Dynamic outside air management system and method

Abstract

An outside air management system in which the air is cooled by a first refrigeration condenser to a temperature either above or somewhat below the dewpoint of the incoming air so as to remove either none of the moisture to be removed, or a significant portion of it. The air then is sent to a desiccant wheel which removes the remainder of the moisture to be extracted. The temperature of the air leaving the wheel is above the desired delivery temperature. Then a heat exchanger and a second condenser remove sensible heat from the heated air leaving the desiccant wheel to bring the air to the desired temperature. Thus, the temperature and humidity are controlled substantially independently of one another. A heat pump embodiment of the invention allows the reversal of the flow of refrigerant in the system, allowing it to be used to either heat or cool.

1 . An outside air supply management system for a building, said system comprising
 (a) first cooling apparatus for cooling incoming outside air to a variable first temperature, at which a quantity of moisture is removed from said outside air, said quantity varying from zero to a substantial quantity,   (b) a variable capacity desiccant wheel controllable for removing from said air substantially all of the remainder of the moisture designed to be removed from the air received from said first refrigeration unit and issuing dehumidified air at a desired dewpoint, and a temperature above a desired temperature to be maintained at a utilization location,   (c) a second cooling apparatus for cooling air from said desiccant wheel to a second temperature desired to be maintained at a utilization location,   (d) at least one air mover for moving said outside air through said first cooling apparatus, said desiccant wheel, and said second cooling apparatus to said utilization location, and   (e) a programmed controller for controlling the operation of said cooling apparatus and said desiccant wheel to achieve the temperatures and dewpoint specified above and thereby control the humidity and temperature of the air delivered to said utilization location substantially independently of one another.   
     
     
         2 . A system as in  claim 1  in which each of said first and second cooling apparatus comprises a refrigeration evaporator, and a single compressor supplying both of said evaporators with refrigerant, and at least one expansion valve controlled by said controller to govern the cooling provided by said evaporators, and a flow re-directing valve operable to convert said system between a cooling system and a heating system in which said evaporators are converted into condensers used for heating. 
     
     
         3 . A system as in  claim 1  including a desiccant regeneration sub-system comprising an air mover for moving return air from said utilization location to heating apparatus, said heating apparatus, including a desuperheater and then to said desiccant wheel to regenerate the desiccant therein, said programmed controller being programmed to set said first temperature at a level sufficient to assure regeneration of the desiccant in said desiccant wheel. 
     
     
         4 . A system as in  claim 1  in which said cooling apparatus includes at least two evaporators are connected together in a refrigerant flow circuit selected from the group consisting of a parallel connection with a single expansion valve, and a tandem connection with two separate expansion valves, one for each of said evaporators. 
     
     
         5 . A system as in  claim 1  including a conduit for introducing a portion of said return air into the incoming outside air. 
     
     
         6 . A system as in  claim 1  including a heat exchanger forming part of said second cooling apparatus for absorbing heat from the air leaving said desiccant wheel and delivering heat to said return air to heat it before reaching said heating apparatus and said desiccant wheel. 
     
     
         7 . A system as in  claim 1  including equipment for sensing the dewpoint of air in said utilization location, a further dew point detecting equipment for said outside air, said dew point equipment being connected to provide inputs to said controller, the performance characteristics of said desiccant wheel being stored in said controller for use in controlling the speed of said desiccant wheel, and compressor control equipment for changing the output of a compressor in said system to modulate cooling in said system. 
     
     
         8 . A system as in  claim 1  including a thermostat and a CO 2  sensor in said utilization location and delivering signals to said controller, and a desiccant wheel rotator motor connected to be controlled by said controller in accordance with the desiccant moisture reduction needed, a sensible cooling air handling unit receiving conditioned air outside from said outside air supply system, said controller being programmed to increase the internal air temperature design point in response to reductions in outside air volume requirements. 
     
     
         9 . A system as in  claim 1  in which each of said first and second cooling apparatus includes an evaporator, and including a variable compressor for compressing refrigerant gas and supplying it to both of said evaporators, a desuperheater, at least one condenser, a subcooler, and at least one controllable valve for selectively operating said cooling apparatus to produce variable amounts of cooling as needed. 
     
