Author Topic: Energy Reclaimer (Read 3381 times)

Bigwheel · « **on:** May 19, 2007, 06:55:59 PM »

Hi Everyone,

Don't know if this is a worth wild venture, but have been kicking it around for a while. I was hoping I could get some solid input back on what to do. First of all, I run a Geothermal heat pump to heat and cool my home. This is my biggest user of electric out of my bill. When ever the unit runs the two combined uses 22 amps at 220volts continously. The heat pump draws 15 amps and the well uses 7 amps. The system is an open loop setup.(draws water out of the ground and uses the water for heat disapation in the summer and uses the heat from the water in the winter.)

Anyhow, what I propose is taking the discharge water to run a small axial flux generator to try an make my dollar go farther. The water is currently being discharged back into the ground via a drain tile from my home. I would like to take the water and direct it at a pelton style wheel and turn the generator.

The specs. I have to offer is this,

1)the water runs through 1" pvc plumbing

2)the aviable pressure at the jet nozel would be 55psi(this is my cut in for the pressure switch and stays consistant all the time. my well is producing a consistant 17gpm)

3)the aviable gpm is 13(this is what is required by the manufacture of the heat pump)This is what would have to be aviable at the nozzel.

I would like to take the DC energy that could be produced to help charge my battery bank (of which I have yet to buy). I am currently in the process of building a wind generator to do the same think and eventually power some of the lights in the house.

Sorry for the lack of knowledge but got a feeling that the output will be low, but need a little help in the figures to see what might be capiable to produce, that way I can try an figure out how big of an axial flux gererator to make. How big of a wheel to make or buy and what size nozzel to buy or make to get enough force to get the thing spinning. I've already got the discharge parts figured out, That was the easy part.

Thanks again for your help and input, Chad

jimovonz · « **Reply #1 on:** May 19, 2007, 01:55:27 PM »

You say that your cut in for your well pump is 55psi. I presume the same system provides your domestic tap water. Surely the only time the system is anywhere near 55psi is when the valves are closed and no water is flowing i.e. the pump kicks in when the pressure drops below 55psi and only manages to get back above 55psi once all the taps are off. I can't imagine that it takes 55psi to provide 13gpm through 1"PVC. Without spending too much time on it, I come up with a pressure drop of around 5.5psi for 15gpm through a 100ft length of 1" PVC (http://www.plumbingsupply.com/flowchart.html) If you were to introduce a nozzle on the end of your heatpump outlet so as to maintain around 55psi in the pipe (I doubt that your pump could maintain the flow rates you require at this pressure), you would only be making your pump work proportionally harder with no hope of reclaiming any significant portion of the extra energy used.

jimovonz · « **Reply #2 on:** May 19, 2007, 02:01:00 PM »

How deep is your well? It is pretty straight forward to calculate the energy required to lift 13gpm up a given height. From this information you could get an idea of how efficient your pump is. The amount of energy it takes to do this is lost and no portion is recoverable unless you can dispose of the water at some level below your current ground level (which is probably not a good idea in any case due to contamination issues).

Norm · « **Reply #3 on:** May 19, 2007, 02:01:55 PM »

Kind of a roundabout way of doing things...

It would be

better to use the wind and solar in the first

place ....then charge up batteries run the heat

pump with an inverter.

Get a waterpumper windmill to pump the water,

the regular electric pump only kicks in when the

wind stops blowing.

Have a solar water heater to preheat the water.

( :>) Norm.

jimovonz · « **Reply #4 on:** May 19, 2007, 03:14:31 PM »

Just out of interest, if your existing pump were 100% efficient your well would have to be over 190m (623ft) deep to use 7A at 220V (1540w) to lift 13gpm (0.82l/s) (190 x 0.82 x 9.81 = 1528w).

This is just to get the water to the surface. There will be some pressure drop through the heat pump at this flow rate to account for as well.

scottsAI · « **Reply #5 on:** May 19, 2007, 06:06:38 PM »

Hello Bigwheel,

220 * 7 = 1.54kw, one big pump. 2Hp

Based on 55psi at 17gpm, you need 0.52hp or 0.38 watt,

assuming 60% eff pump/motor then 0.64kw.

Are these numbers measured or from the label?

If you need to lift the water 100' then you need 1.18kw (lift + psi)

Lifting is the distance above the ground water, not how deep the well is.

