Wednesday, September 5, 2012

CryoBUG Demo Unit Design in Process

Well sometime later today I hope to receive my enclosure from Front Panel Express in Washington. I am having mixed feelings of excitement and anxiety in anticipation of seeing what I have been working on come into reality. I just hope that I didn't make any major blunders in my enclosure layout.

Here's a look at some of my virtual piping design work...
Top View of basic piping (click on image to enlarge)

In the meantime there has been good progress made on fabrication of the Cold Head assembly that will be used on this initial pre-production CryoBUG demonstration unit.

Below can be seen the connection side of the actual "Cold Head" itself. The final (evaporator) cap tube is tightly coiled around the suction return line, and although it can not be seen in this image, enters on the left side, and then continues down into the copper head below. the stainless steel tubing is the thermowell used for measuring the temperature of the copper head, through use of a thermocouple probe.

To mount the Cold Head to the CryoBug, I am using a conflat half nipple which will be welded on to the Cold Head back side pictured above. Because of concerns about possible thermal conduction from the cold feed and return connections on the inside to the outer 2" stainless steel tubing of the half nipple, a copper tube was bonded to the inside which will eventually be connected to the air cooled condenser liquid line. It is hoped that this will maintain close to ambient temperature on the 2" tubing, extending back into the conflat mounting flange, and thereby avoid condensation or ice up problems on these parts.

The Inside of space will be insulated with an expanding polyurethane foam, same as to be used for insulating the HX Stack.

Here is a shot of the complete Cold Head assembly prior to be welded together...

For future versions, I have some redesign ideas that may alleviate the thermal conduction problems, as well as simplify the overall design. This particular Cold Head that I am using was designed for a specific application by a 3rd party, and has been greatly modified to suit my purposes. The price was right (as in "free"), so I really can't complain too much.

In my next post I will be showing images of my enclosure panels when they arrive, and an initial pre-fitting to render the complete enclosure.


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