Heat dissipation system with hygroscopic working fluid

Abstract

A system and method for transferring heat from a process source and dissipating it to the ambient atmosphere. The system uses a low-volatility, hygroscopic working fluid to reject thermal energy directly to ambient air. Direct-contact heat exchange allows for the creation of large interfacial surface areas for effective heat transfer. Heat transfer is further enhanced by water vapor pressure gradients present between the equilibrium moisture content of the working fluid and the ambient air. Cyclic absorption and evaporation of atmospheric moisture dampens variations in cooling capacity because of ambient temperature changes. The low-volatility and hygroscopic nature of the working fluid prevents complete evaporation of the fluid and a net consumption of water.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority of U.S. Provisional Patent Application Ser. No. 61 / 345,864 filed May 18, 2010, which is incorporated herein in its entirety by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]This invention was made with government support under Cooperative Agreement No. DE-FC26-08NT43291 entitled “EERC-DOE Joint Program on Research and Development for Fossil Energy-Related Resources,” awarded by the U.S. Department of Energy (DOE). The government has certain rights in the invention.FIELD OF THE INVENTION[0003]This invention relates to the dissipation of degraded thermal energy to ambient air.BACKGROUND OF THE INVENTION[0004]Cooling and thermal energy dissipation are universal tasks in industry. Common heat rejection processes include steam condensation in thermoelectric power plants, refrigerant condensation in air-conditioning and refrigeration equipment, and process cooling during chemical...

AI Technical Summary

Problems solved by technology

However, few of these opportunities for once-through cooling are expected to be available in the future because of competition for water sources and recognition of their impact on the environment.

These technologies are used routinely in industry, but each one has distinct drawbacks.

In the sensible cooling case, air is an inferior coolant compared to liquids, and the resulting efficiency of air-cooled processes can be poor.

In addition to larger surface area requirements, air-cooled heat exchangers approach the ambient dry-bulb temperature, which can vary 30° to 40° F. over the course of a day and can hinder cooling capacity during the hottest hours of the day.

Choosing the lowest initial cost option can have negative energy consumption implications for the life of the system.

The key drawback of this approach is the associated water consumption, which in many areas is becoming a limiting resource.

Obtaining sufficient water rights for wet cooling system operation delays plant permitting, limits site selection, and creates a highly visible vulnerability for opponents of new development.

These systems can use less water compared to complete latent cooling, but the performance benefit is directly related to the amount of water-based augmentation, so these systems do not solve the underlying issue of water consumption.

Sensible cooling with air is costly because of the vast heat exchange surface area required and because its heat-transfer performance is handicapped during the hottest ambient temperatures.

Latent or evaporative cooling has preferred cooling performance, but it consumes large quantities of water which is a limited resource in some locations.

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