Method and apparatus for re-heat dehumidification utilizing a variable speed compressor system
A heating, ventilation, and air conditioning (HVAC) system for regulating humidity of an enclosed space. The HVAC system includes an evaporator coil. A metering device is fluidly coupled to the evaporator coil. A variable-speed compressor is fluidly coupled to the condenser coil and the evaporator coil and a controller is operatively coupled to the variable-speed compressor. A humidity sensor is operatively coupled to the controller and exposed to the enclosed space. Responsive to a determination that the relative humidity of the enclosed space exceeds the maximum humidity threshold, the controller adjusts a speed of the variable-speed compressor to increase latent capacity of the HVAC system. Responsive to a determination that the relative humidity of the enclosed space falls below the minimum humidity threshold, the controller adjusts a speed of the variable-speed compressor to decrease latent capacity of the HVAC system.
1. A heating, ventilation, and air conditioning (HVAC) system for regulating humidity of an enclosed space, the HVAC system comprising:
an evaporator coil;
a thermostatic expansion valve fluidly coupled to the evaporator coil via a distributor line;
a variable-speed circulation fan for circulating air around the evaporator coil;
a condenser coil fluidly coupled to the thermostatic expansion valve;
a variable-speed compressor fluidly coupled to the condenser coil and the evaporator coil;
a controller operatively coupled to the variable-speed compressor;
a three-way valve fluidly coupled to the condenser coil;
a re-heat coil fluidly coupled to the three-way valve, the re-heat coil being positioned downwind of the evaporator coil;
a humidity sensor operatively coupled to the controller and exposed to the enclosed space, wherein the humidity sensor is configured to measure a relative humidity of the enclosed space and detect if the relative humidity of the enclosed space exceeds a maximum humidity threshold or falls below a minimum humidity threshold;
a variable-speed condenser fan operatively coupled to the controller for circulating air around the condenser coil;
a first temperature sensor disposed in a return air duct, the first temperature sensor being operatively coupled to the controller;
a second temperature sensor disposed in a supply air duct, the second temperature sensor being operatively coupled to the controller, the first temperature sensor and the second temperature sensor measuring a temperature difference between the return air duct and the supply air duct;
wherein the controller is configured to:
responsive to a determination that the relative humidity of the enclosed space exceeds the maximum humidity threshold, adjust a speed of the variable-speed compressor to increase latent capacity of the HVAC system;
responsive to a determination that the relative humidity of the enclosed space falls below the minimum humidity threshold, adjust a speed of the variable-speed compressor to decrease latent capacity of the HVAC system;
determine if at least one of over-cooling and over-heating of air in the enclosed space occurs based on a change in the temperature difference;
responsive to a positive determination of over-cooling of air in the enclosed space, reduce a speed of the variable-speed condenser fan; and
responsive to a positive determination of over-heating of air in the enclosed space, increase the speed of the variable-speed condenser fan.
2. The HVAC system of claim 1 , wherein the HVAC system is a package HVAC system.
3. The HVAC system of claim 1 , wherein the HVAC system is a split HVAC system.
4. The HVAC system of claim 1 , wherein the humidity sensor measures the relative humidity of the enclosed space at periodic time intervals.
5. The HVAC system of claim 4 , wherein the periodic time intervals comprise five seconds.
6. The HVAC system of claim 1 , comprising:
the variable-speed circulation fan for circulating air around the evaporator coil and operatively coupled to the controller;
a distributor line temperature sensor thermally exposed to the distributor line and operatively coupled to the controller; and
wherein the controller adjusts a speed of the variable-speed circulation fan to increase latent capacity of the HVAC system responsive to a determination that a temperature of fluid in the distributor line exceeds an optimal distributor line temperature.
7. The HVAC system of claim 6 , wherein the speed of the variable-speed compressor is adjusted prior to adjusting the speed of the variable-speed circulation fan.
8. The HVAC system of claim 1 , wherein the speed of the variable-speed compressor is adjusted prior to adjusting the speed of the variable-speed condenser fan.
9. The HVAC system of claim 1 , wherein the controller is configured to increase a speed of the variable-speed compressor responsive to a determination that the relative humidity of the enclosed space exceeds the maximum humidity threshold.
10. A heating, ventilation, and air conditioning (HVAC) system for regulating humidity of an enclosed space, the HVAC system comprising:
an evaporator coil;
a thermostatic expansion valve fluidly coupled to the evaporator coil via a distributor line;
a variable-speed circulation fan for circulating air around the evaporator coil;
a condenser coil fluidly coupled to the thermostatic expansion valve;
a variable-speed compressor fluidly coupled to the condenser coil and the evaporator coil;
a controller operatively coupled to the variable-speed compressor;
a three-way valve fluidly coupled to the condenser coil;
a re-heat coil fluidly coupled to the three-way valve, the re-heat coil being positioned downwind of the evaporator coil;
a first temperature sensor thermally exposed to the distributor line and operatively coupled to the controller;
a humidity sensor operatively coupled to the controller and exposed to the enclosed space wherein the humidity sensor is configured to measure a relative humidity of the enclosed space and detect if the relative humidity of the enclosed space exceeds a maximum humidity threshold or falls below a minimum humidity threshold;
wherein the controller is configured to:
responsive to a determination that the relative humidity of the enclosed space exceeds the maximum humidity threshold, adjust a speed of the variable-speed compressor to increase latent capacity of the HVAC system;
responsive to a determination that the relative humidity of the enclosed space falls below the minimum humidity threshold, adjust a speed of the variable-speed compressor to decrease latent capacity of the HVAC system;
responsive to a determination that a temperature of fluid in the distributor line exceeds an optimal distributor line temperature, reduce a speed of the variable-speed circulation fan to increase latent capacity of the HVAC system and lower a temperature of the evaporator coil;
determine if at least one of over-cooling and over-heating of air in the enclosed space occurs based on a change in an air temperature difference between a return air duct and a supply air duct over time;
responsive to a positive determination of over-cooling of air in the enclosed space, reduce a speed of a variable-speed condenser fan; and
responsive to a positive determination of over-heating of air in the enclosed space, increase the speed of the variable-speed condenser fan.