Exhaust Heat Recovery System converting exhaust heat to electricity

Exhaust Heat Recovery System converting exhaust heat to electricity

Bradley is a 25 year old studying a PhD in mechanical and manufacturing engineering at RMIT University in Melbourne.

Bradley’s exhaust heat recovery system is designed to convert a small fraction of the waste exhaust heat from a Honda engine into electricity. Thermoelectric generator (TEG) technology and heat pipe technology are utilised for this product. The use of this technology allows the system to be solid state. A bench type proof of concept model was manufactured. This model uses a 50CC Honda petrol 4 stroke engine.

One potential application would be in Honda generators. A problem with generators powered by an internal combustion engine is that the engine thermal efficiency is quite low. Typically an engine has a thermal efficiency of approximately 25% on average. The other 75% of the energy in the fuel is wasted as heat in the cooling system and exhaust gases. Converting even a small fraction of this waste heat into electricity with an exhaust heat recovery system can make a noticeable improvement in the fuel consumption, CO2 emissions and fuel costs. The electricity generated from an exhaust heat recovery system would reduce the load on the generator which consequently reduces the load on the engine therefore cutting the fuel consumption.

Another potential application for this product would be on Honda electric start lawn mowers (Push mowers and ride on mowers). All electric start mowers require a battery to power the starter motor. Unfortunately, the battery will go flat over time and will require recharging. Two current methods for recharging the battery are either plugging it into a 240V socket (inconvenient, easy to forget) or using an alternator attached to the engine (added cost, weight, complexity, unreliability). An exhaust heat recovery system using TEGs could replace the alternator of the engine.

This system could potentially be more reliable than an alternator because it is solid state, could potentially be cheaper than an alternator and could potentially use less fuel because there is no load on the engine.

Bradley Orr’s Exhaust Heat Recovery System® was a finalist of the 2015/16 Honda Invention Competition for the public category.

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