Experimental Setup for Determining Ammonia-Salt Adsorption and Desorption Behavior Under Typical Heat Pump Conditions: Experimental Results
de Boer, R.
van der Pal, M.
Energieonderzoek Centrum Nederland
For the aim of obtaining a better understanding of the performance of a salt-ammonia sorption reactor/heat exchanger a new test-rig was developed. This test-rig enables the measurement of the performance in adsorption and desorption mode of different sorption reactor designs. It measures the speed of uptake and release of ammonia gas of various salt-ammonia reactions under well-controlled and well-monitored process conditions, similar to the heat pump conditions. The test-rig measures the ammonia uptake and release under controlled pressure and temperature conditions. Temperatures of the salt reactor can be varied from ambient temperature up to 200°C and the ammonia pressure can be varied between 0.02 to 2 MPa. These conditions can be set independently and repeated at regular time-intervals. Besides NH3-mass-flow meters, pressure and temperature sensors, the setup also contains an endoscope to observe any macroscopic structural changes in the material during uptake and release of ammonia. Measurements so far have shown a liquid phase of LiCl.3NH3 at pressures of 0.5 MPa and temperatures exceeding 90oC. Voilent foaming is observed at 120oC resulting in salt losses. A correlation was determined between the reaction rate of MgCl2(2-6)NH3 and the relative pressure gradient yielding a reaction time of about 1500 seconds for a relative pressure difference of 1. Multiple sorption cycles of the CaCl2(2-4)NH3 reaction, showed a reduced activity from 85% of the theoretical maximum sorbed mass at the first sorption cycle, to 15% after 300+ cycles.
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