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Jim Smith, Mikael Salonvaara and Jensen Zhang Building Energy and Environmental Systems Laboratory (BEESL). Material Emissions and Pollutant Transport in Building Envelopes T1.A Experimental – VOC Extraction. VOC Extraction – Primary Focus.
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Jim Smith, Mikael Salonvaara and Jensen Zhang Building Energy and Environmental Systems Laboratory (BEESL) Material Emissions and Pollutant Transport in Building EnvelopesT1.A Experimental – VOC Extraction
VOC Extraction – Primary Focus Development of a Procedure / Standard to determine the initial concentrations of emitted VOCs from building materials. • Uses for Standard: • An important parameter for predicting the VOC emission rates over a long period of time. • The method can be useful for rapid screening of materials, enabling manufacturers to compare different production processes in order to reduce VOC emissions from their products.
VOC Extraction: Schematic PI&D PPBRAE GRINDING BOWL RECIR PUMP 50 LITER CHAMBER RECIR PUMP VIBRATION TABLE PPBRAE
VOC Extraction: System MIXING ASSEMBLY GRINDINGBOWL RECIR PUMP CLEAN AIRCONNECTION 50 LITER CHAMBER EXHAUST CONNECTION GREYWOLF CONNECTION
OSB: Specimen preparation SAMPLE BEFORE GRINDING AFTER GRINDING
Data Analysis • Mass exhausted from the chamber & re-circulation loop : where, i=1, 3, 5, represent the starting time point of each decay, respectively. • Mass of each TVOC & individual VOCs for each period of the decay: First Decay Second Decay Third Decay • Note that t6 should approach infinity in the evaluation, or be sufficiently large so that the remaining VOCs in the source becomes negligible. • Specific values for t6 depend on the material, and recommendations will be provided/defined during the data analysis.
Data Analysis • The total emittable mass (M) for a given compound or TVOC is found by summation of the calculated mass ventilated in all decay periods: • Mass adsorbed in the material at equilibrium before each decay period: where, Mei represents the VOC mass adsorbed in the material right before the start of decay period i, g.
Data Analysis • Partition Coefficient, Kpi: • The partition coefficient is calculated for each equilibrium condition before each decay period: • Rate Constant (slope of the isotherm curve), Kci: • The rate constant Kci is estimated for the concentration range between two adjacent equilibrium conditions right before the decay periods: Where, • Mei = Mass of a VOC or TVOC in material sample at equilibrium before decay period i - g • Cei = Equilibrium concentration right before decay period i - g/m3 • Vloop = Volume of the chamber including the recirculation loop – m3 • Vmat = Volume of material – m3
Initial VOC Concentrations and Partition Coefficients TVOC from OSB: • Measured initial concentration: 41 g/m3 • Total mass density of the material: 526 kg/m3 • TVOC content: 0.0078% mass (not listed in MSDS) • With an emission factor of 0.5 mg/(m2h), it takes 1.5 month to deplete from one-sided surface • Partition coefficients (Kpi, rate constant (Kci), and sorption curve
What is next? • Sorption curves for individual VOCs • Analyze data obtained for gypsum board and fiberglass insulation • Refine and improve test procedure • Evaluate the accuracy and repeatability of the test method • Conduct tests for additional materials • Compare results with data from other laboratories • Virgin Tech. (Prof. John Little) • NRC/IRC (Dr. Don Yong) • Concordia University (Prof. Fariborz Heighihag) • Tsinghua University (Prof. Yinping Zhang/Dong Yang)