Modified homogeneous relaxation model for the R744 trans-critical flow in a two-phase ejector

Abstract

Highlights The modified homogeneous relaxation model of the R744 two-phase ejector was proposed. The application range of the proposed model is for a motive nozzle pressure above 59 bar. The proposed model improved the motive nozzle mass flow rate accuracy when compared to the homogeneous equilibrium model.

Numerical investigation of the effect of the shape of the nozzle on the flash boiling phenomenon

“…where: a0 = -1.021449◊10 7 Pa, a1 = 191947.9 Pa/K, a2 = -1484.872 Pa/K 2 , a3 = 6.011561 Pa/K 3 , a4 = -0.01327243 Pa/K 4 , a5 = 1.479618◊10 5 Pa/K 5 and a6 = -6.156445◊10 -9 Pa/K 6 .…”

“…5% lower than those of the HEM. Subsequently, the HRM from [6] was modified by applying the genetic algorithm optimization of the relaxation time correlation by Haida et al [7]. Then the studies on the impact of the relaxation time definition on the CO2 two-phase flow behaviour as well as on the model accuracy were carried out.…”

Simulation of heat pumps for simultaneous heating and cooling using CO2

“…Gustav Lorentzen (1994) argued that carbon dioxide is the best fluid to replace CFCs and HCFCs. Carbon dioxide is a natural refrigerant with significant advantages such as non-toxicity, nonflammability, zero ozone depletion potential, interesting heat transfer properties, compatibility with usual lubricants, easy accessibility, low cost and high heating capacity (Haida et al, 2018). In the view of increasingly stringent regulations on greenhouse gases, carbon dioxide appeared again as an interesting fluid.…”

Experimental and computational analysis of a R744 flashing ejector

“…However, the authors reported that information on temperature, quality and critical flow rate would be required to define a suitable correlation for the relaxation time. More recently, Haida et al [18] have implemented a Homogeneous Relaxation Model (HRM) in ANSYS Fluent. Three different formulation of the HRM relaxation times were confronted with an HEM scheme, including a modified HRM formulation calibrated by means of genetic algorithms.…”