Displacement ventilation systems and methods

Abstract

A heating, ventilation, and/or air conditioning (HVAC) system includes an air handling unit configured to condition an outdoor air flow to generate a ventilation air flow. The HVAC system includes a terminal unit fluidly coupled to the air handling unit. The terminal unit includes a plenum configured to receive the ventilation air flow and a blower configured to draw a return air flow from a space serviced by the HVAC system across a heat exchanger of the terminal unit and into the plenum to condition the return air flow. The blower is configured to mix the ventilation air flow and the return air flow to generate a supply air flow. A displacement ventilation (DV) diffuser is configured to receive the supply air flow. The DV diffuser is configured to direct the supply air flow through a filter of the DV diffuser and into the space.

1 . A heating, ventilation, and/or air conditioning (HVAC) system, comprising:
 an air handling unit configured to condition an outdoor air flow to generate a ventilation air flow;   a terminal unit fluidly coupled to the air handling unit and comprising:
 a plenum configured to receive the ventilation air flow; and 
 a blower configured to draw a return air flow from a space serviced by the HVAC system across a heat exchanger of the terminal unit and into the plenum to condition the return air flow, wherein the blower is configured to mix the ventilation air flow and the return air flow to generate a supply air flow; and 
   a displacement ventilation (DV) diffuser fluidly coupled to the terminal unit and configured to receive the supply air flow, wherein the DV diffuser is configured to receive a filter configured to filter the supply air flow, and wherein the DV diffuser is configured to direct the supply air flow through the filter and into the space.   
     
     
         2 . The HVAC system of  claim 1 , comprising the filter, wherein the filter comprises a high efficiency particulate air (HEPA) filter configured to capture particles having a size between 1.0 micron and 3.0 microns in diameter. 
     
     
         3 . The HVAC system of  claim 1 , wherein the heat exchanger is configured to circulate a working fluid at a temperature above a first dew point temperature of the return air flow to cool the return air flow without dehumidifying the return air flow. 
     
     
         4 . The HVAC system of  claim 3 , wherein the air handling unit comprises an additional heat exchanger configured to operate below a second dew point temperature of the outdoor air flow to cool and dehumidify the outdoor air flow. 
     
     
         5 . The HVAC system of  claim 3 , comprising:
 one or more sensors configured to acquire feedback indicative of a temperature of the return air flow, a humidity of the return air flow, or both; and   a controller communicatively coupled to the one or more sensors and configured to receive the feedback, wherein the controller is configured to determine the first dew point temperature based on the temperature of the return air flow, the humidity of the return air flow, or both.   
     
     
         6 . The HVAC system of  claim 5 , comprising a chiller system configured to provide the working fluid to the heat exchanger, wherein the controller is configured to control the chiller system to maintain the temperature of the working fluid above the first dew point temperature. 
     
     
         7 . The HVAC system of  claim 1 , wherein the terminal unit comprises an additional filter, and wherein the blower is configured to draw the return air flow across the additional filter. 
     
     
         8 . The HVAC system of  claim 7 , wherein the additional filter comprises a HEPA filter, a MERV-6 filter, or a MERV-8 filter. 
     
     
         9 . The HVAC system of  claim 1 , wherein the terminal unit comprises a reheat coil configured to receive the supply air flow and heat the supply air flow. 
     
     
         10 . The HVAC system of  claim 1 , comprising:
 a ventilation duct fluidly coupling the air handling unit and the terminal unit;   an exhaust duct fluidly coupled to the space and to an outdoor environment; and   an exhaust blower configured to draw an exhaust air flow from the space and discharge the exhaust air flow to the outdoor environment via the exhaust duct, wherein the air handling unit, the ventilation duct, and the terminal unit do not receive a portion of the exhaust air flow from the exhaust duct.   
     
     
         11 . The HVAC system of  claim 1 , wherein the terminal unit is configured to be positioned adjacent to a ceiling of the space and the DV diffuser is configured to be positioned adjacent to a floor of the space. 
     
     
         12 . A displacement ventilation (DV) diffuser, comprising:
 an enclosure comprising an inlet configured to receive an air flow and an outlet configured to discharge the air flow, wherein the enclosure is configured to receive a high efficiency particulate air (HEPA) filter such that the HEPA filter extends across the outlet and is configured to filter the air flow; and   a grille removeably coupled to the enclosure and configured to secure the HEPA filter to the enclosure.   
     
     
         13 . The DV diffuser of  claim 12 , comprising the HEPA filter, wherein the HEPA filter is configured to capture particles in the air flow having a size between 1.0 micron and 3.0 microns in diameter. 
     
     
         14 . The DV diffuser of  claim 12 , wherein the enclosure comprises a first wall and a second wall, wherein the first wall and the second wall converge at a vertex of the enclosure, and wherein the grille is configured to extend from the first wall to the second wall. 
     
     
         15 . A heating, ventilation, and/or air conditioning (HVAC) system, comprising:
 an air handling unit comprising a first heat exchanger configured to dehumidify an outdoor air flow to generate a ventilation air flow;   a terminal unit configured to receive the ventilation air flow and comprising:
 a second heat exchanger configured to circulate a working fluid; and 
 a blower configured to draw a return air flow across the second heat exchanger to condition the return air flow and to mix the return air flow with the ventilation air flow to generate a supply air flow; and 
   a displacement ventilation (DV) diffuser configured to receive the supply air flow and comprising a filter configured to filter the supply air flow, wherein the filter comprises a high efficiency particulate air (HEPA) filter.   
     
     
         16 . The HVAC system of  claim 15 , comprising:
 a chiller system configured to supply the working fluid to the second heat exchanger; and   a controller configured to determine a dew point temperature of the return air flow based on feedback from a sensor exposed to the return air flow, wherein the controller is configured to adjust the chiller system to maintain a temperature of the working fluid above the dew point temperature of the return air flow.   
     
     
         17 . The HVAC system of  claim 15 , wherein the terminal unit is disposed within a space serviced by the HVAC system, and the DV diffuser is configured to discharge the supply air flow along a floor of the space serviced by the HVAC system. 
     
     
         18 . The HVAC system of  claim 15 , comprising:
 an exhaust duct fluidly coupled to an outdoor environment and to a space serviced by the DV diffuser; and   an exhaust blower configured to draw an exhaust air flow from the space and discharge the exhaust air flow to the outdoor environment via the exhaust duct, wherein the air handling unit and the terminal unit do not receive a portion of the exhaust air flow from the exhaust duct.   
     
     
         19 . The HVAC system of  claim 15 , wherein the terminal unit comprises an additional filter, wherein the blower is configured to draw the return air flow across the additional filter and the second heat exchanger. 
     
     
         20 . The HVAC system of  claim 19 , wherein the terminal unit is configured to provide access to the additional filter from a space serviced by the DV diffuser, such that the additional filter is replaceable by an occupant located within the space.