Peace Corps appropriate community technology/Cookstove Operation Function and Design Principles

* To discuss the principles of heat transfer and heat loss * To discuss the design principles for energy saving cookstoves

* Aprovecho Institute, Helping People in Poor Countries, pp. 77-84 * Evans and Boutette, Lorena Stoves, pp. 20-25 * Large format illustration of a twopot, two-damper, sand/clay cookstove * Illustrations of heat transfer and heat transfer within a cookstove

These illustrations should be prepared before beginning the session.

* For this session you will need to have operating examples of fuel-saving sand/clay cookstoves. A dampered singer or concrete stove could be built for this session, due to their quicker construction and drying time. * After the session and during the remainder of the training, you should encourage the participants to use the cookstoves (as well as open fires) in preparing their daily meals.

Indicate and describe the function of the cookstove baffles, damper, tunnel (flue) ant chimney.

An important point to raise during this discussion is that often stove programs (as well as development programs in general) introduce a new technology concentrating on construction, with little attention to training the users in operation and maintenance. In the case of cookstoves, people will be able to operate the stove only as they understand it. It is possible that they will not operate it as it was designed to function and, therefore, will not gain its full benefit. Likewise, If the stove is damaged, they may be unable to repair it. Mention that these Issues will be covered in more detail and that it is of utmost importance to remember to involve the stove users in all steps of the development process.

Post the illustration of the two-pot cookstove and use it to indicate the sequence for starting and maintaining a fire.

* Ask the participants to define radiation, conduction and convection. * Encourage the participants to illustrate their definitions with examples gained from their experience with the cookstoves. * Discuss ways in which radiation, conduction and convection work for and against cookstoves. * Ask where radiant, conductive and convective heat losses occur in the stove. * Ask for examples of possible ways to minimize heat loss in stoves. * Post the illustrations on heat transfer and heat loss and use them for reference during the discussion. * Refer to Helping People in Poor Countries (See Resources) for background information on heat loss and heat transfer.

* Briefly review the twelve essential design guidelines found on Lorena Stoves. * Mention the importance of understanding these design guidelines and the principles of heat transfer and loss before constructing a stove.

* To discuss the importance of user input in the design process * To discuss the principles of sand/clay ("Lorena") mixes

This session requires preparation. Step 2 asks for three separate trainers to run through the three suggested roles. These trainers should be familiar with the particular stove design on which their roles will be focusing (See Trainer Notes under Step 2 for more specific information on the role-playing procedure).

Three types of cookstoves are suggested as the basis for the role playing: the Lorena, the Louga and the Java Chimneyless (See Lorena Stoves), These stoves were selected because they originated in three different parts of the world and their designs incorporate specific cultural and environmental needs. Each of the three trainers to be involved in the role playing should be thoroughly versed with one of these cookstoves and their cultural/environmental origins. Each trainer should be prepared to play the role of a villager from the country of origin of his/her cookstove For example, the trainer responsible for the Lorena Stove would play a highland Guatemalan villager, reflecting that particular stove's origin. Each "villager" should have pots and pans of the type and size used to design the particular stove and any other props that could add to the authenticity of the role-playing situation (i.e., dressing as a Guatemalan villager). The idea is for the "villager" to manifest needs that will lead the work groups to discover the particular design suited to those needs (for instance, the Lorena for the Guatemalan highlander). The villager should try not to "give away" the stove design and allow the work groups to experience designing the stove with the villager's participation. It may be necessary for the trainer to occasionally step out of the role of the villager to help explain certain technical points during the conversation. This design process should involve drawing the stove layout on the ground and arranging the pots according to the design principles discussed in the previous session and Lorena Stoves. Explain that each of the work groups will continue the process by actually building and using the stove they and the "villager' have designed.

The following questions may help stimulate discussion: * What do you remember about soils from the earthen block session? * What are the three components of soil? * What distinguishes one type of soil from another? * What are the characteristics of clay, sand and silt? * How do they feel? * How and where would you find clay? Sand? Have containers of different soil types available to circulate so that people can feel and see the diference. Conduct the soil tests for clay, if they haven't already been completed in the session on earthen blocks (see Lorena Stoves for details). Distinguishing between usable and unusable clays is important Make and fire clay balls to demonstrate that good Clay holds together and poor clay flakes apart. If time permits, conduct a field-walk to clay and sand deposits.

