Call for papers: Special Issue on Recent advances in ejector technology: applications and modeling

The combined effects of entrainment, mixing, and compression as well as its many practical advantages (i.e., simplicity of construction, the lack of any mechanically operated parts, the reliability, the little maintenance, the low cost, and the long lifespan) are the characteristics making the ejector an interesting solution for many energy engineering systems (i.e., refrigeration technologies, high temperature energy conversions systems, and fuel cell systems). In particular, the increasing need for thermal comfort has led to a rapid increase in the use of cooling systems and, consequently, electricty demand for air-conditioning systems in buildings. Heat-driven ejector refrigeration systems appear to be a promising alternative to the traditional compressor-based refrigeration technologies for energy consumption reduction (also taking into account the recent regulations concerning working fluids and energy saving targets). Furthermore, ejectors can be applied in trans-critical R744 systems, to be applied in large-scale commercial refrigeration systems, for energy savings. In addition, ejectors can be applied in advanced energy conversion systems: recirculation system of fuel cell systems (i.e., PEMFC, SOFC systems), in ejector-ORC cycles, in Chemical-Looping-Combustion systems and topping cycles.

Despite the simple component design, ejector technologies were not been able to penetrate the market because of (a) highly irreversible phenomena and (b) the high influence of the ejector performance on the efficiency of the whole system, especially in off-design operating conditions. Indeed, the efficiency of the ejector-based system (the “system-scale”) relies, mainly, on the ejector performance (the “component-scale”, i.e., the primary and secondary mass flow rates, the pressure recovery, the operation modes, …). Unfortunately, ejectors are characterized by extremely complex fluid dynamic interactions and, for this reasons, their correct design, operation, and scale-up (towards large-scale industrial applications) rely on the knowledge of the fluid dynamics at the “local-scale” (i.e., boundary layers subject to adverse pressure gradients, shock waves, under-expanded jets, flow reparation, recirculation, turbulence mixing phenomena bounded by near-wall regions,…) and at the “component-scale” (i.e., the entrainment ratio—defined as the ratio between the secondary and the primary mass flow rates; it measures the recirculation ratio and it is a measure of the performance of the ejector). Indeed, the global behavior, at the “component-scale, is the result of the flow features inside the ejector at the “local-scale”. The many relationships between the different scales makes the estimation of ejector fluid dynamics a very challenging task; this task is even more complex owing to the many relationships between the ejector fluid dynamics and the various variables characterizing the system (i.e., geometrical parameters, operating temperature and pressures, refrigerant properties, …). In this respect, multiphase Computational Fluid-Dynamics (CFD) simulations are particularly useful to study the fluid dynamics in large-scale reactors. Reliable predictions of the ejector fluid dynamics with this approach are, however, limited up to now. One important drawback concerns the closure models for the turbulence and multi-phase phenomena. One difficulty for the model development and validation results from the fact that we still have a lack of knowledge on local phenomena, which determine the flow characteristics and which should be considered in the closure models. To this end, experimental data with high resolution in space and time are requested.

This special issue aim to collect contributions concerning the state-of-the-art on ejector technology. In particular, the main focus of the volume would be on ejector fluid dynamics (without and with mass transfer) and ejector applications by using theoretical, experimental, and numerical modeling approaches.

To this end, the special issue, considers three main tracks:

Track#1. Advances in ejector-based refrigeration systems

Ejector technology for commercial refrigeration systems (i.e., advanced system layouts to integrate ejectors in large-scale R744 plants, estimation and evaluations of energy savings in large-scale applications, …)

Ejector technology to promote renewable energies (i.e., solar-based systems with/without advanced storage systems, screening of working fluids in ejector-based systems …)

Track#2. Advances in ejector-based energy conversion systems

Ejector technology in fuel cell based systems (i.e., design procedures and optimization, …)

Ejector technology in advances energy conversion systems (i.e., ORC, CLC, topping cycles)

Track#3. Prediction of ejector performance: modeling approaches

Advances in numerical approaches: computational fluid dynamic approaches (i.e., simulation of flash boiling flows, real gases, gas-liquid ejectors, …)

Advances in numerical approaches: lumped-parameter approaches (i.e., advanced modeling approaches for single and two phase flows, two-phase sound velocity estimation procedures, …)

Submission Format and Guideline

All invited papers must be clearly written in excellent English and contain only original work, which has not been published by or is currently under review for any other journal or conference. A detailed submission guideline is available as “Guide to Authors” at: https://www.elsevier.com/journals/energy/0360-5442/guide-for-authors

All manuscripts and any supplementary material should be submitted through Elsevier Editorial System (EES). The authors must select as “VSI: Ejector technology” when they reach the “Article Type” step in the submission process. The EES website is located at: http://ees.elsevier.com/egy/default.asp.

Submission Timeline

Submission Deadline: 01 May 2018

Acceptance Deadline: 30 Oct 2018

Expected Publication: December 2018

Guest Editor:

Dr. Giorgio Besagni

Ricerca sul Sistema Energetico - RSE S.p.A.

Email: giorgio.besagni@polimi.it

or giorgio.besagni@rse-web.it