Re: How much pump is enough? How much is too much?
 

@ blueline - MCP655 performs better but has higher heatdump than MCP600. Depends on your rad as to which is better for you. For 13.8v - independant PSU that can provide 13.8v instead of 12v - that's how.

@tigger - If temps are good enough for you, pump is good enough for you. Looks fine to me. Yes, could be better... but it can always be better. Bigger rad, more powerful fans on rad, bigger pump, different CPU Block with lower c/w rating (storm, mp-05-sp)... whether it's good enough is down to whether you consider your current temps to be good enough, and how much cash you're willing to dump into it to make it better, and how much noise you wanna put up with. More airflow always = better performance than less airflow, but results in more nosie.

ie: YOU create the definition of what is good enough for YOU.

How to post pics? Hit the "Reply" button instead of using quick-reply, and use the "Manage-Attachments" button to attach an image to a post, or publish from your own webspace...

Re: How much pump is enough? How much is too much?
 

I know there is a 12volt version, but for a cheap power supply for the RD-30 couldn't you use the +12 and -12 on a cpu psu?

Re: How much pump is enough? How much is too much?
 

The -12v line is very weak, usually little more than 1 amp.

Re: How much pump is enough? How much is too much?
 

i think i'll refute the bases for this post on how much heat is created by the pump . sure you will loss output power than the input power and a % of it will be loosest as heat but this is not the biggest factor. Most of it is loses in the inefficiencies of how a motor works .. A motor works because a current is passed though a wire around the Satator which creates a magnetic field which then attracts or repels the magnets in the rotor which creates a rotation . The losses involved in this process is where MOST of the electricity is lost not to heat . i believe that this post shouldn't be a sticky cause it's not based on fact . and therefore should be "DE-stickyed" as it's putting alot of people wrong. i agree with the general idea of the post but may it should be re-written with theoretical pumps creating theatrical heat.

Re: How much pump is enough? How much is too much?
 

Conservation of energy. You put into a motor a set amount of electrical energy. You get out an amount of physical work. Those two are not equal. The rest of the input energy IS output as heat. The only discussion that can be made is for an inline pump and how much of this heat is transfered to the water.

I'm not even going into the whole moving the water creates heat discussion...just talking about the pump itself.

Re: How much pump is enough? How much is too much?
 

Conservation of energy. You put into a motor a set amount of electrical energy. You get out an amount of physical work. Those two are not equal. The rest of the input energy IS output as heat. The only discussion that can be made is for an inline pump and how much of this heat is transfered to the water.

I'm not even going into the whole moving the water creates heat discussion...just talking about the pump itself.


totally agree the dedate is how much of it is turned into heat ... and i believe this numbers are very wrong

and yeah there is friction and sound created that i agree aren't worth going into

Re: How much pump is enough? How much is too much?
 

eee

Re: How much pump is enough? How much is too much?
 

Motors are indeed inefficient and how inefficient they are could easily be determined by graphs of performance in operation (or getting graphs for similar motors if these are not available). Although any graph won't tell where the heat goes which is the question you are shooting for.

Pumps tend to have a large amount of sealing apparatus on moving components and this will contribute a large amount of friction which I believe you are ignoring. Heat generating by this is very much more likely to enter the water than heat from the motor. Therefore this is likely to be what is warming up the water in the pump.

I'm not exactly sure that sound and vibration can be completely ignored in terms of losses. Doesn't sit right but that maybe cos im eating a burger.

Either way i think i may have said this before in a thread somewhere but a pump is not a right fit (including if it is too big):
- operating in a weird part of its range i.e. running two fast or two slow.
- if you are pumping too much / too little mass flow of water compared to air going through your fans. A little bit on the air excess side is better thermodynamically. A little more water is better noise wise.

Has anyone tried putting a pump in a sealed chamber and letting it get very hot. A insulated pump is not transferring heat to the air. So heat is forced to travel to the water. Compare insulated and uninsulated cases and you've got some nice numbers to work off. For extra science points put thermocouples on bits of the pump. the bits that get relatively hotter may indicate what is putting heat where.

Re: How much pump is enough? How much is too much?
 

[quote=

Has anyone tried putting a pump in a sealed chamber and letting it get very hot. A insulated pump is not transferring heat to the air. So heat is forced to travel to the water. Compare insulated and uninsulated cases and you've got some nice numbers to work off. For extra science points put thermocouples on bits of the pump. the bits that get relatively hotter may indicate what is putting heat where.[/QUOTE]

UMM yes .... well close enough

i disbelieved this guys numbers so much that i spent a few days creating this rest rig .. What you can see in this pic is my modded 655 pump which has max 78watts at 12.24 volts and 2 resisters two mounted to a heat sink and other in the water. Three were three needed to get the wattage the same as what the pump would be put into the water. I am basing my numbers on the authors numbers which i believe is 15 watts of heat for 24watts of electricity. The resister is adding 37.4 watts of heat to the loop and with the pump set to minimum speed its adding 5.1watts. So there is a total of 42.5 watts being added to the loop .For the second test i didn't run any power through the resisters i ran the pump at a higher wattage instead, of 68watts of electricity. This should mean it would make 42.5 watts of heat
.
i then ran these two test systems for an hour and measured the water temp

To my surprise after taking ambient air temp into account the temperatures were closes enough to say they were the same of 30 degrees C over ambient..

