Help: waste heat recovery-ORC

The Organic Rankine Cycle is a normal Rankine cycle wich operates at lower tempreature ranges and uses organic fluids like propane, butane etc. or refrigerants as working fluids.

Refrigeants are used because the cycle is deigned to work in low tempreature ranges where the main purpose is to recover waste heat from industrial processes and plants like power plants exhaust, geothermal plants, etc.

The refrigerants are used because they have boiling point much lower than freezing point of water. Thus with a very small heat supply they can reach boiling tempreatures.

The main objective to use the refrigerants is that they have very low boiling point as compared to water or other fluids. And the main point s to be considered over the choice of the working fluid are as follows :

1. The fluid must not be superheated to the extent as in regular Rankine cycle. The degree of superheat must be small if any because the aim is to recover low grade heat power.
The fluid must preferably remain DRY after expansion so as to avoid heat losses if the fluid became two phase after expansion and the heat recovery would be difficult.
So a refrigerant which would be DRY is preferred so as Regenerative feed can bw used.

2. The fluid must remain STABLE and must not DESINTEGRATE at higher tempreatures, which ususally happens with Refrigerants. They must not Corrode the working surfaces.

3. The Condensation tempreature must be higher than the freezing tempreature of the fluid.

4. The latent heat of Vaporisation of the fluid and the density must be higher so that it can absorb more heat from the source for same volume or flowrate, thus reducing the quantity of fluid and the pumping required.

5. It n=must be safe and environmentally non hazardous.

In the prevailing conditions as of today there are many MIXTURES of refrigerants being tried to have qulities like mentioneed above, and lesser heat loss in expansion , greateer heat carrying capacity and much safer in working.

The one new reefrigerant in common use today is : R245fa which is available in market. just enqiure about it.

Rohan_sK

The Organic Rankine Cycle is a normal Rankine cycle wich operates at lower tempreature ranges and uses organic fluids like propane, butane etc. or refrigerants as working fluids.

Refrigeants are used because the cycle is deigned to work in low tempreature ranges where the main purpose is to recover waste heat from industrial processes and plants like power plants exhaust, geothermal plants, etc.

The refrigerants are used because they have boiling point much lower than freezing point of water. Thus with a very small heat supply they can reach boiling tempreatures.

The main objective to use the refrigerants is that they have very low boiling point as compared to water or other fluids. And the main point s to be considered over the choice of the working fluid are as follows :

1. The fluid must not be superheated to the extent as in regular Rankine cycle. The degree of superheat must be small if any because the aim is to recover low grade heat power.
The fluid must preferably remain DRY after expansion so as to avoid heat losses if the fluid became two phase after expansion and the heat recovery would be difficult.
So a refrigerant which would be DRY is preferred so as Regenerative feed can bw used.

2. The fluid must remain STABLE and must not DESINTEGRATE at higher tempreatures, which ususally happens with Refrigerants. They must not Corrode the working surfaces.

3. The Condensation tempreature must be higher than the freezing tempreature of the fluid.

4. The latent heat of Vaporisation of the fluid and the density must be higher so that it can absorb more heat from the source for same volume or flowrate, thus reducing the quantity of fluid and the pumping required.

5. It n=must be safe and environmentally non hazardous.

In the prevailing conditions as of today there are many MIXTURES of refrigerants being tried to have qulities like mentioneed above, and lesser heat loss in expansion , greateer heat carrying capacity and much safer in working.

The one new reefrigerant in common use today is : R245fa which is available in market. just enqiure about it.

hmmm... oh we were sure about couple of points u mentioned... but were really doubtful about the rest...
really thanks a lot for your effort rohan...
i think we would be able to use R245fa... i found its properties and it really suits our need... thanks again...