TXV vs fixed orfice

[Sergei]

If you look at a liquid line sight-glass in a slightly undercharged system, you will see that the liquid comes in bursts (or if you like, lots of bubbles, followed by little or no bubbles, followed by lots of bubbles and so on).
Also, varying conditions for the condenser will affect the liquid levels (for example a fan speed controller that's trying to cope with a hunting TXV)

Usually, slightly undercharge system has clear sight-glass or it has a few bubbles in this sight-glass. This can be explained by pressure fluctuation in condenser. If we have higher pressure in condenser(more refrigerant in it due to higher density), we will have a few bubbles in liquid line.
According to your scenario we have 2 opposite states of the system:
1. Liquid line is full of liquid, evaporator is full of liquid and liquid is in the suction line.
2. Liquid line is half full(a lot of bubbles), evaporator is less that 90% full, no liquid in suction line.
I have 2 questions.
1. Where is the refrigerant in state 2(compare to state 1)?
2. Why do these states change so quickly that TXV doesn't have time to react?

[The MG Pony]

Usually, slightly undercharge system has clear sight-glass or it has a few bubbles in this sight-glass. This can be explained by pressure fluctuation in condenser. If we have higher pressure in condenser(more refrigerant in it due to higher density), we will have a few bubbles in liquid line.
According to your scenario we have 2 opposite states of the system:
1. Liquid line is full of liquid, evaporator is full of liquid and liquid is in the suction line.
2. Liquid line is half full(a lot of bubbles), evaporator is less that 90% full, no liquid in suction line.
I have 2 questions.
1. Where is the refrigerant in state 2(compare to state 1)?
2. Why do these states change so quickly that TXV doesn't have time to react?

Viking is 100% right, things do not all ways work the way paper says they will. Remeber the paper is how our modles think it will work, reality oft has other plans! If we work realy realy hard we can get the two to match up for the most part!

I just accept it comes in bursts and does odd things when under charged!

[Sergei]

Remeber the paper is how our modles think it will work, reality oft has other plans! If we work realy realy hard we can get the two to match up for the most part!

Thank you for your very valuable advice, but I have 30 years experience in refrigeration. How old are you?
I believe this forum about exchanging opinions and about proving your point. If you don't know how to prove your point, get additional theoretical knowledge as well as practical. Good luck.

[The MG Pony]

Thank you for your very valuable advice, but I have 30 years experience in refrigeration. How old are you?
I believe this forum about exchanging opinions and about proving your point. If you don't know how to prove your point, get additional theoretical knowledge as well as practical. Good luck.

Oh I intend to, for the several years I been playing with it as a hobby I've loved it and plan on taking to engeenering, after all I've found my nich where natural aptitude and the love of technology mix perfectly!

My point was make a system and try it! as theoreticle is cute and all but I prefer real world knowledge and it will be fare more use full to have a modle system on your bench that you can observe and test it against theoretical knowledge. So my staement stands, build a system and see it! I'd do that now if it wheren't for the fact I'm away.

Again practical experiance with a real world modle system will yeild far superior resualts then a paper world gustimate, thats what I meant by practical experiance FYI

[nike123]

Oh I intend to, for the several years I been playing with it as a hobby I've loved it and plan on taking to engeenering, after all I've found my nich where natural aptitude and the love of technology mix perfectly!

My point was make a system and try it! as theoreticle is cute and all but I prefer real world knowledge and it will be fare more use full to have a modle system on your bench that you can observe and test it against theoretical knowledge. So my staement stands, build a system and see it! I'd do that now if it wheren't for the fact I'm away.

Again practical experiance with a real world modle system will yeild far superior resualts then a paper world gustimate, thats what I meant by practical experiance FYI

n!

How on earth, do you think that somebody could do some work and understand that what he do, without theoretical knowledge.
That is like comparing some alchemist, who his hole life makes chemicals with no knowledge about their chemical laws and properties, and some chemical engineer who knows very well what to expect of chemical experiment and laws behind processes in that experiment.
That is why is necessary, that this industry, somehow, "eliminate" those who don't understand what they are doing.