[Stoves] Thermodynamics of a brazier cooking system modeled to mimic the lead brazier of a Roman ship

[Daniel]

People forget that lead conducts heat. Much better than iron, not as good as aluminum or copper. Hard to melt a stove made of lead with any decent amount of surface area. Also, charcoal burns better damp than wood. Also dries faster if exposed to heat. - Dan D.

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On Mar 11, 2019 10:05 PM, Crispin Pemberton-Pigott <crispinpigott at outlook.com> wrote:
>
> Charcoal is not affected by moisture (dries easily). 
> Charcoal weighs less so more can be accommodated. 
> Charcoal can be loaded (as they demonstrate) 250 g at a time and burn properly 
>
> The authors seem to have overlooked the usefulness of having hot water. They write saying that the water was for cooling the lead so as not to melt. No way! It was to create hot water! 
>
> When the hot water is added to the cooking efficiency the result is well into the 40's. Tier 5. 
>
> So the Romans were not so dumb. 
>
> They cite Jim's three stove fire efficiency of 22%. That is about the actual efficiency of a Rocket Stove if the char is discarded. I think there is a lesson there for the Gold Standard folks who have bene assuming the TSF was 10% efficiency, or less of the improved stove failed to match the anticipated fuel saving forecast. 
>
> This has implications for the calculation of fraction of non-renewable energy (fNRE). 
>
> Regards 
> Crispin 
>
>
> -----Original Message----- 
> From: Nikhil Desai <pienergy2008 at gmail.com> 
> Sent: Monday, March 11, 2019 8:08 PM 
> To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org> 
> Cc: Crispin Pemberton-Pigott <crispinpigott at outlook.com>; cec1863 at gmail.com 
> Subject: Re: [Stoves] Thermodynamics of a brazier cooking system modeled to mimic the lead brazier of a Roman ship 
>
> If charcoal had higher energy density, why wouldn’t they take only charcoal aboard? 
>
> I wonder what tradeoff was implied in fuel stocks, efficiency, food stocks, and meal plans. 
>
> Comparisons with military land campaigns and trade caravans could teach us how design contextual stove testing protocols with variable test sequences. 
>
> Never too late. 
>
> Nikhil 
> Skype: nikhildesai888 
>
> > On Mar 11, 2019, at 7:20 PM, Crispin Pemberton-Pigott <crispinpigott at outlook.com> wrote: 
> > 
> > Roman engineering of cooking aboard ship is studied, including thermal efficiency. 
> > Regards 
> > Crispin 
> > 
> > ++++++++ 
> > 
> > By Ehud Galili 
> > 
> > "Underwater explorations along the Israeli coast recovered more than twenty lead braziers, used for cooking aboard, dated to the Roman-Early Byzantine period. Few lead braziers from additional underwater Mediterranean sites were reported. To thermodynamically study the operation of this unique innovation, a steel model of a typical lead brazier was designed and constructed. The model, topped by a copper alloy cooking pot holding water, was used to experimentally analyze the temperatures, combustion, energy balance and efficiency of this "cooking system". The energy sources were charcoal and firewood. Water in the brazier's double-sided walls dispersed and absorbed the heat, preventing thermal melting of the original lead braziers. Maximum temperature measured at the fire bowl's bottom, when burning charcoal and firewood, did not exceed 104 °C and 101 °C, respectively. Thermal efficiency: the ratio between energy used for heating and evaporation of the water in the cooking pot, to the energy released by the burning fuel, depended on the type and mass of the fuel. It significantly increased from 5.7% to 14.5% with the increase in charcoal mass, from 0.250 kg (minimum mass in the present study) to 0.315 kg (maximum mass). The thermal efficiency of 0.604 kg wood was ~15.8%. Practical cooking using the model was successful. The results provide deeper understanding of the technology used for cooking aboard during the Roman period. Although the available repertoire of materials and technologies was limited relative to modernity, the final result shows the overall competence of Roman craftsman to define an engineering problem and solve it satisfactorily." 
> > 
> > https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww. 
> > academia.edu%2F38519714%2FThermodynamics_of_a_brazier_cooking_system_m 
> > odeled_to_mimic_the_lead_brazier_of_a_Roman_ship&data=02%7C01%7C%7 
> > C9c96d3708a574f56492f08d6a67ecd83%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7 
> > C1%7C0%7C636879460873447785&sdata=%2BLfXno6nnHycJ1wOUd1WDerNLE3Oo% 
> > 2BgyC13KD9Jfg3M%3D&reserved=0 
> > 
> > Open Access. 
> > Journal of Archaeological Science: Reports 16 (2017) 19-26 
> > 
> > <winmail.dat> 
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