Abstract:
In optimum working conditions catalytic converters are the most effective and reliable source for reducing pollution caused by vehicles. But unfortunately their conversion efficiency decreases rapidly below certain temperature and is almost zero during the startup and warming periods. In cities where the soak time for different vehicles is low, there is need to improve the conversion efficiency of the catalyst to minimize the cold start emissions from engine. For this purpose, different methods have been used such as installation of adsorbing unit between two working catalysts, use of electrically heated catalyst and heating of the catalyst in the additionally mounted combustion chamber. These methods are quite effective to reduce cold start up emissions but have some disadvantages like extra energy is required to operate these techniques and as additionally system for these methods are used so they become very bulky. In present study heat storage capacity of the phase change material is used to keep the catalyst heated during the soak period. A phase change material (PCM), having melting point of 237oC nearly close to light off temperature of catalyst along with insulation, is used and catalyst embedded in this PCM is tested. During operation PCM is melted and energy of gases is stowed in melted PCM. When engine was switched off PCM solidified and latent heat stored in PCM released keeping catalyst at optimal temperature to get maximum conversion efficiency for next trip.
