KapSchicht: Capillary assisted vaporization of water for thermal heat pumps


Lache, Marten © Copyright: Lehrstuhl fuer Technische Thermodynamik der RWTH Aachen


Marten Lache

Sorption Systems Engineering


+49 241 80 90471


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Adsorption heat pumps often employ the natural refrigerant water since water combines a high enthalpy of vaporization with benign environmental properties. However, under typical working conditions of adsorption heat pumps, water has a very low saturation pressure, which hinders the evaporation process. Better evaporation of the refrigerant can be obtained by higher wall superheats in the evaporator but at the cost of efficiency losses in the heat transfer process. Therefore, the development of evaporators with high overall heat transfer coefficients is crucial for efficient evaporation of water at low pressures.

To enhance heat transfer, macroscopic structures such as micro-fins as well as microscopic structures such as (porous) coatings have been proposed. These structured surfaces enable capillary action to wet the heat exchanger surface with a thin liquid film, which improves the heat transfer into the refrigerant.



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Project Details

Project Duration

September 1, 2014 to December 31, 2016

Project Partner

Pallas GmbH & Co. KG