Experimental and Computational Investigations of Air Flow and Thermal Patterns in Air Conditioned Power Transformers Room

Abstract

The present paper deals with experimental and numerical investigations of the influence of ventilation and air Conditioning supply and extract openings on Air flow pattern and the temperature in a large industrial transformers room. This work focuses on air flow patterns and thermal behavior in industrial building. The effectiveness of a air flow system is mainly determined by the removal of internally produced heat from the transformers in the room (if any) and the supply of fresh air of acceptable quality in the room to replace warm air and reduce thermal load in the zone in question. This is targeted to attain desired temperature regulation for human thermal comfort and machine safe operating thermal conditions. The present experimental facilities include a main actual transformers room which is part of an industrial facility and having principal dimensions of 17 m long x 14 m wide and 6 m high. It includes mainly four dry type transformers; mounted on a concrete skid. The air supply comprises single supply circular duct with four supply outlets. The Extracted air side consists of a single circular duct located at the other end of the room. The transformers were identical units that have the dimensions of length 1.6 m x 2.0 m wide and 2.0 m high. The present local velocity measurements were obtained with a heated wire velocimeter while Platinum Resistance thermometers were employed to measure local temperatures in the room and vicinity of heat source. A numerical study was carried out to define the optimum airside design of the HVAC systems that provides the optimum ventilation and energy utilization. The present model is packaged as a Computational Fluid Dynamics (CFD) program embedded in Code. The numerical approach solves the partial differential equations governing the transport of mass ,three momentum, energy and species in a three dimensional domain under steady state conditions. Grid nodes were densely located in the vicinity of the heat source. The primary objective of the present work is to assess the airflow characteristics and Heat transfer in large air-conditioned configurations with large heat source; reasonably good agreement between measured and predicted air velocities and temperatures were reported. The paper ends with a brief discussion and conclusion. INTRODUCTORY REMARKS Rooms containing electrical power distribution equipment require special attention when designing the air conditioning and ventilation system to attain proper operating conditions. Due to their location in the building, electrical closets are typically served by the building air conditioning system and are provided with conditioned air to meet both heating and cooling requirements. Spaces containing substations or service switchgear are often located near the building perimeter and may be served by conditioned air or outside air ventilation. Because the cooling loads of these equipment can be relatively very high, it is often desirable to avoid mechanical cooling and the associated capital and energy costs.