Ahmed Medhat

Air Flow Characteristics in Air-Conditioned Multipurpose Hall

SUMMARY This paper focuses on both experimental investigation and numerical modeling of full-scale modelled air-conditioned multipurpose hall fully operable. Two methodologies were used, firstly full scale experimental setup was incorporated to map the hall making use of a well-developed fully automated .wireless mobile test rig remotely controlled by pre-programmed computer and using high precision state-of-the-art measuring instruments. While the Second methodology was a numerical modeling using a well developed [CFD] 3DHVAC and Fluent computer simulation programs. Physical and Numerical investigations enable the analyses of the influence of Reynolds, Archimedes and Prandtl numbers for the air as well as the effects of shape, location, inlet air velocity of supply outlet on the flowing air parameters. These parameters include throw, drop, air induction, room local velocities, humidity ratio and temperatures distributions. The forced air supply of cooled air streams out of high wall mounted, downward inclined jets is investigated with mechanically extracted air from the top of the split air-conditioning units. On the other hand an experimental traversing mechanism, computer-based and operated by PLC was developed and used to map the velocity and temperature contours. The room was typically used as the chairman office, meeting room and seminar room. One of the main conclusions is that good agreement between both of full-scale physical modeling and numerical modeling were reported .While the reported comparisons concluded that qualitative agreements were shown, some discrepancies were also observed in the thermal parameters for comfort conditions required by different occupants. PROBLEM FORMULATION The airflow distribution in its final steady pattern is a result of different interactions such as, the airside design, objects distribution, thermal effects, occupancy movements, etc, see references [1 to 14]. The airside design and internal obstacles are the focus of the present work. The forced air supply of cooled air streams out of high wall mounted, 15 0 downward inclined jets is investigated with mechanically extracted air from the top of the split units as shown in figure 1. This configuration played an important role in the main flow pattern and the creation of main recirculation zones. The internal obstacles would naturally obstruct the airflow pattern in different ways and means, by for example increasing the recirculation zones size, relocating these and or deflecting the main airflow pattern. The present work followed both experimental and numerical approaches to properly understand and analyze room air flow patterns. A ready available commercial Fluent Computational code, [15] was used to predict the air flow patterns and thermal behavior. On the other hand an experimental traversing mechanism, computer-based and operated by PLC was developed and used to map the velocity and temperature contours. The room was typically used as the chairman office, meeting room and seminar room.

Experimental and Numerical Computations of Air Flow Characteristics in Air-Conditioned Multipurpose Hall

This paper focuses on both experimental investigation and numerical modeling of full-scale modelled air-conditioned multipurpose hall fully operable. To evaluate and optimize the thermal parameters affecting the zone comfort conditions. This is accomplished through the application of two different modeling approaches. First approach is to carry out experimental full-scale mapping of the hall making use of a well-developed experimental technique depending on artificial intelligence rig, which is constructed to be fully automated .wireless mobile test rig remotely controlled by preprogrammed computer and using high precision state-of-the-art measuring instruments. While the Second approach is to carry out a numerical modelling using a well developed [CFD] 3DHVAC and Fluent codes and computer simulation programs. Physical and Numerical investigations enable the analyses and investigations of the influence of Reynolds, Archimedes and Prandtl numbers for the air as well as the effects of shape, location, inlet air velocity of supply outlet on the flowing air parameters. These parameters include throw, drop, air induction, room local velocities, humidity ratio and temperatures distributions. Collected, information and data obtained from physical modeling compared with corresponded numerical modeling results, while gained data from both techniques were compared with statistical data collected from occupancies of this multipurpose hall to evaluate the validation of these modeling techniques. Such data and information will have a great impact on air distribution modeling assessments and contribute for a detailed knowledge of spatial and temporal distributions of local velocity and temperature, Thus, better understanding of fluid flow interaction in air-conditioning spaces also showed and identified the velocity fluctuations components modelling, which play a vital role in the validation of the numerical modeling. The forced air supply of cooled air streams out of high wall mounted, downward inclined jets is investigated with mechanically extracted air from the top of the split airconditioning units. The internal obstacles would naturally obstruct the airflow pattern in different ways and means, by for example increasing the recirculation zones size, relocating these and or deflecting the main airflow pattern. On the other hand an experimental traversing mechanism, computer-based and operated by PLC was developed and used to map the velocity and temperature contours. The room was typically used as the chairman office, meeting room and seminar room.

