Verification of numerical prediction of 3-D air-conditioned flow behavior in full and reduced scale room models

Abstract

The processes of heat transfer and fluid flow in the air-conditioned spaces have an overwhelming impact on human life; we should be able to deal with them effectively. In many processes the prediction and forecasting increase the effectiveness of our dealing. The numerical prediction models are one of the most suitable methods in many processes, the analyses and understand the various flow and heat transfer phenomena.The present work, made use of a developed numerical code 3DHVAC, developed by Khalil [1], modified by Kameel [2], and Kameel and Khalil [3,4]. This prediction model was developed to predict the airflow characteristics in the air-conditioned spaces, such as the air velocities, temperatures, and air turbulence under steady state processes. The validity of this program was critically assessed by way of comparisons with experimental, numerical and analytical solutions in more than test cases, Kameel and Khalil [3,4]. In the present work, the 3DHAVC program will be utilized to predict the flow regimes in the full-scaled room models. Comparisons between published experiments and predictions are given firstly for full-scale model; followed by the reduced-scale model experiments. The present work also indicates the difference between the two different cases in term of modeled flow regimes and turbulence.The present work demonstrates the inherent effects of room geometry and configuration on the numerical model effectiveness, such as the discrepancies between the present predictions and those previously obtained results (by numerical methods or experimentally), numerical residuals, numerical errors, and convergence in the predicted flow regimes, turbulence, and heat transfer characteristics. The present work illustrates the comparisons between the flow characteristics in the various cases utilized by the 3DHVAC program. Finally, the present work gives also the limitations and factors of computational scheme, such as the treatment of the grid node distributions, airflow characteristics and the boundary conditions, that must be taken in consideration for converged optimum results.The present work demonstrates the limitations of the reduced-scale models in the simulation of the airflow in the air-conditioned spaces; it also identifies types of the air flow regimes in Air-conditioned spaces, that can be predicted using the reduced-scale models.

Energy Efficient Hospitals Air Conditioning Systems

“…Fluid properties such as densities, viscosity and thermal conductivity were obtained from references. The present work made use of the Computer Program 3DHVAC, which was developed, by Khalil [5] and modified later by Kameel [7,8], and by Kameel and Khalil [9][10][11][12][13]. The program solves the differential equations governing the transport of mass, three momentum components and energy in three-dimensional configurations under steady and unsteady conditions.…”

“…More discrepancies were also observed in situation with heating flows than those of ventilation or cooling. For more details of validations for present application (Surgical Operating Theatres) review the work of Kameel and Khalil [13] and [22][23][24]. These papers describe the validation of the turbulence model to use it for the prediction of airflow characteristics in the surgical operating theatres.…”

“…Ventilation and air distribution pattern have a great effect on the IAQ; also air movement in a room becomes of vital importance to comfort. To design and construct ventilation system that is capable of efficiently fulfilling all requirements, often even contradictory, is a great challenge [1][2][3][4][5][6][7][8][9][10][11][12][13][14].…”