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09-09-2006, 09:13 AM #1
what is suitable water flow velocity in Evaporator?
we are dealing with Hstars Brand heat exchangers, our water flow velocity in evaporator is about 2m/s, however, one of our customer told us that the speed is too much, that will cause cooper vibration, he told me a good and easy solution to reduce velocity at inlets is to increase the nozzle size.
However, I donot think 2m/s is too fast, anyone tell me what is the right velocity of flow rate?
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09-09-2006, 10:13 AM #2
Re: what is suitable water flow velocity in Evaporator?
2 m/s is not too fast. Ask the customer what speed he's fine with, and sell that evaporator to him, under written acceptance of responsibility.
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09-09-2006, 03:39 PM #3
Re: what is suitable water flow velocity in Evaporator?
HELLO CHISTINE,
We meet again. The velocity of 2 m/s is within the admissable limit. The velocity will also depend on the flow rate. The user has to maintain the parameters. I do not think that there is any need to make any changes to your heat exchangers.
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09-09-2006, 04:10 PM #4
Re: what is suitable water flow velocity in Evaporator?
Originally Posted by chistineLast edited by US Iceman; 09-09-2006 at 04:12 PM. Reason: font edit
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10-09-2006, 03:54 PM #5
Re: what is suitable water flow velocity in Evaporator?
Hi,
Suitable velocities of water in pipes for various types of installation:
Water:
- city supply 0,6-1,5 m/s
- general supply 1,5 - 3,0 m/s
- boiler supply 2,0 - 3,0 m/s
- supply of suction pumps
and disposl pipe-lines 0,75 - 1,5 m/s
- hydraulic fluid up to 12 m/s
Hope this will help
Best regards, Josip
It's impossible to make anything foolproof because fools are so ingenious...
Don't ever underestimate the power of stupid people when they are in large groups.
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10-09-2006, 08:09 PM #6
Re: what is suitable water flow velocity in Evaporator?
Hi My Friend,
The water velocities are clearly defined in the Carrier Air Conditioning Design hand book chapter 3-21.
Max. water vel. to minimise erosion
operation Velocity
hr/year fps
1500 15
2000 14
3000 13
4000 12
6000 10
8000 08
So 2 m/sec. is not so high (6.6 fps)
patrickj
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11-09-2006, 07:12 AM #7
Re: what is suitable water flow velocity in Evaporator?
Hi, Samarjit Sen,nice to see you here, and thank you Nonickname and partrikj, Thank you all,now I am clear about the water velocity in the Evaporator,however, Mr iceman, I mean the tube velocity,and I actually, want to listen to your opion about the difference about the tube velocity and nozzle velocity.
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11-09-2006, 05:26 PM #8
Re: what is suitable water flow velocity in Evaporator?
The nozzle velocity is wht you find in the water inlet & outlet nozzles to the heat exchanger. On a DX chiller the nozzle velocity may also impact (literally) the tubes. In some designs you may find an impingement plate to provide some protection of the tubes from this.
Likewise, the tube velocity has several considerations; erosion, keeping the tube clean, or vibration.
Part of the issue with vibration related issues may be due to the tolernaces of the tubes in the baffles or tube supports too.
Needless to say there is a lot more more to shell & tube exchanger design than film coefficients or pressure drop.
Heat transfer is only one function. The mechanical design is a second criteria.