Physical and Numerical Modeling Evaluations for Air- Conditioned Multipurpose Hall

This paper focuses on both physical and numerical modeling of full- scale modeled air-conditioned multipurpose hall fully operable. To evaluate and optimize the thermal paramete rs affecting the zone comfort conditions. This is accomplished through the application of two different modeling appr oaches. First approach is to carry out experimental full-scale modeling utilizing a developed experimental technique de pending on artificial intelligence rig, which is constructed to be fully automated .wireless mobile test rig remotely controlled by pre-programmed computer and using high precision state-of-the-art measuring instruments. While the Second approach is to carry out a numerical modeling using a well developed [CFD] 3DHVAC code and computer simulation program. Physical and Numerical investigations enable the analyses and investigations of the i nfluence of Reynolds, Archimedes and Prandtl numbers for the air as well as the effects of shape, location, inlet air velocity of supply outlet on the flowing air param eters. These parameters include throw, drop, air induction, room local velocities, humidity ratio and temperatures distributions. Collected, information and data obtained from physi cal modeling compared with corresponded numerical modeling results, while gained data from both techniques were co mpared with statistical data collected from occupancies of this multipurpose hall to evaluate the validatio n of these modeling techniques. Such data and information will have a great impact on air distribution mode ling assessments and contribute for a detailed knowledge of spatial and temporal distributions of local velocity and t emperature, Thus, better understanding of fluid flow interaction in air-conditioning spaces also showed and identified the velocity fluctuations components modelling, which play a vital role in the validation of the numerical modeling . One of the main conclusions is that good agreement between both of full-scale physical modeling and numerical modeli ng were reported .While the reported comparisons concluded that qualitative agreements were shown, some discrepa ncies were also observed in the thermal parameters for comfort conditions required by different occupants.

Towards Energy Efficient Air-Conditioned Space: Fluid Flow and Thermal Behavior

This paper focuses on both experimental investigation and numerical modeling of full-scale modelled air-conditioned multipurpose hall fully operable. Two methodologies were used, firstly full scale experimental setup was incorporated to map the hall making use of a well-developed fully automated wireless mobile test rig remotely controlled by pre-programmed computer and using high precision state-of-the-art measuring instruments. While the Second methodology was a numerical modeling using a well developed [CFD] 3DHVAC and FLUENT computer simulation programs. Physical and Numerical investigations enable the analyses of the influence of Reynolds, Archimedes and Prandtl numbers for the air as well as the effects of shape, location, inlet air velocity of supply outlet on the flowing air parameters. These parameters include throw, drop, air induction, room local velocities, humidity ratio and temperatures distributions. The forced air supply of cooled air streams out of high wall mounted, downward inclined jets is investigated with mechanically extracted air from the top of the split air-conditioning units. On the other hand an experimental traversing mechanism, computer-based and operated by PLC was developed and used to map the velocity and temperature contours. The room was typically used as the chairman office, meeting room and seminar room. One of the main conclusions is that good agreement between both of full-scale physical modeling and numerical modeling were reported. While the reported comparisons concluded that qualitative agreements were shown, some discrepancies were also observed in the thermal parameters for comfort conditions required by different occupants.© 2013 ASME

Energy Modelling of Modern Residence in Egypt

The present paper aims to develop/investigate an innovative approach for affordable houses for the medium income families, forming the major category of the Egyptian society using Design-Builder simulation and emphasizing the mechanical HVAC systems and their impact on energy consumption. Design-Builder ( a simulation user-friendly interface) for Energy-Plus (an energy simulation engine for energy modeling in buildings, heating, cooling, lighting, ventilating and other energy flows) is utilized to create a “virtual environment” in which the HVAC system effect is studied. Extensive field surveys are made to collect data regarding occupancy behavior, light and equipment schedules and other mechanical systems usage in such application. The majority of surveys indicated that split system (heat pumps) + mechanical ventilation (exhaust fan for bathroom and kitchen) are most common in the Egyptian society. The subject facility is located in Cairo, Egypt. The layout of this building/house has been developed by research architects in the Housing & Building National Research Centre HRBC taking into their consideration the medium income citizens, [1] needs and limited budget, the energy efficiency concepts as well as the previous work carried in the field of sustainable architecture. The individual buildings are formed of three floors containing twelve 100 m2 apartments. Each apartment consists of three bedrooms, a bathroom, a kitchen and a lounge.Copyright

Experimental and Computational Investigations of Thermal Patterns and Relative Humidity in Different Surgical Operating Theatres

The present work fosters experimental measurements and mathematical modelling techniques to primarily determine the thermal and the relative humidity characteristics in the airconditioned surgical operating theatre. The present work also demonstrates the effect of the various designs of surgical operating theatres and operational parameters on the flow pattern and temperatures characteristics. The present work is a part of a more comprehensive investigation of the more important factors affecting the air environments in surgical operating theatre. Measured and predicted temperatures and relative humidity profiles are shown to be in good agreement. The present paper introduces several recommendations regarding the optimum design requirements of operating theatres to provide hygiene and comfort environment. Relative humidity affects our comfort in numerous ways both directly and indirectly. It is a thermal sensation, skin moisture, and discomfort, tactile sensation of fabrics, health and perception of air quality. Low humidity affects comfort and health. Comfort complaints about dry nose, throat, eyes and skin occur in low humidity conditions, typically when the dew point is less than 0 o C. Low humidity can lead to drying of the skin and mucous surfaces. On respiratory surfaces, drying can concentrate mucous to the extent that celery clearance and phagocyte activities are reduced, increasing susceptibility to respiratory disease as well as comfort. It was found that any increase in humidity from the low winter levels decreased absenteeism. Excessive drying of the skin can lead to lesions, skin roughness, and discomfort and impair the skin’s protective functions. Dusty environments can further exacerbate low humidity dry skin conditions; it was also found that drying from low humidity can contribute to irritation. Eye discomfort increased with time in low humidity environments with dew point temperature less than 2 o C.

