Water Temperature at the Outlet of Pipe 2

[jrrocks]

Hi Team,

I want to calculate temperature of fluid (Cooled water) at the outlet of pipe (carbon steel)?
I have data as below -
Flow - 3 m3/hr
Pipe nominal Dia - 20mm
Length - 20 meters
25mm thick fiberglass insulation
Water inlet temperature - 4°C
Room temperature - 30°C

 

[LittleInch]

About 4.1 C

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[LittleInch]

At 3 m3/hr your water in present in the 20m tube for a magnificent 7.5 seconds.
Even if you blew a blow torch onto bare metal you wouldn't get any real temperature increase, never mind 20mm tubing with 25mm insulation in what is just a warm room.

I'll correct my estimate to 4.01 C now I've worked out the velocity and time spent in the tube.

It'll probably heat up more due to internal friction losses in the water as it's going fairly fast ( 2.7 m/sec)

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mk3223]

It's like to open the refrigerator to have the cooler air blowing to you in a hot day. The actual temperature of the cold air is increased depending on the several factors, such as the room temperature, any fan blowing, distance away from refrigerator opening door, etc.

 

[racookpe1978]

This forum is not for homework.
Assuming this is a live problem, what are the temperatures? Your dashes (or minus signs) are not clear.
Water inlet = -4 degrees, or 4 degrees?
Room air = 30 degrees, or -30 degrees?

Still air in the room? No fans, no wind?

(By the way, good observations above on the length of time inside the pipe. Room temperature will have almost no effect at all.)

 

[jrrocks]

Its a real situation. And temperatures are positive.

I want to convince my mate that there will be slight rise in the temperature while flowing through the longer length of pipes.

But don't have evidence to prove.

 

[racookpe1978]

Well, first, consider a static situation. (If the above dynamic heat trasnfer solutions do not convince him.)

Room Temp = 30 deg, Water in pipe = 4 degrees.
20 mm pipe, 25 mm insulation blanket, 20 m length of pipe.
Pipe is horizontal, air around pipe is natural circulation, water is stagnant (not moving).

How much energy is transferred?

 

[LittleInch]

Well try this.

Your mass flow is 0.83 kg/sec.

To raise that mass flow ONE C takes 3.5 kW.
(3000 kg/hr ÷ 3600 × 4150 J/kg/C)

That's not feasible for a temp difference of 25 C inside a 20mm insulated pipe20 long.

Imagine this the other way around, 30 C water in an insulated pipe in a room with 4 C air. That's not going to emit 3.5 kW is it?

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Also: If you get a response it's polite to respond to it.

 

[IRstuff]

LL, wow, you nailed it!

I got 4.0124 C

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[jrrocks]

Thank you folks..!!

 

[LittleInch]

So does 0.012 degrees count as a "slight rise" or have you just lost the bet??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[jrrocks]

Actual rise we saw is 4.1°C

 

[LittleInch]

I think that's the accuracy of your device myself.

But certainly in the right area.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.