Thermal runaway of single cells within a large scale lithium-ion battery is a well-known risk that can lead to critical situations if no counter measures are taken in today's lithium-ion traction batteries for battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEV) and hybrid electric vehicles (HEVs). The United Nations have published a draft global technical regulation on electric vehicle safety (GTR EVS) describing a safety feature to warn passengers in case of a thermal runaway. Fast and reliable detection of faulty cells undergoing thermal runaway within the lithium-ion battery is therefore a key factor in battery designs for comprehensive passenger safety. A set of various possible sensors has been chosen based on the determined cell thermal runaway impact. These sensors have been tested in different sized battery setups and compared with respect to their ability of fast and reliable thermal runaway detection and their feasibility for traction batteries.

Online diagnostics for monitoring of battery cells in a battery pack is necessary in order to determine the state of the battery pack, like its age and safe operation. It could also provide the possibility to adjust the operation strategy of the battery management system and the load to increase the battery lifetime and safety. Impedance spectroscopy is a well-known measurement technique for electrochemical systems, such as a battery half-cell. Once the method is implemented in the battery management system and performed online during operation it could provide a monitoring system for the whole pack. Current solutions are either inaccurate or too big, expensive and energy inefficient. The presented approach proposes a dual use of the battery charger which incorporates a switched mode amplifier to generate the stimuli current necessary to perform an electro impedance spectroscopy. A suitable control is designed to overcome the non-linearities and instabilities introduced by the output filter and the current crossover effects of the electronic switches. This inexpensive, energy efficient technology could allow impedance monitoring of every cell in the battery pack and make a better prediction of the state of the battery possible.

A system has been developed for continuous determination of off-gas composition and off-gas volume rate during EAF steelmaking. It comprises devices for gas sampling and analysis of carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen and argon, and of measurement of off-gas temperature. The data are processed by a computer to set up the differential heat balance which indicates the flow rates of chemical and sensible heat of the off-gas leaving the furnace at each moment. Several operations during the melting process were investigated with respect to energy utilization. For instance, the hydrogen content during injection of natural gas decreases strongly with increasing oxygen input. During coal injection there is high loss of chemical energy due to non-complete combustion. Also, the extent of combustion depends on the position of the coal lances. Injection of oxygen in the upper furnace part leads to lower loss of chemical but higher loss of sensible heat. The system is optimized at present to decrease the dead time between gas sampling and print out of the analysis.KEY WORDS: EAF steelmaking; DC EAF; off-gas composition in EAF steelmaking; heat balance of EAF steelmaking; process control of EAF steelmaking.Fossil energy carriers, oxygen and other matter (e.g. dust) can be introduced via three natural gas-oxygen burners, a four-lances manipulator and six oxygen injectors, respectively. The addition of slag formers is carried out together with the scrap in one of the two baskets and, if desired, during melting, through a hole in the furnace roof. Tapping of the steel is performed through an eccentric bottom tap hole. The slag flows out of the furnace door on the side opposite to the tap hole. The furnace gas leaves the furnace via a direct withdrawal system. It is combusted, quenched and cleaned from dust with cloth filters. The furnace is operated with a hot heel to preserve a good electrical contact between charged scrap and bottom anode. Development of Continuous Off-gas AnalysisExperiments had been carried out at GMH for some time to conduct the continuous analysis with a mass spectrometer. A large problem was the sampling procedure. It was attempted to draw the gas sample continuously with a lance introduced, through a small opening, into the movable offgas elbow which connects the off-gas channel with the furnace, or into the gap between elbow and fixed off-gas channel. But in this manner the gas sample was falsified by the uncontrolled infiltration of air. Placement of the sampling location closer to the furnace introduced the problem that the lance opening became clogged by slag and metal droplets. Also dust formed, together with condensed water, a tight plug closing the lance. A detailed description of the encountered difficulties is given elsewhere.9) Finally, a sampling system was developed which is rather sophisticated but works very satisfactory. The sampling port is directly attached to the furnace and has a design that makes it less sensitive for build up of deposits of slag and dust. Ther...

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