Air conditioning system and control method

Abstract

A cooling and dehumidification system including at least one passive heat transfer device with desiccant coated on some extent of the exposed surface, another passive heat transfer device without desiccant coating, a compressor through which refrigerant flows, an expansion device, a refrigerant control valve, and valves to direct airflow in relation to the passive heat transfer devices.

What is claimed is: 
     
         1 . An air-handling system comprising:
 a heat pump configured to move heat energy between a plurality of passive heat transfer devices;   
       the plurality of passive heat transfer devices, defining a first surface of at least one of the plurality of passive heat transfer devices that is thermally in contact with the heat pump and a second surface of at least one of the plurality of passive heat transfer devices that is exposed to allow the transfer of heat to or from the heat pump;
 a desiccant in thermal contact with the exposed surface of at least one passive heat transfer device and configured to exchange moisture with air; 
 a plurality of air directing valves configured to direct process and regeneration air to and from the plurality of passive heat transfer devices with desiccant; 
 a heat pump reversing device configured to change the direction of heat flow in the heat pump between two modes of operation; 
 a control system with communication lines to control air directing valves, reversing device, and heat pump operation; and 
 a control operation process operating a control mode in which desiccant regeneration time is modulated. 
 
     
     
         2 . The system of  claim 1  wherein the passive heat transfer devices comprise tube and fin heat exchangers or microchannel heat exchangers. 
     
     
         3 . The system of  claim 2  wherein the desiccant forms a coating on the exposed surface of the heat exchanger fins. 
     
     
         4 . The system of  claim 3  wherein the desiccant forms a partial coating with an uncoated section first exposed to airflow followed by a desiccant coated second section exposed to airflow. 
     
     
         5 . The system of  claim 1 , further comprising, a passive heat transfer device without desiccant configured for exchanging sensible heat with ambient air. 
     
     
         6 . The system of  claim 1 , further comprising, a passive heat transfer device without desiccant configured for exchanging sensible heat with indoor air. 
     
     
         7 . The system of  claim 1  wherein the desiccant comprises at least one of silica gel, alumina, zeolite or a metal-organic framework (MOF) material. 
     
     
         8 . A method for handling air in a space comprising the steps of:
 moving, with a heat pump, heat energy between a plurality of passive heat transfer devices, in which a first surface of at least one of the plurality of passive heat transfer devices is thermally in contact with the heat pump and a second surface of at least one of the plurality of passive heat transfer devices is exposed to allow the transfer of heat to or from the heat pump;   providing a desiccant in thermal contact with the exposed surface of at least one passive heat transfer device and configured to exchange moisture with air;   directing, through a plurality of air directing valves, process and regeneration air to and from the plurality of passive heat transfer devices with desiccant;   changing a direction of heat flow in the heat pump between two modes of operation; and   controlling the plurality air directing valves, reversing device, and heat pump operation in a control operation mode to modulate desiccant regeneration time.   
     
     
         9 . The method of  claim 8  wherein the passive heat transfer devices comprise tube and fin heat exchangers or microchannel heat exchangers. 
     
     
         10 . The method of  claim 9  wherein the desiccant forms a coating on the exposed surface of the heat exchanger fins. 
     
     
         11 . The method of  claim 10  wherein the desiccant forms a partial coating with an uncoated section first exposed to airflow followed by a desiccant coated second section exposed to airflow. 
     
     
         12 . The method of  claim 8 , further comprising, exchanging, using a passive heat transfer device without desiccant, sensible heat with ambient air. 
     
     
         13 . The method of  claim 8 , further comprising, exchanging, using a passive heat transfer device without desiccant, sensible heat with indoor air. 
     
     
         14 . The method of  claim 8  wherein the desiccant comprises at least one of silica gel, alumina, zeolite or a metal-organic framework (MOF) material.