Contained growing space and environmental control system

Abstract

A controlled and closed agricultural system includes a growing space and an air handling system having a heat exchanger and cooling coil. The heat exchanger is capable of transferring sensible and latent heat and is in fluid connection with a recirculating air duct and an outside air duct. The recirculating air duct is in fluid connection with the growing space and one or more recirculation fans, while the outside air duct is in fluid connection with one or more outside air fans positioned to cause outside air to flow countercurrent to recirculating air through the heat exchanger. A cooling coil is positioned within the recirculating air duct, downstream of and in series with the heat exchanger. The cooling coil circulates a heat transfer fluid to remove additional heat from the recirculating air.

What is claimed is: 
     
         1 . A controlled agricultural system, comprising:
 a growing space; and   a heat exchanger capable of transferring sensible and latent heat, the heat exchanger in fluid connection with both a recirculating air duct and an outside air duct, the recirculating air duct in fluid connection with the growing space and one or more recirculation fans, the outside air duct in fluid connection with one or more outside air fans positioned to cause outside air to flow countercurrent to recirculating air through the heat exchanger; and   a cooling coil within the recirculating air duct, downstream of and in series with the heat exchanger, the cooling coil circulating a heat transfer fluid to remove heat from the recirculating air.   
     
     
         2 . The controlled agricultural system of  claim 1 , wherein the growing space comprises a closed green house. 
     
     
         3 . The controlled agricultural system of  claim 1 , wherein the growing space is closed and comprises light impermeable outer walls and grow lights positioned inside the closed growing space. 
     
     
         4 . The controlled agricultural system of  claim 1 , wherein the cooling coil comprises a direct expansion evaporation cooling coil. 
     
     
         5 . The controlled agricultural system of  claim 4 , further comprising a compressor and a condensing coil external to the recirculating air duct for removing heat from the heat transfer fluid. 
     
     
         6 . The controlled agricultural system of  claim 1 , further comprising a recirculation damper within the outside air duct and positioned to recirculate a portion of the outside air from downstream of the heat exchanger to upstream of the heat exchanger. 
     
     
         7 . The controlled agricultural system of  claim 1 , further comprising a heat source positioned to provide heat to the recirculating air downstream of the heat exchanger. 
     
     
         8 . The controlled agricultural system of  claim 1 , further comprising a CO 2  monitor positioned to monitor a CO 2  content in the recirculating air duct. 
     
     
         9 . The controlled agricultural system of  claim 8 , further comprising a CO 2  generator and CO 2  controller in communication with the CO 2  monitor, the CO 2  generator having an outlet positioned to add CO 2  to the recirculating air duct. 
     
     
         10 . A controlled agricultural system, comprising:
 a growing space; and   a first heat exchanger capable of transferring sensible heat, the first heat exchanger in fluid connection with both a recirculating air duct and an outside air duct, the recirculating air duct in fluid connection with the growing space and one or more recirculation fans, the outside air duct in fluid connection with one or more outside air fans positioned to cause outside air to flow countercurrent to recirculating air; and;   a second heat exchanger capable of transferring latent heat, the second heat exchanger in fluid connection with the recirculating air duct in series with the heat wheel such that recirculating air passes through the second heat exchanger prior to passing through the first heat exchanger; and   a cooling coil within the recirculating air duct, downstream of and in series with the first heat exchanger, the cooling coil circulating a heat transfer fluid to remove heat from the recirculating air.   
     
     
         11 . The controlled agricultural system of  claim 10 , wherein the growing space comprises a closed green house. 
     
     
         12 . The controlled agricultural system of  claim 10 , wherein the growing space is closed and comprises light impermeable outer walls and grow lights positioned inside the closed growing space. 
     
     
         13 . The controlled and closed agricultural system of  claim 10 , further comprising a compressor and a condensing coil external to the recirculating air duct for removing heat from the heat transfer fluid, and wherein the cooling coil comprises a direct expansion evaporation cooling coil. 
     
     
         14 . A method for treating air within a growing space of a closed agricultural system, the method comprising:
 recirculating air from a contained growing space through an air handling system, the air handling system comprising at least one heat exchanger to reduce the energy content of the recirculating air;   passing the recirculating air exiting the at least one heat exchanger across a cooling coil circulating a heat transfer fluid to further reduce the heat content of the recirculating air;   returning the recirculating air passing the cooling coil to the contained growing space; and   passing outside air through the at least one additional heat exchanger, the outside air passing counter-current to and separated from the recirculating air.   
     
     
         15 . The method of  claim 14 , further comprising circulating the heat transfer fluid through a compressor and a condensing coil while passing outside air across the condensing coil to cool and condense the heat transfer fluid, and wherein the cooling coil comprises a direct expansion evaporator cooling coil. 
     
     
         16 . The method of  claim 14 , wherein the at least one heat exchanger comprises an enthalpy wheel. 
     
     
         17 . The method of  claim 14 , wherein the at least one heat exchanger comprises a desiccant wheel and a heat wheel. 
     
     
         18 . The method of  claim 14 , further comprising monitoring a temperature and humidity of the recirculating air. 
     
     
         19 . The method of  claim 14 , further comprising controlling the temperature and humidity of the growing space by monitoring the temperature and humidity of the recirculating air in the recirculating air duct downstream of the cooling coil and controlling operation of the at least one heat exchanger and the cooling coil. 
     
     
         20 . A controlled air system, comprising:
 a contained space;   a heat exchanger capable of transferring sensible and latent heat, the heat exchanger in fluid connection with a bifurcated duct, the duct having a recirculating air portion and an outside air portion, the recirculating air portion in fluid connection with the contained space and one or more recirculation fans, the outside air portion in fluid connection with one or more outside air fans positioned to cause outside air to flow countercurrent to recirculating air; and   a cooling coil within the recirculating air portion of the bifurcated duct, downstream of and in series with the heat exchanger, the cooling coil circulating a heat transfer fluid to remove heat from the recirculating air.