Emissions and efficiency of an improved conventional liquefied petroleum gas cookstoves in Pakistan

Liquefied petroleum gas (LPG) is considered as one of the most convenient and clean fuels for domestic cookstoves and is a popular choice, particularly in urban areas. Considering the limited fossil fuel resources, increasing emissions with ever increasing LPG demands, it is important to improve thermal efficiency and reduce emissions of the existing LPG cooking stoves by incorporating design modifications. This study reports design modification in the form of loading height optimization and consequent evaluation of thermal performance and emissions of two of the most widely used LPG fueled medium-scale cooking stoves, Sa and Sb, in Pakistan. Using two standard pots Pa and Pb, Water Boiling Test (WBT) 4.2.3 is adopted to evaluate the thermal efficiencies, and an emission collection hood is used for the assessment of carbon monoxide (CO) emissions. In the first part of the study, variation in the performance of stoves is evaluated with varying loading heights at fixed thermal power input. Once the loading height was optimized, in the second part, the efficiencies of the stoves were evaluated with varying thermal inputs at fixed/optimum loading height. Averaging for both pots, the thermal efficiency of stove Sa was increased by around 20% and that of stove Sb by 13% during the high power phase (HPP) of WBT after loading height optimization. The results were comparable for the low power phase (LPP). Both stoves showed a decline in thermal efficiencies with increase in thermal power input. At optimum loading heights, the lowest CO emissions were observed. The results also indicate that the optimal loading height would reduce the LPG consumption and cost for both cookstoves.