Performance assessment of a sample nanorefrigerant cooling process as a function of flow Reynolds number, evaporator and ambient temperatures

Abstract

In this paper available experimental data of nanorefrigerant, NRF cooling process are processed using MATLAB to determine the coefficient of performance COP as a function of Reynolds number, Re of NRF, evaporator and ambient temperatures, Te and Ta as a novelty. The cooling process performance assessment of NRF is provided in comparison with a pure refrigerant, R through relative COP term, COPr. The used data ranges with 20–70 nm of Al2O3 in R134a are at varying volume fraction, φ of 0.075–0.303% and volumetric flow rate, Q of 6.5–11 L/h for Ta in 294–306 K and Te in 288–309 K. Re calculations are based on the thermophysical parameters evaluated at Te not only in the cited experimental ranges of Q, φ but also extrapolated for the extended range of Q of 15–25 L/h for a generalization purpose. Since data processing is under the interactive influence of the parameters the functional relationships of COP, Re, φ, Te are expressed as 3D graphical plots which are the start of a trial-error procedure. The experimental data are expressed in terms of fitted equations for functional relationships between various non-dimensional parameters as Re, COP, (COP*φ), (COP*Te/Ta*φ), (Re*Te/Ta*φ), (Re*Te/Ta), and COPr to provide a practical assistance for whom designing and using NRF cooling. A functional relationship of Re*(Te/Ta) with COPr at varying φ is found as the most critical output of the study due to the practice of the appeared parameters in cooling performance assessment. COPr>1 corresponds to φ>0.151% for the processed data ranges.