In ejector refrigeration systems, the performance of the ejector is critical to the performance, capability, size and cost of the whole system. Construction of mathematical models has been used as an effective method for analyzing the performance of the ejector as well as the whole refrigeration system. These models can also be used to guide system operation, interpret experimental results and assist in system design and optimization. The overall objective of this paper is to provide a review of various researches of the mathematical model on the hydrodynamic and thermodynamic character within the ejector. The paper first briefly describes ejector including fundamental principle, flowing and mixing mechanism and the method of model establishment. Then various models consisting of ideal assumptions, governing equations, auxiliary conditions, solution methods and main results are presented. The models can be classified into two main categories: (i) steady thermodynamic models which can be further subdivided into single-phase flow model and two-phase flow model and (ii) dynamic models which are also subdivided according to the flowing phases considered. It has been shown that the dynamic models have higher prediction precision and give more information compared with the steady thermodynamic models. In addition, the simplified empirical and semi-empirical models based on measured data are briefly discussed. This review is useful for understanding the evolution process and the current status of the mathematical models on ejector and highlighting the key aspects of model improvement such as the mixing mechanism, the capture of the shock wave, etc.

Progress of mathematical modeling on ejectors

Design and characterization of an electronically controlled variable flow rate ejector for fuel cell applications

Ejectors used in refrigeration systems as entrainment and compression components or expanders, alone or in combination with other equipment devices, have gained renewed interest from the scientific community as a means of low temperature heat recovery and more efficient energy use. This paper summarizes the main findings and trends, in the area of heat-driven ejectors and ejector-based machines, using low boiling point working fluids, which were reported in the literature for a number of promising applications. An overall view of such systems is provided by discussing the ejector physics principles, as well as a review of the main developments in ejectors over the last few years. Recent achievements on thermally activated ejectors for single-phase compressible fluids are the main focus in this part of the review. Aspects related to their design, operation, theoretical and experimental approaches employed, analysis of the complex interacting phenomena taking place within the device, and performance are highlighted. Conventional and improved ejector refrigeration cycles are discussed. Some cycles of interest employing ejectors alone or boosted combinations are presented and their potential applications are indicated.

https://www.mdpi.com/2411-5134/4/1/16/pdf

Current Advances in Ejector Modeling, Experimentation and Applications for Refrigeration and Heat Pumps. Part 1: Single-Phase Ejectors

This paper presents a numerical study of a steam ejector using CFD with the objective of identifying suitable experimental conditions that allows for a reliable ejector cycle operation. The flow structure and the mixing process inside the ejector were assessed for a range of operating conditions typical for a solar driven air conditioning system. The effect of varying the condenser pressure was studied. It was found that for relatively low condenser pressures (

A CFD analysis of the flow structure inside a steam ejector to identify the suitable experimental operating conditions for a solar-driven refrigeration system

Mixing layer effects on the entrainment ratio in steam ejectors through ideal gas computational simulations

Design aspects of pulsed sieve plate columns

Design aspects of ejectors: Effects of suction chamber geometry

Present work deals with the development of a computational fluid dynamics (CFD) model for understanding the hydrodynamics in sieve and pulsed-sieve plate extraction columns. The model is based on Eulerian–Eulerian approach along with standard k–ɛ model for turbulence. The CFD model has been validated by comparing (i) the height of the accumulated layer of the dispersed phase under the plate, and (ii) hold-up of the dispersed phase on the sieve plates with the corresponding values calculated by the correlations reported by Laddha and Degaleesan [Laddha, G.S., Degaleesan, T.E., 1976. Transport Phenomena in Liquid Extraction. Tata McGraw Hills Publishing Co. Ltd., pp. 305–330]. Model predictions were found to be within ±10%. The validated model has been extended to study the regime transition in pulsed-sieve plate columns. Overall, the developed CFD model is found to be able to predict the hydrodynamic aspects of plate extraction columns: like variation in hold-up above and below the plate, movement of continuous phase across the plate and through the downcomer, different operating regimes at different pulsing velocities, etc.

Randheer L. Yadav

Papers

Design aspects of pulsed sieve plate columns

Design aspects of ejectors: Effects of suction chamber geometry

CFD modeling of sieve and pulsed-sieve plate extraction columns