Kmix value for industrial ventilation
1-If there is a perfect air mixing, what is the Kmix equal to? Tell me where you find the information.
2-What’s the typical Kmix value for industrial ventilation?
3-IAQ control application to control CO: An automobile garage was contaminated with carbon monoxide. You only have a carbon monoxide meter available and need to use dilution ventilation to control workers over-exposure to CO. If you measure 3500 ppm of CO in the room before turning on dilution ventilation system, and 2000 ppm after 5 minutes of dilution ventilation. Please determine the total time that will take to reduce CO concentration from 3500 ppm to TLV level so that workers will not be overexposed? Assume the room conditions and dilution ventilation system don t change. Hint: use equation 21B in page 4-14.
4-IAQ control application to control temperature: During the summer, the temperature in a large warehouse reaches a steady-state temperature averaging 35 F greater than the outside temperature when the dilution volume flow rate is Q of 50,000 cfm. What volume flow rate would be required if you want to lower the temperature difference to 10 F? Hint: use equation 22 in page 4-15 and example 4-9.
5-What is the TLV for acetone? You need tell me both the TLV value and where you find the value (e.g. online link).
6-A factory located in Colorado has an assembly facility located at the altitude of 5,000 ft and temperature of 70 F. Please use two different methods to determine the df (3 decimals). You must show your calculation processes or show me where to find the answer, and include appropriate unit for full credit.
7-The factory in Colorado is using acetone as solvent, which can be emitted uniformly at the rate of 7 lbs / hour into the plant atmosphere environment. What is q, the emission volume flow rate for acetone? Hint: You need to decide which equation to use (equations 14 and 15 in page 4-3).
8-The factory in Colorado will use a dilution ventilation system to control the average airborne acetone concentration in the factory no more than the 50% of the TLV. Assume a perfect air mixing exists in the factory. What is the dilution air volume flow rate, Qd, needed for the ventilation system. Hint: You firstly need to determine which equation (16 and 17 in page 4-5) to be use.
9-The factory in Colorado has an assembly room of 250,000 cubic feet. Please determine the air change rate (N, ACH) needed to control airborne acetone concentration under 50% TLV. Hint: You need firstly determine which equation of 19 to be used.
10-If the air mixing Kmix is 3 in the Colorado factory, please recalculate Qd and N needed to control airborne acetone concentration under 50% TLV. Other factors (250,000 cubic feet, altitude of 5,000 ft, temperature of 70 F, uniform emission rate of 7 lbs / hour) remain the same.
11-A chemistry lab with 22,000 cubic feet was contaminated with hydrogen sulfide. If dilution air is provided for 15 minutes, what will the average H2S concentration be? Assume STP, q = 0, C1 =1,500 ppm, Kmix = 1.0, and Qd = 2000 scfm.
Sample Solution
Effective ventilation is more crucial than ever in the COVID-19 age. For example, if you want to provide at least 4 air changes per hour (ACH) to every student in a classroom, or a minimum of 20 cubic feet per minute (cfm) of fresh outside air for each person (OA/person) in an open office complex, you’ll want to do everything you can to make sure that the desired airflow reaches each student or office worker. We can estimate the actual amount of air arriving at a certain location using complicated procedures that include temperature and carbon dioxide measurements, computational fluid mechanics, and tracer gases. We might be able to report after that.
