Waste Heat Recovery - A Recent Approach

Most of our energy is wasted whenever we move our body whether consciously or unconsciously.  So how can we utilize that energy? It can actually be saved. In a recent invention, an engineering student ‘Kancharla Sampath Reddy’ invented a mobile charger which can be charged by heart beats.

What he did was a very intelligent thing. In this device a sensor is used which gets triggered whenever you breath in or out. This sensor is in turn connected to a gearbox. When this sensor is triggered, it activates the gearbox which drives the turbine. The turbine develops a voltage of 3-5 Volts. This voltage can then be given to mobile, so that we can charge it easily. This charger is cost effective too! You will be surprised to know that it costs only around Rs.150. Kancharla Sampath Reddy is a student at Arjun College of Technology and is currently studying Electronics Engineering.

In another attempt, scientists of Iowa state university have successfully tried to recover energy from plastic. The research was performed under the leadership of Najeeb Kuzhiyil and Song-Charng Kong. The idea is to recover energy from polystyrene also called as Styrofoam present in the high volume plastic. The polystyrene content of any high volume plastic is about 22%. So it would a profitable deal in terms of environment and money to tap this ‘waste energy’ which would otherwise go waste.

The test which was conducted was simple. The researchers used ‘Bio diesel’ as a solvent for the experiment. The scientists dissolved polystyrene peanut size balls in Bio diesel in varying proportions. When this fuel was used, the test results were astonishing. The engine power increased as the concentration of polystyrene increased from 0 to 5 %. Polystyrene however failed to keep up with expectations once the concentration exceeded 5%. It was hence confirmed from the experiment that engine power can be increased by advancing the injection time. This can be achieved by increased bulk modulus and increase in viscosity of fuel i.e.; by addition of about 5% polystyrene in bio diesel. However it was also observed that concentrations of soot, NO_x, HC, and CO increased on advancement in injection time.

The study was also performed under varying engine conditions viz; fuel injection timing and exhaust gas recirculation timing.  When the study was conducted for same injection timing, it was found that higher soot was produced whenever higher polystyrene concentrations were used.

This study hence successfully demonstrated that polystyrene-biodiesel blends could be used in diesel engines with minor modifications to the fuel system and by proper adjustments to conditions in which engine operates.

From both these experiments it is evident that there are a lot of options available for recovery of waste energy. We only need to tap it especially in the era of global warming when the fuel is becoming dearer. The only thing which man can do is to invent new resources of fuel and best utilize the existing ones.

Image Source: Battery Chargera