Passive intensification of the ammonia absorption process with NH3/LiNO3 using carbon nanotubes and advanced surfaces in a tubular bubble absorber

The present study aims to quantify experimentally the individual and simultaneous effects of CNTs (carbon nanotubes) and advanced surfaces on the performance of an NH3/LiNO3 tubular bubble absorber. Operating conditions are those of interest for use in air-cooled absorption chillers driven by low temperature heat sources. Firstly, experimental tests were performed with the tubular absorber fitted with an inner smooth surface to analyze the effect of adding carbon nanotubes (0.01 wt%) to the base mixture NH3/LiNO3. Then, the tubular absorber was tested using an inner advanced surface tube both with and without adding carbon nanotubes to the base mixture NH3/LiNO3. The advanced surface tube is made of aluminum and has internal helical micro-fins measuring 0.3 mm in length.