TO-22-C049 - Design, Ventilation and Noise Assessment of an Outdoor HVAC Duct Exposed to Solar Radiation for Pre-Heating of Fresh Air

The requisite amount of ventilation air of the HVAC system depends on heating/cooling load. The load on HVAC system varies with the condition of outdoor ventilation air that may requires additional heating, cooling and humidification or dehumidification. In most of the cases, outdoor air is more economical to use than recycled return air. The heat transfer in an exterior rectangular duct is a function of solar irradiation, air gap width, mass flow rate and pressure, wall and air temperatures. The significance of analysis of an outdoor HVAC rectangular duct is important, for example, in modeling photovoltaic solar wall structures. The complete duct design is based on complete information for the given design conditions and limitations of operation results. The design of an outdoor duct is either based on a velocity method, an equal friction method or a static pressure recovery method. The design of mass flow rate through the duct is based on heating/cooling load on the ventilation system. The aim of the paper is to present an improved method for design, ventilation and noise assessment of an outdoor duct for pre-heating of fresh air through an example of an outdoor duct [2.5 mm aluminum rectangular duct with a size of (0.25 m (H) X 1.0 m (W) X 3.0 m (L))]. The given outdoor duct is exposed to a steady solar heat flux and is installed on a well insulated building façade. The sensitivity analysis for an outdoor duct is conducted for critical design of ventilation requirements and materials with supply of varying outdoor mass flow rate to a single building zone. The improved method is useful for accurately predicting ventilation air requirements through an outdoor duct. Noise, defined as 'a sensation of unwanted intensity of a wave', is perception of a pollutant and a type of environmental stressor. An environmental stressor such as noise may have detrimental effects on various aspects of health. The unwanted intensity of a wave is a propagation of noise due to transmission of waves (viz. physical agents) such as sun, light, sound, heat, electricity, fluid and fire. The noise scales/charts are calculated from the newly devised noise measurement equations and their units by the author. Furthermore, based on these newly devised noise measurement equations, noise assessment calculations of an outdoor HVAC duct exposed to solar radiation are also presented.