And just how much pressure drop difference is their between say a small ( K1 type) 438mm and a 2165mm (Length) assuming heights are the same ,lets say 530mm. (Myson).
I'm actually a fluid mechanics lecturer! i'm an aerothermal engineer
Is a circulator in this case not just a paddle wheel pump? the fluid which you push out of the discharge goes round the circuit and comes back to the suction (inlet). The fluid returning to the suction will obviously be at lower pressure than the discharge but if there is too much resistance (head/friction etc) then the paddle wheel will not send any water around the system at all - ie a tall block of flats.
I'm going to work out the pressure loss tomorrow and actually quantify how much head loss i've got. There's also a whole host of parameters to fiddle with on the pump so i'll check them first.
Quoting from the book
"In closed loop systems, there is a maximum elevation an accelerator can transfer fluid to. This is dependent on a number of factors primarily fluid viscosity, density and flow velocity".
Reading a bit further down
"The height of the fluid is limited as the two legs of the system are not balanced. There is significantly more resistance in the vertical leg immediately after the discharge of the accelerator than the leg after the restriction. The accelerator must be able to generate sufficient pressure to overcome the loss caused by the fluid friction and the internal loss from the elevation change."
If that is in your book, it is referring to a pump moving a liquid to a higher level. In this case, the accelerator/pump is not transferring a fluid to a higher level, there is an equal volume flowing from high to low level and the two legs of the system are balanced.Quoting from the book
"In closed loop systems, there is a maximum elevation an accelerator can transfer fluid to. This is dependent on a number of factors primarily fluid viscosity, density and flow velocity".
Reading a bit further down
"The height of the fluid is limited as the two legs of the system are not balanced. There is significantly more resistance in the vertical leg immediately after the discharge of the accelerator than the leg after the restriction. The accelerator must be able to generate sufficient pressure to overcome the loss caused by the fluid friction and the internal loss from the elevation change."
You would have known that.
I've no idea what the restriction referred to is.
You had thought the pump head referred to the height of the building and now you are just making smoke to hide your embarrassment.
Having castigated Sanji for his bad workmanship, I think I should now come to his defence.
Danfoss have produced The Heating Book which goes into considerable detail about the design of District Heating Systems for towns and blocks of flats. Chapter Four has a section on the effects of gravity in high rise buildings which makes interesting reading as it tends to agree with Sanji's views.
In this chapter, the gravity effects of the risers of an 18 storey (54m) building are calculated as follows:
Flow Temp: 95oC - Density: 962.2 kg/m3
Return Temp: 70oC - Density: 977.8
Δρ = 15.6 kg/m3
Δp = 54 × 15.6 x 9.81
= 8.264 Pa = 8.3 kPa
This accounted for 30% of the pressure differential in the index circuit!
Although most of the book is not relevant, talking about power stations etc, some of it is very interesting and useful. I learnt all about valve authority and that the heat loss from a vertical uninsulated pipe is 20% less than from a horizontal one.
I learnt all about valve authority and that the heat loss from a vertical uninsulated pipe is 20% less than from a horizontal one.
To be picky, Onetap, in what circumstances might the flow be pumped downwards?Onetap said:you will get (apparent) reduced head losses if you're pumping the flow upwards because of the gravity circulation effect;
I take it all back; you are capable of rocket science.Agile said:Thats why I hold my soldering iron vertical when I want it to warm up quickly and horizontally when I want it to rest and keep itself cooler.
To be picky, Onetap, in what circumstances might the flow be pumped downwards?Onetap said:you will get (apparent) reduced head losses if you're pumping the flow upwards because of the gravity circulation effect;
To be picky, Onetap, in what circumstances might the flow be pumped downwards?Onetap said:you will get (apparent) reduced head losses if you're pumping the flow upwards because of the gravity circulation effect;
When the boiler is on the top floor!
I have forgotten where it was, perhaps a Birmingham tower block?
Tony
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