Humidification-dehumidification systems and methods at low top brine temperatures

A method of operating a humidifier, comprising:

• flowing a first liquid stream comprising a condensable fluid in liquid phase and a dissolved salt through a first fluidic pathway of a first heating device, wherein the first liquid stream is heated within the first heating device to form a heated first liquid stream;
• injecting the heated first liquid stream into a main liquid inlet of a humidifier comprising a plurality of stages, wherein the plurality of stages comprises a first stage, a last stage, and one or more intermediate stages positioned between the first stage and the last stage;
• injecting a gas stream comprising a non-condensable gas into a main gas inlet of the humidifier;
• flowing the heated first liquid stream through the humidifier in a first direction from the first stage to the last stage and simultaneously flowing the gas stream through the humidifier in a second direction from the last stage to the first stage, wherein heat and mass are transferred from the heated first liquid stream to the gas stream to produce a vapor-containing humidifier gas outlet stream and a concentrated liquid stream;
• flowing an extracted liquid stream comprising at least a portion of the concentrated liquid stream from an intermediate liquid outlet of the humidifier to a first tank;
• and
• after flowing the extracted liquid stream to the first tank, flowing the extracted liquid stream to the first heating device,
• wherein the intermediate liquid outlet of the humidifier is a liquid outlet of the first stage or one of the one or more intermediate stages of the humidifier.