Simplified Procedure for Calculating Exhaust/Intake Separation Distances

摘要

The purpose of this research project is to provide a simple yet accurate procedure for calculating the minimum distance required between the outlet of an exhaust system and the outdoor air intake to a ventilation system to avoid reentrainment of exhaust gases. The new procedure addresses the technical deficiencies in the simplified equations and tables that are currently in ANSI/ASHRAE Standard 62.1-2016, Ventilation for Acceptable Indoor Air Quality (ASHRAE 2016a), and model building codes. This new procedure makes use of the knowledge provided in Chapter 45 ofthe 2015 ASHRAE Handbook-HVAC Applications (ASHRAE 2015), and was tested against various physical modeling and full-scale studies. The study demonstrated that the new method is more accurate than the existing Standard 62.1 equation, which under-predicts and overpredicts observed dilution more frequently than the new method. In addition, the new method accounts for the following additional important variables: stack height, wind speed, and "hidden " intake. The new method also has theoretically justified procedures for addressing heated exhaust, louvered exhaust, capped heated exhaust, and horizontal exhaust that is pointed away from the intake.