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net and primary energy in biomass boiler

 
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dirac



Joined: 06 Jun 2013
Posts: 3

PostPosted: Thu Jun 06, 2013 11:01 pm    Post subject: net and primary energy in biomass boiler Reply with quote

Hi everyone:

Mi question is about the difference between net energy and primary energy in the case of biomass boiler. The primary energy is the energy before any transformation, in this case the energy inside the pellets, but the net energy is the entrance of energy in the boiler, they are the same??

Thanks in advance.
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Little John



Joined: 08 Mar 2008
Posts: 5666
Location: UK

PostPosted: Thu Jun 06, 2013 11:54 pm    Post subject: Re: net and primary energy in biomass boiler Reply with quote

dirac wrote:
Hi everyone:

Mi question is about the difference between net energy and primary energy in the case of biomass boiler. The primary energy is the energy before any transformation, in this case the energy inside the pellets, but the net energy is the entrance of energy in the boiler, they are the same??

Thanks in advance.
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Tarrel



Joined: 29 Nov 2011
Posts: 2447
Location: Ross-shire, Scotland

PostPosted: Fri Jun 07, 2013 12:40 am    Post subject: Reply with quote

No they are not the same. No boiler is 100% efficient, so the energy entering the water in the boiler will be less than that contained within the pellets. Heat will be lost up the flue for example.
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dirac



Joined: 06 Jun 2013
Posts: 3

PostPosted: Fri Jun 07, 2013 7:23 pm    Post subject: Re: net and primary energy in biomass boiler Reply with quote

I am not a spam, I am only a man with curiosity.
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dirac



Joined: 06 Jun 2013
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PostPosted: Fri Jun 07, 2013 7:30 pm    Post subject: Reply with quote

Tarrel wrote:
No they are not the same. No boiler is 100% efficient, so the energy entering the water in the boiler will be less than that contained within the pellets. Heat will be lost up the flue for example.


Ok Tarrel, I agree, but how can you measure the net energy?? the performance of the boiler changes depending on the different working conditions, with this in mind, the only way to measure the net energy performance is with a mass sensor in the silo of pellets and a multiplication by the LHV, or there is another way to measure it?
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Little John



Joined: 08 Mar 2008
Posts: 5666
Location: UK

PostPosted: Fri Jun 07, 2013 8:17 pm    Post subject: Reply with quote

dirac wrote:
Tarrel wrote:
No they are not the same. No boiler is 100% efficient, so the energy entering the water in the boiler will be less than that contained within the pellets. Heat will be lost up the flue for example.


Ok Tarrel, I agree, but how can you measure the net energy?? the performance of the boiler changes depending on the different working conditions, with this in mind, the only way to measure the net energy performance is with a mass sensor in the silo of pellets and a multiplication by the LHV, or there is another way to measure it?
The only net energy that matters is in the heat generated by the boiler in either the air in the space in which it resides or in the temperature of the water it is heating.
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Tarrel



Joined: 29 Nov 2011
Posts: 2447
Location: Ross-shire, Scotland

PostPosted: Fri Jun 07, 2013 8:36 pm    Post subject: Reply with quote

stevecook172001 wrote:
dirac wrote:
Tarrel wrote:
No they are not the same. No boiler is 100% efficient, so the energy entering the water in the boiler will be less than that contained within the pellets. Heat will be lost up the flue for example.


Ok Tarrel, I agree, but how can you measure the net energy?? the performance of the boiler changes depending on the different working conditions, with this in mind, the only way to measure the net energy performance is with a mass sensor in the silo of pellets and a multiplication by the LHV, or there is another way to measure it?
The only net energy that matters is in the heat generated by the boiler in either the air in the space in which it resides or in the temperature of the water it is heating.


Agreed. In fact, both. Even leakages of heat from pipes, storage tanks, etc, might be acceptable if they are within the insulated envelope of the building.

I don't know for sure, but I guess boiler manufacturers work out their stated efficiencies in controlled conditions; burning a set weight of pellets and measuring the temperature rise of a set volume of water, for example?
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woodburner



Joined: 06 Apr 2009
Posts: 3376

PostPosted: Fri Jun 07, 2013 11:05 pm    Post subject: Reply with quote

You can measure the difference in temperaure between the inlet and outlet of the boiler and use a doppler flowmeter to measure the amount of water moved. This allows the calculation of net poweroutput.
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BritDownUnder



Joined: 21 Sep 2011
Posts: 238
Location: Hunter Valley, NSW, Australia

PostPosted: Sat Jun 08, 2013 1:29 am    Post subject: Reply with quote

The following link from Australia has some techniques that the author used to improve the efficiency of a stove by feeding the air direct from the outside through a pipe. He claims 80% efficiency for his stove.

http://www.mtbest.net/wood_stove.html

I quite like this website for advice on various things especially as it is Australian based but the author can be quite David Icke in some of his more philosophical articles.
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