Check out this link: (Is what I used to calculate the numbers above)

http://www.engineeringtoolbox.com/pumps-power-d_505.html

A motor will not draw more power than it needs to do the job, not counting it's efficiency.

The quiescent power of a motor is fixed, smaller will have small power needs, big = big.

The same load adds the same to each motor depending on motors efficiency.

Clearly a case of bigger is not better.

A motor heats up based on how it's loaded, so a larger motor may run cooler, implying it may last longer. Most people error on oversizing a motor, too small it will not work.

The oversized motor will draw more power.

I would expect there is some excess kinetic energy in the water as it comes rushing out.

That would be the 55psi at 17 gpm or 380 watts - head losses (flow through the pipes).

Not sure how much is left as it exits the system.

Lets say its 50w or even 100w, what you willing to do to extract it?

Adding nozzles will add more load to the motor, regenerating that power will not improve things for you.

Like the others suggest, Solar/wind and make sure your will insulated

Have fun,

Scott.

Bigwheel · « **Reply #6 on:** May 19, 2007, 09:02:23 PM »

Hi again,

The well was drilled to a depth of 136 feet. The static water depth was 18 feet down(that was 7 years ago) Though, when I put in the mail box, I hit the water at three feet down, so needless to say the water is high around this part of michigan. The most ideal setup would of been to install a closed loop(coils in the ground) when I installed the heat pump. But that would of cost me another 8 grand to get that done. I can buy a lot of electric at the rates I'm paying. Orginally had forced air got tired of the cost of natural gas. Get a better rate with electric at .05/KW(winter rate) to .07(summer rate) Not bad compared to other places in the US.

Now for some more details on what I left out.

The pump is submurged and if I remember correctly 1 1/2 hp pump. I asked for a higher gpm one because I knew I would be running a sprinkler system later on. At my water tank in the basement, using a stop watch and a five gallon bucket, I measured 17 gpm. The heat pump (refrigerant to water heat exchanger) is only 8 feet away. There is constant water pressure inside the heat cxchanger( ie. 70 to 55 psi). There is a 24 volt silnoid valve on the dump side which releases the water and thus flows outside. Continuing down the line (about 4 feet) is a ball control valve. The valve is set for 13 gpm and the gauge on my water tank reads at 55 psi. I have opened the ball valve all the way and the pressure goes to nothing and the well is unable to keep up the output. The whole system discharge is 1"pvc.

The only other thing I can think of doing is to use the discharge to water the lawn in the summer. But would have to manually keep one zone on at a time inorder to do so. The biggest amout of usuage would be in the winter time. I really hate wasting things and feel that pumping the water back into the groung is a waste. My mind is always turning and thought the ideal might have some potential even if it's 50 to 100 watts. Thanks again for your input. Chad

zap · « **Reply #7 on:** May 20, 2007, 08:24:37 AM »

Sounds like a good idea to me Chad. If the static water table is still 18 feet then an 'inline' alternator, if they even exist, could be used to recover even more of the waste waters energy. If the water table is indeed only 3 feet then a sump pit would seem to be appropriate with a possible slight increase in head pressure. Whether or not it's worthwhile would take some figuring.

A member of this board, Nando, is very knowledgeable in these matters and he may respond to this post. Much of the time he will tell the poster to respond to him directly through email. If he doesn't post here I would suggest contacting him through his email address which is posted as "nando37-at-tx-dot-rr-dot-com Correct theanti-spam".

Good luck with the project and please keep us informed if it ever moves past the thinking stage.

finnsawyer · « **Reply #8 on:** May 20, 2007, 08:42:53 AM »

I've had two heat pumps in my life for heating and cooling houses. The first required 10 gallons per minute and the second 4 gallons per minute. Both used a flow control valve. Does your system have such a valve. If so you need to take its characteristics into account. They are designed to operate with the output free flowing into atmospheric pressure, not any kind of a back pressure such as you would get from a nozzle. You need to make sure that adding the nozzle will still alow the proper flow (which may not actually be 13 gallons per minute - I'm a bit skeptical of that figure). If you have a sizable drop in elevation on your property you could still try to capture some power from the flow due to the change in gravitational potential. One other thing. Simply adding the nozzle may make the pump work harder to provide the flow through the heat pump negating any gain from the addition of the turbine.

finnsawyer · « **Reply #9 on:** May 20, 2007, 08:50:23 AM »

A little post script. Your system must have a check valve to prevent back flow. It is usually incorporated into the flow control valve. Look for it. The flow rate should be marked on the valve, which should be made of brass.

