Community Research and Development Information Service - CORDIS

Novel adsorption heat pump based on metal supported zeolites for more efficient heating and refrigerating

Zeolite-water adsorption heat pumps have been subject to intensive research activity as they appeared to be a very attractive technology, particularly for the domestic market. Heat transfer within the machines, however, must be improved for them to reach full development. This project has led to the important realisation that zeolites are not an appropriate adsorbant in heat pumps and has thus opened avenues for further research regarding the use of metal hydrates as adsorbants.

The technical feasibility of zeolite-water adsorption machines has been demonstrated through numerous prototypes. Despite this, their development is still limited due to the poor heat transfer thus far achieved. The economic optimisation of these systems depends upon improvements in specific power output, which requires adsorbers with high thermal conductivity and heat exchangers well adapted to the adsorbant bed. It was anticipated that the use of sintered metals such as a structuring material for the deposition of zeolites would strongly enhance the thermal conductivity by which heat is supplied to and removed from the adsorbants. The aim of this project was to integrate the water adsorption capacity of zeolites with the heat conductivity of sintered metal substrates to simulate an absorption/ desorption unit of a heat pump for heating and cooling. The most important factors for success are the selection of a zeolite with a high adsorption capability and good coatability. For porous metal substrates properties such as coatability, heat conductivity, heat capacity and pressure drop, determine their applicability. The objectives of the project were to improve coefficient of performance (COP) values for heating up to 1.7 - 1.9 with a cycle time of 10 - 20 minutes, increasing the heat conductivity by up to 50 - 100 times the value of the bed of zeolite pellets. The final objective was to overcome the main problem, the poor heat transfer currently achieved which means that a short cycle time is impossible and thus the volume, weight and cost of the machine is not economically feasible.

Reported by

Gastec NV
Wilmersdorf 50
7300 Apeldoorn
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