Thermo-Economic Analysis of Central Tower Receiver

Title: Thermo-Economic Analysis of a Concentrated Solar Thermal Power Plant (CSP) with a Central Tower Receiver for Direct Steam generation (DSG)

Duration: April 2013-October 2013
Supervisor: Rafael Eduado Guedez Mata (KTH, Stockholm, Sweden)
Adviser and Examiner:

Prof. Andrew Martin
Prof. Bjorn Laumert

In completion of a Master’s Thesis and an internship, this research was conducted at Concentrating Solar Power and Techno-Economic Analysis Group in Heat and Power Division in KTH Royal Institute of Technology, Stockholm, Sweden.

The project was performed under TESCONSOL umbrella, a KIC Innoenergy project of the European Institute of Technology in Co-operation with Gas Natural Fenosa and TOTAL as Industrial Partners. As a part of research team established to build up a tool to analyze the Solar Thermal power plants, a model was developed to analyze Direct Steam Generation (DSG) in Solar Central Receiver Tower system.

Ivanpah Solar Thermal Power Plant, being the latest in Concentrating Solar Power and based on Direct Steam Generation principle, was considered as the basic framework for this work.

Tasks Performed:
  • MATLAB was used to model the heat transfer phenomena in the central tower and to optimize the regenerative Rankine power cycle of the power plant.

  • FORTRAN programming language was used to design new DSG components required for the dynamic simulations in TRNSYS.

  • TRNSYS was used for the dynamic simulations of the DSG Central Tower Solar Thermal Power Plant, which forms the basis for the thermo-economic analysis performed afterward.


A large scale power plant of 123 MW (capacity of one of the central towers of Ivanpah CSP plant) was modeled based on a Regenerative Rankine Power Cycle. The components of this power block were thermo-dynamically modeled (e.g. Steam turbines were modeled using Stodola Expansion Model) and optimized to get the required mass flow rate of water-the working fluid.

A new architecture for the receiver structure was proposed based on the literature review. Further, an optimized mass-flow rate was calculated to establish the heat-transfer at the receiver, using pressure drop and Critical Metal Temperature as critical conditions. Moreover, a manufacturer's guide was used to develop a database of selecting dimensions of the pipes (Material AISI 316L) with respect to maximum working pressure and corresponding Critical Metal Temperature.

Along with the heat transfer analysis, these critical conditions limited the number of sets of diameter and thickness of the pipes of the receiver. The final dimensions were chosen based on allowable pressure drop, overall efficiency, and financial analysis.

These dimensions were used to develop a Trnsys component which was programmed using Fortran.