Liquid desiccant regeneration system, systems including the same, and methods of operating the same

Abstract

A liquid desiccant regeneration system and method of liquid desiccant regeneration are described. The liquid desiccant regeneration system includes a liquid desiccant regenerator having an engine producing a heated exit stream, and at least one dehydrating tube comprising a first water vapor permeable wall. A low concentration liquid desiccant stream feeds into the liquid desiccant regenerator, while a high concentration liquid desiccant stream exiting the liquid desiccant regenerator. A carrier stream and the low concentration liquid desiccant are in contact with opposite sides of the first water vapor permeable wall, and the low concentration liquid desiccant stream is heated by heat from the heated exit stream to drive water from the low concentration liquid desiccant stream through the first water vapor permeable wall to the carrier stream to form a humidified carrier stream. As a result, the desiccant concentration in the high concentration liquid desiccant stream is higher than a desiccant concentration in the low concentration liquid desiccant stream.

1 . A liquid desiccant regeneration system, comprising:
 a liquid desiccant regenerator comprising
 an engine producing a heated exit stream, and 
 at least one dehydrating tube comprising a first water vapor permeable wall; 
   a low concentration liquid desiccant stream feeding into said liquid desiccant regenerator; and   a high concentration liquid desiccant stream exiting said liquid desiccant regenerator,   wherein a carrier stream and the low concentration liquid desiccant are in contact with opposite sides of said first water vapor permeable wall, wherein the low concentration liquid desiccant stream is heated by heat from the heated exit stream to drive water from the low concentration liquid desiccant stream through the first water vapor permeable wall to the carrier stream to form a humidified carrier stream, wherein a desiccant concentration in said high concentration liquid desiccant stream is higher than a desiccant concentration in said low concentration liquid desiccant stream.   
     
     
         2 . The liquid desiccant regeneration system according to  claim 1 , wherein said heated exit stream is selected from the group consisting of heated heat exchange fluid, an exhaust stream, or both. 
     
     
         3 . The liquid desiccant regeneration system according to  claim 1 , wherein the heated exit stream is an exhaust stream and the carrier stream comprises the exhaust stream. 
     
     
         4 . The liquid desiccant regeneration system according to  claim 1 , further comprising a heat exchanger, wherein the heated exit stream contacts and heats the carrier stream in the heat exchanger. 
     
     
         5 . The liquid desiccant regeneration system according to  claim 4 , wherein the carrier stream comprises ambient air, recirculated air from a space being air conditioned, or a combination of both. 
     
     
         6 . The liquid desiccant regeneration system according to  claim 1 , wherein the heated exit stream is heated heat exchange liquid exiting the engine, and wherein the heated heat exchange liquid contacts and heats the low concentration liquid desiccant stream, the carrier stream, or both. 
     
     
         7 . The liquid desiccant regeneration system according to  claim 1 , wherein the heated exit stream is heated heat exchange liquid exiting the engine and a heated exhaust stream;
 wherein the heated heat exchange liquid contacts and heats the low concentration liquid desiccant; and   wherein (a) the heated exhaust stream contacts and heats the carrier stream, or (b) the carrier stream comprises the heated exhaust stream.   
     
     
         8 . The liquid desiccant regeneration system according to  claim 1 , wherein high concentration liquid desiccant stream is directed through an air conditioning system, wherein said air conditioning system comprises:
 at least one dehumidification tube comprising a second water vapor permeable wall, wherein process air stream and the high concentration liquid desiccant stream are in contact with opposite sides of the second water vapor permeable wall, wherein moisture from said process air stream passes through the second water vapor permeable wall to the high concentration liquid desiccant stream.   
     
