Question

Two of the most widely used cooking stoves in Ghana are the wood-burning cookstove and Gyapa charcoal cookstove. 

According to published emissions testing results, the PM2.5 emission rates of the wood-burning stove are 169.8 mg min–1 and 9.95 mg min–1 , respectively.1 Use Excel and solve parts a–d for each 1-minute time step. Include plots showing the change in concentration with time. 

(a) For a kitchen sized 2.5 m x 2.5 m x 2.5 m, calculate the PM2.5 concentration in units µg m–3 after 60 minutes of cooking for both stoves. Assume the initial PM2.5 concentration is zero, airflow through a poorly-ventilated room occurs at 0.35 m3 min–1 , the deposition velocity of PM2.5 is 0.04 cm s–1 , and the cookstove emission rates are constant regardless of cooking stage. 

(b) For both stoves, how long would it take after cooking for the PM2.5 concentration to return to zero? 

(c) The World Health Organization (WHO) emissions target for an unvented stove is 0.23 mg min–1 . What would the PM2.5 concentration be after 60 minutes of cooking on a stove that meets the WHO target? 

(d) Airflow through a well-ventilated room occurs at 1.7 m3 min–1 , what would the PM2.5 concentration be after 60 minutes of cooking on a stove that meets the WHO target here?