M.Sc Thesis


M.Sc StudentVardi Ariel
SubjectAdsorption-Based Thermoacoustic Refrigeration
DepartmentDepartment of Energy
Supervisor ASSOCIATE PROF. Guy Ramon


Abstract

The rise in energy demand for space cooling applications, especially air-conditioning (AC), has been on the rise in recent decades. Its use of energy worldwide has tripled between 1960 and 2016, currently taking a 16% share of electricity usage from the peak worldwide demand and will triple once more by 2050. This rise puts a huge strain on current electricity grids, as well as driving up global emissions of greenhouse gasses worldwide. To accommodate that change, major improvements in efficiency, productions costs and energy consumption of refrigeration devices are needed, especially devices used for space cooling such as ACs. The most prevalent technology used today for cooling applications is the vapor compression

refrigeration cycle. It uses toxic refrigerants to achieve high efficiencies. These gases are harmful to our planet’s atmosphere which created worldwide governmental incentives to phase out their use completely in the coming decades. In this thesis we propose an alternative cooling technology that uses non-toxic gases to produce cooling at high efficiencies using very simple components that require no maintenance and have great scalability. This proposed device uses an acoustic-driven mechanism with a sorption process to drive a heat-pump. A theoretical model has been derived and an experimental setup was built to prove the hypothesis. Both theoretical and experimental methods have shown the existence of the sorption-based mechanism and its ability to compete with already existing technologies, such as the vapor-compression cycle. The experimental system was able to achieve Coefficient of Performance (COP), the ratio of heat power pumped in the system and the mechanical power invested, ranging between 1.5-3.5 using an un-optimized system, improving on the classical acoustic-driven mechanism by 2-3 times its efficiency. Theoretical results have shown good agreement with experimental results and predicted even better improvements, with COPs of 70%-90% from the maximal COP achievable, when choosing to work with different gas mixtures and allowing favorable working conditions of the refrigerator. This development puts thermoacoustic refrigeration on the map to be a potential alternative technology to vapor-compression refrigeration and can compete with other upcoming alternative technologies.