Proportional dehumidifier control

Abstract

A water-to-air system using a modulating/proportionate control valve to regulate the amount of sensible reheat when operating in a dehumidification mode is disclosed. When in the reheat/dehumidification mode of operation, the modulating valve regulates the volume of water through a condenser coil to regulate refrigerant temperature to provide for sufficient reheating of the equipment supply air temperature within a narrow range, regardless of the inlet water temperature. The air conditioning system may be any type of water-cooled system, including a water source heat pump or water-cooled air conditioner.

1 . A method for controlling the dehumidification of a water-to-air refrigeration system having water flow provided by a water source, a refrigeration circuit through which a refrigerant gas flows, and an air circuit having an inlet and an outlet, the method comprising:
 operating the water-to-air refrigeration system in dehumidification mode;   sensing outlet air temperature via a temperature sensor and generating a temperature signal;   reducing the water flow via a modulating valve if the temperature signal is below a predetermined set point;   wherein air passes through a reheat coil to be rewarmed prior to being exhausted through the air outlet;   wherein the reduced water flow reduces the amount of heat absorbed by water passing through the reheat coil, thereby raising the temperature of the refrigerant gas in the refrigeration circuit; and   wherein the raised temperature of the refrigerant gas passing through the reheat coil increases the amount of heat rejected into air passing through the reheat coil, thereby resulting in an increased outlet air temperature.   
     
     
         2 . The method of  claim 1  further comprising a closed loop controller configured to regulate the modulating valve based on the temperature signal. 
     
     
         3 . The method of  claim 3  further comprising a logic controller configured to control the closed loop controller to control a set point of the outlet air. 
     
     
         4 . The method of  claim 1  wherein the reheat coil and condenser are in direct series. 
     
     
         5 . The method of  claim 1  wherein the predetermined set point is set by a user. 
     
     
         6 . The method of  claim 1  wherein a second temperature sensor measures the air inlet temperature, and operates the modulating valve to a differential temperature between the two temperature sensors. 
     
     
         7 . A water-to-air system comprising:
 a water source configured to provide water to the system;   a condenser connected to the water source, the condenser having a water inlet and a water outlet for receiving water from the water source;   a modulating valve connected to the condenser;   a compressor having a refrigerant inlet and a refrigerant outlet;   an evaporator being configured to convert heat from air to refrigerant;   an air circuit for circulating air in a space, the air circuit having an air inlet and an air outlet; and   a temperature sensor located at the air outlet, the temperature sensor being configured to sense the outlet air temperature and generate a temperature signal;   wherein when the temperature signal is below a predetermined set point, the modulating valve reduces the water flow to the condenser, thereby raising the refrigerant condensing temperature.   
     
     
         8 . The system of  claim 7  wherein the modulating valve is located at the water outlet. 
     
     
         9 . The system of  claim 7  wherein the modulating valve is located at the water inlet. 
     
     
         10 . The system of  claim 7  further comprising a second temperature sensor located at or near the air inlet.