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Old 03-17-2010, 09:40 AM   #1
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It is time for me to install a heater of some sort in NAUSIKAA. Let's face it, I am getting older and begining to enjoy my home comforts too much. I have also been considering different possibilities for electrical power supply - not that I use much but it is always nice to have fully charged batteries. Now I have discovered one unit that should be able to provide me with both heat and electrical power - the Whispergen, It uses fuel efficient, quiet Stirling technology which all sounds great but does any of our members have some practical experience of this unit.

The Stirling engine was invented by a Scots minister, Robert Stirling, in 1816 so the concept is not new. It is used in Swedish and Australian submarines (Collins class) but if it is so old, reliable and fuel efficient why does it not have a greater following? The Whispergen is made in New Zealand.

Any information will be gladly received.

Aye // Stephen
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Old 03-17-2010, 12:50 PM   #2
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The Stirling engine was invented by a Scots minister, Robert Stirling, in 1816 so the concept is not new. It is used in Swedish and Australian submarines (Collins class) but if it is so old, reliable and fuel efficient why does it not have a greater following? The Whispergen is made in New Zealand.
I guess one of the reasons is that Stirling engine is good at generating low power from low temperature difference, but people usually more power hungry than that.

Wikipedia have a very good article on Stirling engines. The "Analysis" section should shed some light on the issues involved.

Some interesting quotes from other sections of the article:

"""

The design challenge for a Stirling engine regenerator is to provide sufficient heat transfer capacity without introducing too much additional internal volume ('dead space') or flow resistance, both of which tend to reduce power and efficiency. These inherent design conflicts are one of many factors which limit the efficiency of practical Stirling engines.

"""

"""

Towards the end of the [20th] century, several companies developed research prototypes of medium-power engines and in some cases small production series. A mass market was never achieved because the unit costs were very high and some technical problems remained unsolved. Now in the twenty-first century, some commercial success is starting to become feasible, notably with combined heat and power units. """
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Old 03-17-2010, 11:33 PM   #3
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In all probability because the world's engine manufacturers were tooled up for combustion engines which required fuel - namely oil products, that the Stirling was not able to get a foothold.

Whereas the Wankel found a very small niche.

Maybe as a result of oil being a wasting asset - engines like the Sterling will find their place.
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Old 03-18-2010, 04:01 AM   #4
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Originally Posted by Nausikaa View Post
It is time for me to install a heater of some sort in NAUSIKAA. Let's face it, I am getting older and begining to enjoy my home comforts too much. I have also been considering different possibilities for electrical power supply - not that I use much but it is always nice to have fully charged batteries. Now I have discovered one unit that should be able to provide me with both heat and electrical power - the Whispergen, It uses fuel efficient, quiet Stirling technology which all sounds great but does any of our members have some practical experience of this unit.

The Stirling engine was invented by a Scots minister, Robert Stirling, in 1816 so the concept is not new. It is used in Swedish and Australian submarines (Collins class) but if it is so old, reliable and fuel efficient why does it not have a greater following? The Whispergen is made in New Zealand.

Any information will be gladly received.

Aye // Stephen
Looking at the specs, LINK, it appears that the unit is not very fuel efficient--800W power per 1/5 gallon or 4 kW hr power per gallon diesel burned. I compare this to my own Onan 8kW genset which burns .9 gallon diesel to obtain 8kW and .5 gallon to provide 4 kW power per hour. My Onan is "old" technology from the early 1990's. Much smaller gensets exist than the one I have and I'd think they might be more efficient than mine as well.

If the sterling system is more cost effective than the regular diesel system and if one really needs more heat than power, than it might be a great idea.

A genset can have a heat exhanger put onto it to pull off waste heat. Considering that a diesel engine can be assumed to have 80 percent of it's energy wasted as heat, that would mean my genset puts off 20 kW in waste heat when it is providing 4 kW of power and twice that when providing 8 kW of energy...I don't know how much one could reasonably pull out of something like my genset into a heat exchanger/heating system but I think it is worth considering and we'll certainly be looking more at that as we get into colder climates. We're expecting to re-plumb our main engine heat exchanger to allow us to pull off heat for the cabin and we'd talked about doing the genset too but actually don't use the genset enough to make it worthwhile.

We do use a wood and coal burning stove for heat--it is nice but certainly not very "green" ...

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Old 03-18-2010, 04:36 PM   #5
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We do use a wood and coal burning stove for heat--it is nice but certainly not very "green" ...
If you use wood, it is green.
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Old 03-21-2010, 01:04 AM   #6
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If your wood is green you just need to let it season a bit longer, then it will burn nicely.
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Old 03-21-2010, 03:08 AM   #7
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ya'all are a bunch of comedians
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Old 11-06-2010, 12:32 AM   #8
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From what I can tell, the Whispergen's relatively limited (for now) following is largely because it's rather more pricey than conventional gensets. Depending on who you ask and how complex the installation is, the rig appears to cost somewhere between $10k and $20k (USD/CDN).

Looking at the unit from a purely technical standpoint, it makes a lot of sense for a boat in the middle to higher latitudes. If you need cabin heat and you're in an area that's less than ideal for solar power, a Stirling generator is an elegant, logical solution. In the tropics, you don't need the heat, and solar is likely to be a more economical source of electricity.

The residential and light commercial CHP market appears to be a fertile breeding ground for this sort of device. I suspect we will see more of them in the coming years as the "economy of scale" factor kicks in and the prices become competitive with conventional internal combustion designs.
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