Heat dissipation systems with hygroscopic working fluid

A method for heat dissipation of a process fluid using a first hygroscopic working fluid and a second hygroscopic working fluid comprising:

• removing heat from the process fluid through a first process heat exchanger to absorb thermal energy for dissipation using the first hygroscopic working fluid and from a second process heat exchanger to absorb thermal energy using the second hygroscopic working fluid;
• flowing an air stream through a first fluid-air contactor;
• flowing the first hygroscopic working fluid through the first fluid-air contactor to transfer thermal energy and moisture between the first hygroscopic working fluid and the air stream;
• and
• flowing the air stream passing through the first fluid-air contactor subsequently through a second fluid-air contactor;
• flowing the second hygroscopic working fluid through the second fluid-air contactor to transfer thermal energy and moisture between the second hygroscopic working fluid and the air stream;
• adjusting heat load across the first process heat exchanger and the second process heat exchanger to counterbalance net moisture transferred from the air stream to the first hygroscopic working fluid in the first fluid-air contactor with an equivalent amount of moisture transferred from the first hygroscopic working fluid in the first fluid-air contactor to the air stream over a daily ambient temperature cycle;
• wherein the first hygroscopic working fluid and second hygroscopic working fluid are substantially separate and provide a desiccant concentration gradient so as to regulate the amount of sensible heat transfer versus latent heat transfer during the daily ambient temperature cycle, and
• each of the first and second process heat exchanger transfer heat from the process fluid to each of the first and second hygroscopic working fluid, respectively, via sensible heat transfer.