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View Full Version : TXV or some kind of adjustable valve for high temp/pressure VAPOR R134a?







Stefan Weiss
13-02-2014, 09:52 PM
We are simulating an organic rankine cycle on a small scale, but we are unable to find a tiny expander for work output (opposite of compressor work input). At this scale, we are mostly just testing a heat exchanger for the generator (evap) so we plan on putting in an expansion valve between the generator (evap) and the condenser.

The only problem is that since the cycle is running "backward" with a liquid refrigerant pump (in lieu of a vapor compressor), after the generator (evap) the refrigerant would normally be going to the turbine/expander but instead we need a way to expand vapor 400psia @ 239degF to 154psia @ 195degF (constant enthalpy) doing no work. In this dummy cycle, the only work being done is on the heat exchangers. Could I just use some kind of needle valve to dial in the pressure drop?

Aurel STDL
16-02-2014, 08:21 AM
What is the proposed performance of the turbine for you cycle?

Stefan Weiss
17-02-2014, 04:24 PM
What is the proposed performance of the turbine for you cycle?

For this cycle, none. This is just a dummy cycle to test our heat exchanger as a condenser and evaporator with no output of performance. In the next scale the system will actually have output of about 50KW. I just need to expand the gas to a low pressure/temperature for the condenser. If this was plotted on a PH diagram, it would be a rectangle (instead of a Star Wars Sandcrawler shape) with the flow going clockwise.

Aurel STDL
19-02-2014, 10:20 PM
It is an interesting concept to test an heatexchangers for ORC. Here is a design of an microscale ORC concept with outflow turbine. https://grabcad.com/library/oracon-organic-rankine-cycle-concept-1

Stefan Weiss
19-02-2014, 10:50 PM
So can I just use a needle valve or a gas pressure regulator?

Magoo
20-02-2014, 01:59 AM
A swageloc needle control regulator will handle the high pressures.

Stefan Weiss
26-02-2014, 07:14 PM
A swageloc needle control regulator will handle the high pressures.

Great. I'll try it. Thanks for you help!