Cristhian Almeida-Rivera

Cristhian Almeida-Rivera
Organisation For The Prohibition Of Chemical Weapons · Technical Secretariat - Inspectorate Division

Doctor of Philosophy

About

40
Publications
8,890
Reads
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481
Citations
Citations since 2016
5 Research Items
243 Citations
2016201720182019202020212022010203040
2016201720182019202020212022010203040
2016201720182019202020212022010203040
2016201720182019202020212022010203040
Introduction
Skills and Expertise
Additional affiliations
January 2005 - October 2014
Unilever
Position
  • Research & Supply Chain Manager

Publications

Publications (40)
Chapter
Aiming at a more structured approach toward the synthesis of product and processes in the food and drink sector, we proposed a methodology that exploits the synergy of combining product and process synthesis work streams. It is supported by decomposing the problem into a hierarchy of design levels of increasing refinement, where complex and emergin...
Article
In this dissertation a life-span inspired perspective is taken on the conceptual design of grassroots reactive distillation processes. Attention was paid to the economic performance of the process and to potential losses of valuable resources over the process life span. The research was cast in a set of goal-oriented engineering and specific scient...
Article
Full-text available
The supercritical-carbon-dioxide (Sc-CO 2) drying process could be a promising technology for sensitive food products. The use and applicability of this technology to foodstuff drying is still under investigation with very limited available data. In this contribution, a mathematical model is derived to describe the changes in water concentration in...
Article
The potential benefits of applying reactive distillation (RD) processes are taxed by significant complexities in process development and design. The design problem is formulated in the wider context of process development and engineering. From that perspective design methods for RD units developed over the last decades are classified and described....
Article
In this contribution the Product-driven Process Synthesis methodology was used as a well-defined structured approach for the conceptual design of an extraction process for the isolation of intact oil bodies from soybeans. In the first part of this work, the product-related design stages of the Product driven Process Synthesis methodology were addre...
Article
In this contribution the Product-driven Process Synthesis methodology was used as a well-defined structured approach for the conceptual design of an extraction process for the isolation of intact oil bodies from soybeans. In the first part of this work, the product-related design stages of the Product-driven Process Synthesis methodology were addre...
Article
Full-text available
Several experimental methods for measuring porosity, bulk density and volume reduction during drying of foodstuff are available. These methods include among others geometric dimension, volume displacement, mercury porosimeter, micro-CT, and NMR. However, data on their accuracy, sensitivity, and appropriateness are scarce. This paper reviews these e...
Article
Several empirical/theoretical models are available in the open literature to predict the volume shrinkage coefficient (Sv). However, the few reported theoretical models do not consider the variation of the porosity as a function of water content during drying. In this contribution, a theoretical model was used to describe Sv as a function of water...
Article
For thermo-sensitive food products, supercritical-carbon-dioxide (SC-CO2) drying process could be a promising technology. The process takes place in three steps: (i) removal of water from the food matrixes, (ii) adsorption of the water removed in the adsorber bed, and (iii) regeneration of the adsorber with hot air. In this investigation, a mathema...
Article
Quantitative supply chain modelling has contributed substantially in fields such as automotive, logistic, hardware, etc. However, these methods and optimization have not been employed widely in the food industry despite all the potential benefits they may bring to this sector.The objective of this work is to develop a supply chain model for the foo...
Article
A mathematical model of the margarine production process was developed by considering the votator barrel as a series of well mixed stages and employing heat and mass transfer equations.The model was solved using a commercial simulation package to give predictions of product temperature, mechanical dissipation and heat transfer rate. These predictio...
Article
The pore formation during drying is controlled by two mechanisms which are represented by two functions. These functions are expected to be universal, thus recurrent and applicable to relevant physical properties of the products during drying. This contribution aims at studying the sensitivity of shrinkage and collapse functions in predicting the p...
Article
Unilever as a fast moving consumer goods company needs to have its supply chain deliver a reduction of inventory, increased flexibility of producing ‘on demand’ whilst reducing the overall costs. Furthermore, as intermediate products are made batch-wise, a minimum batch size is needed when manufacturing the product. The batch vessels have a limited...
Article
In this work, two problem specific models are developed for the ice cream scheduling problem. These models are based on product type dedicated time slots and more efficient methods of handling the intermediate inventory limitations. The first model aggregates the intermediate inventory tanks and the second model directly relates the time slots of t...
Article
Volume change is one a fundamental aspect in characterization of drying processes. Several attempts to simulate the volume change during drying have been reported in the open literature. However, so far no theoretical approach has been used to support these simulations, especially when it comes to dealing with the springback effect. In this contrib...
Article
Here we studied the emulsification process carried out in an extensional-flow unit. By means of rigorous population and momentum balances we captured the phenomenological description of the first principles occurring in such unit. The strong feature of our model approach resides in the fully mechanistic description of the governing phenomena. A pop...
