Advanced Power Generation Cycles Using Multi Component Working Fluids

P M V SubbaraoProfessor

Mechanical Engineering DepartmentIndian Institute of Technology Delhi

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Rankine Cycle with Organic Mixtures : Component Layout

ORC with mixtures

T-s plane for mixtures of R22/R114

Mixtures of Organic Working Fluids

• A siloxane is any chemical compound composed of units of the form R2SiO, where R is a hydrogen atom or a hydrocarbon group.

• They belong to the wider class of organosilicon compounds.

• Hexamethyldisiloxane is a chemical compound with the formula O[Si(CH3)3]2.

Hexamethyldisiloxane (MM)

Molecular Structure

Molecular Formula C6H18OSi2

Molecular Weight 162.38

 Properties

Density 0.764Melting point -59 ºC

Boiling point 101 ºC

Refractive index 1.3765-1.3785

Flash point -1 ºCWater solubility insoluble

Decamethyltetrasiloxane (MD2M)

Molecular Structure

Molecular Formula C10H30O3Si4

Molecular Weight 310.68

 

Properties

Density 0.854

Melting point -68 ºC

Boiling point 194 ºC

Refractive index 1.389

Flash point 62 ºC

saturation curves in the T-x plane for the MM/MD2M mixture

xMM

T-s diagram for MM (50%)/MD2M (50%)

Simple Rankine Cycle with Organic Mixtures

T-s plane for mixtures of MM/ND2M

Superheat Cycles

• For heat exploitation at comparatively high temperature, a saturated cycle requires a working fluid with a very high critical temperature which implies an unrealistically low condensation pressure.

Supercritical cycles

Kalina Cycle with Subcooler

Effect of turbine inlet pressure on first law efficiency

The Superheat Kalina Cycle

Comparison of Exergy destruction in various components of the Ammonia water cycles