Exhaust Recirculation - A Technology to Minimize Energy Use in Aircraft Painting Operations

摘要

The mandate in DoDD 5000.1 to manage risk as an element of acquisition cost control enabled Robins AFB's justification for incorporation of 80% exhaust recirculation into the design for construction of a corrosion control facility (CCF) for C-5 aircraft that will enter service in 2007. A key tool in developing their justification was the LaPuma model, a process model into which a user inputs facility and process parameters to calculate the steady-state background air concentration of process-derived contaminants as a function of percent exhaust recirculated. The assumption that isocyanates-the exposure risk driver in topcoats-are an inert, ideal gas rather than a reactive, sticky vapor causes their concentration to be overestimated, and exposure data from the C-5 CCF are expected to clarify the extent and moment of this overestimation. In 2005 Elmendorf AFB followed Robins lead and precedents in designing a C-17 CCF at 80% recirculation to save several $M in construction costs and $0.5M annually in fuel costs to operate. Predicted isocyanate concentrations for a (smaller) F-22 component repair facility (CRF) required interpretation and Elmendorf specified a conventional design in their bid request. That the only proposal whose cost was within the project budget included 80% recirculation created a situation that was ultimately resolved by a meeting of the design team, users, bioenvironmental engineering and the successful bidder that ended in consensus that the proposed design as modified in the meeting constituted an acceptable risk benefit trade. However, that the situation arose demonstrates the need for explicit guidance to ensure that future decisions about recirculating hangar designs be made early on as a consensus among key offices at base level.