Insights on thermal efficiency analysis for the water boiling test

The Water Boiling Test (WBT) is one of the most common methods used for analyzing biomass cookstoves. For example, thermal efficiency, time to boil, and emissions metrics are assessed. These metrics are used as part of cookstove development including informing decisions about the suitability of cookstoves for dissemination. As these metrics have been used extensively, significant efforts have been extended by many individuals to refine and expand the implementation of the metrics. This work continues this effort by focusing on the thermal efficiency metric. For the WBT, thermal efficiency is the amount of heat that is transferred to the water in a pot on the cookstove compared to the amount of heat available from combustion. Thermal efficiency analysis can be expanded by exploring the impact of measurement uncertainties and by providing transient estimations to further opportunities for cookstove comparisons and insights into the testing process. This work will present a method for estimating transient thermal efficiencies that are validated by experiment. In addition, a statistical model for assessing the impact of measurement uncertainties is described. From these efforts, insights on expanding WBT analysis are presented.