Direct heat from 1KW turbine

[oliver90owner]

Ivan,

Was just thinking about you comment above re 200W heatpump availability - any idea of what the COP would be for a typical fridge or freezer unit (running at a high internal temperature)?  There are a lot of dumped units out there. 
Typical larder fridge has a bare collector which obviously frosts up (as there is a drain, to a tray over the pump motor, for auto-evapoaration of condensation).  Some fridges are very economical to run these days, so considering this, they can only have improved efficiency in two ways better insulation/sealing and reduced heatpumping costs.

I am not going to pull my Bodge fridge apart to test its COP in running warm water

Regards, RAB

[mikethebee]

I certainly see the sense in what guydewdney says, I think about the heat generated at the valve when I pump air into my cycle tyres.

Ivan has the sense of my thinking regarding a low rpm, higher torque source such as a VAWT.

As you both have so much more experience of the 'building' bit I am discouraged by your comments. I was thinking that finding the generating bits and weatherproofing the electrics seems potentially a lot more difficult and expensive than the mechanical equivalent should be.

Thanks for the comments, I think I will see how the planned VAWT turns out as a power source before working on 'capturing' that energy. Things may have moved on in the process.

[evan]

Hello,

I have: Two 48 Volt Windturbines 900W at 26mph, about 18Amp. Three cables (AC) rectified to DC feeding a battery bank of 200AH. All fused, dioded and switched. The battery bank is feeding a 1kW resistor for heat.

I've edited the units above for correctness

I don't need electricity DC or AC, I need heat. (and later hot water)

I'm fed up with LDR's who don't work and lack of easy to install shunt regulators to controll the difference between maximum 55Volt - 40Volt. Experts say that the battery bank should live for ever and the power from them should never be out of the maximum.

What I want is a "pulse width modulated load diversion regulator", inpout AC and output DC directly into the 1kWh resistor giving me heat 24 hours a day according to the windspeed.

That sounds like a reasonable setup, and it should work fine with a good dump load controller like a Tristar 45.   

What are you using currently, and what is the problem you're having?

[Other-Power]

Ivan,

Was just thinking about you comment above re 200W heatpump availability - any idea of what the COP would be for a typical fridge or freezer unit (running at a high internal temperature)?  There are a lot of dumped units out there. 
Typical larder fridge has a bare collector which obviously frosts up (as there is a drain, to a tray over the pump motor, for auto-evapoaration of condensation).  Some fridges are very economical to run these days, so considering this, they can only have improved efficiency in two ways better insulation/sealing and reduced heatpumping costs.

I am not going to pull my Bodge fridge apart to test its COP in running warm water

Regards, RAB

COP of a heat pump is 1 + COP as a fridge.  COP between 2 - 3 is typical for a domestic fridge.

High start currents of the motor is the only down side of doing this the rest is all doable.

Jonathan

[welshboy]

Hi Ivan,

stick something that is warmish, say 15degC in the fridge and the radiator at the back gets hot.

Now, run a slinky into the ground, gut the fridge, make a heat exchanger/pinch one from a combi boiler, maybe two or three, not to had to work out how much surface area would be needed.  7watt circulation pump, or again how ever many are needed, run from said renewable source.  Do the same with the radiator and there we go. 

I would do it if i had more time, would be cheap as well, made from throw away items.

The only thing that might be worth doing is changing the pressure of the throttle valve and the refrigerant so the radiator is at a lower temperature, up the COP and that should do it.

Easy.

Why not use a solar panel instead of the ground loop (suggestion above) running on thermosyphon to the heat exhanger using the gutted fridge and the second heat exchanger using wookey's thermosyphon to a dhw tank. Thats winter heating sorted in principle. Summer from the solar panel ?

[dhaslam]

A fridge has direct heat transfer, unlike  a normal heat pump that has a heat exchanger for the ground loop.   Using   copper pipe for the ground loop  should give a better COP than a heat pump but needs a lot of copper.  The normal refrigerant might not suit high output temperatures.     The Savonius wind turbine  should be able to get started in a wind gust but may not be able to get sufficient rotation speed without gearing up.   

[Other-Power]

A fridge has direct heat transfer, unlike  a normal heat pump that has a heat exchanger for the ground loop.   Using   copper pipe for the ground loop  should give a better COP than a heat pump but needs a lot of copper.  The normal refrigerant might not suit high output temperatures.     The Savonius wind turbine  should be able to get started in a wind gust but may not be able to get sufficient rotation speed without gearing up.   

Ultimately the COP is determined by the temperature difference that the heat pump (be it delivering heat or removing heat ie a fridge) is trying to achieve, the lesser this temperature difference the greater the COP, this is why delivering domestic hot water results in a lower COP.  Using copper pipe would give one the same increase in temperature as plastic but in a shorter length of pipe, this could result in freezing the ground.  A fridge does not have a direct heat transfer it uses air to move the heat out of the inside of the fridge, this is less efficient than using a plated fluid to fluid heat exchanger.  Normal refrigerants should be ok for low temperature increase, the back of a fridge gets rather hot.

Direct drive via a variable speed input, such as a wind turbine, is also far from ideal as one would have to use a compressor other than a scroll compressor which is the most efficiency means commercially available.  Better to go for a grid tie and go from there down the standard route.

I would like to see a sub 500 watt input heat pump.

Jonathan

[billi]

its an old thread and i am tired

Nothing new even i read about  direct driven heatpumps by windturbines about 20 years ago  sad enough that we are able to developp other ideas so fast ( i bought my first mobile phone ten yeaers ago )


My conclusion for now feed the power in a battery and run the heatpump from that .... do you know a DC heatpump ? If not an inverter is needed

billi