Final 12 months, within the the spring, I met Steen Carlsen. He has travelled extensively in Asia and East Africa, together with Zambia, which is why I got here to listen to of him. Steen has a background in electronics and electrical engineering and we now have had many attention-grabbing conversations already. Sadly, Steen is terminally sick, and is in a rush to understand just a few tasks earlier than it’s too late. When he confirmed me his photo voltaic oven challenge, I urged we inform about it right here, within the hope that his detailed description of this easy and essential know-how might attain extra individuals who would profit enormously.
It’s our hope that this report will function a technical supply for anybody who desires to make directions for constructing and utilizing photo voltaic ovens in areas of the world the place any of the extra fashionable approaches are usually not but attainable. Steen mentions refugee camps as locations the place no commodity, not to mention power, is a given.
The report accommodates uncommon and really detailed technical particulars on the rules of thermal conductivity. It’s a should learn for anybody who must handle temperatures in any system actually. It’s an train in capturing, confining, and never losing thermal power.
The next are excerpts from Steen’s report. Download the full report here.
Issues, design calculations, development, check and analysis of a cavity walled photo voltaic oven
Using fossil fuels presents many issues, not least in refugee camps. Single-walled photo voltaic ovens have proved to work in Ladakh (within the Himalayas), though, the next working temperature is desired. This report investigates the feasibility of designing a twin (i.e., cavity) wall and double-glazed photo voltaic oven, with the purpose to boost the working temperature as close to to 100 levels Celsius as attainable.
A prototype has been constructed and examined in Aarhus, Denmark (Latitude 56o 16’N; Longitude 10o 20’E), the place it reached a most temperature of 83.zero levels Celsius on August 13, 2022. The check of the oven complied effectively with the theoretical calculations.
A vital design course of is so as to add up the three warmth flows — the one from the conduction, the one from the convection, and the one from the radiation. Realizing the sum of every of those three warmth move contributions (denoted ΣP) and figuring out the distinction in temperature between the specified temperatures TA and TB, I can now calculate the ensuing thermal resistance RTh = |TB – TA| / ΣP.
In a thermal system, a thermal resistor compares to an electrical resistor in an electrical system.
In a thermal system, a thermal capacitance compares to an electrical capacitance in an electrical system.
In a thermal system, a warmth move compares to an electrical present in an electrical system.
In a thermal system, a temperature compares to a voltage in an electrical system.
Based mostly on calculations, check outcomes, and the teachings discovered, I imagine that the temperature of a subsequent prototype will be elevated by one other 5–15 levels Celsius. The design, the know-how, the selection of supplies and required instruments have been aimed to be tailored to the situations in refugee camps. I’ve tried to make use of both recycled or low-cost light-weight supplies. I’ve strived to make a design that may be made by a talented handyman.
From the early 20th century, hay containers have been used extensively to cut back the consumption of gasoline. It appears apparent to merge the features of photo voltaic ovens and of hay containers, which might suggest gasoline/firewood financial savings even in the course of the wet seasons. One other extra function for the photo voltaic ovens is to sterilise contaminated water to cut back the excessive mortality price brought on by muddy ingesting water.
Picture by Steen Carlsen
This report is geared toward refugees, refugee camp managers, NGOs and different organisations, do it your self folks — and whoever may need an curiosity. In any design — in any exercise — a suggestions from the top consumer is essential. Please assist me enhance by offering me with suggestions, might it’s recommendations, questions, experiences, or no matter.
There’s, nevertheless, a deadline for the suggestions, as I undergo from numerous incurable ailments. It’s my hope with this report to succeed in out to organisations and people who’ve an curiosity to make use of the report and hopefully to take my work ahead.
It’s my want that this report shall be accessible freed from cost to everybody on the web. I’ve no financial pursuits on this challenge.
Aarhus, Denmark, December 16th 2022.
Steen Carlsen MSc. E.E.
Regenburgsgade 11, 8000 Aarhus C. Denmark.
Mail: carlsen@power-electronics.dk
Cell: +45 23636968
As a reference and comparability, please see web page 90 in USAID’s report Fuel-Efficient Stove Programs In Humanitarian Settings.
