V. W. Bhatkar^a,*, Anirban Sur^b,*

Frontiers in Heat and Mass Transfer, Vol.17, pp. 1-5, 2021, DOI:10.5098/hmt.17.12

Abstract A jet pump or an ejector uses primary fluid flow as motive fluid to entrained secondary fluid. In this paper, the main intention is to find suction flow rate, primary flow rate, secondary flow rate, loss factors and ejector efficiency for an applied pressure. The values of the different loss factors estimated are primary nozzle loss factor (Kp)=0.06, suction loss factor (Ks)=0.04-0.1, mixing loss factor (Km)=0.07-0.1 and diffuser loss factor (Kd)=0.0289. It is found that with the increase in pressure across the ejector, efficiency increases with increase in flow ratio and decrease in pressure ratio. More >

Rachedi Khadraoui¹, Latra Boumaraf^1,*, Philippe Haberschill²

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.5, pp. 1115-1128, 2023, DOI:10.32604/fdmp.2022.022674

Abstract A theoretical investigation is presented about a double evaporator ejector refrigeration cycle (DEERC). Special attention is paid to take into account the influence of the sub-cooling and superheating effects induced by an internal heat exchanger (IHX). The ejector is introduced into the baseline cycle in order to mitigate the throttling process losses and increase the compressor suction pressure. Moreover, the IHX has the structure of a concentric counter-flow type heat exchanger and is intentionally used to ensure that the fluid at the compressor inlet is vapor. To assess accurately the influence of the IHX on the DEERC performance, a mathematical… More > Graphic Abstract

Lixing Zheng^1,*, Weibo Wang², Yiyan Zhang¹, Lingmei Wang³, Wei Lu²

CMES-Computer Modeling in Engineering & Sciences, Vol.133, No.1, pp. 153-170, 2022, DOI:10.32604/cmes.2022.021235

Abstract An improved model to calculate the length of the mixing chamber of the ejector was proposed on the basis of the Fano flow model, and a method to optimize the structures of the mixing chamber and diffuser of the ejector was put forward. The accuracy of the model was verified by comparing the theoretical results calculated using the model to experimental data reported in literature. Variations in the length of the mixing chamber L_m and length of the diffuser L_d with respect to variations in the outlet temperature of the ejector T_c, outlet pressure of the ejector p_c, and the… More >

Larbi Afif^*, Nahla Bouaziz

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.5, pp. 1243-1251, 2022, DOI:10.32604/fdmp.2022.021831

Abstract In the present work, a novel Organic Rankine Cycle (ORC) configuration is used for a low-grade heat source cogeneration plant. An investigation is conducted accordingly into the simultaneous production of electricity and cold. The proposed configuration relies on concentrated solar power (as heat source) and ambient air (for cooling). Furthermore, two gas ejectors are added to the system in order to optimize the thermodynamic efficiency of the organic Rankine cycle. The results show that the thermodynamic and geometric parameters related to these ejectors have an important effect on the overall system performances. In order to account for the related environmental… More >

Kaiyong Hu^1,*, Yumeng Zhang¹, Tianrun Zhang¹, Dequan Zhang^2,*, Zhaoxian Yang³

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.4, pp. 1183-1193, 2022, DOI:10.32604/fdmp.2022.019787

Abstract The so-called organic Rankine cycle (ORC) is an effective technology allowing heat recovery from lower temperature sources. In the present study, to improve its thermal efficiency, a preheated ejector using exhaust steam coming from the expander is integrated in the cycle (EPORC). Considering net power output, pump power, and thermal efficiency, the proposed system is compared with the basic ORC. The influence of the ejector ratio (ER) of the preheated ejector on the system performances is also investigated. Results show that the net power output of the EPORC is higher than that of the basic ORC due to the decreasing… More >

Roland Martin¹, Carlos Couder-Castaneda¹

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.1, pp. 47-78, 2010, DOI:10.3970/cmes.2010.063.047

Abstract We develop an unsplit convolutional perfectly matched layer (CPML) technique to absorb efficiently compressible viscous flows and their related supersonic or subsonic regimes at the outer boundary of a distorted computational domain. More particularly subsonic outgoing flows or subsonic wall-boundary layers close to the PML are well absorbed, which is difficult to obtain without creating numerical instabilities over long time periods. This new PML (CPML) introduces the calculation of auxiliary memory variables at each time step and allows an unsplit formulation of the PML. Damping functions involving a high shift in the frequency domain allow a much better absorption of… More >

M. Dandani^1,*, V. Lepiller², A. Ghezal³, P. Desevaux⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.14, No.1, pp. 23-37, 2018, DOI:10.3970/fdmp.2018.014.023

Abstract The present study deals with the numerical visualization of the mixing process in a 2D supersonic ejector. The mixing process is visualized using two CFD flow visualization methods. The first method consists in introducing discrete particles in the secondary flow and computing their trajectories. The second method consists in modeling the diffusion of a passive scalar introduced in one of the two flows. The mixing process is investigated in the case of a conventional 2D supersonic ejector and a second case of an ejector equipped with transverse micro jets. Flow visualizations obtained show the existence of a significant mixing enhancement… More >

C. H. Cheng¹, S. C. Chen²

CMC-Computers, Materials & Continua, Vol.1, No.3, pp. 205-212, 2004, DOI:10.3970/cmc.2004.001.205

Abstract A shear mode piezoelectric actuator is applied to deflect the diaphragm of pressure chamber in the droplet ejector or inkjet printhead. The deflection of the bulge-diaphragm and resulting swept volume is analyzed by analytical and numerical method. With free-body treatment of the model, the analytical exact solutions for the two free bodies of bulge-diaphragm and piezoelectric beam were obtained. Also, the numerical solution by ANSYS is obtained to verify the analytical result. Besides, the whole-model solution coupling the bulge-diaphragm and piezoelectric beam together was obtained by ANSYS to compare with the result of free-body analysis. In order to estimate the… More >