Integral Techno-Economic Analysis of Supercritical Carbon Dioxide Cycles for Concentrated Solar Power

Author(s):  
Francesco Crespi ◽  
David Sánchez ◽  
Tomás Sánchez ◽  
Gonzalo S. Martínez

Previous work by the authors has shown that broader analyses than those typically found in literature (in terms of operating pressures allowed) can yield interesting conclusions with respect to the best candidate cycles for certain applications. This has been tested for the thermodynamic performance (1st and 2nd Laws) but it can also be applied from an economic standpoint. This second approach is introduced in this work where typical operating conditions for CSP applications (current and future generations of solar tower plants) are considered (900 °C and 30 MPa). For these, the techno-economic performance of each cycle are assessed in order to identify the most cost-effective layout when it comes to the Overnight Capital Cost. This analysis accounts for the different contributions to the total cost of the plant, including all the major equipment that is usually found in a CSP power plant such as the solar field and thermal energy storage system. The work is thus aimed at providing guidelines to professionals in the area of basic engineering and pre-feasibility study of CSP plants who find themselves in the process of selecting a particular power cycle for a new project (set of specifications and boundary conditions).

Author(s):  
Francesco Crespi ◽  
David Sánchez ◽  
Tomás Sánchez ◽  
Gonzalo S. Martínez

Previous work by the authors has shown that broader analyses than those typically found in literature (in terms of operating pressures allowed) can yield interesting conclusions with respect to the best candidate cycles for certain applications. This has been tested for the thermodynamic performance (first and second laws) but it can also be applied from an economic standpoint. This second approach is introduced in this work where typical operating conditions for concentrated solar power (CSP) applications (current and future generations of solar tower plants) are considered (750 °C and 30 MPa). For these, the techno-economic performance of each cycle is assessed in order to identify the most cost-effective layout when it comes to the overnight capital cost (OCC). This analysis accounts for the different contributions to the total cost of the plant, including all the major equipment that is usually found in a CSP power plant such as the solar field and thermal energy storage (TES) system. The work is, thus, aimed at providing guidelines to professionals in the area of basic engineering and prefeasibility study of CSP plants who find themselves in the process of selecting a particular power cycle for a new project (set of specifications and boundary conditions).


Author(s):  
Ojas Satbhai ◽  
Subhransu Roy ◽  
Sudipto Ghosh

Abstract In this work, numerical experiments were performed to compare the heat transfer and thermodynamic performance of melting process inside the square-shaped thermal energy storage system with three different heating configurations: an isothermal heating from left side-wall or bottom-wall or top-wall and with three adiabatic walls. The hot wall is maintained at a temperature higher than the melting temperature of the phase change material (PCM), while all other walls are perfectly insulated. The transient numerical simulations were performed for melting Gallium (a low Prandtl number Pr = 0.0216, low Stefan number, Ste = 0.014, PCM with high latent heat to density ratio) at moderate Rayleigh number (Ra ≊ 105). The transient numerical simulations consist of solving coupled continuity, momentum, and energy equation in the unstructured formulation using the PISO algorithm. In this work, the fixed grid, a source-based enthalpy-porosity approach has been adopted. The heat transfer performance of the melting process was analyzed by studying the time evolution of global fluid fraction, Nusselt number at the hot wall, and volume-averaged normalized flow-kinetic-energy. The thermodynamic performance was analyzed by calculating the local volumetric entropy generation rates and absolute entropy generation considering both irreversibilities due to the finite temperature gradient and viscous dissipation. The bottom-heating configuration yielded the maximum Nusselt number but has a slightly higher total change in entropy generation compared to other heating configurations.


1996 ◽  
Vol 118 (1) ◽  
pp. 50-57 ◽  
Author(s):  
A. A. Jalalzadeh-Azar ◽  
W. G. Steele ◽  
G. A. Adebiyi

A model is developed and experimentally verified to study the heat transfer in a high-temperature packed bed thermal energy storage system utilizing zirconium oxide pellets. The packed bed receives flue gas at elevated temperatures varying with time during the storage process and utilizes air for the recovery process. Both convection and radiation are included in the model of the total heat transfer between the gas and the pellets. It is found that thermal radiation and intraparticle conduction do not play a major role in the overall heat transfer in the packed bed under the specified operating conditions. An uncertainty analysis is performed to investigate the propagation of the uncertainties in the variables to the overall uncertainty in the model predictions and the experimental results.


1991 ◽  
Vol 113 (1) ◽  
pp. 27-32 ◽  
Author(s):  
M. J. Taylor ◽  
R. J. Krane ◽  
J. R. Parsons

This study explores the behavior of a flat-slab, sensible heat thermal energy storage system, the physical design and operation of which have been optimized to minimize the production of entropy by thermodynamic irreversibilities. The analytical model is developed in Part I of this work. This part includes a description of the numerical model and the presentation and interpretation of the results of a system optimization study. The major results of this study show that: 1) any Second Law model of a thermal energy storage system must include a distributed storage element in order to make realistic estimates the thermodynamic performance of the system; 2) unconstrained optimization of the design of a thermal energy storage system tends to yield a system that is undesirably large, but by constraining the number of transfer units (NTU), it is possible to design systems of a realistic size without seriously degrading the thermodynamic performance; 3) counterflow systems operated without a dwell period are the most efficient type of system; and 4) the use of a dwell period with a counterflow system, or the operation of a system in parallel flow instead of counterflow, degrades the thermodynamic performance of the system and increases the required system size (NTU) in comparison to a counterflow system operated without a dwell period.


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