Alberto de la Calle

Energy recovery using salinity differences in a multi-effect distillation system

AbstractThe use of Salinity Gradient methodologies to recover part of the osmotic energy in the brine of multi-effect distillation (MED) systems is explored here. Measurements from a membrane-based Pressure Retarded Osmosis laboratory system have been used to estimate the energy that would be recovered from this brine, when a source of low-salinity water is available locally (such as industrial or municipal wastewater). This methodology has been evaluated for a specific case study (72 m3/d solar/gas MED system) at different temperatures.

Control strategies in a thermal oil – Molten salt heat exchanger

This paper presents a preliminary control scheme for a molten salt – thermal oil heat exchanger. This controller regulates the molten salt mass flow rate to reach and maintain the desired thermal oil temperature at the outlet of the heat exchanger. The controller architecture has been tested using an object-oriented heat exchanger model that has been validated with data from a molten salt testing facility located at CIEMAT-PSA. Different simulations are presented with three different goals: i) to analyze the controller response in the presence of disturbances, ii) to demonstrate the benefits of designing a setpoint generator and iii) to show the controller potential against electricity price variations.

Improvements in BondLib, the Modelica Bond Graph Library

Bond graphs are a natural method for representing power flows in physical systems and they represent the most basic graphical paradigm that is still fully object-oriented. This paper describes a new version of BondLib, the Modelica bond graph library. The library was created for Modelica with graphical Dymola support, and its object-oriented design allows the wrapping of bond graph models offering a user-friendly environment for modeling physical system in multiple energy domains. The new improvements try to reduce the deployment and training cost for end-users by making the error diagnostics easier.

Dynamic Modeling and Simulation Study of Falling Film Evaporation and Condensation

Falling film evaporators and condensers have demonstrated a good performance in air-conditioning and refrigeration. A study of falling film evaporation and condensation models is presented in this document. Two different evaporator models and a condenser model are being developed considering a trade-off between efficiency and accuracy. These models are based on classical Newtons viscosity law and Nusselt falling film theory. Two libraries, with evaporator and condenser components, compatible with Modelica. Fluid, Modelica. Thermal and Modelica. Media have been implemented. The presented simulations have the expected behaviour. These models will be used to complete a model of a heat pump.

Modelling Thermo-chemical Hydrogen Generation in a Solar Plant

Abstract This article presents the work-in-progress of dynamic modelling works of hydrogen generation in Hydrosol3D project. This project has been based on the results of the Hydrosol II project where a pilot plant at the Plataforma Solar de Almeria (CIEMAT) with the aim of producing continuously hydrogen was set up. The hydrogen is produced from water and concentrated solar radiation, based on a two step cycle process. In this process different chemical reactions occur, with an important dependence of the temperature inside the reactors. Several dynamic models for simulation and control system design are been developed currently and its progress is presented in this work-in-progress article. The mathematical models of the different subsystems are presented and first simulation results are commented.