Flow Pattern and Heat Transfer in Air-Conditioned Hall: Experimental and Numerical Investigations

This paper focuses on both experimental investigation and numerical modeling of full-scale modeled airconditioned multipurpose hall fully operable. To evaluate and optimize the thermal parameters affecting the zone comfort conditions. This is accomplished through the application of two different modeling approaches. First approach is to carry out experimental full-scale mapping of the hall making use of a welldeveloped experimental technique depending on artificial intelligence rig, which is constructed to be fully automated .wireless mobile test rig remotely controlled by pre-programmed computer and using high precision state-of-the-art measuring instruments. While the Second approach is to carry out a numerical modeling using a well developed [CFD] 3DHVAC and Fluent codes and computer simulation programs. Physical and Numerical investigations enable the analyses and investigations of the influence of Reynolds, Archimedes and Prandtl numbers for the air as well as the effects of shape, location, inlet air velocity of supply outlet on the flowing air parameters. These parameters include throw, drop, air induction, room local velocities, humidity ratio and temperatures distributions. Collected, information and data obtained from physical modeling compared with corresponded numerical modeling results, while gained data from both techniques were compared with statistical data collected from occupancies of this multipurpose hall to evaluate the validation of these modeling techniques. Such data and information will have a great impact on air distribution modelling assessments and contribute for a detailed knowledge of spatial and temporal distributions of local velocity and temperature, Thus, better understanding of fluid flow interaction in air-conditioning spaces also showed and identified the velocity fluctuations components modelling, which play a vital role in the validation of the numerical modeling. The forced air supply of cooled air streams out of high wall mounted, downward inclined jets is investigated with mechanically extracted air from the top of the split air-conditioning units. The internal obstacles would naturally obstruct the airflow pattern in different ways and means, by for example increasing the recirculation zones size, relocating these and or deflecting the main airflow pattern. On the other hand an experimental traversing mechanism, computer-based and operated by PLC was developed and used to map the velocity and temperature contours. The room was typically used as the chairman office, meeting room and seminar room. One of the main conclusions is that good agreement between both of full-scale physical modeling and numerical modelling were reported .While the reported comparisons concluded that qualitative agreements were shown; some discrepancies were also observed in the thermal parameters for comfort conditions required by different space users.

ENERGY EVALUATIONS BETWEEN AIR-COOLED VS WATER-COOLED COOLING SYSTEMS IN EGYPTIAN PRIVATE BUILDINGS

The present study addresses the vital energy conservation concepts in the form of optimization and comparisons between the uses of air-cooled vs. water-cooled cooling systems. On those bases, Egypt could be divided into six main climatic regions where each region shall use an optimum and economical individual HVAC system configuration whatever this system is aircooled or water-cooled system. Also, this paper proposes and recommends a design criteria’s, which could be implemented in the Egyptian energy codes based on enhanced knowledge of weather data .It yields selection criteria for typical size ranges, where a water-cooled air conditioning system is more economical than an air-cooled system and vise versa. One of the conclusions of this work is that for newly designed projects, located almost in all Egyptian climatic regions, with any cooling capacities ,could be designed based on water-cooled system with minimum initial and running cost taking into consideration the availability of different water sources in Egypt.

Optimization of Building Energy Efficiency in Egypt

This investigation is a case-study based exercise to set minimum requirements for Egyptian Energy Efficiency Building Code applicable for New Commercial Buildings at different governorates. These investigations are devoted to the analysis and validation of simulation tasks and are directly related to collectively gathered data gained form experimental works and practical applications. In practical operation, achieved data from the Building Management System (BMS) are collected and compared with the numerical simulation methodologies utilizing the Visual DOE 3.1 and HAP-E20II programs. The case study dealt with multi-story (fourteen levels) office building located in Cairo owned by an International Pharmaceuticals Company. The building is centrally air-conditioned using two air-cooled 300 T.R (1050 kW cooling) chillers system; two pipes fan-coil units and three central station air handling units for feeding treated fresh air. Intelligent Building Management System (BMS) is superimposed to whole electro-mechanical systems and works on weekly-programmed bases. The footprint area of the building is about 600 m/ floors including all activities and also recreation center, parking, conference, meeting and food court zones. Building simplifications and occupancies, lighting, appliances, visitors and operation period’s schedules were carried out in a detailed manners then it fed to computer based on Cairo Weather data and executed using DOE2 and HAP programs. Gained gathered data were tabulated from both programs and compared with measured data. This study demonstrates that: during normal operations criteria, there is a good agreement in annual energy consumption behaviors and curve shapes between numerically simulated data and the experimentally collected data. While the energy predicted demands are 7% lower in values than the actual measured demands. Moreover according the actual operations of the annual energy consumption behaviors and curve shapes are slightly offsets towards high limits than the predicted consumption and predicted consumption is lower then actual by about 20%.