Multiple fan HVAC system with optimized fan location
A heating, ventilation, and air-conditioning (HVAC) system that includes an outdoor heat exchanger (HX) and outdoor fans. The outdoor fans are arranged in either an in-line configuration or a staggered configuration to satisfy one or more requirements to optimize the airflow across the outdoor HXs.
1 . A heating, ventilation, and air-conditioning (HVAC) system that circulates a refrigerant, comprising:
an outdoor heat exchanger (HX) comprising a length and a projection, wherein the length is a straight line across the outdoor HX from one end to another end of the outdoor HX, the projection is of a distance between top and bottom ends of the outdoor HX in a horizontal plane, and the length and the projection are perpendicular to each other;
outdoor fans, each outdoor fan comprising a center, a diameter, and a perimeter; and
a compressor operable to circulate the refrigerant through a refrigerant circuit including the outdoor HX;
wherein the outdoor fans are arranged in a staggered configuration relative to two planes parallel with the length of the outdoor HX with a different number of outdoor fans in one plane than the other and spaced by a separation distance to satisfy at least one of the following conditions: a ratio of a distance between the centers of the outdoor fans on one of the planes to a largest diameter of the outdoor fans is from 1.3 to 2.1, the ratio of the distance between the centers of the outdoor fans on one of the planes to the length of the outdoor HX is from 1.5 to 2.1, a ratio of the separation distance to the projection is between zero and 0.45, or a ratio of a distance between the center of any outdoor fan on one plane and the center of any outdoor fan on the other plane to the distance between the centers of the outdoor fans on the same plane is from 0.5 to 1 such that an airflow across, and thus the thermal energy exchange with, the outdoor heat exchanger is maximized for the satisfied conditions.
2 . The system of claim 1 , wherein the outdoor HX is formed in an arc and the outdoor fans are arranged in the staggered configuration to also satisfy the condition that a ratio of a shortest distance and the longest distance between the centers of the outdoor fans and the arc of the outdoor HX is from 0.75 to 1.
3 . The system of claim 1 , wherein the HVAC system is a package rooftop HVAC unit.
4 . The system of claim 1 , further comprising a pair of outdoor HXs arranged in a V-shape.
5 . The system of claim 1 , wherein the outdoor HX is planar.
6 . The system of claim 1 , wherein the outdoor HX is formed in a non-planar configuration.
7 . The system of claim 1 , further comprising an indoor HX and an expansion device operable to control flow of the refrigerant through the refrigerant circuit.
8 . The system of claim 1 , wherein the outdoor fans are identical to each other.
9 . The system of claim 1 , wherein at least one of the outdoor fans has at least one parameter different from at least one other of the outdoor fans, including at least one of diameter, number of blades, blade design, fan motor size, or fan type.
10 . The system of claim 1 , further comprising a controller operable to control the operation of the compressor and the outdoor fans.
11 . The system of claim 10 , wherein the HVAC system comprises a variable refrigerant flow system and the outdoor fans comprise variable speed fans.
12 . The system of claim 1 , further comprising three or five outdoor fans arranged in a staggered configuration.
13 . A method of operating a heating, ventilation, and air conditioning (HVAC) system, comprising:
operating a compressor to circulate a refrigerant through refrigerant circuit including an outdoor heat exchanger (HX) comprising a length, a projection, and ends, wherein the length is a straight line across the outdoor HX between the ends, the projection is of a distance between top and bottom ends of the outdoor HX in a horizontal plane, and the length and the projection are perpendicular to each other; and
moving air across the outdoor HX by operating outdoor fans, each outdoor fan comprising a center, a diameter, a radius, and a perimeter;
wherein the outdoor fans are arranged in a staggered configuration relative to two planes parallel with the length of the outdoor HX with a different number of outdoor fans in one plane than the other and spaced by a separation distance to satisfy at least one of the following conditions: a ratio of a distance between the centers of the outdoor fans on one of the planes to a largest diameter of the outdoor fans is from 1.3 to 2.1, the ratio of the distance between the centers of the outdoor fans on one of the planes to the length of the outdoor HX is from 1.5 to 2.1, a ratio of the separation distance to the projection is between zero and 0.45, or a ratio of a distance between the center of any outdoor fan on one plane and the center of any outdoor fan on the other plane to the distance between the centers of the outdoor fans on the same plane is from 0.5 to 1 such that an airflow across, and thus the thermal energy exchange with, the outdoor heat exchanger is maximized for the satisfied conditions.
14 . The method of claim 13 , wherein the outdoor HX is formed in an arc and the outdoor fans are arranged in the staggered configuration to also satisfy the condition that a ratio of a shortest distance and the longest distance between the centers of the outdoor fans and the arc of the outdoor HX is from 0.75 to 1.
15 . The method of claim 13 , further comprising a pair of planar outdoor HXs arranged in a V-shape.
16 . The method of claim 13 , wherein the outdoor HX is planar.
17 . The method of claim 14 , wherein the outdoor HX is formed in a non-planar configuration.
18 . The method of claim 13 , further comprising operating an indoor HX and an expansion device to control flow of the refrigerant through the refrigerant circuit.
19 . The method of claim 13 , wherein the outdoor fans are identical to each other.
20 . The method of claim 13 , wherein at least one of the outdoor fans has at least one parameter different from at least one other of the outdoor fans, including at least one of diameter, number of blades, blade design, fan motor size, or fan type.
21 . The method of claim 13 , further comprising controlling the operation of the compressor and the outdoor fans using a controller.
22 . The method of claim 21 , wherein the HVAC system comprises a variable refrigerant flow system and the outdoor fans comprise variable speed fans.
23 . The method of claim 13 , further comprising three or five outdoor fans arranged in a staggered configuration.
24 . An outdoor unit for a heating, ventilation, and air-conditioning (HVAC) system that circulates a refrigerant, comprising:
an outdoor heat exchanger (HX) comprising a length, a projection, and ends, wherein the length is a straight line across the outdoor HX between the ends, the projection is of a distance between top and bottom ends of the outdoor HX in a horizontal plane, and the length and the projection are perpendicular to each other;
outdoor fans, each outdoor fan comprising a center, a diameter, a radius, and a perimeter; and
a compressor operable to circulate the refrigerant through a refrigerant circuit including the outdoor HX;
wherein the outdoor fans are arranged in a staggered configuration relative to two planes parallel with the length of the outdoor HX with a different number of outdoor fans in one plane than the other and spaced by a separation distance to satisfy at least one of the following conditions: a ratio of a distance between the centers of the outdoor fans on one of the planes to a largest diameter of the projection fans is from 1.3 to 2.1, the ratio of the distance between the centers of the outdoor fans on one of the planes to the length of the outdoor HX is from 1.5 to 2.1, a ratio of the separation distance to the projection is between zero and 0.45, or a ratio of a distance between the center of any outdoor fan on one plane and the center of any outdoor fan on the other plane to the distance between the centers of the outdoor fans on the same plane is from 0.5 to 1 such that an airflow across, and thus the thermal energy exchange with, the outdoor heat exchanger is maximized for the satisfied conditions.
25 . The outdoor unit of claim 24 , wherein the outdoor HX is formed in an arc and the outdoor fans are arranged in the staggered configuration to also satisfy the condition that a ratio of a shortest distance and the longest distance between the centers of the outdoor fans and the arc of the outdoor HX is from 0.75 to 1.
26 . The outdoor unit of claim 24 , further comprising a pair of planar outdoor HXs arranged in a V-shape.
27 . The outdoor unit of claim 24 , further comprising three or five outdoor fans arranged in a staggered configuration.