Ramiz Kameel

Energy Efficiency, Air Quality, and Comfort in Air-Conditioned Spaces

To design an optimum HVAC airside system that provides comfort and air quality in the air-conditioned spaces with efficient energy consumption is a great challenge. This paper evaluates recent progresses of HVAC airside design for the airconditioned spaces. The present evaluation study defines the current status, future requirements, and expectations. It has been found that, the experimental investigations should be considered in the new trend of studies, not to validate the numerical tools only, but also to provide a complete database of the airflow characteristics in the air-conditioned spaces. Based on this analysis and the vast progress of computers and associated software, the artificial intelligent technique will be a competitor candidate to the experimental and numerical techniques. Finally, the researches that relate between the different designs of the HVAC systems and energy consumption should concern with the optimization of airside design as the expected target to enhance the indoor environment.Copyright

Numerical Investigation of the Airborne Contaminant Age in Surgical Operating Theatres

The present paper is devoted to investigate influence of the airside design of the HVAC systems of the surgical operating theatres on the airborne contaminant age distribut ion and on the Indoor Air Quality (IAQ). The present work stressed on the importance of the airborne contaminant age distribution and its relation with the airflow distribution. The present paper utilizes a Computational Fluid Dynamics CFD model in the pre diction procedure. The present paper discusses several practical designs to provide useful recommendations for the designers.

Energy Efficiency Analyses of Air-Conditioning Systems in Commercial Buildings in Egypt

Many buildings around the world utilize HVAC systems to provide the thermal comfort conditions for the occupants and users of these buildings as well as providing adequate conditions for special environmentally sensitive equipment. The appropriate air conditioning system design would necessarily provide the comfort and hygiene conditions with as low as possible initial capital and operating costs. The present study provides comprehensive analyses and comparisons between the water-cooled vs. air-cooled chillers with packaged water-cooled DX unit systems under the local Egyptian climatic conditions, primary water and energy prices and legistilations. The present study presents a comparison among the various systems according to the equipment and installation, operating, and maintenance costs. Based on the above analyses and the data collected with the prevailing prices, energy, water and maintenance costs at January 2003 in Egypt. It is apparent that water-cooled packaged units are of superior performance in terms of energy consumption and initial costs.Copyright

THE PREDICTION OF AIRFLOW REGIMES IN SURGICAL OPERATING THEATRES: A COMPARISON OF DIFFERENT TURBULENCE MODELS

The air quality of the indoor environment is capable of affecting human comfort in a multitude of ways, depending on the contaminant. Airborne contaminants range from toxic substances such as carbon monoxide to nuisance matter such as large dust particles. There are literally thousands of air contaminants, each of them affects on the human body. It is necessary to understand how the body handles pollutants as well as the contaminants themselves and the symptoms they inflict on the human body. The airborne contaminant affects human health at different levels depending on the nature and type of contaminant. Hospitals and other health care facilities are complex environments that require ventilation for comfort and to control hazardous emissions for patients, personnel and visitors. Indoor air quality is more critical in health care facilities than in most other indoor environments due to many dangerous microbial and chemical agents present and due to the increased susceptibility of the patients, especially immunosuppressed persons. To arrange ventilation capable of efficiently fulfilling all, often-even contradictory, needs is a great challenge; adequate solutions have not yet been found for many indoor air quality problems. In addition, the importance of good indoor climate is not yet unanimously recognized. Therefore, nosocomial infections due to contaminated air continue to cause unnecessary costs and sufferings, and health care personnel remains subject to several occupational exposure risks. In addition, indoor climate fails often to be comfortable, Healthy Building 2000. Proper predictions of airflow regimes inside the healthcare applications, especially the surgical operating theatre, enhance our design decisions of the HVAC systems or even the earlier architecture design. Proper turbulence models can aid in that task, which lead engineers to accurate description of the airflow characteristics inside the surgical operating theatres. The present work is devoted to predict the airflow regimes inside different configurations of surgical operating theaters, using three different turbulence models. These three models are; namely standard k-e model (Launder and Spalding), RNG model and the phenomenological model of (Li and Zhao) that based on DNS (Directly Numerical Simulation) data. The three models were utilized to predict the airflow regimes, turbulence heat transfer interactions. The obtained results suggest the use of the approximate model for engineering purpose. The k-e model is superior in predicting flow characteristics in near wall and steep gradient zones.

