James Adam Buckland
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2015-03-17 Design and Characteristics of a Solar Field mechanical_engineering

This is a report Alexandre Oudet, Jean-Fraņcois Olivier, Heinrich Boeing, Akshaya Kumar, and I compiled in March 2015, as part of the MJ2412 Renewable Energy Technology course at KTH, in Stockholm. We designed and evaluated the feasibility and necessary physical and mechanical constraints on a number of potential technologies involved in the construction and operation of a solar field. Physical models were developed in conjunction with financial data, to estimate the potential supply and forecasted demand in the region. An iterative method was used to calculate all relevant power plant variables to some optimal efficiency.

The Government of the Kingdom of Morocco has recently launched a program to increase the penetration of solar power in the national energy market. Thus, an contract has been promised to the independent energy production corporation able to deliver 100 MWe of base-load capacity from a concentrated solar power (CSP) plant to the grid at the lowest price.

At SolenKRAFT AB, our group of R&D Engineers has been appointed responsible for providing a suitable initial design to meet the required capacity and operating strategy. This report will present a technically viable solution, and clearly state the limitations and problems with the project. No cost estimation will be performed. Of the different types of solar concentrators (presented in Figure 1) we consider those suitable for industrial use at medium to high power at temperatures of above 250°C.

These devices use reflective surfaces to mirror sunlight, and are differentiable by their variable geometries. There are three types: a) parabolic trough, b) central tower, and c) parabolic-mirror CSP plants. We choose the parabolic trough in order to meet our base-load capacity requirement of 100 MWe. In a parabolic trough, sunlight is concentrated towards a receiver carrying a heat transfer fluid. With water as the transfer fluid, steam is directly generated for use in a power plant. However, the stability of a water-based receiver is uncertain, and steam-based heat storage is complex. We thus propose the use of an oil-based fluid for heat transfer. These oils are single-phase fluids with an efficient heat transfer coefficient, and a temperature range fitting our needs, as well as the possibility for direct storage. Synthetic oils are preferred over mineral oils for their lesser flammability. We will employ this working fluid in a thermodynamic Rankine cycle, detailed in Section 4.