Anybody know of any manufactures using electric/electronic control for opening/closing of compressor suction and discharge valves?
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Anybody know of any manufactures using electric/electronic control for opening/closing of compressor suction and discharge valves?
Nope, why would you want such things?
The thought had come from talking to a compressor manufacturer about whether they used different valve plates when using different refrigerants or working at different temps, they seemed to be happy to use the same plate for a range of situations. I had thought there might be a benefit to having the discharge from the compressor more closely match the required high side pressure, whether for different systems or just for changes in operating conditions, or possibly use the opportunity of controlling the opening/closing of the valves as some sort of capacity control for a fixed speed compressor. Im probably talking cr4p though.
A system designed correctly from the outset cover things pretty well.Quote:
Originally Posted by seanf
Back pressure & crankcase pressure regulators & unloaders cover suction pressure.
Condenser fans cover discharge pressure.
Restricting things causes inefficiency, inefficiency costs power, power cost money.
Also probably won't work properly anyway for all conditions.
Your last statement is true though:)
Hi RANGER1,
I guess I was think more about energy being wasted for compression.
If you have a compressor discharging at a fixed pressure to open the valves mechanically, its going to be a high pressure to allow it to work at the highest operating temperature of the condensor. But then if you have a low ambient, it still has to discharges at that high pressure to open the valves even though you could run the system at a lower condensing temperature. If that makes sense?
^^What I hadnt thought of was how the pressure in the discharge line is whats really acts to keep the discharge valves closed and only a small part the valves.
Sent,
Why would discharge pressure be higher in compressor compared to condenser?
Valve springs pretty easy to open, once pressure in cylinder overcomes Spring pressure & discharge pressure, gas discharges into discharge line.
This would only happen if valve plate ports were to small restricting flow.
If a compressor is designed & suited to certain refrigerants, can't see it happening.
Have you you had experience with this problem first hand, or heard of something.
RANGER1,
Like you said it would need to be higher to actually leave the cylinder and move into the lower pressure discharge line. But as your saying all you would need to have is a small spring pressure to only allow the valve to open once the pressure had reached just above the discharge line pressure. That was me talking cr4p earlier. (Maybe Im remebering wrong but thinking about the force thats required to open a discus discharge valve is more substantial.)
The thought first came from talking to a manufacturer about how they used the same valve plate for a range of situations, but like you said the discharge side shouldnt be a problem neither the suction, only minor inefficiencies with changes in refrigerant.
The only other thought would be that you could use electric/electronic valves to control the amout of refrigerant entering the cylinder and do away with pressure regulating valves and have it act as an unloader if needed.
Nothing that restricts flow is going to make a compressor more efficient. They want to flow as freely as possible. That said, you can make valves that are more efficient in mechanical terms than the typical spring and disc or reed style devices but you would probably apply it to the suction side; or you can set up a scavenge arrrangement which is a slightly different means of internally compounding the compression cycle or even an economizer type of arrangement. R