Applied-

Transporter to move heavy goods based on the fact that air resistance is much lesser than friction..

Detailed project on aerodynamics involving drag ratio,bernoulli's theorem,lift coefficient,glide ratio etc...

Perfect heat engine/refrigerant..

Some way to increase fuel efficiency(using chemical methods)...

Water purification plant involving actual ion exchange or equivalent methods...

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I'll think of some more n let u know..

Rate if twas useful...