INVESITGATING EFFECTS OF SENSOR ARRANGEMENT AND HARDWARE CHANGES ON MEASURED RANGE-HOOD CAPTURE EFFICIENCY PERFORMANCE

Abstract

Kitchen range hoods remove contaminants released by cooking and are instrumental in maintaining acceptable indoor air qualities. Capture efficiency testing was developed to provide a unified metric describing the performance of a range hood based on its ability to remove contaminated air from the cooking space. The current testing standard set forth in ASTM-E3087 involves releasing an inert tracer gas into a test chamber that simulates a residential kitchen and then measuring the concentration of the tracer gas at three locations to include the air within the chamber, in the chamber exhaust ducting, and finally at the inlet to the chamber. The ASTM standard specifies that a single sensor must be used for all three concentration measurements.

This research study investigates two alternate testing methods that are both based on using an array of three concentration sensors to perform those measurements necessary for determining capture efficiency. The first method requires manual data entry for each concentration measurement for ten test points. The second method involves automated recording of approximately one thousand test points. Both proposed methods intend to reduce potential operator error in the test, thereby reducing uncertainty of capture efficiency measurements.

A series of validation tests showed with 95% confidence that both proposed multi-sensor methods produce results that are statistically similar to those gathered using the standard method outlined in ASTM-E3087. On average, the manual-method results differed from the standard method by 1.502% while automatic results differed by 1.516%. Repeatability of each multi-sensor method was then assessed by comparing the standard deviations of tests performed with both methods. The manual method reported results with standard deviations of 1.573% on average, compared to 1.769% for the automatic method. This suggests the automatic method is less repeatable, likely due to it lacking a means to filter outlier measurements.

Finally, an additional study made use of the manual multi-sensor method to test the impacts of test chamber hardware layouts. This investigation showed that moving the tracer emitters two inches further from a sample range hood resulted in an 18% percent reduction in measured capture efficiency at the low-speed setting.