Kamil Śmierciew

The use of nanoparticle-infused blended refrigerants is essential for achieving an effective sustainable system. This investigation analyses the efficiency of three nano-refrigerants (CuO-R152a, TiO2-R152a and TiO2-R113a) on the basis of the thermal performance and energy usage of the compressor using MATLAB-Simulink in the vapour compression refrigeration cycle with a two-phase flow domain. Also, nanoparticle volume concentrations of 0.1%–0.5% in the basic refrigerants are investigated. In the Simulink model, the outcomes are calculated mathematically. Using the NIST chemistry webbook, the thermo-physical characteristics of base refrigerants were calculated, and different numerical models were used to compute the characteristics of nano-enhanced refrigerants. MS Excel was used to perform the liquid–vapour interpolation. It was discovered that refrigerants with nanoparticles have superior heat-transfer properties and operate most excellently at an optimal volume fraction of 0.1% for TiO2-R152a and CuO-R152a with a coefficient of performance (COP) as 10.8. However, the other blended nano-refrigerant TiO2-R113a performed the best at 0.5% of nano-particle volume fraction with a COP value of 5.27.

This paper describes the procedure of design and manufacture of a micro-ejector proposed for miniature ejection refrigeration systems. It describes the procedure of design, fabrication, and experimentation on supersonic micro-ejectors and makes the case for isobutane as a working fluid for such systems. It was demonstrated that it is possible to design and fabricate a micro-ejector with a cooling capacity of approximately 3 W. The discussed micro-ejector was driven by a heat source with temperature below 60 °C. The evaporation temperature was approximately 15 °C. For these operating parameters, the reported entrainment ratio was approximately 0.20. The difficulties in fabricating the micro-ejector due to its small dimensions are discussed in the paper. Additionally, the potential difficulties and solutions related to ensuring and maintaining stable operation of the testing stand are presented. The performance of the proposed system is demonstrated and discussed, including relations between mass entrainment ratio, compression ratio, cooling capacity, and temperature.