Pro/Forums - View Single Post - can we agree on the basis of "C" in C/W ?

bobo5195 · 10-26-2005, 09:48 AM

Bill:
I think this has illuminated the basis of C, the conditions are know and if you look at the SD to eff equation it is quite obvious how C is related to other inputs at least according to the first law of thermodynamics. The eff rules tell you what needs to be measured and for what case. The NTU relationship i sent you shows the relation with area and how to convert U about the place.

My worry is that there is a significant wall of knowledge coming up. I’ve spent 4 years getting my knowledge to this level (at what is supposedly the 3rd best mech eng course in the world) and a lot of things are already causing me to stop and think. The level is hitting the literature wall out there and becoming more on vague on what’s important and what is not. The 2nd law approximations established in the book i mentioned are some guys thinking. This guy admittedly is the former head of research at delphi so i figure he knows rads but it is still unconfirmed.

I mentioned the book above because that book will allow anyone here to go out and design one damn rad if read properly. Its 1000 pages long and is complete head **** but its everything that’s needed. It even contains notes on thermosypons so ppl here can work out exactly how good they think they are and if they are worth it (i believe they are not), maybe start a flame war with JoeC if they wish (this forum seems to like flame wars and it think that’s a good thing if handled well). I could summerise a lot of the work in there and help with the difficult bits but it’s a lot of my time to do that. There’s another book by Keys and London called compact heat exchangers which basically goes into the level here. At the library there’s a set of reference notes on this that im figuring are about 5000 pages thick but I don’t really want to be touching those. I get the feeling that the entire area is imprecise science with a lot of the info being in big labs.

Its all a question of what you want to know.

In further to your edits:

I’ve never actually built a test rig before and to be honest some people here know more than me about the practical stuff. My one suggestion as I have mentioned in my posts is calculating C/W two different ways for rads. I’ll have a look at any suggestions but my practical engineering is not so good. The only thing I would caution on is keeping it simple. A vacuum test chamber is not simple for example. If your going to spend money on complicated stuff make sure it’s a good set of sensors and maybe labview.

I do enjoy the ramblingness of forums. I feel that we have answered the C question here.

I recommend that book for reasons mentioned above, I am without doubt that it will answer all of your questions that can be answered and it will save me a lot of hassle writing information up and ME getting it wrong. Its not payback; its just as you can well accept answering a lot of simple and not so questions and checking that your answering right can be boring and repetitive.

10-26-2005, 09:48 AM	#70
bobo5195 Cooling Savant Join Date: Aug 2005 Location: uk Posts: 400	Bill: I think this has illuminated the basis of C, the conditions are know and if you look at the SD to eff equation it is quite obvious how C is related to other inputs at least according to the first law of thermodynamics. The eff rules tell you what needs to be measured and for what case. The NTU relationship i sent you shows the relation with area and how to convert U about the place. My worry is that there is a significant wall of knowledge coming up. I’ve spent 4 years getting my knowledge to this level (at what is supposedly the 3rd best mech eng course in the world) and a lot of things are already causing me to stop and think. The level is hitting the literature wall out there and becoming more on vague on what’s important and what is not. The 2nd law approximations established in the book i mentioned are some guys thinking. This guy admittedly is the former head of research at delphi so i figure he knows rads but it is still unconfirmed. I mentioned the book above because that book will allow anyone here to go out and design one damn rad if read properly. Its 1000 pages long and is complete head **** but its everything that’s needed. It even contains notes on thermosypons so ppl here can work out exactly how good they think they are and if they are worth it (i believe they are not), maybe start a flame war with JoeC if they wish (this forum seems to like flame wars and it think that’s a good thing if handled well). I could summerise a lot of the work in there and help with the difficult bits but it’s a lot of my time to do that. There’s another book by Keys and London called compact heat exchangers which basically goes into the level here. At the library there’s a set of reference notes on this that im figuring are about 5000 pages thick but I don’t really want to be touching those. I get the feeling that the entire area is imprecise science with a lot of the info being in big labs. Its all a question of what you want to know. In further to your edits: I’ve never actually built a test rig before and to be honest some people here know more than me about the practical stuff. My one suggestion as I have mentioned in my posts is calculating C/W two different ways for rads. I’ll have a look at any suggestions but my practical engineering is not so good. The only thing I would caution on is keeping it simple. A vacuum test chamber is not simple for example. If your going to spend money on complicated stuff make sure it’s a good set of sensors and maybe labview. I do enjoy the ramblingness of forums. I feel that we have answered the C question here. I recommend that book for reasons mentioned above, I am without doubt that it will answer all of your questions that can be answered and it will save me a lot of hassle writing information up and ME getting it wrong. Its not payback; its just as you can well accept answering a lot of simple and not so questions and checking that your answering right can be boring and repetitive.