[Stoves] SA Paraffin Geyser and water heaters in general

Paul S. Anderson psanders at ilstu.edu
Sun Apr 10 16:45:14 CDT 2011


Dear Andrew, Philip, Crispin and all,

A useful topic for our Stoves Listserv.  My comments:

1.  The SA device (and others like Kelly Kettles) are single function  
devices.  Very appropriate in many situations.  Although other  
functions (include cooking of food) could occur before the hot gases  
go to the water heater in a chinmey, let's keep the focus on the  
single function so we do not get side tracked.

2.  The use of a parafin (kerosene) burner is almost a mote point.   
There must be a heat source, and the basic concept is that the heat  
can be turned off when the water heating is finished.  Easily done  
with fuels like parafin, alcohol, LPG, electricity.  Not so easy when  
burning dry biomass, but some devices are more suitable than others.

The batch aspect of TLUDs can be an advantage here.  Building a  
3-stone fire under the water heater would not be so good.  But the  
SOURCE of the heat is not our main topic.

3.  I request from Philip Lloyd (because he has tested the SA unit and  
might still have one handy) (or anyone else?) to tell us the diameters  
of the central chimney flue and of the outer shell, giving us the size  
of the annulus in which the water passes.  Also heights.  We need to  
know (calculate) the surface area of the hot chimney and the volume of  
water that is in the device at any one time.  There would be major  
differences if those dimensions were changed.  We already have the  
volume of water (200 liters) put through the geyser in (how much?)  
time.  Is there any insulation on this device?

4.  There are two important alternative water heating technologies to  
consider and compare.  One has a pipe (probably a copper coil) inside  
the chimney flue.  Here the surface area for heat exchange becomes  
highly important.

   The other has a pipe coiled around the chimney flue, which would be  
drastically less efficient.

5.  So, I appeal now to the engineer-types who are reading this:  How  
do we maximize and improve upon this?  And at what costs (increases in  
price)?

6.  If anyone has contact with the SA geyser company, feel free to  
copy them into this discussion.  The objective is to expand the  
acceptance of the water heating technology, increasing their business  
as well as creating business for people in other countries.  Less  
fuel, more service/value for the customer, and greater flexibility of  
heat sources.  (for example, that company could consider having a  
small TLUD as an alternative source of heat.  I and others will gladly  
assist them to add that option.)

NOTE:  There are other special purpose heat-using devices that we  
should consider (such as 2 - 4 cups of hot water for tea in the  
morning), but please use other Subject titles if you want to discuss  
them.

Paul
-- 
Paul S. Anderson, PhD
Known to some as:  Dr. TLUD    Doc    Professor
Phone (USA): 309-452-7072   SKYPE: paultlud   Email: psanders at ilstu.edu
www.gtz.de/de/dokumente/giz2011-en-micro-gasification.pdf   (Best ref.)


Quoting Crispin Pemberton-Pigott <crispinpigott at gmail.com>:

> Dear Andrew P
>
>> I remember posting something about another (or the same?) SA paraffin
> geyser some time ago.  Crispin, have you seen this one?
>
> There are several of these devices available, three I can think of. One is
> called the "Geyser 2000". It might be the original 'modern' one.
>
> The ones with cloth wicks which can be seen at holiday camps.
>
> I would class it as a type of Kelly Kettle. I don't have any idea how old
> the principle involved is (single heating tube immersed in water).
>
>> It ought to be a fairly easy to adapt a number of different wood/biomass
> burner designs
>> to this type of boiler.
> http://www.cbuying.co.za/index.php/paraffin-geyser
> http://www.slideshare.net/GreatNews/paraffin-water-geyser
>
> I agree. It has a heck of a lot of draft so there is a need to seriously
> look at the excess air in the pipe. From the look of it, there is a lot of
> room to improve it. I didn't get enough from numbers from the two sites that
> would allow one to calculate the thermal efficiency. Like most small
> paraffin burners, virtually no one tests the combustion efficiency and
> thermal efficiency of their devices, and even in good intentions they do,
> they will often get answers that are not all that helpful.
>
> The best I can calculate is that the thermal efficiency is 69% based on the
> fuel at 44 MJ/kg and a density of 0.83 and the 200 litres was heated from 20
> to 50 deg. That is not particularly impressive given that we can find pots
> on stoves working in a similar range.
>
> I have written to Prof Philip Lloyd and SABS (South African Bureau of
> Standards) and asked if it falls under their regulation as a 'cooking
> device' in which case is would have to comply with SANS 1906 (non-pressure
> heating and cooking appliances under 3.5 kW).
>
> Regards
> Crispin in Cape Town
>
>
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