So I’ll have to take back what I said a few posts ago .. and say even thought the high inefficiency of a pump sounds crazy it seems to be correct

Re: How much pump is enough? How much is too much?
 

off the top of my head and really badly remembered and probably wrong:

A really bad pump as a peak eff of about 9%
A normal cheaply made pump eff of 30%
a well made cheap pump with 2D rotor is 40%
To get over 60% you need a 3D CNCed machine piece of kit.

My old lecturer used to have a turbo compressor in his office ( 1/4 million plus RPM for pumping air) i think he said that it was 96% eff but it looked like it cost at least $100 to machine and air is alot easier to move than water.

It is easy to make a cheap pump that performs good enough with injection moulding. The complex shaped air turbos are hard as nails to make.

Re: How much pump is enough? How much is too much?
 

Efficiency would indicate what electrical energy is wasted, some of which is going to be expended as heat, part of which may or may not end up in the cooling loop.

The pumping action is, IMO, the main source of pump induced heat. It can be calculated as a function of flow and pressure. In fact, you can calculate the heat induced this way, for each element within a loop, all of which will add up to the pressure differential at the pump inlet/outlet.

Maybe someone still remembers the formulae?

Re: How much pump is enough? How much is too much?
 

Hydraulic power[W] = Flowrate[m³/s] * Pressure[mH2O] * Fluid density[kg/m³] * g[9.81 m/s²]

You know the input power (electrical), then global efficiency is the ratio between hydraulic power and input power. For instance, a Laing DDC 10 W has a peak efficiency of ~17 % where a Laing D5 is ~14 %. Quite bad, but normal for such little pumps. The bigger the pump is, the better the efficiency will be generally.

Heat induced by an element uses the same formula, but pressure become its pressure drop instead. At final : hydraulic power provided by pump = sum of all heat induced by each element due to flow (to fight against friction), all water movement is converted to heat.

Re: How much pump is enough? How much is too much?
 

NB I have never actually seen a water cooling pump in the flesh. But have actually made one in my uni course (100mm diameter brass rotor with an ally body powered by a 200W motor, think the best were managing about 30% eff (real to actual hydraulic power) at 6 litres per minute and 10meters of head or something like that).

Those numbers seem reasonable. (hydraulic power (W) = delta P (pa) * Q (kg/m/s), Q being the mass flow rate).

Numbers are low due the pumps not avoiding restrictions and cavitations. Cavitation occurs due to the rotors action. At the start due to centrifugal action the water is moving slowly while at the end it is moving pretty fast. Also the flow channel is expanding. This means that you will get areas of gas build up inside the pump sucking the water backwards. Also the blade designs are often straight when you actually want to curl them so the water around. Same with the inlet where you want a nice little deathspike to smooth the flow around so the loss factor is lower.

I was thinking that I could do a nice little business in upgrading D5’s with a “tuning kit”, hehehehe

Re: How much pump is enough? How much is too much?
 

I was thinking that I could do a nice little business in upgrading D5’s with a “tuning kit”, hehehehe

yeah i have turned my D5 from a 18 watt pump to a 80watt ... one she sure kicks ass now

Re: How much pump is enough? How much is too much?
 

18 to 80w might not be far of the mark actually

I was thinking heatsink / liquid cool the motor so it can be overvolted.

Add a 3D impeller, overhung volute diffuser vanes maybe even a variable geometry setup, ported output area to ½ inch tubing and watch it go. Efficiency would make it in the range of a 80 watt water cooling setup with the current tech and there would probably be less heat dump (due to pumping) and certainly less noise/ vibration to boot.

CAUTION: this post is powered by beer (budvar) to be precise hence is as inaccurate as an alcoholics ramblings

Re: How much pump is enough? How much is too much?
 

Where in the UK are you? Can send you some...

Re: How much pump is enough? How much is too much?
 

Cheers it would be nice to see some of these things in the flesh. Despite my ramblings on these forums I am still yet to actually see any watercooling components with my own eyes so it would be useful to play with some stuff. An old (doesn’t have to working) waterblock would be useful, if it is not too much trouble.

I am based in London now working for a product design company, but the address is for my home in good old Wales.

We’ll have to see if I come up with a nice cunning plan for making watercooling mainstream! I think I have something devious in mind…

Re: How much pump is enough? How much is too much?
 

Aslong as I have a flow (sometimes it stops) I can use the Liang DCC 12 plus/ultra @8,2V= zero noise.
OK the water going IN to my CPU-cooler is very coold, around ambriant temperature (5*12cm rad).
If my CPU/GPU gets hot my NG-BIG runs the pump and the fans alot faster.

Re: How much pump is enough? How much is too much?
 

Sooooo......

Which pumps have a high efficiency and why is that good for WCing?

Re: How much pump is enough? How much is too much?
 

Well designed centrifugal pump with curved blades. I.e what you normall have but curve the blades.

Beign well made maters more. Woudl really question 50% though, is that including drive/IC.

Not point going 3D with water pumps as not benefit