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•Artificial Neural Networks (ANNs) are used to predict comfort parameters.•Hourly indoor air temperature and relative humidity in building were predicted one day to one month in ...advance in hot-humid region.•ANN model performances are characterized by mean square error and the coefficient of correlation.•The experimental building is built with cement hallow block in the town of Douala-Cameroon.
The prediction of the air temperature (IT) and relative humidity (IH) in a building can help to reduce energy consumption for air conditioning. The purpose of this work was to apply the artificial neural network (ANNs) for an hourly prediction, 24–672h in advance of (IT) and (IH) in buildings found in hot-humid region. The inputs used in the model are 12 last values of indoor and outdoor air temperature and relative humidity. The experimental building is built with cement hallow block in Douala-Cameroon. IT and IH were collected for 24 months. The experimental data were used to determine the optimal ANN structure with levenberg-marquardt algorithm using Matlab software. The optimal structure was the multilayer perceptron (MLP) with 36 input variables, 10 hidden neurons and two neurons in the output layer. The activation functions were respectively the hyperbolic tangent in the hidden layer and the linear function in the output layer. Moreover, the IT and IH results simulated by using the ANN model were strongly correlated with the experimental data, with the coefficient of correlation of 0.9850 for IT and 0.9853 for IH. These results testified that ANN can be used for hourly IT and IH prediction.
Pyrolysis and combustion processes of pellets built with three Cameroonian biomass were performed in a thermobalance to determine their thermal degradation profiles and the associated kinetic ...parameters. The four samples were heated from ambient temperature to 900 °C under three low temperature rates (5, 10, and 20 °C/min) and under non-oxidative (nitrogen) or oxidative (synthetic air) atmospheres. The kinetic parameters associated to the pyrolysis or combustion of the four samples were estimated through the Extended Independent Parallel Reaction (EIPR) model, taking into account the emissions of extractives or not, depending on the sample. The thermal degradations of the pellets were finally compared to those of the three base materials with their proportions.
Industrial production in developing countries (DC) is frequently perturbed by electric energy supply difficulties. To overcome this problem, generators are used in self-generation of energy, but this ...leads to an increase of electricity-related expenses. This article assesses the impact of electricity self-generation on Cameroonian industrial companies. The model described in this article is based on data collected through a survey of a representative sample of industrial companies and from numerous previous thematic and statistical studies. The results of our analyses show that expenses related to electricity in industrial companies in Cameroon have increased five times due to electricity rationing and untimely power cuts. The article also suggests some solutions to improve the electricity self-generation capacity of industrial companies.
•Pellets were produced with three Cameroonian forest- and agro-industrial waste in three different proportions.•Their combustion was performed in an equipped pellet domestic stove.•The CO and TSP ...emissions were measured at higher levels for Cameroonian pellets than that for EN+ pellets in the same stove.•The combustion efficiency was evaluated between 68.5 and 80.2% with the Cameroonian pellets, in the same range as that (78.2%) of EN+ pellets.•The best proportion (60/30/10) of the three base materials was determined in terms of the combustion efficiency.
In Sub-Saharan houses, the growing demand of fuels calls for the identification of new renewable and local resources such as biomass, suitable for energy production in small-scale stoves. In these countries, the three-stone-fire type is the most common stove and its use usually leads to high gaseous and particulate emissions. In the present study, combustion experiments of pellets made with three Cameroonian biomass in three different proportions were performed in a domestic pellet stove. The gaseous and particulate emissions were measured in derivations of the exhaust tube through appropriate gas analyzers or collecting filter. The CO concentration was measured between 476 and 675 mg/Nm3, depending on the pellets. The Total Suspended Particles (TSP) were measured in the range 130–240 mg/Nm3, depending on the pellets. These gaseous and TSP emissions were much higher than that obtained when burning normalized EN+ pellets in the same pellet stove. The combustion efficiency was evaluated between 68.5 and 80.2%, depending on the pellets, through standard computations. These values were found in the same range as that (78.2%) obtained when burning normalized EN+ pellets in the same domestic pellet stove.
