Humidity control and air conditioning

Abstract

Air conditioning systems that cool and dehumidify spaces within enclosures, buildings having such systems, and methods of controlling humidity within a space. Embodiments adjust speed of a blower or fan motor based on inputs from sensors within the system, using automated processes, to reduce airflow rates to provide for lower temperatures of the cooling coil and to increase the ratio of latent to sensible heat transfer. Fan speeds may be increased as appropriate to avoid frost formation on the cooling coil, to give priority to cooling when temperatures within the space are high, or periodically to provide for mixing within the space.

1 . An air conditioning system for cooling and dehumidifying a space within an enclosure, the air conditioning system comprising:
 a cooling coil positioned within the system and configured to cool air to be delivered from the air conditioning system to the space;   a first fan positioned and configured to move the air through the cooling coil and to the space;   a first electrical motor connected to and configured to turn the first fan;   a first variable-speed drive system configured and at least electrically connected to drive the first electrical motor;   a first sensor positioned and configured to sense a first condition within at least one of the space and the air, wherein the first condition comprises a humidity;   a second sensor positioned and configured to sense a second condition at the cooling coil; and   a controller that is in communication with the first variable-speed drive system and in communication with the first sensor and the second sensor, wherein the controller is configured to cause the first variable-speed drive system to change the speed of the first electrical motor in response to the first condition sensed by the first sensor and in response to the second condition sensed by the second sensor.   
     
     
         2 . The air conditioning system of  claim 1  wherein the controller is configured to cause the first variable-speed drive system to reduce the speed of the first electrical motor in response to an excessive humidity condition sensed by the first sensor. 
     
     
         3 . The air conditioning system of  claim 1  wherein the second condition is a temperature at the cooling coil. 
     
     
         4 . The air conditioning system of  claim 1  wherein the controller is configured to cause the first variable-speed drive system to stop reducing the speed of the first electrical motor to avoid frost formation on the cooling coil. 
     
     
         5 . The air conditioning system of  claim 1  wherein the controller is configured to cause the first variable-speed drive system to increase the speed of the first electrical motor to avoid frost formation on the cooling coil. 
     
     
         6 . The air conditioning system of  claim 1  wherein the cooling coil is an evaporator coil, and wherein the air conditioning system further comprises, within a single enclosure for the air conditioning system, an expansion valve, a compressor, an electric second motor connected to and configured to turn the compressor, a condenser coil, a second fan configured to blow air through the condenser coil, and an electric third motor connected to and configured to turn the second fan. 
     
     
         7 . The air conditioning system of  claim 1  further comprising a third sensor positioned and configured to sense a third condition within at least one of the space and the air, wherein the third condition comprises a temperature within at least one of the space and the air, and wherein the controller is in communication with the third sensor and the controller is further configured to forgo causing the first variable-speed drive system to reduce the speed of the first electrical motor in response to the first condition sensed by the first sensor, if the third condition exceeds a threshold. 
     
     
         8 . The air conditioning system of  claim 7  wherein the third sensor comprises a system controller located within the space, and the threshold is relative to a temperature set point of the system controller. 
     
     
         9 . A building comprising the air conditioning system of  claim 1 , wherein the building forms the enclosure. 
     
     
         10 . A method of controlling humidity within a space, the method comprising at least:
 providing or obtaining an air-conditioning unit, the air conditioning unit comprising a cooling coil and a variable-speed fan, wherein the fan is positioned and configured to move air through the cooling coil to the space;   measuring humidity using an automated process to obtain a humidity measurement;   using an automated process, using the humidity measurement to determine whether to reduce the humidity;   using an automated process, and dependent upon the humidity measurement, lowering the speed of the fan to decrease the cooling coil temperature, thus increasing the latent component of energy absorption at the cooling coil, resulting in a reduction of the humidity relative to a humidity level that would have resulted from not lowering the speed of the fan;   using an automated process, measuring a second condition at the cooling coil; and   using an automated process, controlling the speed of the fan using the second condition to avoid frost formation on the cooling coil.   
     
     
         11 . The method of  claim 10  further comprising, using an automated process, measuring a first temperature within the space, and wherein the reducing of the speed of the fan is performed only if the first temperature is below a first threshold temperature. 
     
     
         12 . The method of  claim 10  wherein the second condition is a temperature of the cooling coil and the speed of the fan is controlled using the second temperature to avoid having the second temperature drop below freezing. 
     
     
         13 . The method of  claim 12  further comprising, repeating at least a plurality of times the lowering of the speed of the fan, wherein the lowering of the speed of the fan is performed in discrete increments, the speed of the fan is held substantially constant for a period of time for each of the distinct increments, the temperature of the cooling coil is measured during each period of time, and the lowering of the speed of the fan is performed in a subsequent discrete increment only if the temperature of the cooling coil is above a first temperature threshold. 
     
     
         14 . The method of  claim 12  further comprising, raising of the speed of the fan, wherein the raising of the speed of the fan is performed in discrete increments, the speed of the fan is held substantially constant for a period of time for each of the distinct increments, the temperature of the cooling coil is measured during each period of time, and the raising of the speed of the fan is performed in a subsequent discrete increment only if the temperature of the cooling coil is below a second temperature threshold. 
     
     
         15 . A method of controlling humidity within a space using an air-conditioning unit, the air conditioning unit comprising a cooling coil and a variable-speed fan, wherein the fan blows air through the cooling coil, the method comprising in any order:
 receiving a temperature set point for the space;   measuring an actual temperature within the space;   evaluating whether the actual temperature within the space is within a predetermined offset of the temperature set point;   measuring an actual humidity in at least one of the space and air drawn from the space; and   evaluating whether the actual humidity exceeds a predetermined humidity threshold;   if, and only if, the actual temperature within the space is within the predetermined offset of the temperature set point, and the actual humidity exceeds the predetermined humidity threshold, lowering the speed of the fan to reduce the humidity.   
     
     
         16 . The method of  claim 15  further comprising monitoring at least a first condition of the cooling coil and increasing the speed of the fan to avoid freezing of the cooling coil. 
     
     
         17 . The method of  claim 16  wherein the monitoring of the first condition of the cooling coil comprises monitoring of a temperature at the cooling coil. 
     
     
         18 . The method of  claim 16  wherein the lowering of the speed of the fan comprises in the following order, lowering the speed by a discrete speed increment, operating the fan at a substantially constant speed for a discrete increment of time, measuring the first condition, and repeating the lowering of the speed by a discrete speed increment, operating of the fan at a substantially constant speed for a discrete increment of time, and measuring of the first condition, until the first condition reaches a first threshold value. 
     
     
         19 . The method of  claim 18  wherein the increasing of the speed of the fan comprises increasing the speed by a discrete speed increment, operating the fan at a substantially constant speed for a discrete increment of time, measuring the first condition, and repeating the increasing of the speed by a discrete speed increment, operating the fan at a substantially constant speed for a discrete increment of time, and measuring the first condition, until the first condition reaches a second threshold value. 
     
     
         20 . The method of  claim 19  wherein the first condition comprises a temperature at the first coil, the first threshold value is a first temperature above freezing and the second threshold value is a second temperature above the first temperature. 
     
     
         21 . The method of  claim 15  further comprising increasing the speed of the fan after a first time period to insure proper air distribution within the space, and then returning after a second time period to the lowering of the speed of the fan to reduce the humidity.