Measurements of grease emission and heat generation rates of electric countertop appliances (RP-1631, part 1)

Abstract

The main objectives of this research were to improve the understanding of the characteristics of the grease emission and heat generation from electric countertop appliances, and to determine the amount of grease particulate/vapor production as well as sensible and latent heat gains from 20 commercial electric countertop appliances under cooking conditions. The grease particulate and vapor were captured by a Type II hood, and the concentrations were measured using EPA Method 5 in the exhaust duct under an exhaust flowrate of 0.24 m3/s (500 cfm). An energy balance protocol was used to determine the heat generation of these appliances during both idle and cooking conditions. The results indicate that the rate of grease particle and vapor emissions concentration for the 20 appliances tested ranged from 0.12 to 8.27 mg/m3. Only three appliances, the hot plate range, rapid cook oven (cooking with chicken wings or pizzas), and hot dog roller, generated more than 5 mg/m3 of grease at 0.24 m3/s (500 cfm) exhaust flow rate (i.e., 1.18 mg/s in emission rate), which is the threshold of the requirement to use a Type I hood by ASHRAE Standard 154 and UL 710B. The grease particulate matter caught by the EPA Method 5 was itemized by weight and analyzed as follows: filter catch, probe (acetone) catch, impinger (DI water) catch, and solvent extract (dichloromethane). The cooking sensible convective heat had a similar trend as the cooking energy consumption rate, except for the deep fryer and steamer countertop. However, the cooking latent convective heat depended more on the food material and whether or not steam was used to heat the food. The largest cooking latent convective heat was given by the steamer countertop, and the lowest was given by the hot plate and rice cooker. The effects of the duration of the test and the cooking time on the test results were also studied. It was found that three replicate tests with about 40 minutes each could generate similar reults as a 4-hour long test, hence a longer test duration (such as the 8-hour cooking test specified in UL 710B) may not be necessary. The study provides previously unavailable data of grease emission and heat generation rates for the design and analysis of kitchen spaces with countertop electrical appliances. They are used to update the current Table 5A; Recommended rates of radiant and convective heat gain from unhooded electric appliances during idle (ready to cook) conditions of chapter 18 in the ASHRAE Handbook of Fundamentals.