Stonebrain · « **Reply #10 on:** May 20, 2007, 09:55:12 AM »

Hi Chad,

If you pump up the water say 20' and drop it 10' again

at 100% efficiency(which is unlikely) you can recover 50%

of the energy of your pump only.This mean you can recover

only a very small proportion off the energy your pump is taking.

Surely not worth the investments.

Better put windgenny and/or solar to cover the needs of your installation

Instead of 'wasting' the wind by letting it flying by and 'wasting' the sun

by letting heat your roof for nothing.

By the way,letting the water go back in the ground is not a waste,but making it

evaporate in the sun to keep the gras green in the heat of the summer is a waste.

On the other hand pumping water right in the groundwater can be bad because of potential polution.

cheers,

stonebrain

scottsAI · « **Reply #11 on:** May 20, 2007, 10:13:06 AM »

Hello Bigwheel,

Wow, Yes you have energy you can recover, prevention is better.

I have 0.5Hp well pump,54' down in 64' well, ground water 10-12'

I use an UPS for backup power, the efficiency sucks. The pump is one of the larger loads.

For backup bought a RV pump, 4.7gpm open flow, 45psi, can deliver 40psi at 2.5gpm.

I connected the RV pump to suck up through my pump, ran it for 20 min worked very will.

Power has not failed since, no further testing.

I bet your wondering; why is he telling you this?

Your well pump is gross over kill for what you need. A much smaller surface pump can supply the water your Heat pump needs, this can work with ground water 22' or less. Earlier calculations suggest 400 watt or so pump is needed.

A check valve before expansion tank with T branch before it going to the new pump.

Run the smaller pump when the heat pump runs. If house water demands water the new pump will get a boost, should not cause a problem. I will leave it there, we can discuss it further if you like the idea.

Recovery of energy in the water is possible, as you described. Eliminate the flow controller and make the nozzles of the water turbine become the flow controller, greatly enhancing energy recovery efficiency. The smaller pump will cost less. The energy recovery will need about 300w generator.

The 7a for well pump is this a measured value? Huge power loss going on here.

Have fun,

Scott.

Bigwheel · « **Reply #12 on:** May 20, 2007, 03:54:49 PM »

Hi again,

Like the idea of the secondary pump. Going to have to check into that one. As for the 7 amp measurment. I used a meter with a clamp to record the draw of the pump. Did the sam for the heat pump also. At the time was trying to caculate the loads for the house incase of an emergency and would have to run the backup generator. My 5500 watt one is just too small. The biggest fear would be in the winter time. Don't care if it's summer. It's just like camping out I tell the kids and wife. Since finding this board and really pursuing RE I seen alot of great ideas that I would like to impliment here. Thanks again for all the input keep posting the ideas. Chad

scottsAI · « **Reply #13 on:** May 20, 2007, 05:48:15 PM »

Hello Bigwheel,

Will it wont cost much to find out if the second pump would work.

1/2 HP ELECTRIC WATER PUMP POOL FARM POND ALUMINUM

Item number: 220112365478

Power Voltage:110V / 11060Hz / 370W / 3,450 RPM

1/2 HP Long Lasting Motor

Flow Rate Up to: 1180 GPH 40 Liters Per Minute

Dynamic Head up to 240 Ft. 80 M

Suction Lift Up To 24 Ft.

Fluid Temperature Up To 140 Deg F.

Maximum Ambient Temperature 104 Deg F.

1" Inlet And 1" Outlet Threaded

US $14.99 Place Bid >

End time: 19 hours 47 mins (May-21-07 12:21:52 PDT)

Shipping costs: US $29.99

gph = 19gpm, 24' lift looks good.
w just what is needed.

This pump will not do 55psi, if that is an absolute requirement...

Not sure why the need for 55psi, other than to keep from depleting the main water pressure?

I can understand the flow rate, it should be based on source water temperature.

Anybody know how solid these requirements are?

From a thermo heat transfer I do not see why the exact 13gpm is required or the pressure?

Have fun,

Scott.

thefinis · « **Reply #14 on:** May 20, 2007, 07:58:01 PM »

I don't understand why the water pump would run all the time the ac unit does unless the pressure tank is waterlogged. That might explain the high amp usage by making the water system run without the pressure tank as a cushion/accumulator. See if the pump cuts on whenever a faucet is turned on and shuts down right after turning it off. If it does it needs air added to the tank or the tank bladder or needs the pressure switch set for a greater difference between cut in and cut out settings. For less energy usage try lowering pressure settings and look into installing that small pump, a 1/2 hp should furnish the water needed for anything but yard sprinkler watering with the depths you are stating for standing water levels.

