Expansion noise - capillary tube into evaporator

[mad fridgie]

The problem you are going to have is choosing adesign point for your cap. the nature of the hot water heating beast is that it is always in a wide range of flux (compared to say a fridge which generally is more stable once the cabinet is at the required temperature)
maybe you should look at a single pass water heating system, controled by head pressure, this will give you a constant to work with, so then you only have to optimised around SST.
I do not think you should use your sight glass at all to judge charge. The only benefit (excluding moisture) is to show that you have flow. (Gauges would show the same)

[Chef]

I do not think you should use your sight glass at all to judge charge. The only benefit (excluding moisture) is to show that you have flow. (Gauges would show the same)

Your quite right that selecting charge on a sight glass in this system would be almost useless. But it does show what condition the refrigerant is at as it enters the tube and for research and cap size changes it can be very useful.

It would be great if one could buy a glass tube - say 300mm long - about the same diameter as the compressor discharge tube to see the refrigerant condition. What a tool that would be.

Chef

[desA]

The problem you are going to have is choosing adesign point for your cap. the nature of the hot water heating beast is that it is always in a wide range of flux (compared to say a fridge which generally is more stable once the cabinet is at the required temperature)

I think that this is the key, here. The varying heat-loads, on both the evaporator side & condenser side, keep the system in relative dis-equilibrium.

maybe you should look at a single pass water heating system, controled by head pressure, this will give you a constant to work with, so then you only have to optimised around SST.

A very good idea. This kind of device ends up with far less in the way of variables. It's a way of thinking, more than anything else.

I do not think you should use your sight glass at all to judge charge. The only benefit (excluding moisture) is to show that you have flow. (Gauges would show the same)

Not to judge charge, but more of an overall indication of the instantaneous state of the system. Charge optimisation has always to be done together with a number of other parameters - even then, things change on the day...
These RHVAC systems are a lot more sensitive than many folks would have us believe.

[nike123]

Maybe this article could have some interesting information.

[desA]

Maybe this article could have some interesting information.

Interesting article. Does anyone have access to this paper through a University library?

ScienceDirect, as usual, want an enormous amount (USD 31.50) for a paper - an incredibly greedy company is Elsevier, considering that the authors pay to have their paper published.

[chemi-cool]

Very interesting discussion.

I have learnt a few new things today.

I may add one thing concerning the noise.

1. would it be quieter if a few smaller diameter cup tubes will be instead of one large diameter?

2. Because the refrigerant is R 134a, in a short time it most likely will block the cup tube, my suggestion is to use a small 1\4 drier, size 052 and braze the cup tube to the 1\4 tube on the outlet.

And Des, how about some work today?

[desA]

I may add one thing concerning the noise.
1. would it be quieter if a few smaller diameter cup tubes will be instead of one large diameter?

Interesting thought. I wonder if anyone has thoughts on this?

2. Because the refrigerant is R 134a, in a short time it most likely will block the cup tube, my suggestion is to use a small 1\4 drier, size 052 and braze the cup tube to the 1\4 tube on the outlet.

Isn't that what we have at the start of this capillary? Is R-134a worse than other refrigerants for blockage?

And Des, how about some work today?

The R&D is part of my work...

[desA]

Maybe this article could have some interesting information.

Thanks Nike. My curiosity overcame my miserly tendencies. I downloaded the paper a few minutes ago. I'll study it over the next few days.

There is always something useful in these papers.