vary hermetic compressor speed

Posts: 3
Since: 05/Oct/2010

Best regards

I am doing a project which consists of varying the temperature in a small cooling chamber, but varying the pressure in the refrigerant. I have considered the possibility of varying the pressure by varying the speed of the compressor..... I would like to know how feasible this idea is..... and if possible if you can help me with ideas on how to vary the compression speed without having to use a variable frequency drive............ The compressor must be of hermetic type...... The hermetic type compressor which type of motor uses?............

Posts: 6
Since: 24/Sep/2010

Hello

in principle it is impossible to do that unless you use a VCC compressor electronically controlled clutch vcc = variable capacity compressor the motors used by the compressors are induction some rsir that are induction also second if several the frequency you run the risk of breaking the engine better said burn the engine, the other option is with an expansion valve but I have not tried it consists of varying the flow of refrigerant that enters the evaporator by opening or closing the valve.

I recommend the vcc that you can possibly vary the speed with the electronic board

look at this link if you are convinced also comes out how it works http://www.embraco.com/ingles/lancamentos.htm

Posts: 2.929
Since: 13/Apr/2003

What Rogarro says is true is impossible.

It's impossible?

Really with the known procedures, if it is impossible.

But you could invent or adapt somebody.

If we do not use the imagination, we would still continue to use only VET or capillaries.

But there are already the electronics.

After this dichotomy.ç

That seems to you to maintain or vary the pressures of the refigerant, varying the condensation tenp.

If we achieve a system that handles evaporation and condensation pressures, according to the toe. real or required, perhaps it could be controlled.

Posts: 3
Since: 05/Oct/2010

Thank you for the information you are giving me..... Thank you Rogarro for the link I sent from the vcc, I did not know that there were such compressors.... now I was thinking if it is possible to make an electronic device and adapt it to a hermetic compressor (normal, like the refrigerator in my house for example), which would consist of varying the average voltage that reaches the compressor (I do not know if this is the same principle for the design of the vcc), in order to vary its compression speed, with ac-ac converters or something.

A question, if I do not misinterpret when making a variation of the speed of the compressor what would vary would be the flow of refrigerant that circulates towards the condenser?.... and in this way the condensation temperature would vary?.... only?.... or evaporation?....

Begro the expansion valve to which you refer serious of the modulating type that is to say that a percentage is kept open depending on the desired temperatures and pressures or only open or closed, thus varying the flow of refrigerant that reaches the evaporator?

Rodolfo suggests that I use electronic systems to vary both the evaporation and condensation temperature, with electronic controls for both expansion valve and compressor respectively?

Best regards

Posts: 576
Since: 16/Oct/2004

There are hermetic compressors of small displacement and direct current. 12 or 24 v

With one of those and a potentiometer you already have the solution.

It's another option

Best regards

Posts: 126
Since: 18/May/2004

If your query is for a question from the Institute so that you discover the limits of that question, I think rodolfo comes closer with the solution of a KVP valve that controls the evaporation pressure and this is limited by the power of the installation, in a home refrigerator, I see it very impractical unless it is only a theoretical study to see what would be needed.

That is, the most correct option depends on the power of the installation, by the type of components that are on the market and what is the purpose of the installation.

Posts: 11
From: 09/Sep/2010

! Hello cordial greeting!

Pretending to vary the temperature, varying the pressure in the refrigerant is: A design purpose to control the temperature in a variable way?.  Or is it intended for an experimental test?

If the purpose is to control temperatures in a variable way, with a certain selection range, simply by using a temperature control or thermostat, of the digital type that can be programmed, you can easily do it, without jeopardizing the operation of the compressor.

If your purpose is truly experimental and the priority is that it is by pressure management, you could achieve that goal either using an electronically adjustable expansion valve, but in this I have a doubt, I do not know what maximum and minimum can be controlled with this type of valves.

Another way would be to install a distributor system type bypasses, capillary detubes, two or more, taking advantage of the fact that with a change in the length of the tube or in its internal diameter, it can be achieved that a greater or lesser amount of refrigerant enters the Evaporator or Frieza.

The bypass system would have to be designed using sunenoid valves for each capillary bifurcation or by manual cutting valves, which would allow manual selection which capillary should be with passage.

With solenoid you can control by means of manual switches.

Best regards

2jj