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Thermal - Mechanical Engineering Research

Thermal

Thermal research aims at developing fundamental understanding of heat and mass transfer at various scales (nano, micro and macro) and in a wide range of thermal sciences applications.

Thermal Research at KhalifaThe main interest in the department focus on the experimental, theoretical, and computational investigations in following areas:

  • Laser-diagnostics in combustion, PIV measurements in combustion, turbulence statistics measurement in combustion
  • Experimental, computational, and theoretical investigation of turbulent and laminar combustion phenomena
  • Heat and mass transfer at multiscales
  • Multiscale modelling using discrete particle simulation methods (Dissipative Particle Dynamics, Molecular Dynamics, Lattice Boltzmann, and Cellular Automata).
  • Conventional Computational Fluid Dynamics Techniques (Finite Volumes and Finite differences)
  • Forced, natural and mixed convection applications in single and multi–phase fluid flow

 

The Thermal research group at the department of mechanical engineering is currently overseeing the implementation of the following research projects:

Optimizing Thermal Energy Storage Operation in Solar Power Plants

The Citrate Soluble Loss of the Dihydrate Process


Optimizing Thermal Energy Storage Operation in Solar Power Plants

Abstract

Thermal energy storage systems are designed to store extra heat in order to release it at a more appropriate time. There are many industrial applications that can utilize the thermal energy storage concept, such as oil drilling and solar power generation. A model depicting the operation of a dual–tank molten salt thermal energy storage system was developed to be used to optimize its charging and discharging operations. Concentrated solar power plants produce electricity using generators attached to turbines supplied with pressurized solar–generated steam. Sunbeams are focused onto a small aperture producing immense heat that is used to generate steam to drive the turbines of conventional Rankine cycle power plants. The sporadic nature of solar energy would normally result in a varying electrical output corresponding to the varying solar radiation. However, integrating a properly–sized TES system into the operation of these solar thermal power plants will guarantee a continuous and smooth supply of electricity. The TES system can be thermally charged during high radiation periods then it can be thermally discharged at night and during low radiation periods or cloud covers thus streamlining the electric output of the plant by regulating its thermal energy input.

Optimizing Thermal Energy Storage Operation


The Citrate Soluble Loss of the Dihydrate Process

Abstract

The dihydrate process is the most common method for extracting phosphates from mined phosphate-rich rock. Optimizing the dihydrate process can take several paths, one of which is the minimization of phosphate loss. Phosphate loss can occur in many ways and is mainly attributed to the formation of gypsum crystals. One type of loss arises from the formation of dicalcium phosphate dihydrate, or DCPD. Gypsum and DCPD have almost the same molecular weight and density; moreover, they share the same monoclinic crystal lattice structure, all of which will facilitate the formation of a solid solution of both crystals. This lattice loss is known as the citrate soluble loss and can be thermodynamically controlled as has been experimentally proven. A thermodynamic model was developed to predict the limits of distribution of phosphates between the liquid and the solid phases in the extracting reactor of the dihydrate process. A detailed computer code based on the thermodynamic model was generated to carry out different simulations of the process using several inputs of temperatures and liquid phase content of sulfates and phosphates. Experimental data of equilibrium constants were regressed and included in the model obtaining a more accurate depiction of the thermodynamic equilibrium. In addition, published lime solubility data was used to express the self–interaction parameter of phosphoric acid, while the Edwards–Maurer–Newman–Prausnitz Pitzer–based method was incorporated into the model to write the activity coefficients of all species. The model was validated by comparing its predictions to experimental citrate soluble loss data yielding very compatible results.