SIMULATION OF FLOW, HEAT TRANSFER & RELATIVE HUMIDITY CHARACTERISTICS IN AIR -CONDITIONED SURGICAL OPERATING THEATRES

One of the main objectives of ideal air distribution in heating, ventilation, and air conditioning systems is to create proper combination of temperature, humidity, and air motion in the occupied zone of the air -conditioned room. Recent advances in air co nditioning technologies and applications had led to better performance, development and modifications to air flow pattern in air conditioned rooms design for ultimate comfort, Berglund 1 , Hosni et al. 2 and Medhat 3 . The healthcare requirements take differ ent views depending on the air conditioning applications. The healthcare in residential applications is completely different than those in the medical applications, due to the nature of applications, and occupants. Pioneers in the medical applications enfo rced many restrictions to the comfort criteria requirements to form health criteria. These criteria were accumulated and compiled to healthcare standards such as ASHRAE standard for the residential and commercial applications and the National Health Servic e (NHS) standard for the healthcare applications. Recent development of experimental measuring techniques for air temperature, relative humidity, velocities, and turbulence intensities in flow regimes had aided better understanding of flow phenomena, heat transfer and turbulence interactions. Extensive efforts are exerted to adequately predict the air velocity and turbulence intensity distributions in the room and to reduce the energy requirements and noise to ultimately produce quite and energy efficient air conditioning systems. The present work fosters mathematical modeling techniques to primarily predict what happens in the air -conditioned surgical operating theatre in terms of flow regimes, heat transfer and their interactions. The governing equations o f mass, momentum and energy are commonly expressed in the present finite difference form with source terms that represent pressure gradients, turbulence, viscous action, and heat transfer interactions. A full three dimensional computational scheme, 3DHVAC, Khalil 4-6 , Kameel 7,8 , and Kameel and Khalil 9-11 , was developed and used to predict the air flow regimes, relative humidity and heat transfer characteristics under actual room geometrical and operational conditions. The paper demonstrates the usefulness of utilizing such numerical procedures to adequately predict air conditioned air behavior in operating theatres.

IMPACT OF INDOOR ENVIRONMENT ON HUMAN HEALTH "EGYPTIAN EXPERIENCE"

This study is concerned with the impact of indoor environment on t he local National health in air conditioned spaces. The present study is carried out in different applications in Egypt. Two different methods are utilized in the present study. An experimental measurement program and comprehe nsive survey are carried out for some air conditioned applications. The numerical methods are also utilized to simulate applications that represent the effect of indoor environment on occupancy health using different indoor air quality indices. The present study is carried out in different applications of healthcare hospitals, com mercial buildings and residential premises etc.

EFFECT OF SWIRL ON FLAME CHARACTERISTICS IN FURNACES

This paper reports the effect of swirling on the transient fl ame characteristics using a numerical method. A numerical me thod that is designed to predict the transient flow characteristic s in three-dimensional furnace configurations at high Reynolds numbers is incorporated in the present work. Numerical analysis is followed to represent the effects of the swirl number on flow and heat transfer in fire tube boiler furnaces. The effec t of air stream swirl on the recirculation zone was also investigated, and is presented in the present work. Radial swirl was found to ha ve an observed significant effect on the flow field. The present study aimed at presenting the furnace flow characterist ics under air stream swirl design conditions for optimum effective combustion. The present work made use of 3DTCOMB, a three dimensional time-dependent numerical scheme to obtain a more comprehensive view of the flame development in the different fire-tube boiler furnaces and in power plant boilers with multi-burners. The time dependent results are meant to demonstrate the present numerical capabilities and to assis t designers and engineers to pursue optimum design with reasonable cost.

Energy efficient air conditioning systems in hospitals operating theatres

Optimization of airflow regimes, heat transfer for comfort and hygiene in operating theatres is one of the main goods of energy efficient building strategies. Most of operating theatres operates on 100 % fresh air principles; typically requiring excessive fresh air cooling loads particularly in hot and humid climates. Attempts were reported by Kameel and Khalil (2000, 2001, and 2002), Hosni et al. (1996) to specially optimum room flow pattern and turbulence levels. The present work fosters a mathematical approach to numerically predict the flow regimes, heat transfer and relative humidity in surgical operating theatres of different geometries. Full three-dimensional solves of the governing conservation equations of mass, momentum, energy and species concentration was utilised in the present work with the k-/spl epsiv/ turbulence model closure. The orthogonal grid nodes mapping the flow field comprised 144000 grid nodes and made allowance for adequate represent of the operating table geometry. Predicted air velocity contours and dry bulb temperature distributions were obtained for a 6/spl times/5/spl times/3 m operating theatre. Those predictions were compared to experimental data published in the literature; quantitative agreements were generally shown. The predictions adequately outlined the various regimes that were in trend-wise agreement with experiments. Parametric design modifications were also carried out to endeavor the enhancement of energy efficiency of the systems in operating theatres.

Experimental Investigation of Flow Regimes in An Operating Theatre of 1200-Beds Teaching Hospital

Optimum design of air condition in surgical operating theatres requires more careful and refined control of flow and temperature characteristics to achieve sterile and comfort conditions. The present work is devoted to analyze the performance of HVAC system design in practical operating theatre in 1200-beds of Egyptian modern teaching hospital. The present experimental program comprises field measurements of air velocity, and temperature, in the vicinity of supply air diffusers and operating area. The obtained experimental results illustrate the distinct interaction of the HVAC system design parameters. The present work introduced some recommendations to ensure prevailing aseptic conditions and also demonstrated the effect of air conditioning system design on the temperature distribution the operating theatres.

Experimental and Numerical Investigations of Temperature and Relative Humidity in Different Surgical Operating Theaters

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, 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. This paper is devoted to the numerical and experimental investigations of the influence of the surgical operating theatre geometrical and airside design on the temperature and relative humidity distributions to create sterile conditions in the theatre. The present work offers examples of measured relative humidity profiles in an operating theatre in (New Kasr El-Aini Teaching Hospital – 1200 beds – Cairo University – Egypt). These experimental results were carried out to verify the proposed numerical procedure and particularly in the vicinity of the supply outlets and operating table.