Measurements of adsorption kinetics at sub atmospheric pressures employing volumetric apparatus

Abstract

With increasing demand in cooling-based appliances such as air conditioners in today’s society, more non-renewable energy sources which release greenhouse gases are being used. As a result, there is an increase in demand for greener technologies that are also just as efficient. One solution is the usage of adsoption technology which uses renewable and harmless materials, and natural refrigerant such as ethanol vapour and water vapour. This leads to the technology being increasingly seen as a suitable alternative for future chillers. Therefore, thorough research on this technology is currently being conducted all over the world.

In this project, physisorption between three different pairs of adsorbent-adsorbate systems were studied: RD silica gel-water, RD silica gel-ethanol, and Maxsorb III (pitch based activated carbon) -ethanol systems. An experimental apparatus (Constant Volume Variable Pressure apparatus-CVVP) was designed, assembled and tested for this project. After the assembly and testing, volume calibration for the apparatus was carried out as it is essential to know in further experimental calculation.

All experiments were conducted at low pressures and in isothermal conditions. Adsorption experiments were conducted at 30°C, 40°C, 50°C, 55°C and 60°C. For all experiments, the adsorption uptake data was calculated and then analyzed. Subsequently, the validations of the experimental data with the standard adsorption isotherms were done. These were Langmuir, Tóth and Dubinin-Astakhov isotherms. Also, a comparison of adsorption uptakes between the three different systems was conducted as well.

The detailed explanations for the standard experimental procedure, the deduction of the uptakes, analysis and the validation of the experimentally measured data are provided in the respective chapters of this report.