Dynamic cycle air conditioner with incremental dehumidification in an indirect evaporative cooler

Abstract

Dynamically cycling of air in an indirect evaporative cooler. A heat exchanger includes a dry passage separated from a wet passage by a membrane, the dry passage including an intake portion, an outlet portion, and a loop portion. By selectively passing intake air from the intake portion and/or recirculation air from the loop portion using a mixing valve, air is moved into and through the loop portion. The air within the heat exchanger can be selectively passed outside through the outlet portion and/or recirculated by the mixing valve. In this manner air is able to be circulated a number of loop circuits through the loop portion, enabling cooling and/or dehumidifying of air.

What is claimed is: 
     
         1 . An indirect evaporative cooler apparatus comprising:
 a heat exchanger comprising a dry passage and a wet passage, the dry passage in thermodynamic communication with the wet passage and separated from the wet passage by a substantially liquid-impermeable membrane having a hydrophobic surface facing the dry passage and a hydrophilic surface facing the wet passage, the dry passage comprising an intake portion, an outlet portion, and a loop portion;   a mixing valve disposed in the dry passage and configured to selectively pass intake air from the intake portion, recirculation air from the loop portion, or a combination thereof;   a first fan disposed downstream of the mixing valve and adapted to move a first volume of air into and through the loop portion;   a diverting valve disposed in the dry passage and configured to selectively pass outlet air to the outlet portion, recirculation air to the mixing valve, or a combination thereof; and   a controller adapted to operate the mixing valve, the first fan, the diverting valve, and a combination thereof, to circulate air a number of loop circuits through the loop portion for cooling and dehumidifying the first volume of air.   
     
     
         2 . The apparatus of  claim 1 , wherein the number of loop circuits is based on one of dry passage air temperature, dry passage air relative humidity, or a combination thereof. 
     
     
         3 . The apparatus of  claim 2 , wherein the controller is adapted to open the mixing valve and to close the diverting valve in order to pass intake air and to increase pressure in the loop portion upon detection of dry passage air relative humidity being at or above a threshold value. 
     
     
         4 . The apparatus of  claim 2 , wherein the controller is adapted to close the mixing valve from passing intake air and the diverting valve from passing outlet air upon detection of dry passage air temperature being at or above a threshold value. 
     
     
         5 . The apparatus of  claim 2 , wherein the controller is adapted to open the mixing valve for passing intake air and the diverting valve for passing outlet air upon detection of dry passage air temperature being below a threshold value. 
     
     
         6 . The apparatus of  claim 1  further comprising a water source having an associated pressure valve, and a nozzle configured to wet the wet passage for evaporative cooling of the substantially liquid-impermeable membrane. 
     
     
         7 . The apparatus of  claim 6 , wherein the controller is adapted to set a water pressure of the water source. 
     
     
         8 . The apparatus of  claim 1  further comprising a water nozzle disposed within the dry passage and adapted to dispense condensed water from the first volume of air. 
     
     
         9 . The apparatus of  claim 8 , wherein the controller is adapted to open the mixing valve and to close the diverting valve in order to pass intake air and to increase pressure in the loop portion for dispensing condensed water. 
     
     
         10 . A method of dynamically cycling air in an indirect evaporative cooler, the method comprising:
 having a heat exchanger comprising a dry passage and a wet passage, the dry passage in thermodynamic communication with the wet passage and separated from the wet passage by a substantially liquid-impermeable membrane having a hydrophobic surface facing the dry passage and a hydrophilic surface facing the wet passage, the dry passage comprising an intake portion, an outlet portion, and a loop portion;   selectively passing intake air from the intake portion, recirculation air from the loop portion, or a combination thereof by a mixing valve disposed in the dry passage;   moving air into and through the loop portion by a first fan disposed downstream of the mixing valve;   selectively passing outlet air to the outlet portion, recirculation air to the mixing valve, or a combination thereof by a diverting valve disposed in the dry passage; and   circulating air a number of loop circuits through the loop portion for cooling and dehumidifying the first volume of air by a controller adapted to operate the mixing valve, the first fan, the diverting valve, and a combination thereof.   
     
