Heat transfer through tubes

[Peter_1]

Hello all,

Sorry for my absence the last 2 weeks.
We needed to start up some units and it took some much time I hadn't time to read posts here.

First of all my perhaps silly question: suppose we have a refrigerant boiling inside a copper tube at 0°C, copper thickness of 1 mm (or another thickness in inch), what will be the calculated temperature at the outside of the copper tube?
You have to take in account the thermal resistance of the copper, but also - I think - the resistance from the refrigerant to the inside surface of the tube and also the resistance from the outside from the tube to the surrounding air.
In a technical discussion, someone stated that there will be a difference of 5K.
I laughed with him and said it will be perhaps 0.1K or even less.
So I need a prove that he's wrong.

Chemi, I will contact you this evening or tomorrow regarding your PM question. Have to play now this afternoon as barkeeper.

I see now that BESC5240 replied me http://www.refrigeration-engineer.co...ead.php?t=2465
I'm realy very surprised because we worked together at the same company some years ago - we sat in fact besides each other in the same office (those good old days Bruno) - and it's like he's saying: he knows a lot of system design.
He's in fact someone who knows a lot of DWM/Copeland machines, he knows all the Danfoss stuff (and if say all, it's realy all the stuff), he calculated many supermarkets systems, packs, he was our spokes person with a big French company, ..
I realy enjoyed working with him.
We lost each other now 2 years I think.

He could be a real benefit for this forum but I don't know if he he will find the time for this.

So guys, I will ask you to help him because he realy deserves this.
I also know that if he 's asking for help, then the problem will be not that simple to solve. I also thinks that he wants a calculated prove for his problem.

I will call him tomorrow it his office to give us more information so that we can help him.

Marc, thanks for the algorithm you gave me for the refrigerant. The soon I find some time, I will try to work with it.

[chemi-cool]

Hi Peter.

In ribbed copper tubes it will almost be the same temp, depending on the surround air temp.

Chemi

[Superheatman]

Hello all,

Sorry for my absence the last 2 weeks.
We needed to start up some units and it took some much time I hadn't time to read posts here.

First of all my perhaps silly question: suppose we have a refrigerant boiling inside a copper tube at 0°C, copper thickness of 1 mm (or another thickness in inch), what will be the calculated temperature at the outside of the copper tube?
You have to take in account the thermal resistance of the copper, but also - I think - the resistance from the refrigerant to the inside surface of the tube and also the resistance from the outside from the tube to the surrounding air.
In a technical discussion, someone stated that there will be a difference of 5K.
I laughed with him and said it will be perhaps 0.1K or even less.
So I need a prove that he's wrong.

Chemi, I will contact you this evening or tomorrow regarding your PM question. Have to play now this afternoon as barkeeper.

I see now that BESC5240 replied me http://www.refrigeration-engineer.co...ead.php?t=2465
I'm realy very surprised because we worked together at the same company some years ago - we sat in fact besides each other in the same office (those good old days Bruno) - and it's like he's saying: he knows a lot of system design.
He's in fact someone who knows a lot of DWM/Copeland machines, he knows all the Danfoss stuff (and if say all, it's realy all the stuff), he calculated many supermarkets systems, packs, he was our spokes person with a big French company, ..
I realy enjoyed working with him.
We lost each other now 2 years I think.

He could be a real benefit for this forum but I don't know if he he will find the time for this.

So guys, I will ask you to help him because he realy deserves this.
I also know that if he 's asking for help, then the problem will be not that simple to solve. I also thinks that he wants a calculated prove for his problem.

I will call him tomorrow it his office to give us more information so that we can help him.

Marc, thanks for the algorithm you gave me for the refrigerant. The soon I find some time, I will try to work with it.

Hi..it would depend a lot on the cleanliness of the copper tubes..also the design"cut" of the tube surface which pushes the evaporating refrigerant "tightly" against the tube wall..different manufacturers have different ideas...however an approach of 2 degrees kelvin is not unrealistic and can be bettered....also obviously the quality of the evaporator water is of prime importance...anything less than pristine quality water will detract from the heat exchange process..most large chiller evaporator water systems are treated with biocide to stop "growth"...this is the start of the degradation of the water quality but is normally needed...best regards..Superheatman

[Peter_1]

Well,.. let's take ripple-fin copper like Chemi said and take a measurement just on the outer surface of the copper. Inside the copper, the boiling refrigerant.