Turbine suitable for exhaust waste heat recovery

[akshaykhiladi]

hey guys,
i m new here, i m working at recovering waste heat from exhaust from an automobile using a heat exchanger and then turning a turbine using a working fluid such as steamor refrigerant but still mnot sure which turbine will be suitable for me to use considering the dimensions of the vehicle.
i will be highly obliged to get some suggestions

 

[Pkruse]

You are dealing with what is called “low quality heat.” Simply put, this can represent a huge amount of energy, but since it is at such a low temperature you cannot practically extract much of it. As an extreme example, the ocean has a significant temperature difference between the surface and depths. It is therefore possible in theory to extract a huge amount of energy from the ocean; nobody has yet found a practical and profitable means of doing this.

In large gas turbines, they extract a great deal of useful energy from the exhaust and the intercoolers in various combined cycle systems. Each time they extract energy in stages, the exhaust gets cooler. Then finally it is still hot, but not hot enough to practically extract more energy. This final exhaust is also “low quality heat.”

But some plants have pushed the definition of “low quality” down to lower and lower temperatures, so that the final exhaust can now be at a lower temperature than in the past. They do this with various closed cycle mostly organic working fluids that boil at lower temperatures than water. Perhaps you could package a system based on Lithium-Bromide to be useful for your application. But don’t expect the product to be cheap.

 

[Pkruse]

Perhaps a turbine might be useful for your design. But if you pick the right working fluid, you might be better served by a commercially available pneumatic motor instead.

 

[akshaykhiladi]

the size of turbine must be as small so that can be fitted . i expect it top be around 7 to 8 inches .
please suggest

 

[akshaykhiladi]

are quasiturbines a solution for me ?

 

[Pkruse]

I don't know what a quasiturbine is.

Perhaps you mean a micro turbine. Lots are in use in many applications that physical size and smaller. But they are expensive enough so as not to be practical for the amount of heat available to recover from an automobile.

Think of a common turbocharger. It is basically a cheap and less efficient micro turbine.