Sub-wet bulb evaporative chiller with pre-cooling of incoming air flow

Abstract

An evaporative chiller cooling water to below ambient wet bulb temperature. Sub-wet bulb chilling is achieved by pre-cooling incoming air upstream of the saturator. The incoming air is ambient air at ambient air temperature that is cooled using the coolness of the lower temperature outgoing air exiting the saturator. The pre-cooling lowers the temperature of the incoming air and lowers its wet bulb temperature below that of ambient air. The saturator water is chilled to below the ambient wet bulb temperature. The air in the saturator flows across the water as it gravity drips or flows from the top to the bottom of the saturator. The pre-cooled air flows across the saturator with the coolest air directed across the bottom of the saturator where the coldest water is flowing and with the hottest air directed across the top where the hottest water is flowing to provide gradient chilling.

1 . An evaporative chiller using thermal storage material or media to provide enhanced cooling, comprising:
 a saturator with a liquid inlet and a liquid outlet, wherein liquid to be cooled enters the saturator through the liquid inlet and drains by gravity through the saturator and exits through the liquid outlet; and   means for delivering a volume of air to the saturator at temperatures below a temperature of ambient air entering the chiller,   wherein the delivering means comprises a first thermal storage matrix positioned along a first side of the saturator, a second thermal storage matrix positioned along a second side of the saturator, and at least one fan operable to at least periodically reverse direction of the air delivered to the saturator to alternately flow first through the first thermal storage matrix or first through the second thermal storage matrix before entering the saturator.   
   
   
       2 . The chiller of  claim 1 , wherein the air delivered to the saturator is directed to flow through the saturator transverse to a direction of flow of the liquid in the saturator. 
   
   
       3 . The chiller of  claim 1 , wherein the first and second thermal storage matrices comprise a thermal storage media permeable to air flow, the thermal storage media being cooled to a temperature in a temperature range below the temperature of ambient air entering the chiller due to flow of air exiting the saturator through the first and second thermal storage matrices. 
   
   
       4 . The chiller of  claim 3 , wherein wet bulb temperatures of the volume of air entering the saturator are lower than an ambient wet bulb temperature measured external to the evaporative chiller. 
   
   
       5 . The chiller of  claim 3 , wherein temperatures of the volume of air exiting the saturator are lower than the temperatures of the volume air entering the saturator, whereby one of the first and second thermal storage matrices receiving the volume of air exiting the saturator is cooled to temperatures below the temperature of ambient air. 
   
   
       6 . The chiller of  claim 3 , wherein the at least one fan is operated to reverse the flow of air in an opposite direction on a time period in the range of 2 minutes to at least 30 minutes. 
   
   
       7 . The chiller of  claim 6 , wherein the time period is at least about 2 minutes and wherein each of the first and second thermal storage matrices has a thickness, defining an air flow path, that is less than about 3 feet. 
   
   
       8 . The chiller of  claim 1 , wherein at least one of the first and second thermal storage matrices comprises a volume of material including at least one material selected from the group of: stone, glass, metal, plastic, wood, concrete, cement, ceramic, encapsulated phase change material, and a blend of materials including at least one of such materials. 
   
   
       9 . The chiller of  claim 8 , wherein at least a portion of the material comprises particles with a substantially spherical shape. 
   
   
       10 . The chiller of  claim 8 , wherein a temperature gradient is formed in the first and second thermal storage matrices during operation of the evaporative chiller whereby matrix media proximate to the liquid inlet of the saturator are at a higher temperature than matrix media proximate to the liquid outlet of the saturator. 
   
   
       11 . The chiller of  claim 8 , wherein at least a portion of the material is arranged as one or more larger, spaced-apart pieces. 
   
   
       12 . The chiller of  claim 8 , wherein at least a portion of the material comprises porous blocks of the material containing air paths to allow air passage through the blocks. 
   
   
       13 . The chiller of  claim 1 , wherein the air delivered to the saturator has a first temperature near the liquid inlet of the saturator and a second temperature near the liquid outlet of the saturator that is lower than the first temperature. 
   
   
       14 . An evaporative chiller for cooling water to a temperature below the ambient air wet-bulb temperature, comprising:
 a saturator in which water is able to flow from a top portion to a bottom portion, the saturator extending vertically within the chiller with a first side and a second side both permeable to air flow;   means for moving ambient air into the chiller as incoming air to flow through the first and second sides of the saturator; and   a heat exchanger at least partially positioned upstream of the first side of the saturator for first cooling the incoming air to a range of temperatures below ambient temperature and for second directing the cooled incoming air into the saturator along the first side,   wherein the air moving means operates to move the incoming air alternately through the first and second sides of the saturator and wherein the heat exchanger comprises a first matrix of thermal storage material positioned adjacent the first side of the saturator and a second matrix of thermal storage material positioned adjacent the second side of the saturator such that the incoming air alternately passes through one of the first and second matrices prior to entering the saturator.   
   
   
       15 . The chiller of  claim 14 , wherein air moving means comprises at least one fan that is reversible to move the incoming air alternately through the first and second sides of the saturator for periods of time of at least about 2 minutes in duration. 
   
   
       16 . The chiller of  claim 14 , wherein the thermal storage material comprises particles or air permeable configurations of media selected from the group of media consisting of stone, glass, metal, ceramic, plastic, wood, concrete, cement, encapsulated phase change material, or a mixture including at least one of such materials. 
   
   
       17 . The chiller of  claim 16 , wherein the portions of the heat exchanger at the higher end of the range of temperatures include a volume of the particles or air permeable configurations of media in the first and second matrices positioned proximate to the top portion of the saturator and wherein the portions of the heat exchange at the lower end of the range of temperatures include a volume of the particles or air permeable configurations of media in the first and second matrices positioned proximate to the bottom portion of the saturator, whereby a temperature gradient is provided in each of the first and second matrices of the thermal storage material. 
   
   
       18 . The chiller of  claim 14 , wherein the water flowing near the bottom portion is at a temperature below the wet-bulb temperature of the ambient air. 
   
   
       19 . An evaporative cooling system, comprising
 a chiller comprising a saturator and a heat exchanger generating a stream of pre-cooled air at an air inlet to the saturator by cooling ambient air to temperatures below ambient air temperature by transferring heat from the ambient air to air exiting the saturator through an air outlet;   a space cooling system including a heat exchanger with a liquid side; and   a water circulation system pumping water exiting a bottom of the saturator through the liquid side of the space cooling system heat exchanger,   wherein the chiller heat exchanger comprises a first bank of air-permeable media positioned upstream of the air inlet of the saturator and a second bank of air-permeable media positioned downstream of the air outlet of the saturator and further comprises one or more fans periodically reversing direction of flow of the ambient air, the stream of pre-cooled air, and the air exiting the saturator in the chiller.   
   
   
       20 . The system of  claim 19 , wherein the pre-cooled air temperatures range from a higher temperature proximate to a top of the saturator and a lower temperature proximate to the bottom of the saturator. 
   
   
       21 . The system of  claim 19 , wherein the water exiting the bottom of the saturator is at a temperature at least about 5° F. lower than a wet-bulb temperature of the ambient air. 
   
   
       22 . The system of  claim 19 , wherein the thermal storage material comprises particles or air permeable configurations of media selected from the group of media consisting of stone, glass, metal, ceramic, plastic, wood, concrete, cement, encapsulated phase change material, and a mixture containing at least one of such materials. 
   
   
       23 . The system of  claim 19 , wherein the pressure drop during operation of the chiller is less than about 0.4 inches WC for each of the first and second banks.