Finis

Bigwheel · « **Reply #15 on:** May 21, 2007, 08:27:02 PM »

Thanks for the lead on the pump. Waiting to make the purchase though, went and pulled the top off the liner for the the well to try and see how far down the pump is. Looks like some type of inside support is blocking my view. going to try and rig something to slide along side and drop it down to get an exact reading. Would hate to buy a pump that's rated at 25' and the pumps at 30'. It would be just my luck. Though I did find on the bottom of the cap, it's a 1 hp motor rated at 8 amp Franklin pump. Also, I figure I'm going to need a check valve on the tank side of the tee. To keep the tank from bleeding down and the main pump from kicking on. Don't know if a flapper door style or a ball and spring type is the best for is install. Thanks again for the help. I also did check the the draw down time on the tank and it's close to 2 minutes.

Chad

jonas302 · « **Reply #16 on:** May 21, 2007, 08:54:11 PM »

Hi Bigwheel interesting idea I put a blower wheel off a car on a 36 volt amtech and sprayed it with a 1/2 inch garden hose nowhere near 55psi easily obtained 40 volts no load definatly potential for power probly not much but why not try good luck

Jonas

Bigwheel · « **Reply #17 on:** May 22, 2007, 11:52:34 AM »

Hi Jonas,

Thanks for doing that trial, kind of what I figured would happen. Being a toolmaker on nights, I get a chance to play now and then, tried it out with air and figured it would work with water. Never played with those ametek motors and have thought about ordering one. I have messed around with larger DC motors and feel it's not the way I want to approach this. Clogging to me is like a thorn I can't reach, the more it can be reduced the better off you are. How are the ameteks under load. I hear alot of people using them and there cheap also. I've been messing around with axial flux style and they seem to have the least based on my hand method. Not the correct way, but easy to tell. Once, I finish casting my stator, and figure out a wheel, I've got to at least try it out. Once I get things done I'm going to report back on my findings.

Another thing I wanted to comment to everyone about is thanks for your input. I still have a couple of things to sort out with the well company and need to get that depth on where they put the pump at. Though I'm definetly going to give that second pump a try. As far as the 55 psi, That's what the pump draws down to and maitains while the heat pump is running. This isn't energy that would be aviable all the time. What the heck. Time to take a stand, All of us work hard for our dollars and I don't know about you but tired of giving it away. If what I make from scratch doesn't work at least I can put it towards the wind genny. Thanks again for the trial, Gives me something to shoot for. Thanks again, Chad

tomswift · « **Reply #18 on:** May 24, 2007, 02:59:48 AM »

Hello Bigwheel, I have been reading this thread, and see that there is very little engineering going on with the design of this system which is common on residential water systems. On your system the heat pumps water demand is by far the largest water need. You should never consider an energy recovery system until you have optimized the system in every other way. You say that the heat pump manufacturer recommends 13 gpm (.81 LPS). What is the pressure drop across the heat exchanger at this flow? This information should be in the specifications for the heat pump. From your description of what happens when you open the flow control valve my guess is that the pressure drop at 13 gpm should only be about 5 psi. Using the date of a pump raising water 20 feet (8.7 psi, or 6.1 meters) from the well then raising the pressure to 55 psi (38.8 meters) then with a 5 psi (1.5 meters) drop through the heat exchanger I get total pump work of 45 meters x 8.125 lps x 9.81 g = 360 watts, however 32.7 meters of the head is used by the flow control valve. The flow control valve is costing you 32.7 / 45 or about 70% of the energy put into the pump. Flow control valves are cheap and dirty devices for the contractor to keep the installed cost down, but they can turn around and bite you if you are the one paying the energy bill. http://www.driveswarehouse.com/Drives/AC+Drives/Micro+VFD/L100-007MFU.html is one of many variable speed drives that could be used to control a pump to supply water to your heat pump. With a Gould GS-13 pump head and a three phase motor, http://www.goulds.com/pdf/B5-25GS%201%20.pdf you would have a system where you just dial in the flow you need with no wasted energy.

News:

Author Topic: Energy Reclaimer (Read 3381 times)