Water wheel driven .. Water to air heat pump.

[derekmt]

J...  He assured me that it would work OK for a water to water heat pump even if the river water temp was near zero.  I am not sure why the brine filled mat would not become a massive ice block in the river, but apparently that will not happen.
...

water is at its densiest at 4C ( in shallow water ) so as you chill it below 4C it rises to the surface...  You cant freeze the bottom of a lake or river only the top even if you are chilling the bottom.

[vee-tail]

You cant freeze the bottom of a lake or river only the top even if you are chilling the bottom.
Posted on: January 29, 2013, 03:44:54 PMPosted by: noah 

Ah Ha so thats why the coils have to be as deep as possible, and a river better than a shallow mill leat.
But right now our river is in its's 'monster' mode, flowing very fast and turbulent, no way is a 200m brine mat going to survive in that. However a pair of 100m pipes laid in line with the flow and anchored into the bed rock might survive.  When the spates die down I can experiment and see how long they last.

Starting & stopping a heat pump compressor does appear to be a problem for a waterwheel drive; thanks noah.
I am thinking that it would be better to use the waterwheel & generator for DHW using an immersion heater and large storage cylinder.     

[renewablejohn]

Good luck with anchoring pipes in the stream bed. Been there done that never did find all of the pipe. Hence the suggestion of doing heat exchange trash screen.

[guydewdney]

in hindsight, I would go with the idea of the leccy generation and immersion heater system

[ecogeorge]

You cant freeze the bottom of a lake or river only the top even if you are chilling the bottom.
Posted on: January 29, 2013, 03:44:54 PMPosted by: noah 

Starting & stopping a heat pump compressor does appear to be a problem for a waterwheel drive; thanks noah.
I am thinking that it would be better to use the waterwheel & generator for DHW using an immersion heater and large storage cylinder.     

The whole idea of using a heat pump is the efficiency of heat production,- put 3kw in get 9kw heat out!
Will you generate 3kw of electricity ?
Could you suspend some steel pipes along the river as a ground source , Navitron WR09 heatpump needs a flow of 21 litres minute (which is not much)  through the heat exchanger.
Use grid tie to start compressor (big surge) and run off water wheel electric.
At 3x the heat output with a cop of 3 which should be easy to achieve I'd be seriously considering a heatpump.
rgds George.

[RobNute]

One thing I would say is that for simplicity and ease of control an immersion directly coupled to the generator takes some beating. That is what we have, the three phase ac from the genny goes straight to the immersion ( 3 phase ) and you can start the wheel in gear, load switched on and it comes up to a balanced speed perfectly. As the revs and volts go up together then so does the load, it just gradually speeds up until the two balance with the amount of water available.  Oversize the load slightly to be on the safe side and you will have a simple setup that will produce heat even with the smallest amount of water. We also made a great overspeed device that cuts the water if it goes over around 8 rpm, read about it here if you are interested,

http://www.navitron.org.uk/forum/index.php/topic,12399.0.html

as you mention, overspeeding wheels are frightening things!

Rob

[Ivan]

refrigerant eventually lost through the gaps where the bearings are. True compressors are made for cars - and these would be a good starting point for a DIY mechanical-drive heatpump, but cars also need regassing on a fairly regular basis - something to bear in mind. You could base the system on propane - it works quite well as a refrigerant, but probably not as efficient as some of the gases (some of the CFCs were really good in terms of performance, but not so good environmentally.)

[Other-Power]

Just grid tie it and buy a suitably sized electrical unit. A small unit can be found here http://shoebox.kensaengineering.com/.  I think it would be cheaper and easier.  You can defantly take the heat out of the stream.

[knighty]

in hot places, where people have aircon installed which works as a heat pump in the winter... most systems are available with a built in inverter off the shelf... so you can control how hard/fast the unit works, and so control how much power it uses...

no idea how easy it would be to adjust it's power use depending on how much you're generating (or exporting) but it's worth looking at ?