Analysis of variance and variation coefficient as repeatability criteria of a cookstove based on pellets gasification

In this work is presented a repeatability study applied to a cookstove based on wood pellets gasification (19.03 MJ/kg). The analysis is carried out under a modified water boiling test (WBT 4.2.3). The repeatability of the gasification-based cookstove was assessed by means of two methodologies, such as the variation coefficient (CV, %) and the analysis of variance (ANOVA). The answer variables evaluated under repeatability were the efficiency (& eta;, %), power (P, kW), fuel consumption (FC, g/min), fuel specific consumption (SFC, g/L), energy specific consumption (SFEC, kJ/L), and energy specific consumption per unit time (SFCT, kJ/L-min). By the CV analysis, the global average CV was 4.69% & PLUSMN; 0.87%. Therefore, as CV & LE; 5%, it is concluded that the gasification based cookstove is statistically repeatable. Concerning the ANOVA, the P-values of the variables studied were higher than 0.05 (P>0.05), thereby, it is stated that the improved cookstove is repeatable with a confidence level of 95%. Consequently, it is highlighted that the average thermal efficiency reached by the cookstove is ?29% & PLUSMN; 2.25%, with a confidence level of 95%. This thermal efficiency value is comparable with other biomass cookstoves based on gasification reported in the literature with values between 16 and 38%. The methodology and the results of this work constitute a theoretical foundation for assessing future developments of biomass cookstoves since the results reliability found in the prototypes tested at the laboratory level can be quantified and analyzed.