Journal of Energy Research and Reviews

Energy is the prime mover of development cutting across industrialisation, manufacturing and residential consumption. Recently, Kenya, being ranked high among the most developed countries in Africa, has mapped way for embracement of renewable energy technology with increasing debate on sustainable development and environmental issues associated with fossil fuels, as the prime energy sources.

Generally, Kenya is making efforts to Scale - Up renewable energy programs via construction of stand-alone solutions as well as various types of mini - grids. However, a common problem cutting across all these consumers is quick failure of such projects with very little access to technical solutions or none at all. Substantial developments in solar energy in Kenya, as one of the renewable energy sources, has been mainly challenged by lack of effective capacity building and poor technical support. This cuts across both domestic systems as well as the most rising aspect of small and medium sized minigrids.

This paper aims at investigating the leading role of access to viable technical support services in mitigating solar energy adoption challenges. The paper focuses on challenges faced by small and medium sized consumers in search for technical advice and support prior to purchase, during installation and after purchase and installation stages. The research conducted survey via questionnaries, analyzed data obtained, identified technical support factors in order of priority and gives adaptable recommendation for the state in ensuring that solar projects are sustainable and that customers find value for their money.

Introduction: Foam mat drying involves the change of agricultural material from a high moisture content level to a stable foam which is achieved by moisture reduction mechanism.

Aim: In this study, foam-mat drying process of watermelon was optimized using response surface methodology. Foaming conditions (carboxyl methyl cellulose and egg albumen) and the drying system parameters (air velocity and air temperature) were optimized using response surface methodology.

Methodology: To evaluate the drying behaviour, the drying experiment was designed using design expert software using a central composite design setting variable of drying temperature (60°C – 80°C), air velocity (0.5 m/s – 2 m/s), carboxyl methyl cellulose (0.5% - 2.5%), egg albumen (5% - 15%). Twenty-two runs of the experiment were performed using different levels of variables combinations. Based on the statistical tests performed, the best model that described each response was selected using a polynomial analysis.

Results: The optimum values for the drying conditions were: 77.42^OC, 0.5m/s, 0.5% and 5% for temperature, air velocity, carboxyl methylcellulose and egg albumen respectively and the optimum values for the drying characteristics were: 25.07 KJ/mol, 1.7345E-10 m²/s, 29.019% (wet-basis). 0.742 g/cm³ and 540 minutes (approximately 9hrs) for activation energy, effective diffusivity, moisture content, foam density and the drying time respectively.

Conclusion: The study of the foam-mat drying of watermelon pulp revealed that the inlet temperature, air velocity, CMC and egg albumen has a significant effect on its drying characteristics.

In this study, time series statistical analysis was carried out on the monthly average daily meteorological parameters of global solar radiation, sunshine hours, wind speed, mean temperature, rainfall, cloud cover and relative humidity during the period of thirty one years (1980 – 2010) using IBM SPSS Statistics version 20 with expert modeler to determine the level, trend and seasonal variations for Ogoja and Maiduguri. Seasonal Auto Regressive Integrated Moving Average models were determined for the two locations along with their respective statistical indicators of coefficient of determination, Root Mean Square Error, Mean Absolute Percentage Error and Mean Absolute Error and are found suitable for one step ahead forecast for the studied area. The factor analysis (empirical orthogonal transformation) and descriptive statistical analysis was also carried out for the study areas under investigation. The results indicated that the model type for all the meteorological parameters for Ogoja is simple seasonal while that for Maiduguri is simple seasonal except for rainfall and cloud cover with winter’s additive and ARIMA models respectively. The correlation matrix obtained from the factor analysis for the studied area indicated that the global solar radiation and wind speed are more correlated with the mean temperature. The sunshine hours and mean temperature are more correlated with the global solar radiation. The rainfall is more correlated with the relative humidity; similarly, the relative humidity is more correlated with the rainfall. However, the cloud cover is more correlated to the rainfall for Ogoja while for Maiduguri the cloud cover is more correlated to the relative humidity. The component matrix analysis revealed that two seasons are identified for Ogoja; the rainy and dry seasons while for Maiduguri three seasons are identified; the rainy, cool dry (harmattan) and hot dry seasons. The skewness and kurtosis test for Ogoja indicated that the global solar radiation, sunshine hours, cloud cover and relative humidity are negatively skewed and the wind speed, mean temperature and rainfall are positively skewed while the global solar radiation, sunshine hours, wind speed, cloud cover and relative humidity indicates possibility of a leptokurtic distribution and the mean temperature and rainfall indicates possibility of a platykurtic distribution. The skewness and kurtosis for Maiduguri indicated that the solar radiation, rainfall and relative humidity are positively skewed and the sunshine hours, wind speed, mean temperature and cloud cover are negatively skewed while the global solar radiation, rainfall and cloud cover indicates possibility of a leptokurtic distribution and the sunshine hours, wind speed, mean temperature and relative humidity indicates possibility of a platykurtic distribution.

