Adnan Zahed

Modelling and Simulation of Batch and Continuous Fluidized Bed Dryers

ABSTRACT The performance of batch and continuous fluidized solids dryers has been modeled, with allowance for diffusional moisture transport in the dense phase particles and for interstitial gas-to-particle mass transfer within the dense phase, as well as for interphase exchange resistance between gas bubbles and the dense phase. Two types of boundary conditions are employed. Variations of the bed temperature and product moisture content in the bed with time are predicted numerically under various batch drying conditions. Exit product moisture contents, bed temperatures and outlet air humidities are also predicted for continuous drying at various mean residence times. The model can be used for homogeneous as well as bubbling fluidized bed drying. It can be used for a wide range of materials, including cereal grains and granular synthetic polymeric materials.

ON THE DIFFUSION MECHANISM DURING SPOUTED BED DRYING OF CEREAL GRAINS

ABSTRACT Two alternate mechanisms of cereal grain drying are posed, based on a comparison of predictions from their respective mathematical models with the experimental data of Zuritz and Singh (1982) on spouted bed batch drying of rough rice.

Saudi-KAU Coupled Global Climate Model: Description and Performance

BackgroundA new coupled global climate model (CGCM) has been developed at the Center of Excellence for Climate Change Research (CECCR), King Abdulaziz University (KAU), known as Saudi-KAU CGCM.PurposeThe main aim of the model development is to generate seasonal to subseasonal forecasting and long-term climate simulations.MethodsThe Saudi-KAU CGCM currently includes two atmospheric dynamical cores, two land components, three ocean components, and multiple physical parameterization options. The component modules and parameterization schemes have been adopted from different sources, and some have undergone modifications at CECCR. The model is characterized by its versatility, ease of use, and the physical fidelity of its climate simulations, in both idealized and realistic configurations. A description of the model, its component packages, and parameterizations is provided.ResultsResults from selected configurations demonstrate the model’s ability to reasonably simulate the climate on different time scales. The coupled model simulates El Niño-Southern Oscillation (ENSO) variability, which is fundamental for seasonal forecasting. It also simulates Madden-Julian Oscillation (MJO)-like disturbances with features similar to observations, although slightly weaker.ConclusionsThe Saudi-KAU CGCM ability to simulate the ENSO and the MJO suggests that it is capable of making useful predictions on subseasonal to seasonal timescales.

Transient performance of a natural ventilation solar kiln

A comprehensive thin-layer mathematical model is presented for a natural ventilation solar kiln. The model uses two patterns of air flow through the kiln. In the bidirectional air pattern, air either enters from the bottom of the kiln and leaves at the top of the kiln, or it enters at the top and leaves at the bottom, depending on the temperature difference between the inside and outside of the kiln. The model is capable of predicting the performance of the kiln using either real or mathematically modelled weather data and solar irradiance. The model could also be used to predict both the instantaneous and long-term performance of the bed.

Performance of Single and Multi-stage Spouted Bed Drying Systems

ABSTRACT A mathematical model is developed to predict the performance of single-stage and multi-stage drying systems using spouted beds. The model uses unsteady state analysis for batch operation to simulate the steady state operation of a continuously fed spouted bed. A parametric study is carried out to study the effect of the following parameters on the performance of a single-stage grain drying system: air flow rate per unit mass of the grain in the bed, ambient air temperature and humidity, initial and target moisture contents, the residence time in the bed, and the effectiveness of the heat exchanger to recover the thermal energy in the exhaust air. The parametric study is also extended to investigate the effect of these parameters (except ambient air temperature and humidity) on the performance of the multi-stage system. In addition, the number of stages is also included in the latter study. The results are presented in terms of charts which may be adopted for the design of such systems.

Energy Demands, Resources, Impact, and Technology

Abstract Energy is one of the major factors that is shaping and influencing the life of every nation on Earth. It is through energy that a nation can gain and achieve any considerable degree of development and progress. It is well known that energy supplies, or to be more specific fuel supplies, are limited and for the most part exhaustible. The energy resources are of two main kinds. These are external energy sources of which solar energy is one of Us constituents and internal energy sources of which fossil fuel is also one of its constituents. Historically global energy requirement has been exponentially increasing. Thus it is vitally important to have a clear and current picture and assessment of the global energy situation. This article begins with an accurate assessment of the current world energy demand and resources, with emphasis on the influence of the energy resources of the Kingdom of Saudi Arabia. We will also investigate and analyze in some detail energy-related technologies such as hydrogen ...

Excellence in International Cooperation

This chapter deals with ‘excellence’ in international cooperation. Section 2 discusses different terminologies such as cooperation, collaboration, and aid and the differences between and relationships among them. This is followed by some general insights concerning international cooperation, as a means to put university cooperation in perspective. International cooperation and university cooperation are further explored and elaborated on from this perspective in Sect. 3. Section 4 discusses student, expert, and teacher exchanges and the effects and proceeds of such exchanges. Section 5 deals with three examples of international cooperation.

International Advisory Boards in the World

Many scientific institutions and major industrial organizations, in their keenness to benefit from the experience of internationally prestigious advisory and consultative bodies, draw up long and short-term plans for their formation. These advisory and consultative bodies comprise of elite and authoritative groups of scientific, industrial, and administrative experts.

Saudi University Policy: King Abdulaziz Response

King Abdulaziz University (KAU) is flattered to receive international attention regarding its ambitious efforts to recruit scientific talents. Nevertheless, the title of the News Focus story “Saudi universities offer cash in exchange for academic prestige” (Y. Bhattacharjee, 9 December 2011, p