Feedback control optimization of counter-flow simultaneous heat and mass exchange

A humidification-dehumidification device, comprising:

• a humidifier including a carrier-gas inlet, a carrier-gas outlet, a feed-liquid inlet, and a brine outlet, wherein the humidifier is configured to transfer a vaporized component from feed liquid that is input through the feed-liquid inlet to carrier gas that is input through the carrier-gas inlet in counter-flow to the feed liquid;
• a condenser including a carrier-gas inlet, a carrier-gas outlet, a liquid inlet for condensing-bath liquid, and a liquid outlet for the condensing-bath liquid and condensate, wherein the condenser is configured to transfer the vaporized component from the carrier gas input through the carrier-gas inlet as a condensate to the condensing-bath liquid in counter-flow to the condensing-bath liquid;
• a carrier-gas conduit connecting the carrier-gas outlet of the humidifier with the carrier-gas inlet of the condenser;
• sensors, including (a) at least one flow-rate sensor configured to detect a flow rate of at least one of the carrier gas, the feed liquid, and the condensing-bath liquid and (b) sensors configured to detect at least one of the following state variables in the carrier-gas conduit at the carrier-gas inlet of the humidifier, at the liquid inlet and outlet of the condenser, and at the feed-liquid inlet and brine outlet of the humidifier:
• temperature, pressure and concentration;
• at least one carrier-gas flow controller configured to control the flow of carrier gas in the carrier-gas conduit;
• and
• at least one liquid-flow controller configured to control the flow of at least one of the feed liquid through the humidifier and the condensing-bath liquid through the condenser;
• an automated controller comprising computer-readable memory in communication with a processor, wherein the sensors and the flow controller are in communication with the automated controller, and wherein the computer-readable memory stores software code for:
• generating and communicating commands to the carrier-gas flow controller to flow carrier gas through the humidifier and condenser;
• generating and communicating commands to the liquid-flow controller to control flow, in cross-flow to the carrier gas flow, of at least one of (a) feed liquid through the humidifier and (b) condensing-bath liquid through the condenser;
• calculating ideal changes in total enthalpy rates of the carrier gas and at least one of the feed liquid and the condensing-bath liquid in at least one of the humidifier and the condenser based on at least one state variable communicated by the sensors to the automated controller and the difference between the ideal changes in total enthalpy rates;
• identifying a change in flow rate of at least one of the carrier gas, the feed liquid, and the condensing-bath liquid in at least one of the humidifier and the condenser that will bring the ideal change in total enthalpy rates of the carrier gas and at least one of the condensing-bath liquid and the feed liquid closer to zero;
• and
• based on at least some of the detections by the sensors and the identified change in flow rate, generating and sending commands to at least one of the carrier-gas flow controller and the liquid-flow controller to control the mass flow of at least one of the carrier gas, the feed liquid, and the condensing-bath liquid to achieve the identified change in flow rate to bring the ideal change in total enthalpy rates of the carrier gas and at least one of feed liquid and the condensing-bath liquid through at least one of the humidifier and the condenser closer to being equal.