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ROOM AIR CONDITIONING Chapter 8 PER OLAF TJELFLAAT LARS OLANDER ESA SANDBERG HANNU KOSKELA KIM HAGSTRÖM ALEXANDER ZHIVOV TIMO HAUTALAMPI HÅKON SKISTAD RALF WIKSTEN MAMDOUH EL HAJ ASSAD DGB FUNDAMENTALS, Chapter 8 • INTRODUCTION • Central Recirculation System • BASIS FOR AIR CONDITIONING • Local Recirculation DESIGN • Conclusion • Industrial Process Description • TWO-ZONE MODEL DESCRIPTION • Zonal Models • Requirements for Indoor Environment • Two-Zone Model • Architectural Design for an Industrial • Two-Zone Model Calculation Enclosure • References • Worker Involvement in the Production • EFFECTIVE AND EFFICIENT VENTILATION Process • Ventilation Efficiency Indices • Load Calculation • Contaminant Removal Effectiveness • Characterization of Room Airflow and • Contaminant Removal Efficiency Thermal Conditions Based on • Air Exchange Efficiency Industrial Production Process and • Air Distribution Performance Index Envelope References • Analyses and Actions to Be Considered Prior to Performing Room Air Conditioning Design • AIR RECIRCULATION • Introduction • Different Recirculation Systems DGB FUNDAMENTALS, Chapter 8 • ROOM AIR CONDITIONING • Zonal Air Distribution STRATEGIES • References • Introduction • LOCATION OF GENERAL EXHAUST • Classification for Room Air • Exhausts in Nonstratified Room Air Conditioning Strategies • Exhaust of Buoyant Contaminants • Piston Strategy • Exhausts in Stratified Room Air • Stratification Strategy • Location of General Exhaust to Create • Zoning Strategy Displacement Flow • Mixing Strategy • HEATING OF INDUSTRIAL PREMISES • Application of the Strategy in System • General Selection • The Heating Power Demand • Summary • The Heating Energy Demand • References • Radiant Heating • AIR DISTRIBUTION METHODS AND • Hot Air Blowers DIMENSIONING • Selection of Air Supply Methods and • Air Jets Dimensioning • Floor Heating • Mixing Air Distribution • References • Piston Flow • Displacement Flow INTRODUCTION • The scope of this chapter is to show how to select a strategy and to make calculations to provide efficient room air conditioning for an industrial enclosure. • Design examples for simplified scenarios include different ways to condition industrial halls. BASIS FOR AIR CONDITIONING DESIGN Upon starting design for an industrial enclosure, expected use should be described by informing and questioning the building owner and future users. A scenario of the planned industrial enclosure should be sketched. The scenario should describe: – The different steps of the flow and batch processes of the industrial production. – Space demands for machinery, tools, working, and stocking areas for raw materials and products. – Demand for worker involvement in each part of the industrial process. – Emission of heat and contaminants from each part of the industrial process. – Environmental requirements for each part of the industrial process. The factory scenario must be updated with new information as the design process evolves. Classification for Room Air Conditioning Strategies • The aim of room air conditioning is to maintain desired conditions, target levels, in the room during different operating conditions in the most economical way (energy, cost efficiency). • Depending on the design criteria, the designer may choose different strategies in order to achieve specified targets. FIGURE 8.9 The room air conditioning design and evaluation process. TABLE 2.1 Ideal room air conditioning strategies AIR CONDITIONING PISTON STRATIFICATION ZONING MIXING STRATEGY: DESCRIPTION To create unidirectio- To support flow field To control air conditi- To provide uniform nal air flow field over created by density ons w ithin the selec- conditions throughout the room area by differences by replacing ted zone in the room the ventilated space supply air. the airflow out from the by the supply air and room area w ith allow stratification of supply air heat and contaminants in the other room areas HEAT, HUMIDITY Room dimension EX Room dimension EX Room dimension EX Room dimension EX AND CONTAMINANT DISTRIBUTION (Pictures) X-axis: °C, mg/m3, g/kg Y:axis: Room dim. (e.g. height) SU=supply, EX=exhaust SU T, C, x SU T, C, x SU T, C, x SU T, C, x MAIN Room air flow patterns Room air flow patterns Room air flow patterns Room air flow patterns CHARACTERISTICS: controlled by low controlled mainly by controlled partly by controlled typically momentum unidirectional boyancy. Supply air supply and partly by by high momentum supply air flow , strong distribution w ith low boyancy. supply air flow . enough to overcome momentum. disturbances IDEAL CONTAMINANT- AND 1 8 HEAT REMOVAL EFFICIENCY TYPICAL APPLICATION (An example of a general room air distribution method ) TABLE 8.8 Ideal Room Air Conditioning Strategies FIGURE 8.32 The key flow elements in the zoning strategy. FIGURE 8.33 Two-zone temperature model of the zoning strategy. FIGURE 8.34 Two-zone concentration model of the zoning strategy.
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