The amazing Mr. Cap Tube

[shogun7]

Marc I have to admit that I don't have a clue as to what all your fancy foot work means as I know not about the SI system so I can't repond to that but please tell me what the hell do you mean by CARYOVER

[shogun7]

Rog:
A cap tube does have some load adjustability don’t you know, but nowhere near what a TXV can do, but as the ambient changes, the degree of sub cooling will change in an air-cooled condenser, and as a result, the bubble point and two phase length will change and although head pressure has an effect on flow rate, it’s the changing two-phase length that counters this action. Sub cooling the refrigerant has the greatest effect on flow rate. For my money the manufacturers’ design engineers have to go through many tests before establishing an optimum bore and length and it may change many times before they achieve the most efficient system. So I think I’ll stick with their values. You seem to believe that you know how to better improve a cap tube system; if that’s the case by all means do so and help the world conserve more energy through your advanced technology

[Gary]

Carryover is the coexistance of liquid and vapor in an area that is subcooled or superheated. Specifically it refers to vapor bubbles carried over into the subcooled liquid line or liquid droplets carried over into the superheated suction line.

[shogun7]

Marc That's very cute!. .NOT! so why don't you take Aristotle"s advce? And get off the EGO TRIP you didn't say any thing that is not understood in ASHRAE literature wise guy! Geeezzz your such a Glippy Dork and that last paragraph was totally un called for and just shows what a putz you are!

[RogGoetsch]

This means that when saturated discharge temperatures are higher, in response to higher ambients and higher associated evaporator loads (higher SST's), there will be an overall reduction in capillary pressure drop and so an increase in mass flow by virtue of increases in both volume flow and density of that volume. Of course then, during lower ambients, with the lower associated evaporator loads, there will be an overall increase in capillary pressure drop.

Not that I do a lot with AC, but it seems to me that the load on the system would change only if the user set his thermostat higher on warmer days. Otherwise, the unit starts at the same return air temperature as always.

With the same load and higher ambient, a cap tube would indeed provide increased flow, but a rise in SST (saturated suction temperature) would probably indicate a compressor operating at a less efficient point on its capacity curve due to the higher condensing pressure, and possibly additional load from carryover of some excess liquid refrigerant to the crankcase.

Rog

[RogGoetsch]

Only on the rare occassion when the system is sized to meet the annual maximum load. Most systems, particularly in the states, are sized to maintain a degree of indoor to outdoor temperature difference, desired indoor temperatures are considered relative, relative to outdoor temperatures. Sometimes this difference is 12K. In these circumstances the stat is being used like a safety.

Nice try.

Rog

[frank]

The Daikin Super Inverter systems we sell compare indoor temperatures to outdoor temperatures and float indoor temperatures relative to outdoor temperatures.

Hi Marc

They didn't mention this on the training course

[shogun7]

Marc “Acute semantic aphasia” back at you pal

You have to think about the explanation as well as the description of a
Phenomenon. Explanation often takes the form of a hypothesis. Therefore, whether or
Not people entertain hypotheses is a useful measure in describing the scientific
discovery processes. So in order to convince us of your entire BS, you have to consider and discriminate among several plausible alternative explanations. Therefore, the extent to which subjects critique other hypotheses or entertain alternative hypotheses can measure how broadly they search the hypothesis space and make up their own minds. Capish!!

[RogGoetsch]

Most systems, particularly in the states, are sized to maintain a degree of indoor to outdoor temperature difference, desired indoor temperatures are considered relative, relative to outdoor temperatures. Sometimes this difference is 12K. In these circumstances the stat is being used like a safety.

The Daikin Super Inverter systems we sell compare indoor temperatures to outdoor temperatures and float indoor temperatures relative to outdoor temperatures.... The one good thing I've noticed about this is the reduction in perceived thermal shock.

They didn't mention this on the training course

They do lots including floating outdoor saturation relative to ambient and indoor saturation relative to deviation from setpoint with outdoor temperatures considered. But then they have EEV's which kinda makes it something of an irrelevenace

Hmmmm. After some of the above, Marc might want to consider a disclaimer of some sort, so as not to confuse the lads. Something at the end of his posts like:

“Notice: Many of the claims in this post are entirely fictional and are intended for purposes of entertainment only. Any similarity to actual systems and practices is purely coincidental.”

That ought to cover it!

Rog

[shogun7]

This means that when saturated discharge temperatures are higher, in response to higher ambients and higher associated evaporator loads (higher SST's), there will be an overall reduction in capillary pressure drop and so an increase in mass flow by virtue of increases in both volume flow and density of that volume. Of course then, during lower ambients, with the lower associated evaporator loads, there will be an overall increase in capillary pressure drop.

I think what is as important, if not more important, is the fact that if evaporator loads were to increase then with the increased condenser TD occurring in response, the increased capillary dP is assisted quite nicely by way of the refrigerants PT Curves curvature i.e. the changing dP/dT ratio which increases with increasing saturated temperatures. If you consider that to double the volume flow of a fluid through a duct you'd have to quadruple the pressure difference, then it seems rather clever that our refrigerants have this non-linear PT curve that gives natural assistance here by somewhat shadowing this principle.

So, is the "technology" in the capillary tube or in the "refrigerant" that's in the capillary tube?

Well, if you consider that a capillary tube is different from say a TEV in that it has wall length where a TEV does not, then as it follows that the flow rate through a TEV is not nearly as much affected by the ratio of vapour to liquid pressure drops, Shogun might be right in aportioning technological credit to the capillary tube [/I]

In my very first statement I said:
:

If refrigerant responded the same way as water, the cap tube could never be used as a refrigerant control. Why not? Because when the head pressure was low, the evaporator would be starved, and when the ambient temperature was high, the evaporator would be flooded with liquid (the flow rate would be greater than the rate of vaporization).
However, if there was a way to increase the flow rate when the head pressure was low, and decrease the flow rate at high ambient temperatures, you would have a refrigerant control. This modulating effect is exactly what happens when a cap tube is installed in a well-balanced system.:

Seems to me we're saying the same thing. So is a cap tube considered "technlogy"? Well I leave it up to the reader.