Rooftop air conditioning unit

Abstract

A rooftop air conditioning unit (RTU) is disclosed. The RTU comprises an absorber configured in a supply airstream, a desorber configured in a regeneration airstream, wherein the desorber is fluidically connected to the absorber via a liquid desiccant system and an interchange heat exchanger. The RTU further comprises a first heat exchanger configured upstream of the absorber in the supply air stream, a second heat exchanger configured upstream of the desorber in the regeneration airstream, wherein the first heat exchanger is fluidically connected to the second heat exchanger via a vapor compression system, and one or more secondary heat exchanger configured between the vapor compression system and the liquid desiccant system, wherein the one or more secondary heat exchangers are operable to control temperature of a desiccant associated with the liquid desiccant system into the absorber and/or into the desorber.

1 . A rooftop air conditioning unit (RTU) comprising:
 an absorber configured in a supply airstream;   a desorber configured in a regeneration airstream, wherein the desorber is fluidically connected to the absorber via a liquid desiccant system and an interchange heat exchanger;   a first heat exchanger configured upstream of the absorber in the supply air stream;   a second heat exchanger configured upstream of the desorber in the regeneration airstream, wherein the first heat exchanger is fluidically connected to the second heat exchanger via a vapor compression system; and   one or more secondary heat exchangers configured between the vapor compression system and the liquid desiccant system, wherein the one or more secondary heat exchangers are operable to control temperature of a desiccant associated with the liquid desiccant system into the absorber and/or into the desorber.   
     
     
         2 . The RTU of  claim 1 , wherein the one or more secondary heat exchanger comprise a third heat exchanger configured in a desiccant upstream of the absorber. 
     
     
         3 . The RTU of  claim 2 , wherein the one or more secondary heat exchanger comprise a fourth heat exchanger configured in a desiccant upstream of the desorber. 
     
     
         4 . The RTU of  claim 3 , wherein the first heat exchanger, and a refrigerant side of the third heat exchanger are fluidically coupled to the second heat exchanger, and a refrigerant side of the fourth heat exchanger via the vapor compression system. 
     
     
         5 . The RTU of  claim 4 , wherein a desiccant side of the third heat exchanger is fluidically coupled to a desiccant side of the fourth heat exchanger via the interchange heat exchanger and the liquid desiccant system. 
     
     
         6 . The RTU of  claim 1 , wherein the one or more secondary heat exchangers are operable to control the temperature of the desiccant supplied to the absorber to adjust the temperature and humidity of the supply airstream downstream of the absorber to predefined values. 
     
     
         7 . The RTU of  claim 6 , wherein the predefined value of the temperature of the airstream downstream of the absorber is in a range of 70° F. to 75° F. 
     
     
         8 . The RTU of  claim 3 , wherein the third heat exchanger is operated as an evaporator when the desiccant supplied to the absorber is to be cooled for adjusting the temperature and the humidity of the supply airstream downstream of the absorber to the predefined values. 
     
     
         9 . The RTU of  claim 3 , wherein the third heat exchanger is operated as a condenser when the desiccant supplied to the absorber is to be heated for adjusting the temperature and the humidity of the supply airstream downstream of the absorber to the predefined values. 
     
     
         10 . The RTU of  claim 1 , wherein the one or more secondary heat exchangers are operable to control the temperature of the desiccant flowing into the absorber to a first predefined desiccant temperature to control mass transfer potential from the desiccant to the regeneration airstream at the absorber. 
     
     
         11 . The RTU of  claim 1 , wherein the one or more secondary heat exchangers are operable to increase the temperature of the desiccant flowing into the desorber to a second predefined desiccant temperature to control mass transfer potential from the desiccant to the regeneration airstream at the desorber. 
     
     
         12 . The RTU of  claim 1 , wherein the one or more secondary heat exchanger is a brazed-plate heat exchanger. 
     
     
         13 . The RTU of  claim 1 , wherein the one or more secondary heat exchangers further comprise an upstream metering device or an expansion device for a refrigerant when the corresponding secondary heat exchanger is operated as an evaporator. 
     
     
         14 . The RTU of  claim 1 , wherein the RTU is adapted to be configured at an area of interest (AOI) to supply the airstream having the predefined values of the temperature and humidity at the AOI, and further receive the return airstream from the AOI. 
     
     
         15 . The RTU of  claim 1 , wherein the RTU comprises a controller that is configured to:
 receive a set of instructions pertaining to the predefined values of the airstream to be supplied at the AOI; and   control operation of one or more of the heat exchangers associated with the system to supply the airstream having the predefined values of the temperature and humidity to the AOI.   
     
     
         16 . A liquid desiccant based outdoor air system comprising:
 an absorber configured in a supply airstream;   a desorber configured in a regeneration airstream, wherein the desorber is fluidically connected to the absorber via a liquid desiccant system and an interchange heat exchanger;   a first heat exchanger configured upstream of the absorber in the supply air stream;   a second heat exchanger configured upstream of the desorber in the regeneration airstream, wherein the first heat exchanger is fluidically connected to the second heat exchanger via a vapor compression system; and   one or more secondary heat exchangers configured between the vapor compression system and the liquid desiccant system, wherein the one or more secondary heat exchangers are operable to control temperature of a desiccant associated with the liquid desiccant system into the absorber and/or into the desorber.   
     
     
         17 . The system of  claim 16 , wherein the one or more secondary heat exchanger comprise: a third heat exchanger configured in a desiccant upstream of the absorber; and a fourth heat exchanger configured in a desiccant upstream of the desorber. 
     
     
         18 . The system of  claim 17 , wherein the first heat exchanger, and a refrigerant side of the third heat exchanger are fluidically coupled to the second heat exchanger, and a refrigerant side of the fourth heat exchanger via the vapor compression system. 
     
     
         19 . The system of  claim 16 , wherein a desiccant side of the third heat exchanger is fluidically coupled to a desiccant side of the fourth heat exchanger via the interchange heat exchanger and the liquid desiccant system. 
     
     
         20 . The system of  claim 16 , wherein the one or more secondary heat exchangers are operable as a condenser and/or an evaporator to control the temperature of the desiccant supplied to the absorber to adjust the temperature and humidity of the supply airstream downstream of the absorber to predefined values.