Final Report: Technology for the Reduction of Particulate Matter Emissions for Residential Propane BBQsEPA Grant Number: SU835698
Title: Technology for the Reduction of Particulate Matter Emissions for Residential Propane BBQs
Investigators: Tam, Kawai , Cocker, David , Mejia, Alonso , Christopher, Phillip , Luck, Brian , Madrigal, Andrew , Situ, Kalyn , Tayag, Matthew
Institution: University of California - Riverside
EPA Project Officer: Hahn, Intaek
Project Period: August 15, 2014 through August 14, 2015
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2014) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Built Environment , P3 Awards , Sustainability
The objective of the research is to reduce the amount of PM2.5 emissions by 50% from a residential barbecue using two methods: a grease catchment device to catch grease produced during cooking, and a catalyst filter to reduce any fugitive PM2.5 emissions. The catchment device will be attached below the grill grate, which will prevent meat grease from coming into contact with any open flames. This will prevent grease particles from volatilizing and producing smoke, which carry PM2.5. During the cooking process, the catalyst filter will serve to react with the smoke produced before being released into the atmosphere, PM-free. By preventing the grease from volatilizing and effectively processing the smoke produced, a significant reduction of PM2.5 can be obtained.
To quantify the reduction in the amount of PM2.5 emissions from a residential barbecue using a catchment device and catalyst, our team partnered with the College of Engineering - Center for Environmental Research and Technology (CE-CERT), a facility affiliated with the University of California, Riverside. The testing protocol for our barbecue design was evaluated at CE-CERT using the commercial cooking chamber. The chamber contained a large-sized fume hood connected with air quality monitoring instruments to detect concentrations of total PM and hydrocarbon emissions.
The barbecue design uses a catchment device made out of a galvanized steel sheet that is meant to be slid in and out of the grill during the cooking process. In order to facilitate this action, a rectangular cut on the left side of the barbecue was made to weld steel tracks below the grill grates. Next, three ceramic honeycomb cordierites made of alumina magnesia silicate, were coated with 1 wt % of three metal catalysts. Platinum, rhodium, and nickel, were chosen on a range of catalytic potential for the treatment of smoke produced. Consequently, a smokestack system comprised of a steel mesh baffle with housing and carbon steel pipe, were constructed to support the catalyst and secure it in place. The smokestack was attached to the top-right of the barbecue cover to funnel the hot smoke towards the catalyst and filter the emissions.
A protocol for testing at CE-CERT was determined after preliminary trials in order to obtain an appropriate cooking time, steady-state temperatures, and allocation of burger patties. Cooking time was set at 5 minutes for each cooking cycle to obtain a standard medium rare burger patty. The barbecue, equipped with propane, was set at the highest open flame setting and left to preheat until an equilibrium temperature was reached. An equilibrium temperature range between 290 – 310˚C was considered to be the starting temperature of each cycle as measured by a thermocouple at the catalyst site. Four burger patties with 21% fat content were then allocated for each cooking cycle and placed at the center of the grill grate for maximum heat transfer.
Temperature measurements were recorded every minute with the burger patties being flipped at the 3-minute mark and keeping the grease catchment inside only during the flipping step. Before starting the next cycle, the barbecue was allowed to run until the equilibrium temperature was reached.
As determined per the averaged trials among platinum, rhodium, and nickel catalysts, the most effective at reducing PM2.5 was nickel. When combined with the grease catchment and baffle, PM2.5 was reduced by 40% as compared to the control which did not include any reduction technology (baffle, catchment, or catalyst). Several observations through individual cycles proved difficult to control the smoke produced and keep a fully smoke-contained system. The barbecue was modified to cover a cross section of the back cover and sides to maintain the smoke inside. Further testing showed a continued escape of smoke through the rectangular cut set for the grease catchment.
Using our barbecue design, we implemented a grease catchment, baffle, and nickel catalyst in order to obtain a 40% reduction in PM2.5. The average reduction rate for our technology was 21.2 ± 0.45 mg/m3∙s. With more robust smoke containment, the barbecue can be fully secured and maintain a closed system throughout. By doing so, higher reduction rates and an overall reduction in particle pollution can be achieved. The nickel catalyst was more effective in terms of catalytic activity which can be attributed to the preparation method of the catalyst, the interaction between the metal and substrate, and temperatures present in each cycle of testing.
Compared to platinum and rhodium, nickel conversion temperatures may be lower which is important to consider for the type of grill we are using. Maximum recorded temperatures were approximately 350˚C. Assuming all other variables are constant for each cycle, temperature fluctuations can be attributed to the loss of heat and inconsistency in flipping time. An approximated window of 15 to 20 seconds was given to flip all four patties in consecutive order, however this proved to be difficult. Therefore, the longer the barbecue cover remained open the more untreated smoke was released.