Modeling and simulation of solar thermal electric energy and water production systems -

Abstract

The modeling and simulation of a solar thermal renewable energy system to produce water and electricity in a remote village is investigated in this thesis. This system is composed of parabolic solar collectors, a packed-bed thermal storage tank, a Stirling engine, and a multiple-effect evaporator (MEE) desalination plant. The operation is controlled by an Energy Management System (EMS) for an extended period of time, e.g. a year. The solar collectors are modeled by their heat rate loss equations. The packed bed storage system is discretized into layers reflecting the stratification in the tank, which allows its partial differential equation to be transformed into several ordinary differential equations that are solved using the modified Euler method. The Stirling engine is modeled using a set of work rate equations representing its phases of operation. The MEE is modeled using a set of material and energy balance equations. The components’ models are implemented and integrated into the system’s model using an EMS, which is capable of simulating the operation of the system, given the design parameters, the meteorological data, and the electricity and water demand profiles. This software tool is developed in MATLAB and is used to assess the sizes of the various components of the system based on their energy analysis requirement. These sizes are tuned using a sensitivity analysis approach, which would allow an estimation of the investment plant cost. The results of this tool will quantify the total energy supplied by the collectors to the Stirling engine and to the MEE desalination plant, the electric energy and the fresh water produced, and the components’ and overall system efficiencies. The operational cost is then calculated by carrying out a simulation of the system over an extended period of time, typically a year. Finally, different case studies of a real-like system in a remote village, with no access to water or electricity, are investigated to determine the sizes of the different system