MODELING THE RELATIONSHIPS BETWEEN THE SOLAR ENERGY, TROMBE WALL BROODER SYSTEM PARAMETERS AND THE BROODING CHARACTERISTICS OF INDIGENOUS CHICKEN.
A brooder is a structure where chicken are kept for stimulating optimal growth. Smallholder poultry production in Kenya faces the challenge of appropriate energy source for brooding. This study evaluates by simulation and modelling the performance of a trombe wall in a small-scale brooder. The brooder system under study consist of brick walls and wooden slated floor. The internal dimensions of the brooder being 2.5 x1.2 x 1.5 m. A dynamic model was used for predicting the brooding conditions based on; ambient temperatures, total solar radiation, ventilation size, thickness and colour of the heat absorption wall. The absorption coefficient for glazed brick is 0.35, absorption factor of black colour is 0.9, and the fraction of incident radiation absorbed is 0.89. Considering a wall thickness of 0.15m, thermal conductivity of 0.8 W/m K, density of bricks -1760 kg/m3, surface thermal resistance of the wall - 0.188 m2K, thermal wall surface area of 3.75 m2 and the pen capacity at 30 chicks per square metre. The experimental model of the brooder was solved using a Maltilab computer program with appropriate model equations. A case study of Eldoret town was used, where mean monthly solar radiation is 540 Wh/m2/day to 640 Wh/m2/day and daily ambient temperature of 14.20C to 280C.The resultant glazed brooder surface temperatures were 770C to 850C. In view of the appropriate brooding temperatures for day old chicks being 340C while at 28 days of age required temperature range is 21-240C.Consequently, the trombe wall can be used to optimally regulate brooder temperatures. Further, the design expert software was used to establish relationship within solar radiation, trombe wall surface temperatures and the optimal brooder envelope temperatures. The analyses showed a linear relationship amongst solar radiation, trombe wall surface temperatures and the optimal brooding temperatures. The results are appropriate data for designing a brooder for physical and physiological studies of a chicks.