{"id":102230,"key":"Efficiency_analysis_of_a_solar_cooker","title":"Efficiency analysis of a solar cooker","latest":{"id":1223192,"timestamp":"2026-01-08T22:06:35Z"},"content_model":"wikitext","license":{"url":"https://www.appropedia.org/Appropedia:Copyrights","title":"CC-BY-SA-4.0"},"source":"[[File:Engr 305 class demo.jpg|thumb|Solar cookers]]\n\nHere is an efficiency analysis of [[solar cookers]] based on the [[Efficiency analysis of a solar cooker#Based on the 1st Law of Thermodynamics|1st Law of Thermodynamics]] and the [[Efficiency analysis of a solar cooker#Based on the 2nd Law of Thermodynamics|2nd Law of Thermodynamics]], explaining also how to calculate the [[Efficiency analysis of a solar cooker#cooking power|cooking power]] of any device.\n\n== Based on the 1st Law of Thermodynamics<ref>Ozturk, H. \"Second Law Analysis for Solar Cookers\", http://www.informaworld.com/smpp/1138067100-85020668/content~db=all~content=a713635696, Accessed April 8, 2010</ref> ==\n\n{{Highlight\n| title = <math>\\text{Energy input} \\ = \\ \\text{Energy output} \\ + \\ \\text{Energy losses}</math>\n}}\n\n'''Energy input''' to the solar cooker can be calculated as follows:\n\n{{Highlight\n| title = <math>E_i \\ = \\ I_t \\ \\times \\ A_{sc}</math>\n}}\n\nWhere:\n\n* E<sub>i</sub> is the energy input in W\n* I<sub>t</sub> = total solar energy incident upon plane of the solar air being heated in W/m<sup>2</sup>\n* A<sub>sc</sub> is the surface area of the solar cooker in m<sup>2</sup>\n\n'''Energy output''' from the solar cooker can be found as shown below:\n\n{{Highlight\n| title = <math>E_o={ { m_w c_{pw} ( T_{wf} - T_{wi}) } \\over t }</math>\n}}\n\nWhere:\n\n* E<sub>o</sub> is the energy output in W\n* m<sub>w</sub> is the mass of water in kg\n* c<sub>pw</sub> = specific heat of water in J/kgK\n* A<sub>sc</sub> is the surface area of the solar cooker in m<sup>2</sup>\n* T<sub>wi</sub> is the initial temperature of the water in K\n* T<sub>wf</sub> is the final temperature of the water in K\n* t is the time in seconds\n\n'''Energy efficiency''' of the solar cooker can be found as shown below:\n\n{{Highlight\n| title = <math>\\eta = { \\text{Energy output} \\over \\text{Energy input} } = { E_o \\over E_i} = { {[m_w c_{pw}(T_{wf} - T_{wi})] / t } \\over {I_t \\times A_{sc} } }</math>\n}}\n\n== Based on the 2nd Law of Thermodynamics<ref>Ozturk, H. \"Second Law Analysis for Solar Cookers\", http://www.informaworld.com/smpp/1138067100-85020668/content~db=all~content=a713635696, Accessed April 8, 2010</ref> ==\n\n{{Highlight\n| title = <math>\\text{Exergy input} = \\text{Exergy output} + \\text{Irreversibility}</math>\n}}\n\n'''Exergy input''' to the solar cooker can be calculated as follows:\n\n{{Highlight\n| title = <math>\\Xi_i = I_b [1 - (T_o / T_s) (4/3) ]</math>\n}}\n\nWhere:\n\n* Exergy input in W/m<sup>2</sup>\n* c<sub>pw</sub> = specific heat of water in J/kgK\n* T<sub>o</sub> is the outside temperature in K\n* T<sub>s</sub> is the surface temperature of the sun in K\n\n'''Exergy efficiency''' of the solar cooker can be calculated as follows:\n\n{{Highlight\n| title = <math>\\Psi={ \\text{Exergy output} \\over \\text{Exergy input} }\n= { \\dot{\\Xi_o} \\over \\dot{\\Xi_i} }\n= { {m_w c_{pw} [(T_{wf} - T_{wi}] - T_o \\ln (T_{wf} / T_{wi})]/t } \\over {I_b[1-(T_o/T_s)(4/3)]A_{sc\n}} }\n</math>\n}}\n\nWhere:\n\n* A<sub>sc</sub> is the incident area of the solar cooker\n\nThe ability of a solar cooker to collect sunlight is directly related to the projected area of the collector perpendicular to the incident radiation.\n\n== Cooking power ==\n\nThe primary reference measurement used by ASAE S580<ref>ASABE Technical Library. \"Testing and Reporting Solar Cooker Performance\",http://asae.frymulti.com/abstract.asp?aid=24465&t=2, Accessed April 8, 2010</ref>\nis the '''cooking power''', which can be calculated as follows over 10 minute intervals:\n\n{{Highlight\n| title = <math>P={ { M C (T_2 - T_1) } \\over 600}</math>\n}}\n\nWhere:\n\n* M is the mass of water in kg\n* C is the specific heat of water in J/kgK\n* T<sub>1</sub> is the water temperature at the start of each interval in K\n* T<sub>2</sub> is the water temperature at the end of each interval in K\n\nThis temperature change is detected over 10 minute intervals, thus the equation above is divided by 600 s.\n\n== References ==\n\n<references />\n\n{{Page data\n| authors = User:Rohanm\n| description = Solar cookers turn sunlight into cooking power. Appropedia reviews thermodynamic data, showing how design affects efficiency and heat output.\n}}"}