     
         10 . A system as in  claim 9  in which the refrigerant used in the refrigeration system in which said evaporators are used is R 22  or equivalent. 
     
     
         11 . A system as in  claim 3  in which said system includes an evaporator for each of said cooling apparatus, a condenser and a compressor, and is part of a heat-pump system with at least one valve for selectively reversing the flow of refrigerant through said evaporators and condenser and reverse the functions of said condenser and said evaporators and convert said system from a cooling mode to a heating mode. 
     
     
         12 . A system as in  claim 11  in which said desiccant wheel is operated to transfer moisture from said return air to said incoming outside air for humidification, with said evaporators converted to heaters, and said system includes a desuperheater which is connected for reverse operation as an evaporator. 
     
     
         13 . A method of conditioning outside air to cool and dehumidify said outside air and deliver the cooled and dehumidified air to an internal utilization location in a building, said method comprising the steps of:
 (a) moving outside air into contact with a first variable cooling device and controlling the temperature produced in said outside air to a first temperature to remove from zero to a substantial portion of the moisture to be removed from the air,   (b) moving air from said first cooling device to a desiccant device and controlling said desiccant device to remove from substantially all of the remaining moisture desired to be removed therefrom,   (c) removing heat from the air leaving said desiccant wheel by means of a second cooling device to a temperature desired for said utilization location, and   (d) moving the air leaving said second evaporator to said utilization location.   
     
     
         14 . A method as in  claim 13  including the steps of:
 (e) moving exhaust air from said utilization location to a heat exchanger to absorb heat removed from air leaving said desiccant device,   (f) moving exhaust air from said heat exchanger to a desuperheater and heating said air therein,   (g) using the heated exhaust air from said desuperheater to regenerate the desiccant material in said desiccant device, and   (h) controlling said first temperature so as to eliminate or minimize the need to supplementally heat said exhaust air.   
     
     
         15 . A method as in  claim 13  including using a programmed electronic controller to control the amount of cooling provided in such of said cooling steps and the amount of moisture removed from the outside air by said desiccant device to deliver outside air to a utilization location at a desired temperature and humidity with each quantity being controlled substantially independently of the other. 
     
     
         16 . A method as in  claim 13  including using a programmed electronic controller to control the amount of cooling provided in such of said cooling steps and the amount of moisture removed from the outside air by said desiccant device to deliver outside air to a utilization location at a desired temperature and humidity substantially without reheating said air, and utilizing said controller to compute the level of operation of each of said steps to produce said outside air at the desired temperature. 
     
     
         17 . A method as in  claim 13  including sensing CO 2  levels in the utilization location and delivering corresponding signals to control the steps of moving air to provide the amount of ventilation needed as indicated by said CO 2  levels and increasing the required temperature level of a conditioned space as a function of the reduction in outside air volume. 
     
     
         18 . A method as in  claim 13  including programming a programmable controller to provide set levels of parameters based on the time of year and time of day in the location of the building of said utilization location 
     
     
         19 . An air conditioning system particularly well adapted to condition extremely high-humidity air, said system comprising:
 (a) a first DX coil for cooling incoming outside air to a first temperature,   (b) a desiccant wheel for dehumidifying air received from said wheel,   (c) a heat exchanger selected from the group consisting of a heat pipe structure and a sensible heat wheel receiving air from said desiccant wheel and transferring said heat to another location spaced from the path of said air leaving said desiccant wheel,   (d) a second DX coil for cooling air received from said heat exchanger and delivering the cooled air to a utilization location.   (e) a fan for moving air from said utilization location through said other location to a desuperheater and then to the regenerative side of said desiccant wheel to regenerate the desiccant therein, and   (f) a device for controlling the amount of cooling provided by said first DX coil to reduce said first temperature to near the saturation level of said outside air.   
     
     
         20 . A system as in  claim 19  including a condenser, a single compressor supplying both of said DX coils, at least one expansion valve, and a valve for selectively reversing the flow of refrigerant through said DX coils and said condenser to provide for heating operation of said system, with said desiccant wheel selectively transferring moisture from return air to said outside air for humidification.