Power house building has a high rate of heat generation and conventional Ventilation system uses air washers for supply of air and Electrically Driven Roof Extractors for exhaust. Air from Air Washers is distributed by means of GSS (Galvanized Steel Sheet) ductwork to the TG building comprising ground, mezzanine and operating floor and near various heat sources like turbo-generator, condenser, Boiler feed pump HP & LP heaters, oil coolers (oil room) etc. This paper is based on the study carried out for implementing exhaust ventilation system based on Turbo-ventilators for a 350 MW power plant. The exhaust ventilation system implemented in the project utilizes forced circulation by means of Air washers to supplement the natural exhaust ventilation and increased air flow.

Use of turbo ventilators based on the principles of natural ventilation in place of Electrically Driven Roof Extractors has the potential to reduce auxiliary power consumption significantly. The paper studies the phenomenon of natural ventilation and analyzes the effect of wind and thermal buoyancy on pressure difference to determine the number of ventilators required for achieving the desired ventilation. During the study a method was derived to calculate the capacity of ventilators for site condition. The governing feature of the flow under natural ventilation is the exchange between the inside air of the building and the external ambient air. Both the wind speed of the outside air and temperature variation between the inside and outside air play a controlling feature in the natural ventilation. Two forms of pressure differences were studied: Natural draft inside the building and pressure difference created by wind flow outside the building. In this study the dynamics of buoyancy-driven flows were considered, and the effects of wind on them were examined. The aim behind this work is to give designers/engineers rules and concepts to study the air flow pattern within a building and provide alternative means of exhaust ventilation.