Numerical computations of the fluid flow and heat transfer in air-conditioned spaces

摘要

One of the main objectives of good 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 such as living, conferencing, etc. In the case of the special purposes spaces such as the healthcare buildings the objective of supplying conditioned air are to control the space temperature and humidity as well as to remove or dilute airborne bacterial, microorganisms, and waste anaesthetic gas contaminants. The recent advances in air conditioning technologies and implementation had led to better performance, development and modifications to air flow pattern in air conditioned rooms design for ultimate comfort and healthcare. 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 as well as the cleanliness. The present work fosters mathematical modeling techniques to primarily predict what happens in the air-conditioned spaces (general purposes space and surgical operating theatre) in terms of flow regimes, turbulence, heat transfer and their interactions. The present work is basically concerned with the difference in the manipulation of the air-conditioning in the two different cases, and is based mainly on the numerical solution of Navier-Stocks equations with the aid of k-ε equations to model the turbulent characteristics. The governing equations of mass, momentum, and energy are commonly expressed in a present form with source terms to represent pressure gradients, turbulence, viscous action and heat transfer. The physical and chemical characteristics of the air are obtained from tabulated data in the literature. The flow regimes and heat transfer were consistently found to play an important role in the efficiency and utilization of energy. This behavior was found to be strongly dependent on turbulent shear, mixing, blockages, wall conditions, furniture, and location of supply and return grilles.