Design of Dilution Ventilation for Sensible and Latent Heat

Abstract

Abstract The design of dilution ventilation for control of heat stress requires consideration of both sensible and latent heat. Heat balance equations are used to develop a design procedure which takes into account both forms of heat. By use of the WBGT index in the American Conference of Governmental Industrial Hygienists Threshold Limit Value (TLV) for heat stress, a limiting exposure value for the natural wet bulb temperature in a workplace can be determined. The psychrometric chart constant enthalpy line for moist air associated with this limiting natural wet bulb temperature, along with psychrometric conditions of available dilution air, permits calculation of the amount of dilution ventilation required to satisfy the TLV. For design of dilution ventilation for plants or processes not yet in operation, values for the amounts of latent and sensible heat to be released to the ventilated space and mixing coefficients may have to be estimated. For existing processes or operations, the measurements of ven...