Influence of variability in testing parameters on cookstove performance metrics based on the water boiling test

Abstract

Biomass cookstoves have been studied extensively for several decades. The Water Boiling Test (WBT) has been a widely adopted protocol for obtaining measurements needed to quantify biomass cookstove performance metrics. WBT metrics have been commonly used to evaluate cookstove effectiveness and serve as a basis for comparing biomass cookstoves. This paper demonstrates the influence of variations in testing parameters on measured or calculated metrics, especially since changes in multiple testing parameters may have competing effects on a given metric. In controlled experiments, this study assessed the effects of variations in the presence or absence of a pot lid, firepower, pot size, the initial mass of water, and presence or absence of boiling on the performance metrics of overall thermal efficiency (η), thermal efficiency associated with heating water (ηheat), specific consumption (SC), and the time to reach 90 °C. η was not greatly affected by variations in any of the testing parameters (i.e. no effect was greater than 6% of the base case). SC and ηheat, which are interrelated metrics, can provide additional insights on cookstove efficiency. Although these latter metrics showed a wide range of values due to variations in testing parameters, the use of a lid greatly reduced variations in both ηheat and SC metrics even when there were significant variations in the other testing parameters. Thus, the use of a lid would provide better consistency for cookstove comparisons when using these metrics. The time to reach 90 °C varied widely among changes in testing parameters. Therefore, this metric is difficult to use for cookstove comparison without strict control of testing protocols.