Andreas Poullikkas

The method of fundamental solutions for three-dimensional elastostatics problems

Abstract We consider the application of the method of fundamental solutions to isotropic elastostatics problems in three space dimensions. The displacements are approximated by linear combinations of the fundamental solutions of the Cauchy–Navier equations of elasticity, which are expressed in terms of sources placed outside the domain of the problem under consideration. The final positions of the sources and the coefficients of the fundamental solutions are determined by enforcing the satisfaction of the boundary conditions in a least squares sense. The applicability of the method is demonstrated on two test problems. The numerical experiments indicate that accurate results can be obtained with relatively few degrees of freedom.

The numerical solution of three-dimensional Signorini problems with the method of fundamental solutions

The method of fundamental solutions (MFS) is formulated for three-dimensional Signorini boundary-value problems. The method is tested on a three-dimensional electropainting problem related to the coating of vehicle roofs. The numerical results are in good agreement with available numerical solutions.

Optimization algorithm for reverse osmosis desalination economics

Abstract In this work an optimization algorithm for the calculation of water unit cost from various RO candidate schemes was developed. Such an algorithm may be used for evaluation purposes when many RO candidate schemes are taken into account. The applicability of the method is demonstrated on an example in which six RO candidate schemes are examined.

Effects of two-phase liquid-gas flow on the performance of nuclear reactor cooling pumps

Abstract An important aspect of nuclear energy is safety. One of the most severe accidents in nuclear power generation is the loss of coolant, where the re-circulating coolant of the pressurized water reactor may flash into steam. Under such, two-phase flow, conditions the reactor cooling pumps become unable to generate the same head as that of the single-phase flow case. In this work, high-speed video observations were conducted on a nuclear reactor cooling pump, in which, the bubbles motions into the impeller passages were identified.

Comparison of two methods for the computation of singular solutions in elliptic problems

We compare two numerical methods for the solution of elliptic problems with boundary singularities. The first is the integrated singular basis function method (ISBFM), a finite-element method in which the solution is approximated by standard polynomial basis functions supplemented by the leading terms of the local (singular) solution expansion. A double application of Greens theorem reduces all Galerkin integrals containing singular terms to boundary integrals with nonsingular integrands. The originally essential boundary conditions are weakly enforced by means of Lagrange multipliers. The second method is a singular function boundary integral method which can be viewed as a modification of the ISBFM. The solution is approximated only by the leading terms of the local solution expansion. The discretized equations are boundary integrals and the dimension of the problem is reduced by one. The two methods are applied to the cracked-beam problem giving very accurate estimates of the leading singular coefficients. Comparisons are made and their limitations are discussed.

Two phase flow performance of nuclear reactor cooling pumps

One of the most severe accidents in nuclear power generation is the loss of coolant accident, where the recirculating coolant of the pressurized water reactor may flash into steam. Under such two phase flow conditions, it is well known that the recirculation pump becomes unable to generate the same head as that of the single phase flow case. In this work, an improved model for the calculation of the two phase pump head is developed which is based on the one dimensional control volume method. The model takes into account pump geometry, phase separation, density variation, condensation and compressibility effects of the gas phase.

Assessment of solar electricity production in the United Arab Emirates

In this work the possible large-scale integration of photovoltaic (PV) systems and parabolic trough concentrated solar power (CSP) technologies in the United Arab Emirates (UAE) power system is investigated in technical, economic and environmental terms. The analysis takes into account the available solar potential for UAE and in particular for the Emirate of Sharjah. In order to identify the least-cost feasible option for each renewable energy source for power-generation (RES-E) technology, a parametric analysis is carried out by varying each RES-E candidate system capital cost. From the analysis it is evident that an alternative cost-effective technology to the installation of a 50 MWp PV system might be the utilisation of a 50 MWe parabolic trough CSP system with either a 14.5 h thermal storage system or a 24/7 operation. The advantages of the latter are the dispatchability and the increased electricity output due to the utilisation of a thermal storage system, which leads to higher amounts of annual CO2 avoided emissions. However, the electricity selling prices are higher than the current UAE electricity tariffs; therefore, for the promotion of solar RES-E technologies in the UAE, relevant financial supporting mechanisms need to be developed such as feed-in tariffs or feed-in premiums.

Assessment of Future Sustainable Power Technologies with Carbon Capture and Storage

In this work, a technical, economic and environmental analysis concerning the use of three major power generation plant types including pulverized coal, integrated gasification combined cycle (IGCC) and natural gas combined cycle, with or without carbon dioxide (CO2) capture and storage (CCS) integration, is carried out. For the analysis, the IPP optimization software is used in which the electricity unit cost and the CO2 avoidance cost from the various candidate power generation technologies is calculated. The analysis indicates that the electricity unit cost of IGCC technology with CCS integration is the least cost option with the lowest CO2 avoidance cost of all candidate technologies with CCS integration. Further investigation concerning the effect of the loan interest rate on the economic performance of the candidate plants revealed that up to a value of loan interest of approximately 5.7%, the IGCC plant with CCS retains the lowest electricity unit cost. Above this level, the natural gas combined cycle plant with post-combustion CCS becomes more economically attractive.

Prospective scenarios for the adoption of sustainable power generation technologies in United Arab Emirates

In this work, an optimisation analysis is carried out in order to estimate the optimal power generation expansion strategy, using sustainable power generation technologies for the United Arab Emirates (UAE). Eight alternative configurations of sustainable power generation systems, such as, the integration of carbon capture and storage (CCS) technologies and solar-based power generation systems are examined and compared with the business as usual (BAU) scenario for a range of natural gas price. Based on the input data and assumptions made, simulations indicate that the BAU scenario (i.e. expansion of the power system using conventional power generation technologies) is the least cost option. However, in the case UAE will move towards the use of sustainable power generation technologies, for the reduction of carbon dioxide emissions, the natural gas combined cycle technology integrated with CCS systems and the use of concentrated solar power systems with 24/7 operation are the most suitable alternative technologies.

Parametric assessment of concentrated photovoltaic parks for the Mediterranean region

Solar electricity produced by concentrated photovoltaic (CPV) solar cells is an alternative renewable energy technology for sustainably providing the worlds future energy requirements. Although the technology is relatively recent, it could potentially become viable in regions with high direct irradiance levels, such as the Mediterranean region. The main objective of this feasibility study is to investigate whether the installation of CPV parks in the Mediterranean region is economically feasible. The study takes as an example the available solar potential of the island of Cyprus as well as all available data concerning the current renewable energy sources policy of the island. In order to identify the least cost-feasible option for the installation of 1 MW CPV park, a parametric cost–benefit analysis is carried out by varying the CPV park capital investment, the discount rate and the CO2 emission trading scheme price. The results indicate that in the case where no feed-in tariff scheme is available, the capital expenditure of the CPV park is a critical parameter for the financial viability of the project.