DIY Organic Rankine Cycle

[Aurel STDL]

This is my basic micro ORC concept to be developed as DIY project.

Organic Rankine Cycle | Scoop.it
Microgeneration

ORC converts low temperature heat to mechanical work for generatig elecricity.
The simple ORC consists from 5 basic components: see below.


E-HX - Evaporator heatexchanger
TEX - Turboexpander
G - Generator
C-HX - Condenser heatexchanger
P - Pump

[Aurel STDL]

This is small size turbine designed to operate in closed loop of micro organic rankine cycle.



Turbines | Scoop.it

See 3D design of 65 Watt turbine.

[Aurel STDL]

A picture below shows concept of counterflow heatexchanger.
This represents basic design of evaporator and condenser. Also it is designed to simple make it.
Organic Rankine Cycle | Scoop.it

[pix]

ORC issues

This is small size turbine designed to operate in closed loop of micro organic rankine cycle.



Turbines | Scoop.it

See 3D design of 65 Watt turbine.

Hi,
I am designing my own ORC and I am very involved in this subject.From what I have learned, the most important part is a proper expander.You have to correctly size condenser to your expander. The point is to get desired power with low refrigerant mass flow.The lower mass flow, the better because your condenser ( and energy used for cooling) will be small. I want to use ambient air condenser because I don't want to use water as cooling medium.Secondly, I don't want to use any electrically driven pumps in my system, because any elecricty used in ORC lowers efficiency- thus there will be no water pump and no refrigerant pump.Turbine as expander uses a lot of mass flow per power produced- thus your cooling condenser will be large.In my opinion the best expander for ORC would be ( in order): twin screw compressor, scroll compressor, vane motor. Each one can work in reverse mode and is very efficient in converting gas expansion into rotation.ORC is simply device that takes advantage from a pressure difference of freon between boiler and condenser. There is no problem to efficiently heat up freon to high pressure, the problem is to have a good condenser that is capable of liquifying that gas in amount that matches flow through your expander.
Regards,
pix

[Aurel STDL]

Experiment of pumpless ORC-type cycle for low-t...

Hi pix,

see link above. There is shown an pumpless ORC prototype with described advantages and disatvantages. Similar principle is Matteran energy cycle.

The SterlingThermodynamic Cycle | Organic Ranki...

All parts which I am designing should be easily make and should not be expensive. The firs turbo expander was already made by CNC mill machine, but it is wery complicated to set the program to define blade shape.

But there is possibility to use an 3D print service to make it by additive manufacturing technology.

[pix]

Experiment of pumpless ORC-type cycle for low-t...

Hi pix,

see link above. There is shown an pumpless ORC prototype with described advantages and disatvantages. Similar principle is Matteran energy cycle.

The SterlingThermodynamic Cycle | Organic Ranki...

All parts which I am designing should be easily make and should not be expensive. The firs turbo expander was already made by CNC mill machine, but it is wery complicated to set the program to define blade shape.

But there is possibility to use an 3D print service to make it by additive manufacturing technology.

Hi,
I know Matteran concept. It is a beautiful for ORC. My system will work similiar way.Without need for external electricity.My system must be self starting and operate as long as there is pressure difference between boiler side and condenser side. Don't you think that turboexpander is not so good for ORC?First of all it runs very high rpm, you can't connect it to standard generator without reduction gear.Reduction gear creates energy losses.Also- turboexpander will have a large flow- thus you will need a large cooling means to liquify that flow. I think that any positive displacement machine like pump or compressor will suit ORC nicely. You don't have high rpm, machine works on gas expansion, not on gas kinetic energy( flow).That's why I want to use one of previously mentioned.I want to minimise flow of working medium through expander.I would rather maximise pressure difference. Costs are important also.I don't have CNC machine.Creating turboexpander "from the scrach" on CNC machine must be very expensive.I was thinking to adapt even piston air motor (Dynatork 7 ).But I think the best candidate from the shelf will be any twin screw compressor- moderate rpm, high torque,excellent expansion ratio,moderate refrigerant flow,very robust.
Twin screw expanders
The SRM twin screw compressor
Please see those publications:
http://docs.lib.purdue.edu/cgi/viewc...m%20machine%22

http://www.osti.gov/geothermal/servlets/purl/5115224

Kind Regards,
pix

[Aurel STDL]

Nice things regarding the Dynatork7. I did not see it before. I red some study from University of Nothingham (I think). But they used rotary vane air motor.
(I was then thinking to buy cheap "Made in China" hand air tool set to get the cheap rotary vane motor from it)
I decided to make my own turbine. I can calculate its dimensions and design and also I am surprise what are possibilities of additive manufacturing technology.
3D Metal Printing - Parts | Turbines | Scoop.it

My turbine should run around 5000 rpm, so it is not so fast. Also it depends on working fluids. I have calculated with R134a but there are some new restrictions...

[Aurel STDL]

EVE - Energy Via Exhaust - Exoès | Organ...
I have just found interesting system. It uses pump but it works on a piston engine principle. Just for information.

[pix]

EVE - Energy Via Exhaust - Exoès | Organ...
I have just found interesting system. It uses pump but it works on a piston engine principle. Just for information.

It is positive displacement expander.
Not the best one.I could imagine a lot of friction loses when converting pistons movement to swasch plate rotation.
There are better machines.To name one- double helical rotor machine( screw compressor).
I will use in my ORC my own design of positive displacement expander, it is coming together and it is something completely new.In my opinion no turbine will match it's efficiency and torque, for given gas amount.

Regards,
Pix

[pix]

EVE - Energy Via Exhaust - Exoès | Organ...
I have just found interesting system. It uses pump but it works on a piston engine principle. Just for information.

It is positive displacement expander.
Not the best one.I could imagine a lot of friction loses when converting pistons movement to swasch plate rotation.
There are better machines.To name one- double helical rotor machine( screw compressor).
I will use in my ORC my own design of positive displacement expander, it is coming together and it is something completely new.In my opinion no turbine will match it's efficiency and torque, for given gas amount.

Regards,
Pix

[Aurel STDL]

Hi Pix, I haven´t reply longer time. Regardign the dicussion about efficiency there is also important the overal thermodynamical cycle eff. It is affected by component efficiency, but main affect have the working temperature and working fluid. See the picture of cycle working properties below.
These are properties of my micro scale size demo cycle. Click on the 3D view here, to see the proposed components and design.

Home

[Aurel STDL]

This is proposal with R134a as working fluid. It increase efficiency to 2% overal. It is also mostly affected ba pump efficiency at this scale. There is no available high efficient pump on the market to pump 0,01m3/h of R134a at pressure difference 9055 bar.
Microgenerationconcepts

[Aurel STDL]

I did small correction regarding pump performance. It should pump 0,01m3/h of R134a.
Microgenerationconcepts