 44 of the blades 40, which could impede the flow in the region near the ends 42 and 44 of the blades 40.
In prior fan wheels, the orifice diameter of the inlet orifice is approximately equal the wheel inner diameter defined by the innermost portion of the blades. Therefore, a portion of the housing covers the ends of the blades, and this portion prevents the direct passage of air into the fan wheel. The air must make an abrupt turn around this portion of the housing to enter the fan wheel, reducing efficiency.
The size and shape of the inlet orifice 60 of the housing 34 is optimized to affect the flow of air drawn into the fan wheel 32 and improve the efficiency of the blower fan 30. By optimized, it is meant that the orifice diameter 62 of the inlet orifice 60 of the blower fan 30 is enlarged such that the orifice diameter 62 is substantially equal to the end ring inner diameter 66 of the end rings 36 and 38, partially exposing the ends 42 and 44 of the plurality of blades 40. Additionally, in one example, the inlet orifice 60 can be substantially circular to correspond to the shape of the fan wheel 32.
In one example, for a 42 size fan coil unit, enlarging the orifice diameter 62 of the inlet orifice 60 such that the orifice diameter 62 is approximately equal to the inner diameter 66 of the end rings 36 and 38 reduces the power of the blower fan 30 by approximately 6% at the same operation point (same airflow and same external static pressure) as a blower fan of the prior art, saving costs. The aerodynamic flow of the blower fan 30 reduces the watts consumption of the blower fan 30, reducing the cost of the outdoor unit 23. The size of the blower fan 30 could also be reduced.
The foregoing description is only exemplary of the principles of the invention. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, so that one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.

Claims

1. A blower fan of a fan coil unit, the blower fan comprising:

a fan wheel including a first end ring, a second end ring, and a plurality of blades that extend between the first end ring and the second end ring, wherein the plurality of blades define a wheel inner diameter and each of the first end ring and the second end ring define an end ring inner diameter; and

a housing including an inlet orifice having an orifice diameter, wherein the fan wheel is located within the housing and the orifice diameter is substantially equal to the end ring inner diameter and greater than the wheel inner diameter.

2. The blower fan as recited in claim 1 wherein each of the plurality of blades has a length, and a cross-section of each of the plurality of blades taken substantially perpendicularly to the length is substantially arc-shaped.

3. The blower fan as recited in claim 1 wherein a space is defined between each of the plurality of blades, and each of the spaces is approximately equal.

4. The blower fan as recited in claim 1 further including a wheel disc attached to each of the plurality of blades at a location that is substantially equidistant from a first end and an opposing second end of the plurality of blades.

5. The blower fan as recited in claim 4 wherein the wheel disc includes a hub that receives a shaft of a motor, and the motor rotates the shaft to rotate the fan wheel about an axis of rotation.

6. The blower fan as recited in claim 1 wherein a first end and an opposing second end of each of the plurality of blades is partially exposed by the inlet orifice and uncovered by the housing.

7. The blower fan as recited in claim 1 wherein the fan wheel draws air over a coil of a heat exchanger and into the inlet orifice of the housing and discharges the air through an outlet of the housing.

8. The blower fan as recited in claim 1 wherein the plurality of blades are substantially parallel.

9. The blower fan as recited in claim 1 wherein the fan wheel is substantially cylindrical.

10. A fan coil unit comprising:

a coil, wherein refrigerant flows through the coil; and

a blower fan that draws air over the coil to exchange heat with the refrigerant flowing through the coil, wherein the blower fan includes a fan wheel including a first end ring, a second end ring, and a plurality of blades that extend between the first end ring and the second end ring, wherein the plurality of blades define a wheel inner diameter and each of the first end ring and the second end ring define an end ring inner diameter, and the blower fan includes a housing including an inlet orifice having an orifice diameter and an outlet, wherein the fan wheel is located within the housing to draw the air over the coil and into the inlet orifice and discharge the air through the outlet, and the orifice diameter is substantially equal to the end ring inner diameter and greater than the wheel inner diameter.

11. The fan coil unit as recited in claim 10 wherein each of the plurality of blades has a length, and a cross-section of each of the plurality of blades taken substantially perpendicularly to the length is substantially arc-shaped.

12. The fan coil unit as recited in claim 10 wherein a space is defined between each of the plurality of blades, and each of the spaces is approximately equal.

13. The fan coil unit as recited in claim 10 further including a wheel disc attached to each of the plurality of blades at a location that is substantially equidistant from the first end and the opposing second end of the plurality of blades.

14. The fan coil unit as recited in claim 13 wherein the wheel disc includes a hub that receives a shaft of a motor, and the motor rotates the shaft to rotate the fan wheel about an axis of rotation.

15. The fan coil unit as recited in claim 10 wherein a first end and an opposing second end of each of the plurality of blades is partially exposed by the inlet orifice and uncovered by the housing.

16. The fan coil unit as recited in claim 10 wherein the plurality of blades are substantially parallel.

17. The fan coil unit as recited in claim 10 wherein the fan wheel is substantially cylindrical.

18. A refrigeration system comprising:

a compressor for compressing a refrigerant;

a condenser for cooling the refrigerant;

an expansion device for expanding the refrigerant; and

a fan coil unit including an evaporator coil and a blower fan, wherein the refrigerant flows through the evaporator coil and the blower fan draws air over the evaporator coil to reject heat to the refrigerant,

wherein the blower fan includes a fan wheel including a first end ring, a second end ring, and a plurality of blades that extend between the first end ring and the second end ring, the plurality of blades define a wheel inner diameter and each of the first end ring and the second end ring define an end ring inner diameter, and the blower fan includes a housing including an inlet orifice having an orifice diameter and an outlet, and

wherein the fan wheel is located within the housing to draw the air over the evaporator coil and into the inlet orifice and discharge the air through the outlet, and the orifice diameter is substantially equal to the end ring inner diameter and greater than the wheel inner diameter.