Apparatus and method for passively cooling an interior

Abstract

A system passively cools an interior area within a structure. The system includes a membrane assembly covering a portion of the structure, wherein the membrane has an interior side facing the interior area and an exterior side. The membrane assembly defines a plurality of pores. When a supply of fluid is provided to the membrane assembly, capillary action of the pores redistributes the fluid to create evaporation and, in turn, the desired heat flow. The membrane assembly can include an architectural membrane coated with a porous matrix coating to form the pores. A pump can provide the fluid to the interior side of the membrane assembly. Preferably, the architectural membrane is woven PTFE-coated fiberglass and the porous matrix coating is titanium dioxide and zeolites. The plurality of pores may have radii ranging from about 10 nanometers to 100 microns and a length of about 80 microns.

What is claimed is: 
     
         1 . A system for passively cooling an interior area within a structure comprising:
 a membrane assembly covering a portion of the structure, wherein the membrane assembly has an interior side facing the interior area and an exterior side, the membrane assembly defines a plurality of pores; and   a supply of fluid provided to the membrane assembly such that capillary action of the pores redistributes the fluid to create evaporation and, in turn, heat flow.   
     
     
         2 . A system as recited in  claim 1 , wherein: the membrane assembly includes an architectural membrane coated with a porous matrix coating to form the pores, and
 further comprising a pump for providing the fluid to the interior side of the membrane assembly.   
     
     
         3 . A system as recited in  claim 2 , wherein the architectural membrane is woven PTFE-coated fiberglass and the porous matrix coating is titanium dioxide and zeolites. 
     
     
         4 . A system as recited in  claim 2 , wherein the porous matrix coating is comprised of several layers, said layers having pores with decreasing radii as they approach the exterior side of the membrane assembly. 
     
     
         5 . A system as recited in  claim 1 , wherein the plurality of pores have radii ranging from about 10 nanometers to 100 microns and a length of about 80 microns. 
     
     
         6 . A system as recited in  claim 2 , wherein when saturated with liquid, a liquid content by mass of the porous matrix coating is in a range of approximately 10-50%. 
     
     
         7 . A system as recited in  claim 1 , further comprising a tension system for supporting the membrane assembly. 
     
     
         8 . A system as recited in  claim 1 , further comprising a frame system for supporting the membrane assembly. 
     
     
         9 . A method for passively cooling an interior area within a structure, the method comprising the steps of:
 coating an architectural membrane with a porous matrix coating to form pores;   covering a portion of the structure with the architectural membrane; and   providing a fluid onto the architectural membrane such that capillary action of the pores redistributes the fluid to create evaporation and, in turn, heat flow out of the interior area.   
     
     
         10 . A method as recited in  claim 9 , further comprising the step of calculating a setpoint for the interior area based upon empirical data related to a cooling profile of the interior area, wherein the empirical data includes square footage of the membrane, temperature, humidity, wind and cloudiness. 
     
     
         11 . A method as recited in  claim 10 , further comprising the steps of pumping the fluid onto the membrane assembly at a variable rate based upon the setpoint. 
     
     
         12 . A method as recited in  claim 9 , wherein when saturated with liquid, a liquid content by mass of the porous matrix coating is approximately 10 to 50% and further comprising the step of varying the liquid content based upon a setpoint. 
     
     
         13 . A method as recited in  claim 9 , wherein the pores redistribute the fluid from an interior side of the architectural membrane to an exterior side of the architectural membrane. 
     
     
         14 . A method as recited in  claim 9 , wherein the coating step includes depositing a concentrated slurry including a binding agent and zeolites on the architectural membrane, then heating the concentrated slurry to set the binding agent and form the porous matrix. 
     
     
         15 . A method as recited in  claim 14 , wherein the concentrated slurry includes titanium dioxide as a self cleaning agent. 
     
     
         16 . A method as recited in  claim 9 , further comprising the step of calculating an overall heat transfer coefficient (U-value) for the structure; and calculating a setpoint based upon the U-value. 
     
     
         17 . A structure for passively cooling an interior area comprising:
 a wall structure having a frame;   a membrane assembly covering a portion of the frame, wherein the membrane assembly defines a plurality of pores; and   a liquid on the membrane assembly such that capillary action of the membrane assembly pores spreads the liquid to create evaporation and, in turn, cooling.   
     
     
         18 . A system as recited in  claim 17 , further comprising a fan system for increasing air flow across the membrane assembly. 
     
     
         19 . A system as recited in  claim 17 , further comprising a fan system for providing airflow across the membrane assembly for delivery to a heating and ventilation system.  20 .
 a sustem as recited in  claim 17 , wherein the pores extend from an interior side to an exterior side of the membrane assembly and the membrane assembly includes an architectural membrane coated with a porous matrix coating to form the pores, and   further comprising: a pump for providing the liquid; a fan system for providing airflow across the membrane assembly and into a heating and ventilation system; and a microcontroller for calculating a setpoint for the interior area based upon empirical data related to a cooling profile of the interior area.