(25 pts)Industrial buildings often have air quality monitors to measure whether OSHA or ACGIH standards for contaminant concentrations in the indoor air environment are satisfied. Consider a building in which an indoor air monitoring device records the mol fraction (y) of a particular contaminant every 5 minutes in units of PPM. The sketch below shows several of these readings at times around time t, i.e., at-ti, 1 = 4-1, 1 = 4+1, etc. The data points are separated by equal time spacing, , which for this example is 5 minutes. (PPM) Jya i-1 yi At i-4 I- I- (a) Use the trapezoidal rule of integration to derive a simple expression for the running 15-minute average at time Your expression should contain only y,y;,yi-2, and yi-3. Assume 1-5 minutes. The time increment should cancel out of your final expression (b) Examine the mol fraction record on the spreadsheet "hw 03Problem 02 post.xls" which can be downloaded from the ME 405 web site. Apply your equation from Part (a) to calculate the running 15-minute time average throughout the day. Note: You will not be able to calculate a running 15-minute average for the first few data points for obvious reasons. On the same plot, plot both the instantaneous record and the running 15-minute average (c) Calculate the overall time average mol fraction for this contaminant over the whole day. For this particular pollutant, the OSHA PEL values are PEL-TWA-50 PPM. PEL-STEL 120 PPM, and PEL-C 150 PPM. Determine if the air in this building on this day satisfies OSHA standards. Explain why or why not. (Be sure to check all the criteria.) (25 pts)Industrial buildings often have air quality monitors to measure whether OSHA or ACGIH standards for contaminant concentrations in the indoor air environment are satisfied. Consider a building in which an indoor air monitoring device records the mol fraction (y) of a particular contaminant every 5 minutes in units of PPM. The sketch below shows several of these readings at times around time t, i.e., at-ti, 1 = 4-1, 1 = 4+1, etc. The data points are separated by equal time spacing, , which for this example is 5 minutes. (PPM) Jya i-1 yi At i-4 I- I- (a) Use the trapezoidal rule of integration to derive a simple expression for the running 15-minute average at time Your expression should contain only y,y;,yi-2, and yi-3. Assume 1-5 minutes. The time increment should cancel out of your final expression (b) Examine the mol fraction record on the spreadsheet "hw 03Problem 02 post.xls" which can be downloaded from the ME 405 web site. Apply your equation from Part (a) to calculate the running 15-minute time average throughout the day. Note: You will not be able to calculate a running 15-minute average for the first few data points for obvious reasons. On the same plot, plot both the instantaneous record and the running 15-minute average (c) Calculate the overall time average mol fraction for this contaminant over the whole day. For this particular pollutant, the OSHA PEL values are PEL-TWA-50 PPM. PEL-STEL 120 PPM, and PEL-C 150 PPM. Determine if the air in this building on this day satisfies OSHA standards. Explain why or why not. (Be sure to check all the criteria.)
