US 8,496,234 B1Granted

Thermodynamic balancing of combined heat and mass exchange devices

AssigneesMassachusetts Institute of Technology, King Fahd University of Petroleum and Minerals

InventorsPrakash Narayan Govindan, Gregory P. Thiel, Ronan K. McGovern, John H. Lienhard, Sarit K. Das, Karim M. Chehayeb, Syed M. Zubair, Mohammed A. Antar

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Abstract

A carrier-gas mixture is directed through a fluid flow path in a combined heat and mass transfer device operating at a sub-atmospheric pressure. Heat and mass are transferred from or to the carrier-gas mixture via interaction with a liquid composition that includes a vaporizable component in a liquid state to substantially change the content of the vaporizable component in the carrier-gas mixture via evaporation or condensation of the vaporizable component. The mass flow rate of the carrier-gas mixture is varied by extracting or injecting the carrier-gas mixture from at least one intermediate location in the fluid flow path, and/or the mass flow rate of the liquid composition is varied by extracting or injecting the liquid composition from at least one intermediate location in the fluid flow path; and the flow of the carrier-gas mixture or the liquid composition is regulated to reduce the average local enthalpy pinch in the device.

Claims17

Dependent claims

A method for reducing thermodynamic irreversibilities in a combined heat and mass transfer device, the method comprising:

directing a flow of a carrier-gas mixture through a fluid flow path in a combined heat and mass transfer device, the device operating at a pressure below atmospheric pressure;
transferring heat and mass from or to the carrier-gas mixture by a direct or indirect interaction with a liquid composition that includes a vaporizable component in a liquid state to substantially change the content of the vaporizable component in the carrier-gas mixture via evaporation of the vaporizable component from the liquid composition or via condensation of the vaporizable component from the carrier-gas mixture, producing a flow of carrier-gas mixture having a concentration of the vaporizable component that differs from the concentration of the vaporizable component in the carrier-gas mixture before the heat and mass transfer process;
varying the mass flow rate of at least one of (a) the carrier-gas mixture by extracting or injecting the carrier-gas mixture from at least one intermediate location in the fluid flow path in the combined heat and mass transfer device and (b) the liquid composition by extracting or injecting the liquid composition from at least one intermediate location in the fluid flow path in the heat and mass transfer device;
and
regulating the flow of the carrier-gas mixture or the liquid composition in the combined heat and mass transfer device to reduce the average local enthalpy pinch in the device.

2 more elements

A method for reducing thermodynamic irreversibilities in a humidification-dehumidification system, the method comprising:

directing a flow of a carrier-gas mixture comprising a vaporizable component and a carrier gas through a fluid-flow path in a packed bed humidifier, the system operating at a pressure below the atmospheric pressure;
transferring heat and mass to the carrier-gas mixture by a direct interaction with a liquid composition comprising the vaporizable component in a liquid state as one of its components to substantially increase the content of the vaporizable component in the carrier-gas mixture via evaporation of vaporizable component from the liquid composition;
directing the carrier-gas mixture from the humidifier to a dehumidifier, wherein heat and mass are transferred from the carrier-gas mixture by an indirect interaction with the liquid composition in a fluid-flow path in the dehumidifier, reducing the content of the vaporizable component in the carrier-gas mixture and preheating the liquid composition;
varying the mass flow rate of at least one of (a) the carrier-gas mixture by extracting the carrier-gas mixture from at least one intermediate location in the fluid-flow path in the humidifier and injecting the extracted carrier-gas mixture at a corresponding location in the dehumidifier and (b) the liquid composition by extracting the liquid composition from at least one intermediate location in the fluid-flow path in the humidifier and injecting the liquid composition at a corresponding location in the dehumidifier;
and
regulating the flow of the carrier-gas mixture or of the liquid composition between the intermediate locations of the fluid flow paths in the humidifier and the dehumidifier to reduce the average local enthalpy pinch in the dehumidifier.

3 more elements

Dependencies are inferred from the claim text.