Effect of safety valve types on the gas venting behavior and thermal runaway hazard severity of large-format prismatic lithium iron phosphate batteries

The safety valve is an important component to ensure the safe operation of lithium-ion batteries(LIBs).However,the effect of safety valve type on the thermal runaway(TR)and gas venting behavior of LIBs,as well as the TR hazard severity of LIBs,are not known.In this paper,the TR and gas venting behavior of three 100 A h lithium iron phosphate(LFP)batteries with different safety valves are investigated under overheating.Compared to previous studies,the main contribution of this work is in studying and evaluating the effect of gas venting behavior and TR hazard severity of LFP batteries with three safety valve types.Two significant results are obtained:(Ⅰ)the safety valve type dominates over gas venting pressure of battery during safety venting,the maximum gas venting pressure of LFP batteries with a round safety valve is 3320 Pa,which is one order of magnitude higher than other batteries with oval or cavity safety valve;(Ⅱ)the LFP battery with oval safety valve has the lowest TR hazard as shown by the TR hazard assessment model based on gray-fuzzy analytic hierarchy process.This study reveals the effect of safety valve type on TR and gas venting,providing a clear direction for the safety valve design.

Causes of Odor in Kitchens,Bathrooms,and Toilets of Multi-story Residential Apartments with Natural Ventilation

The causes of an offensive odor in the kitchens,bathrooms,and toilets of residential apartments in multi-story buildings with natural ventilation in Tomsk,Russia,are discussed in this paper.This problem exists in other cities and countries.Wall electric fans can be installed in ventilation grills in kitchens,bathrooms,and toilets of apartments in multi-story residential buildings.Typically,these fans turn on with the light in the bathroom or toilet,so the problem is periodic.Forced airflow from a fan in one apartment disrupts the natural outflow of air in the ventilation system of a residential building designed and built according to building codes and regulations and can cause an unpleasant smell in neighboring apartments.In many cases,it is difficult to determine which apartments have fans and force the neighbors to remove them.Locally,on the scale of one apartment,the problem is solved by installing an air check valve in the ventilation grill,which will block the nuisance airflow from the ventilation system into the bathroom.Globally,the problem is solved by modification and subsequent compliance with building codes and regulations,the implementation of which is controlled by local authorities.