Modelling and simulation of a habitat sample lead to a model which the average resultant dry temperature is of 28.30 °C at the peak hours during the periods of occupation of the house. This result is ...within the acceptable and tolerable thermal comfort zone in humid tropical climate. It thus arises from this study, that housing with the following specifications: cement floor, wall with mixed hollow concrete block and wood plank, and roof with aluminium sheet is thermally well adapted for the Douala climate. Optimization of the thermal behaviour of this housing consists of bringing vegetation around it in order to reduce the thermal loads due to solar heat gain, improving the air replacement and taking into account the thermal inertia of its walls.
Hydrogen demand should significantly increase in the next few years due to rapid growth of energy demand, the refinery industry’s growing needs and applications such as biofuel production. To meet ...the demand advanced processes are being developed throughout the world in a sustainability context. Among the most studied ones is high temperature electrolysis of steam using solar photovoltaic and thermal energy. In this work, a large scale hybrid solar hydrogen production system was designed and optimized. The system consists of the solid oxide steam electrolysis system coupled to a Photovoltaic array through a Direct Current converter and coupled to a Parabolic Trough Collector through a heat exchanger network optimized using a Generalized Reduced Gradient algorithm. Under local tropical conditions, the theoretical production rate of hydrogen per second and per day recorded from simulation of interconnected system based on optimum scenario are respectively 0.064kg/s and 1843.2kg/day. The exergy efficiency, land used and water consumption of system component was also performed.
The aim of this paper is to study the influence of drying temperature on the active ingredients of medicinal plants: the case of total alkaloids of Alstonia boonei Wild. Barks of Alstonia boonei, ...collected on one stem, were cut and dried in the fresh air, and in an electric dryer at 40 ° C, 50 ° C and 60 ° C. Samples from the several drying methods and others of a fresh bark were then subjected to a phytochemical analysis in order to do a quantitative and qualitative study of alkaloids contained in barks. The study revealed that the alkaloid content of the bark of Alstonia boonei decreases when the drying temperature increases. The decay rate of the extraction yield of total alkaloids compared to the samples is 0.00091% for an increase of one degree Celsius. Thus, the extraction yield of total alkaloids is 0.0436% for the fresh sample, 0.0430% for drying at open air and 0.0174% for a drying temperature at 60 ° C. Natural drying of bark at the fresh air or at room temperature limit the losses of alkaloids. PUBLICATION ABSTRACT
this study was conducted in order to assess the effects of dietary Jumbo Cube as source of Monosodium Glutamate (MSG) on production performances of broiler chickens. 320 day-old Ross 308 broiler ...chicks were randomly divided into five groups of 64 chicks each. Negative and positive control groups were fed on basal diet with no supplement (R0-) and 1 gm of antibiotic (R0+) respectively and the 3 others groups were fed on diets supplemented with the quantities of Jumbo cube containing 1 mg, 2 mg and 4 mg of MSG/Kg of feed. Feed intake (FI), feed conversion ratio (FCR), weight gain (WG), blood parameters and intestinal microbial counts were evaluated. Results revealed that feeding broilers with Jumbo Cube as MSG source significantly (P<0.05) decreased FI at the starter phase with no significant effect at the finisher phase. Diet supplemented with 2 mg of MSG/Kg significantly (P<0.05) increased LBW and WG, and decreased FCR. Dietary MSG significantly (P<0.05) has no significant effect on bacteria counts during starter phase. At the finisher phase, GMS induced a significant increase in lactic bacteria and E. coli counts as compared to the control ration without any supplement. White blood cells (WBC) significantly decreased with inclusion of 1mg and 2 mg of MSG/Kg. Dietary MSG markedly decreased albumin/globulin ratio, LDL-cholesterol and creatinine. It was concluded that Jumbo Cube can be used as source of MSG (2 mg/Kg) to improve growth performance in broiler chickens.
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