Numerical Simulation and Performance Investigation of Bubble Pump Refrigerator
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Date
2023-10
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Addis Abab University
Abstract
Approximately 30% of the primary energy consumed worldwide is used for refrigeration. In light of the global search for sustainable energy sources and energy-efficient methods of operation, solar-powered bubble pump refrigeration systems have gained traction as an alternative means of satisfying cooling requirements. Diffusion absorption refrigerators, sometimes referred to as bubble pump refrigerators, are driven by low-grade energy sources such as solar, waste heat, and recovery heat and do not require any mechanical moving components. However, in comparison to other cooling options, this system's coefficient of performance (COP) has been low. To increase the system's efficiency, more research on the effects of various parameters is required. The objective of this study is to enhance understanding of the behavior of the system through an examination of the impact of several critical factors. Using the programs ASPEN PLUS and EES, a thorough numerical simulation was conducted after a thermodynamic and system model was created. Every simulation was run with a standard total pressure of 25 bars. The model was used to forecast how different factors, such as generator heat, concentration of the refrigerant in a rich solution, and refrigerant purity, would affect the system's performance. The significant impact of refrigerant purity at the rectifier's outlet on coefficient of performance (COP) was one of the key finding. It was discovered that the COP rose from 0.15 to 0.36 as the purity improved from 0.950 to 0.999. It was also noted that a generator temperature of 200oC at 240W of thermal input was optimal at 25 bars of total system pressure. Additional heat rises did not appear to have a noticeable impact on the performance of the system. The one thing that makes this research stand out is the study of the effect of hydrogen on the COP of the system. It was observed that both heat absorbed at the evaporator (Qevap) and COP increased steadily and with similar degree of increments as hydrogen mass fraction increased from 0.5 to 0.95. This is due to the higher reduction of the partial of the refrigerant at evaporator inlet causing the refrigerant to lower its temperature further. Generally speaking, with more research done, the bubble pump refrigeration holds a lot of potential to take the place of traditional cooling technologies.
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Keywords
Bubble pump, Planten-Munter principle, Solar refrigeration, Simulation