     
         9 . The liquid desiccant regeneration system according to  claim 8 , wherein said air conditioning system further comprises at least one air conditioning heat exchange tube, wherein:
 (a) said high concentration liquid desiccant stream and a heat exchange fluid are in contact with opposite sides of the air conditioning heat exchange conduits, for cooling said high concentration liquid desiccant stream,   (b) said process air and the heat exchange fluid are in contact with opposite sides of the air conditioning heat exchange conduits, for cooling said process air, or   (c) said high concentration liquid desiccant stream and a first heat exchange fluid are in contact with opposite sides of a first group of said air conditioning heat exchange conduits, for cooling said high concentration liquid desiccant stream, and said process air and a second heat exchange fluid are in contact with opposite sides of a second group of said air conditioning heat exchange conduits, for cooling said process air.   
     
     
         10 . The liquid desiccant regeneration system according to  claim 9 , further comprising:
 a water recovery system, comprising:
 a water recovery heat exchange tube, wherein said humidified carrier air and a water recovery heat transfer fluid are in contact with opposite sides of the water recovery heat exchange conduits, 
 a water reservoir for receiving water precipitating from said humidified carrier air, and 
 a flow control system for controlling transport of a water stream from said water reservoir to one side of said air conditioning heat exchange conduits. 
   
     
     
         11 . The liquid desiccant regeneration system according to  claim 8 , further comprising:
 a high concentration liquid desiccant reservoir, having an inlet in fluid communication with an outlet of said liquid desiccant regenerator and an outlet in fluid communication with an inlet of said air conditioning system;   a low concentration liquid desiccant reservoir, having an inlet in fluid communication with an outlet of said air conditioning system and an outlet in fluid communication with an inlet of said liquid desiccant regenerator; or   both high and low concentration liquid desiccant reservoirs.   
     
     
         12 . The liquid desiccant regeneration system according to  claim 11 , wherein
 (i) a capacity of said high concentration liquid desiccant reservoir is sufficient to operate said air conditioning system continuously for at least one hour,   (ii) a capacity of said low concentration liquid desiccant reservoir is sufficient to operate the liquid desiccant regenerator continuously for at least one hour, or   (iii) both (i) and (ii).   
     
     
         13 . The liquid desiccant regeneration system according to  claim 12 , wherein the air conditioning system consumes high concentration liquid desiccant at the same rate that the liquid desiccant regenerator regenerates the high concentration liquid desiccant from the from the low concentration liquid desiccant. 
     
     
         14 . The liquid desiccant regeneration system according to  claim 1 , wherein the engine generates energy through electrochemical oxidation of a fuel. 
     
     
         15 . A method of operating a liquid desiccant regenerating system, comprising:
 providing a low concentration liquid desiccant stream;   providing a liquid desiccant regenerating system comprising:
 a liquid desiccant regenerator comprising an engine, wherein heat from said engine is used to convert said low concentration liquid desiccant stream to a high concentration liquid desiccant stream, and 
   operating said liquid desiccant regenerating system to produce the high concentration liquid desiccant stream, which has a higher desiccant concentration than the low concentration liquid desiccant stream.   
     
     
         16 . The method according to  claim 15 , wherein said liquid desiccant regeneration system further comprises:
 an air conditioning system that converts the high concentration liquid desiccant stream to a low concentration liquid desiccant stream while dehumidifying process air supplied to an air conditioned space, and   wherein said operating comprises transporting the high concentration liquid desiccant stream to said air conditioning system, then transports the low concentration liquid desiccant stream from the air conditioning system to said liquid desiccant regenerating system.   
     
     
         17 . The method according to  claim 16 , wherein said operating comprises:
 operating said liquid desiccant regenerator continuously, and   operating said air conditioning system intermittently.   
     
     
         18 . The method according to  claim 16 , wherein said operating comprises:
 operating said liquid desiccant regenerator when said air conditioning system is not operating   
     
     
         19 . The method according to  claim 16 , wherein said operating comprises:
 operating said air conditioning system when said liquid desiccant regenerator is not operating.   
     
     
         20 . The method according to  claim 15 , wherein excess electricity produced when said engine is operated is supplied to an external power grid.