[Stoves] kgharris stove test

[Crispin Pemberton-Pigott]

Dear Kirk

>From your original post:

>The high power used in the tests was around 3.25 kw.  

What was the cooking power during the hot start test? That means, from ambient to boiling, the heat gained divided by time to gives Watts (J/sec), and further, what was the heated area of the pot? I want to calculate the heat flux to see if the cooking power is acceptable to, for example, people in Central Java.
 
>At 24C room temperature there was no problem keeping the water in the 93C to 97C test simmering range.  At 30C room temperature the simmering water temperature could not be held below 97C.  The pot skirt had to be raised to release some heat to maintain the test temperature.  

You do not 'fail' by not having the water between those temperatures. Yes, as a result it will increase the evaporation of water from the simmering pot.

>Raising the skirt....

This will reduce the draft and reduce the burn rate and reduce the heat transfer efficiency (aka thermal efficiency).

The effect of this on your calculated result is important. If you evaporate more water, you get a smaller number of litres at the end. This is divided into the mass of fuel you burned (well, not the mass of fuel, but the dry fuel equivalent of the energy that was released from the mass of fuel that went missing). 

The result is that for any given dry mass of fuel equivalent, you get a higher SFC number. Because the number of litres has not effect on the fire (at all) we do not really know what the fuel consumption is, only what the dry fuel equivalent divided by the number of litres remaining is. 

It would be helpful for us if you reported the dry fuel equivalent, or better yet, the actual mass of fuel needed to complete the whole test (hot start and simmer). The reasons is that we can consider what effect the various conditions such as skirt elevated or not, have on the performance.

For example I would be very interested in the power (burn rate) with the skirt in the two positions, and the Heat Flux as well. That is very useful information, particularly if the skirt increases the firepower and set the minimum power level.  It is quite legitimate to make a stove with a skirt and the instructions for turning it down include - 'raise the skirt', or - 'remove the skirt'.

The Chinese heating and cooking stoves almost all have a mechanical insert that is placed in the top of the stove when turning the power down to a long 10 hr burn. Without that device they can't possibly burn 8 or 10 kg of fuel for 10 hrs and have enough left to raise the flame back to life (which is part of the national test). 

You get the idea?  There is no problem with having 'mechanical controls' on the stove to bring the power down to 0.5 kW.

Regards
Crispin