     
         11 . The method of  claim 10 , wherein the number of loop circuits is based on one of dry passage air temperature, dry passage air relative humidity, or a combination thereof. 
     
     
         12 . The method of  claim 11 , wherein the controller is adapted to open the mixing valve and to close the diverting valve in order to pass intake air and to increase pressure in the loop portion upon detection of dry passage air relative humidity being at or above a threshold value. 
     
     
         13 . The method of  claim 11 , wherein the controller is adapted to close the mixing valve from passing intake air and the diverting valve from passing outlet air upon detection of dry passage air temperature being at or above a threshold value. 
     
     
         14 . The method of  claim 11 , wherein the controller is adapted to open the mixing valve for passing intake air and the diverting valve for passing outlet air upon detection of dry passage air temperature being below a threshold value. 
     
     
         15 . The method of  claim 10  further comprising wetting the wet passage by a water source having an associated pressure valve and a nozzle, for evaporative cooling of the substantially liquid-impermeable membrane. 
     
     
         16 . The method of  claim 15 , wherein the controller is adapted to set a water pressure of the water source. 
     
     
         17 . The method of  claim 10  further comprising dispensing condensed water from the first volume of air by a water nozzle disposed within the dry passage. 
     
     
         18 . The method of  claim 17 , wherein the controller is adapted to open the mixing valve and to close the diverting valve in order to pass intake air and to increase pressure in the loop portion for dispensing condensed water. 
     
     
         19 . A system for dynamically cycling air, the system comprising:
 an evaporative liquid reservoir comprising a pressure valve and a channel adapted to transport evaporative liquid;   a heat exchanger comprising:
 a dry passage and a wet passage, the dry passage in thermodynamic communication with the wet passage and separated from the wet passage by a substantially liquid-impermeable membrane having a hydrophobic surface facing the dry passage and a hydrophilic surface facing the wet passage, the dry passage comprising an intake portion, an outlet portion, and a loop portion; 
 a nozzle coupled with the channel and configured to wet the wet passage for evaporative cooling of the substantially liquid-impermeable membrane; 
 a mixing valve disposed in the dry passage and configured to selectively pass intake air from the intake portion, recirculation air from the loop portion, or a combination thereof; and 
 a diverting valve disposed in the dry passage and configured to selectively pass outlet air to the outlet portion, recirculation air to the mixing valve, or a combination thereof; and 
   a controller adapted to operate the pressure valve, the mixing valve, the diverting valve, and a combination thereof, to circulate air a number of loop circuits through the loop portion for cooling and dehumidifying a first volume of air.   
     
     
         20 . The system of  claim 19  further comprising a first fan disposed downstream of the mixing valve and adapted to move the first volume of air into and through the loop portion. 
     
     
         21 . The system of  claim 19  wherein the number of loop circuits is based on one of dry passage air temperature, dry passage air relative humidity, or a combination thereof. 
     
     
         22 . The system of  claim 21 , wherein the controller is adapted to open the mixing valve and to close the diverting valve in order to pass intake air and to increase pressure in the loop portion upon detection of dry passage air relative humidity being at or above a threshold value. 
     
     
         23 . The system of  claim 21 , wherein the controller is adapted to close the mixing valve from passing intake air and the diverting valve from passing outlet air upon detection of dry passage air temperature being at or above a threshold value. 
     
     
         24 . The system of  claim 21 , wherein the controller is adapted to open the mixing valve for passing intake air and the diverting valve for passing outlet air upon detection of dry passage air temperature being below a threshold value. 
     
     
         25 . The system of  claim 19 , wherein the controller is adapted to set a water pressure of the evaporative liquid reservoir. 
     
     
         26 . The system of  claim 19  further comprising a water nozzle disposed within the dry passage and adapted to dispense condensed water from the first volume of air. 
     
     
         27 . The system of  claim 26 , wherein the controller is adapted to open the mixing valve and to close the diverting valve in order to pass intake air and to increase pressure in the loop portion for dispensing condensed water.