SubSie-NoFrost: Sorption Steamers for Evaporation Temperatures Below 0 °C – Antifreeze by Additives

 

Background

Thermally driven sorption chillers and heat pumps provide electricity-saving cooling and heating by utilizing waste heat. Moreover, these machines offer the opportunity to use water as an environmentally friendly refrigerant. However, as a major downside of water, the evaporation temperature is limited to temperatures above 0 °C due to the freezing point of water.

 

Objective

The project SubSie-NoFrost aims to tackle this challenge: The project is part of the thematic research group SubSie, which aims to extend the application range of sorption chillers and heat pumps using water as a refrigerant to temperatures below 0 °C. The technical approach of the subproject SubSie-NoFrost involves the use of additives, which prevent freezing of a water-based adsorption chiller at temperatures below 0 °C. However, preliminary investigations show that the use of additives leads to a significant reduction in heat transfer of the evaporation process. This reduction in heat transfer shall be compensated by selecting additives that are more suitable and by the development of improved evaporator structures. Furthermore, the influence of additives on the performance of water-based adsorption chiller shall be analyzed experimentally and theoretically.

With the extension of the application range of sorption chillers and heat pumps using water as a refrigerant to temperatures below 0 °C, new applications such as food cooling, storage cool, and heat pump applications can be realized, with ambient air as the primary source for driving energy.

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