The energy and exergy of syngas produced from air-steam gasification of wheat straw in a dual-distributor fluidized bed gasifier under different operating conditions were evaluated. Three fluidization velocities (0.35, 0.40 and 0.45 m/s), 3 steam flow rates (0.20, 0.25 and 0.30 kg/min) and 3 biomass: steam ratios (3.00, 4.00 and 5.00 kg/kg) were investigated. The energy values of CO, H₂, N₂, CO₂, CH₄, C₂H₄ and C₂H₆ varied within the ranges of 1627.09-4646.60, 1543.30-2896.11, 274.75-1742.86, 82.03-574.24, 3225.39-4931.40, 1493.35-3777.44 and 892.74-2319.72 kJ/kg fuel, respectively. The overall energy distribution was (CH₄ & CO & C₂H₄ & H₂)>C₂H₆>(N₂ & CO₂). The results showed that when the fluidization velocity (FV) was increased from 0.35 m/s to 0.45 m/s (28.57%), the total energy of syngas increased by 1.16-28.59% depending on the steam flow rate (SFR} and biomass: steam ratio (B:S) used. Increasing the SFR from 0.20 kg/min to 0.30 kg/min (50.00%) decreased the total energy of syngas by 27.23-62.35% depending on the FV and B:S used. Increasing the B:S from 3.00 kg/kg to 5.00 kg/kg (66.67%) decreased the total energy of syngas by 11.86-37.33% depending on the FV and SFR used. The exergy values of CO, H₂, N₂, CO₂, CH₄, C₂H₄ and C₂H₆ were in the ranges of 1486.70-4224.40, 1183.82-2209.00, 60.26-677.26, 54.02-452.97, 2913.74-4448.38, 1404.76-3541.76 and 833.00-2156.42 kJ/kg fuel, respectively. The overall exergy distribution was (CH₄ & CO)>(C₂H₄ & H₂ & C₂H₆)>(N₂ &CO₂). When the FV was increased from 0.35 to 0.45 m/s(28.57%), the total exergy of syngas increased by 1.45-26.93% depending on the SFR and B:S used. Increasing the SFR from 0.20 kg/min to 0.30 kg/min (50.00%) decreased the total exergy of syngas by 26.78-63.26% depending on the FV and B:S used. Increasing the B:S from 3.00 kg/kg to 5.00 kg/kg (66.67%) decreased the total exergy of syngas by 10.32-36.07% depending on the FV and SFR used. The effect of SFR on the total energy and total exergy of syngas was the highest, followed by B:S and FV. The highest energy (20004.54 kJ/kg fuel) and exergy (16886.06 kJ/kg fuel) of syngas were obtained at the FV of 0.45 m/s, the SFR of 0.20 kg/min and the B:S of 3.00 kg/kg.

Removal of lead from Enugu coal with different acids as the leachant under different conditions such as leaching time, particle size, acid concentration, and leachant volume was investigated in this studies. The filtrate from each treatment was analyzed with Atomic Absorption X-ray Spectrometer (AAS) to determine the amount of lead leached. Nitric acid was found to be the best acid for the leaching of lead from Enugu coal. Kinetic studies carried out showed that the dissolution rate increased with: decreasing particle size, increase in stirring speed, acid concentration and leaching temperature. The experimental results revealed that the dissolution rate is a chemical reaction controlled via hydrogen ion concentration [H⁺], with reaction order of 0.9 and the reaction kinetics can be expressed as 1-(1-X)^1/3 =2.566x10^-4(C_HNO3)^0.86 (dp^).992 (L/S)^.44 (SS)^.049 exp^(53.49/RT). A quadratic model was predicted and optimized using second order orthogonal design (Box-Benken) which resulted in Particle size of 40µm, reaction time of 8.5 hours, and HNO₃ concentration of 2mol/dm³. The optimum conditions were validated at model desirability of 1. Experimental value of 96.39% with error of 0.530% was removed.