Enhancement of absorption efficiency for a laminar film flow by hydrodynamic conditions generated by a new type of column wall

Anumerical model is developed to quantify the effects of hydrodynamics on heat and mass transfer during an absorption, for a laminar film flowing over awavywall column. First of all, the modelling is written for a singlewave of thewall shape. Then, an experimental set up, composed of aCCDvideo camera, validates this model. Finally, the model is extended to an entire column. The results include a comparison with the simulation of a smooth column having the same geometrical and operating conditions. Thewavy column dissipates more heat through the wall (43%) due to the presence of a vortex in the furrows. This leads to an increase of the absorptionrate at the interface (10%). Moreover, the wavy column reaches equilibrium more rapidly in spite of a lower mean film temperature

Study of a laminar falling film flowing over a wavy wall column: Part I. Numerical investigation of the flow pattern and the coupled heat and mass transfer

Flow pattern and heat and mass transfer characteristics for a film flowing over a vertical wavy column are numerically investigated in a laminar flow regime. In our approach, the heat and mass transfer coefficients are avoided in order to include hydrodynamics directly in the heat and mass transfer rates. As a consequence the numerical model is decomposed into two steps. Firstly, the flow pattern for a film with a free interface is developed. Secondly, heat and mass transfer are investigated with the incorporation of velocity fields. The heat and mass transfer coefficients increase in laminar flow

Modelling of the coupling hydrodynamic transfer for a gas-liquid countercurrent flow on a wavy surface

This paper concerns laminar countercurrent gas–liquid flow over a wavy wall column, in the case of a falling liquid film. The modelling concerns the coupling of hydrodynamic and heat and mass transfer for an absorption as an example of application. The falling liquid film interacts, through the free interface, with the gas phase. The wavy surface generates particular hydrodynamic conditions with the presence of a vortex in both phases. The consequence of these vortices is an increase of transfers compared to the smooth wall

Acceleration of the retrieval of past experiences in Case Based Reasoning : application for preliminary design in Chemical Engineering

The way to manage knowledge accumulated is one of the firm’s trends, in order to capitalize and to transmit this knowledge. Some Artificial Intelligence methods are devoted to preserve and to reuse past experiences. Case Based Reasoning (CBR) is one of these methods dedicated to problem solving, new knowledge acquisition and knowledge management. CBR is a cyclic method where the central notion is a case which represents an earlier experience. Several cases are collected and stored in a memory: the case base. The goal of this paper is to soften the way to describe problem and to increase the effectiveness of the system during the retrieval of relevant case

Study of a laminar falling film flowing over a wavy wall column: Part II. Experimental validation of hydrodynamic model

The interface position of a film flowing over a wavy wall column is experimentally studied by an optical method composed of a charge coupled device (CCD) video camera. The results are compared with theoretical calculations and show a good agreement between results for both the film thickness and the vortex position. However, there exist some discrepancies because the interface is travelled by waves not accounted for in the mathematical model as it is supposed to be flat. Some characteristics of the waves are experimentally noted. Furthermore, the in¯uence of the viscosity on the film thickness is established as well

Management of innovation and process systems engineering

In this paper, Innovation on technological point of view will be explored. Some tracks for helping for innovative aspects as well as the role of PSE and CAPE methodologies will be analyzed. Some new directions will be proposed as well as some examples of success will be enlighted

Effective retrieval and new indexing method for case based reasoning: Application in chemical process design

In this paper we try to improve the retrieval step for case based reasoning for preliminary design. This improvement deals with three major parts of our CBR system. First, in the preliminary design step, some uncertainties like imprecise or unknown values remain in the description of the problem, because they need a deeper analysis to be withdrawn. To deal with this issue, the faced problem description is soften with the fuzzy sets theory. Features are described with a central value, a percentage of imprecision and a relation with respect to the central value. These additional data allow us to build a domain of possible values for each attributes. With this representation, the calculation of the similarity function is impacted, thus the characteristic function is used to calculate the local similarity between two features. Second, we focus our attention on the main goal of the retrieve step in CBR to find relevant cases for adaptation. In this second part, we discuss the assumption of similarity to find the more appropriated case. We put in highlight that in some situations this classical similarity must be improved with further knowledge to facilitate case adaptation. To avoid failure during the adaptation step, we implement a method that couples similarity measurement with adaptability one, in order to approximate the cases utility more accurately. The latter gives deeper information for the reusing of cases. In a last part, we present a generic indexing technique for the base, and a new algorithm for the research of relevant cases in the memory. The sphere indexing algorithm is a domain independent index that has performances equivalent to the decision tree ones. But its main strength is that it puts the current problem in the center of the research area avoiding boundaries issues. All these points are discussed and exemplified through the preliminary design of a chemical engineering unit operation

Innovation and Knowledge Management : using the combined approach TRIZ-CBR in Process System Engineering

In this article, a TRIZ based model is proposed to support the innovation and knowledge capitalization process. This model offers a knowledge base structure, which contains several heuristics to solve problems, synthesized from a large range of domains and industries and, also, the capacity to capture, store and make available the experiences produced while solving problems

Case Based Reasoning and TRIZ : a coupling for Innovative conception in Chemical Engineering

With the evolutions of the surrounding world market, researchers and engineers have to propose technical innovations. Nevertheless, Chemical Engineering community demonstrates a small interest for innovation compared to other engineering fields. In this paper, an approach to accelerate inventive preliminary design for Chemical Engineering is presented. This approach uses Case Based Reasoning (CBR) method to model, to capture, to store and to make available the knowledge deployed during design. CBR is a very interesting method coming from Artificial Intelligence, for routine design. Indeed, in CBR the main assumption is that a new problem of design can be solved with the help of past successful ones. Consequently, the problem solving process is based on past successful solutions therefore the design is accelerated but creativity is limited and not stimulated. Our approach is an extension of the CBR method from routine design to inventive design. One of the main drawbacks of this method is that it is restricted in one particular domain of application. To propose inventive solution, the level of abstraction for problem resolution must be increased. For this reason CBR is coupled with the TRIZ theory (Russian acronym for Theory of solving inventive problem). TRIZ is a problem solving method that increases the ability to solve creative problems thanks to its capacity to give access to the best practices in all the technical domains. The proposed synergy between CBR and TRIZ combines the main advantages of CBR (ability to store and to reuse rapidly knowledge) and those of TRIZ (no trade off during resolution, inventive solutions). Based on this synergy, a tool is developed and a mere example is treated

An application of a cocitation-analysis method to find further research possibilities on the area of scheduling problems

In this article we will give firstly a classification scheme of scheduling problems and their solving methods. The main aspects under examination are the following: machine and secondary resources, constraints, objective functions, uncertainty, mathematical models and adapted solution methods. In a second part, based on this scheme, we will examine a corpus of 60 main articles (1015 citation links were recorded in total) in scheduling literature from 1977 to 2009. The main purpose is to discover the underlying themes within the literature and to examine how they have evolved. To identify documents likely to be closely related, we are going to use the cocitation-based method of Greene et al. (2008). Our aim is to build a base of articles in order to extract the much developed research themes and find the less examined ones as well, and then try to discuss the reasons of the poorly investigation of some areas