Article
Drying assisted by supercritical carbon dioxide is foreseen to become a promising technology for sensitive food products. In this contribution, a mathematical model is derived to describe the changes in water concentration in both a solid food matrix and a fluid carrier during drying. Finite different element method is used to solve the set of mass...
Article
Despite the wide range of industrial applications of structured emulsions, current approaches toward process design and scale-up are commonly based on trial-and-error experimentation. As this design approach is foreseen to deliver most likely suboptimal process solutions, we propose in this contribution a model-based approach as the way forward to...
Article
Most population balance equation (PBE) models of emulsion drop breakage are based on the assumption of binary drop breakage. We previously developed such a PBE model for high-pressure homogenizers with a daughter drop distribution function exhibiting a maximum probability for two equal sized drops. In this paper, we present a PBE model accounting f...
Article
Although several empirical models are available in the literature to predict density in solid matrices, only a very limited number of theoretical models have been reported. So far, no model considered the possible variation in the initial air volume existing at the beginning of the drying process. In this contribution, a theoretical model to predic...
Article
In this contribution, a mathematical model is built to predict the changes in water concentration in both a solid food matrix and a fluid carrier during supercritical carbon dioxide (SC–CO2) drying. The mass balance equations of the model involve five dimensionless parameters: Peclet number modified Sherwood number, Fourier number, mass ratio and e...
Article
In the last ten years much more processes are being reported to be designed through a process synthesis approach. It has been recognized during those years that (i) processes for structured products are more difficult to design through process synthesis; (ii) process synthesis is disconnected from product development. In a response to those shortfa...
Article
Several models have been reported to predict the porosity during drying. However, currently these models do not allow quantifying the possible evolution of the initial air volume existing at the beginning of the drying process. In this study, a theoretical model was built to predict the porosity of dried materials by taking into account the possibl...
Article
Current efforts in the development of a Product-driven Process Synthesis methodology have been focusing on broadening the design scope to consumer preferences, product attributes, process variables and supply chain considerations. The methodology embraces a decision making activity to be performed at different levels of detail and involving criteri...
Conference Paper
Previously we have used an inverse method to develop a population balance equation (PBE) model for drop breakage in a simulated oil-in-water emulsion (Raikar et al., 2007). A potential advantage of inverse methods is that the drop breakage functions are constructed non-parametrically without the need for mechanistic understanding of the breakage me...
Conference Paper
In the last ten years much more processes are being reported to be desinged through a process synthesis approach. It has been recognised during those years that (i) processes for structured products are much more difficult to design through process synthesis; (ii) processs synthesis is disconnected from product development. In a response to these s...
Article
To quantify rationalization of ingredients and to realize its opportunity during process synthesis, in this contribution we propose an integrated product and process design approach for foods. According to this methodology, once the product concept and geographical market are decided, product attributes that drive consumer liking are identified and...
Article
The interactions between economic performance, thermodynamic efficiency, and responsiveness in reactive distillation process design are explored in this contribution. This motivation is derived from taking a sustainable life span perspective, where economics and avoidance of potential losses of resources (i.e., mass, energy, and exergy) in process...
Article
The paper addresses the steady-state behavior of a reactive flash, characterized by an exothermic isomerization reaction with first-order kinetics and a light-boiling reactant. The dimensionless model distinguishes between the state variables, control parameters, and system properties. The combination of state multiplicity and feasibility boundarie...
Article
The residue curve mapping technique (RCM) has been considered a powerful tool for the flow-sheet development and preliminary design of conventional multi-component separation processes. It does not only represent a good approximation to actual equilibrium behavior, but also it allows performing feasibility analysis of separation processes where non...
Article
This contribution proposes a multilevel modelling approach as a tool for the decision-making task in the early design stages of reactive distillation processes. The proposed model involves formulating the simulation problem at different levels of increasing degree of complexity, in which mass, energy and momentum balances are conveniently applied t...
Article
Full-text available
In the area of drying, simulations techniques are often used to optimize the process parameters and operation conditions. The credibility and the validity of these simulations depend, among others, on the values of the physical parameters involved in the development of the models. Porosity is one of those physical parameters required to perform suc...
Article
Full-text available
The interactions between economics and thermodynamic efficiency in the design of reactive distillation (RD) processes are explored. Our motivation derives from taking a sustainable lifespan perspective, where not only economics, but also exergy-efficiency and controllability should be borne in mind. Furthermore, novel process configurations might b...

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