At indoor ice-skating rinks, the resurfacing machine, known as a Zamboni, is typically powered by means of an internal combustion engine that emits air pollutants into the rink building. Let's model the rink as a CMFR, with volume V = 20,000 m^3 and ventilation rate Q = 250 m^3 min^-1. Assume that the carbon monoxide (CO) concentration in outdoor air is negligible. Also assume that the indoor concentration is zero before the Zamboni begins operation, and the ambient air temperature is 15 C. Consider the carbon monoxide concentration that results from one operation cycle of the Zamboni. To resurface the ice, the Zamboni operates for 15 minutes and emits 100 g min^-1 of CO during operation. (a) What is the peak CO concentration in the air in the rink during and after the single Zamboni operation cycle?
(b) Sketch the CO concentration in the rink air versus time for a 2-hour period beginning with the start of the resurfacing operation.
(c) A skater exercises on the rink for 1 hour beginning immediately after the resurfacing operation is complete. What is the CO concentration at the end of that hour?