Question

Assume that the same person described in Problem 21.9 luckily
survives the charcoal grilling incident, but the next week his oil
furnace flue unluckily springs a leak, and starts leaking CO
into the apartment at a rate of 25 g/min. Recall that the ventilation
rate is only 0. 75 ach. Luckily, after the grill incident, he
bought a CO alarm system. Unluckily, he forgot to set the audible
alarm to "On," so he stays asleep. Luckily, the alarm still
sends a silent alarm signal to the fire department, and they
arrive 45 minutes after the leak started. They break open the
windows and rescue the (lucky/unlucky) person. Create a
spreadsheet to plot the concentration of CO in the apartment as
a function of time for the first 45 minutes after the start of the
leak. Continue the plot for the next 45 minutes, assuming that
when the firemen arrive and break open the windows, the
apartment ventilation rate jumps up to 2.5 ach. Also, they turn
off the oil heater

Answer 1

Write the material balance as a finite difference equation using the expression; At Διν Here Sis the source emission rate of pollutant inside the room Qis the ventilation rate, Vis the volume of the room » C indoor concentration of the pollutant at any time t tis the time (duration of emission of pollutant) is the air exchange rate, expressed in units of air changes per hour (ach) AC/At) is the change in indoor carbon monoxide (CO) concentration corresponding to time interval Δt Take that the initial time corresponding to the start of Carbon monoxide emission as 0 Also assume that Δ-1 min The indoor CO concentration corresponding to the start of emission of CO (t=0 min) is zero Calculate the change in indoor CO concentration, (AC,/At) in the room after the start of emission of CO and before 1 minute, use Equation (1) with indoor CO concentration as Calculate the value of indoor CO concentration for the duration of 1 minute by adding the Indoor CO concentration at t-lmin and the indoor CO concentration between time duration of 0-1 minute Repeat the process for remaining time durations of 90 min. Note: After the 45 minutes use the emission rate, S as zero and the air exchange rate as 2.5 ach for further calculation of change in CO concentration.

Plot a graph for the concentration of CO versus time using the calculated values of indoor 8 CO concentration for every 1 minute time interval from the start of emission of CO to 90 minutes Show the plot of concentration of CO in the apartment as a function of time. Indoor CO concentration versus time E 5000 S 4000 3000 O 2000 드 1000 0 0 10 20 30 40 50 60 70 80 90 100 Time, (minutes)