Air handling unit having a heat shield flow distributor

Abstract

An air handling unit is disclosed, including a motor-driven fan with an annular outlet configured to move air through a housing of the AHU, a primary heat exchanger configured to cool or heat the air passing through the AHU, one or more heat elements placed downstream of the motor-driven fan, the one or more heat elements being configured to transfer heat to the airflow, and a heat shield placed between the motor-driven fan and the one or more heat elements, and configured to reduce heat transfer from the one or more heat elements upstream of the heat shield, and redistribute the airflow upstream and downstream of the heat shield, wherein the heat shield includes a distribution of openings configured to allow air to flow through the heat shield.

1 . An air handling unit (AHU) comprising:
 a motor-driven fan with an annular outlet configured to move an airflow through a housing of the AHU;   a primary heat exchanger configured to cool or heat air moved through the AHU;   one or more heat elements placed downstream of the motor-driven fan, the one or more heat elements being configured to transfer heat to the airflow; and   a heat shield placed between the motor-driven fan and the one or more heat elements, and configured to reduce heat transfer from the one or more heat elements in an upstream direction of the heat shield and redistribute the airflow upstream and downstream of the heat shield, wherein the heat shield comprises a distribution of openings configured to allow air to flow through the heat shield.   
     
     
         2 . The AHU of  claim 1 , wherein the primary heat exchanger comprises a refrigerant-to-air type heat exchanger positioned upstream of the motor-driven fan. 
     
     
         3 . The AHU of  claim 1 , wherein the one or more heat elements comprise electrically powered resistance-type heaters implemented as at least one of: coils, strips, ribbons, and/or combined ceramic/metallic construction. 
     
     
         4 . The AHU of  claim 1 , wherein the heat shield is metallic. 
     
     
         5 . The AHU of  claim 1 , wherein the heat shield is configured to fractionally block the radiated heat from the one or more heat elements, reflect the radiated heat, absorb the radiated heat, and/or transfer the absorbed heat to the airflow moving downstream from the motor-driven fan. 
     
     
         6 . The AHU of  claim 1 , wherein the heat shield comprises at least one of: a smooth profile, a corrugated profile, a louvered profile, and a multiple-layer profile. 
     
     
         7 . The AHU of  claim 1 , wherein the heat shield extends across an internal cross-sectional profile of the housing. 
     
     
         8 . The AHU of  claim 1 , wherein the heat shield is placed at a distance that is about 5% to about 25% of a fan exit diameter away from the annular outlet of the motor-driven fan. 
     
     
         9 . The AHU of  claim 1 , wherein the distribution of openings is formed by at least one of: perforations, slots, louvers, offset-slits, and/or mesh. 
     
     
         10 . The AHU of  claim 1 , wherein each opening of the distribution of openings comprises a diameter or opening length scale of about 2 mm to about 8 mm. 
     
     
         11 . The AHU of  claim 1 , wherein a ratio of total open area to total surface area of the heat shield is between about 30% to about 65%. 
     
     
         12 . The AHU of  claim 1 , wherein the distribution of openings is defined on the heat shield to redistribute the airflow from the motor-driven fan and prevent heated air back-flow from the one or more heat elements. 
     
     
         13 . The AHU of  claim 1 , wherein openings of the distribution of openings are uniformly distributed on the heat shield. 
     
     
         14 . The AHU of  claim 1 , further comprising a fan motor power control module housed in a control box isolated from the airflow moved by the motor-driven fan. 
     
     
         15 . The AHU of  claim 14 , wherein the control box comprises one or more heat sinks protruding into the airflow, the one or more heat sinks being configured to dissipate heat from the fan motor power control module through the control box, and wherein the one or more heat sinks are placed upstream of the heat shield. 
     
     
         16 . The AHU of  claim 1 , wherein the one or more heat elements are controlled by control electronics placed in a control box, and wherein heat generated by the control electronics is at least partially dissipated by the airflow flowing over an end wall of the control box. 
     
     
         17 . The AHU of  claim 16 , wherein heat generated by the control electronics is dissipated through the airflow redirected by the distribution of openings of the heat shield or by one or more slots in the heat shield adjacent to the control box. 
     
     
         18 . The AHU of  claim 1 , wherein the motor-driven fan comprises any one of: a mixed-flow fan, an axial-flow fan, or a centrifugal fan with rotational axis parallel with a longitudinal direction of the AHU, and wherein the motor-driven fan is powered by a direct drive variable speed motor. 
     
     
         19 . The AHU of  claim 1 , wherein the motor-driven fan is a mixed-flow fan comprising:
 a diagonal flow impeller comprising a plurality of blades extending from the diagonal flow impeller, and an axis of rotation of the diagonal flow impeller being arranged in-line with a direction of the airflow through the housing, wherein an air flow path through the diagonal flow impeller has a mean angle that is oriented along a direction divergent from the axis of rotation;   a fan inlet casing disposed circumferentially around a shroud wall of the diagonal flow impeller, defining a clearance between the fan inlet casing and the shroud wall, with upstream and downstream flow control clearances;   a set of axial outlet guide vanes disposed downstream of the diagonal flow impeller, comprising a plurality of vanes extending radially from a stator hub towards a stator shroud, and configured to redirect the airflow exiting the diagonal flow impeller such that the airflow exiting the outlet guide vanes is substantially parallel to the axis of rotation of the diagonal flow impeller; and   a direct drive variable speed motor disposed in the stator hub to drive the diagonal flow impeller of the motor-driven fan.