Constant speed lines on turbocharger compressor performance maps usually have no test data at low pressure ratio and high flow. The engine, however, can force the turbocharger compressor to operate in this region and whole-engine simulation systems need to extend the test data in some way to include this region of the map. A physically based method of estimating the performance at low pressure ratios from measurements made in the rest of the map has been developed and is described in this article. The method requires no detailed geometrical information on the impeller and the stage but extracts the necessary information from the test data available; hence it can be applied to any measured compressor data.The test data over the measured range of speed and flow are used to estimate the work transfer and loss characteristics of the impeller, and the impeller throat area. The Euler equation justifies a linear extrapolation of the work input to higher outlet flow and a new technique based on the density ratio is used to extrapolate the losses. This accounts for choking at the impeller inlet in a similar way to choking at a one-dimensional duct of varying area, where losses are also a function of density ratio. The stage performance at low pressure ratios can then be obtained by recombining the extrapolated loss and work characteristics at higher flows. The method allows the measured performance map to be extrapolated to low pressure ratios on a sound physical basis and to identify physical aspects of the flow in this extreme off-design region, such as the location of increased risk of oil blow-by.

The desire to build more energy efficient homes in the United States has led to the expansion of the residential spray polyurethane foam (SPF) insulation industry. Upon application of SPF, reacting chemicals form expanding polyurethane foam that fills cracks and gaps, reducing infiltration and thermal conductivity of the building envelope. However, more information is being sought on chemical emissions from SPF to better understand occupant exposures and any potential impacts on health. The objective of this investigation was to investigate the emission of flame retardant tris (1-chloro-2-propyl) phosphate (TCPP) from SPF using both micro-chambers and a full scale residential test facility. Two high pressure, open cell foams and one high pressure, closed cell foam were tested using micro-chambers. After 100 hours, TCPP concentrations from the open cell samples were 100 times higher than TCPP concentrations from the closed cell SPF.TCPP emissions from open cell foam were found to correlate exponentially with temperature and vary with flow rate, indicating emission factors from SPF micro-chamber experiments may not directly predict TCPP concentrations in buildings without consideration of material mass transfer properties. Due to the use of TCPP in furniture, SPF has not previously been positively identified as a primary source of indoor TCPP concentrations in actual buildings. This research measured airborne TCPP concentrations in the furniture-free National Institute of Standards and Technology (NIST) Net Zero Energy Residential Test Facility (NZERTF) that contained 15 m 2 of exposed, two-year-old, open cell SPF. The measured NZERTF TCPP emission rates were not directly predicted by emission factors from the micro-chamber measurements, which suggests a mass transfer-based modelling approach is needed for predicting TCPP concentrations from open cell SPF. More research is needed to determine how data from micro-chamber studies can be used to predict exposures of residential occupants to emissions from SPF foam.