Guide the discussion with the following questions: * What roles do sand and clay play in a mix? * How would you test for a good sand/clay mix? Have sample clay/sand mixtures of different proportions available so that participants can see and feel the differences. It is helpful to have dried test blocks available. Refer the participants to pages of Lorena Stoves and discuss the different tests for determining the suitability of the sand/clay mixtures for stove construction. These tests are: test blocks (make some to test later), the palm, ball tests (do during the session) and model stoves. Mention that there will be ample opportunities during the following construction sessions to develop a feel for the correct mix of sand and clay.

* To begin to gather data on insolation for future application to solar projects

* Mazeia, Edward, The Passive Solar Energy Book, pp. 13-20 * Baer, Steve, Sunspots, pp. 118-125 * Attachment II-9-A, "Insolation Meter Data Collection Sheet" * Attachment II-9-B, "Insolation Meter"

Point out that in order to collect data from the insolation meter: * The glazing area should be covered, with the exception of a one or two hour period when data are being collected. * The insolation meter works best at low water temperatures and for short exposure periods (overheated water and heat loss from the meter will cause the data to be misleading). * Water temperatures should be recorded twice during each test period -- at the beginning and at the end. * The difference between these two temperatures is referred to as "T" or "Delta Tee." * Data should be recorded on the "Insolation Meter Data Collection Sheet."

Review each step of the sample sheet with the participants, answering any questions. Explain that they should be recording their data over the next several weeks and that this data will be applied during the solar phase of the training program.

Be sure there are adequate building materials for each work group. Post the following checklist for the construction and use of an insolation meter: ____Paint at least one face of the can flatblack. ____Fill the can no more than 90% full to allow for expansion of the water. ____Weigh the can full of water in kilograms. ____Seal the box tightly. ____Be certain the glazing is wellsealed. ____Measure the collection aperture in square meters. ____Be sure the thermometer can be read without dismantling the meter. ____Be sure the meter is properly oriented. ____Be sure the meter is properly tilted. ____See that the glazing can be completely covered at night.

* To construct the base of a sand/clay cookstove (optional)

Each group should construct a base for one of the three suggested cookstoves to be built during this phase: the Lorena, the Louga and the Java Chimneyless. Explain that the stove base should be solid and not shift. Also mention protecting the base from erosion due to surface runoff of water. Give participants a variety of suggestions, i.e., a level ground base, clay-mortared earthen blocks, cinder blocks, . etc. Encourage the groups to be creative in their use of materials and to try new approaches. Explain that they should feel free to do this at all stages of the stove construction. Before the groups begin construction, mention that they should limit the size of their stove (generally the largest being two pots with a chimney) to be certain there will be time to complete the project.

Tell the work groups they have six hours to complete the stove. Outline the procedure for building the stove bodies in the following manner: * Sift sand and clay through a 5mm or 3mm (3/16" or 1/8") screen mesh. * Mix the dry ingredients to the desired proportions. * Add water and mix well. * Apply the mixture to the stove base. * Add one layer to another, packing each layer well, paying special attention to the edges and being careful to keep the sides straight. * Continue adding layers until the stove mass attains a height of 30-40cm, depending upon the depth of the pots to be used and the height of the firebox. * Trim the stove mass sides and fill in mixture where needed. * Level the surface by gently pulling a wet board back and forth over the surface until it is flat and smooth. Circulate among the work groups and assist them in the construction process where necessary. Encourage group members to rotate tasks in order to gain experience in all phases of the construction. Ask the participants to read Lorena Stoves, pp. 58-65, before the next session.

Mention that they have three hours to complete their stoves. Outline the process in the following manner: * Using the actual pots as templates, position and mark the potholes. * Locate and mark the position of the damper slot and chimney hole (if necessary). * Cut the damper slots with a machete. * Carve out the potholes and chimney with a spoon. * Cut the firebox entrance and connecting tunnels to the last pothole or chimney hole. * Finish the potholes with spoons and by rotating the wet pots so that the pots are deeply sunken. * Build up the baffles under the second and third potholes. * Construct and insert the dampers. * Smooth the stove surfaces. Circulate among the groups offering assistance where necessary. Refer the work groups to Lorena Stoves, pp. 58-65, for more specific information on completing the stoves.