[Stoves] Differences in stove testing
Philip Lloyd
plloyd at mweb.co.za
Tue Feb 14 10:16:40 CST 2017
Dear Cecil
It is not too difficult. "Efficiency"= Useful energy out/energy in. When cooking, it is therefore useful energy supplied to heat pot and its contents/energy of raw fuel fed. When space heating, it is useful heat supplied to space heating/ energy of raw fuel fed. When producing charcoal for heating elsewhere it is energy of charcoal/ energy of raw fuel fed. When there are three useful outputs, it is (useful cooking energy + useful space heat + useful heat in charcoal)/(energy of raw fuel fed).
Hope that helps
Prof Philip Lloyd
Energy Institute, CPUT
SARETEC, Sachs Circle
Bellville
Tel 021 959 4323
Cell 083 441 5247
PA Nadia 021 959 4330
-----Original Message-----
From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Cecil Cook
Sent: Tuesday, February 14, 2017 5:35 PM
To: Nikhil Desai; Discussion of biomass cooking stoves
Cc: Crispin Pembert-Pigott
Subject: [Stoves] Differences in stove testing
Fellow stovers - Tami, Ron, Crispin, Nikhil, et al,
As a physical science challenged social scientist, I still do not quite get the difference between assessing the embodied heat content in a left over mass of charcoal and adding it to the numerator as a valued output versus subtracting it from the denominator used to calculate the system efficiency of a cook stove. If the cook values the charcoal and uses it for some purpose then it constitutes a legitimate output of a char making stove. It is for me as a layman unfair to advantage char making stoves by adding char to the numerator or disadvantage non-char making stoves by subtracting the energy content from the denominator. These stoves are different and should not be tested using a standard one size fits all testing protocol.
It is fundamentally foolish to test char making cook stoves using an efficiency equation that adds the heat value of left over char to the numerator because it is a waste product. If the char has a current or even an eventual economic value to the stove user then we can add an adjustment for the fuel it will purchase and thereby reducing the amount of fuel needed to cook a meal of a given size (which is the primary interest of most cooks). The adjustment to my mind is economic and does not increase the cooking efficiency of a char making stove per se!
I obviously need intensive tutoring to grasp the intricacies of the testing culture and conventions of physical scientists. Can a stove testing cognoscenti someone please help me out of the wilderness.
In search of a practical path to the nirvana of perfect biomass stove tests,
CECook
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