Journal of Energy Research and Reviews

This work investigated the terrestrial solar radiation over Awka, South Eastern Nigeria using meteorological parameters of terrestrial temperature and relative humidity collected during 2013- 2014 respectively, using Davis weather station vantage pros2 (with Integrated Sensor Suite, ISS) positioned close to the ground surface. The data were logged at 30 minutes interval continuously for each day during the period. Hourly, daily and monthly averages of terrestrial radiation during dry and wet seasons were calculated from the data obtained. The result indicated that the terrestrial radiation during dry season is generally higher than during the wet season. The month of March has the highest value of terrestrial solar radiation of 410 Wm^-2 , while the least terrestrial radiation of about 381 Wm^-2 occurred in August. The result also showed that terrestrial solar radiation correlates positively with water vapour and more positively with temperature at 0.57 and 0.81 coefficients respectively. The results obtained from this work provide useful knowledge that is necessary to enhance the deployment of solar energy conversion systems.

Introduction: Thermochemical and biochemical processes are used to convert biomass into useful and sustainable energy. Thermoconversion processes comprises the biomasses burning in an oxygen-rich environment or in the absence of this, where types and fuel properties, process conditions, particles size, air flow rate and fuel moisture affect directly the combustion characteristics, altering the generation and heat transfer and the reaction rates. The combustion chamber temperature is an important factor for the biomasses combustion or other material, because this exerts large influence in the thermal processes efficiency, products yield and composition of the generated products.

Research Problem: For this reason, this paper aims to investigate the high temperature behavior in the combustion chamber of a Drop Tube Furnace (DTF)

Methods: Different thermochemical processes (conventional combustion, pyrolysis and two typical oxy-fuel combustion atmospheres) and five Brazilian biomasses (pine sawdust, sugarcane bagasse, coffee and rice husks, and tucumã seed) are employed. Such monitoring in situ was performed using two thermocouples located inside the furnace: one in the upper and other in bottom part.

Results: For the different biomasses and thermal processes (atmospheres), a trend in the high temperature variations of the combustion chamber and residence times were observed, which can be related to the biomasses feeding system, moisture of samples and specific furnace operation conditions.

Conclusion: This study can support in new projects elaboration of thermochemical conversion systems in lab-scale or industrial for the burning of several biomasses or other materials with purpose bioenergy generation.

A computational analysis in a rotary regenerative air preheater subject to pre-established mass flow rate is performed. The heat transfer rate, the pressure drop and the outlet temperatures of gas streams are calculated from different matrix porosity values. The fluid flow and the convective heat transfer coefficient are determined from correlations. The total heat transfer is obtained using the Effectiveness-NTU method specific to regenerative air preheaters. Three typical regenerative air preheaters with both streams under the laminar flow regime are investigated. A range of porosity values that provide good thermal exchange and low pressure drop in the equipment is chosen for each examined air preheater. The behavior of the outlet temperatures of each gas stream as function of porosity is also analyzed. The results show that the porosity ranges shorten when the typical pressured drop values for each regenerative air preheater are introduced in the analysis. In addition, the behavior of the outlet temperatures is compatible with the behavior of the heat transfer rate as the porosity changes.

This study estimated natural gas demand elasticities in Nigeria. The objective of the study was to examine the responsiveness of natural gas demand to changes in price of natural gas, income and prices of other energy products. The study adopted the bound testing approach to    cointegration within the framework of ARDL to estimate annual time series data over a period of 33 years (1984 – 2016). The findings of this research showed that the elasticity of natural gas demand is relatively price inelastic in both short and long run; cross-price elasticity of gas demand revealed that AGO and LNG are substitute energy products for natural gas in Nigeria; while the estimate of income elasticity of demand is not statistically significant in the short and long run.

By means of observational evidence it is shown that, among the vast amount of heat-work interactions occurring in closed process based transformations, there exists the possibility of doing a transformation characterized by doing useful mechanical work by contraction based compression, while increasing the internal energy. Such thermodynamic transformation has never been considered in processes. However, in reality closed contraction based compression process are physically possible in which net work is produced by contraction of a thermal working fluid while fulfilling the fundamental laws. Thus, the objective is therefore to analyze heat-work interaction modes in closed processes conducted by heat addition, heat extracting and net work done by the process. Therefore, this analysis focuses on the feasible thermodynamic transformations contributing to the achievement of efficient closed processes based thermal cycles. The proposed cycles are characterized by performing mechanical work both in the expansion phase due to heat addition, and in the compression phase due to heat releasing. The cycles achieved are characterized by operating with closed thermal processes in which both transformations with isochoric heat addition and isochoric heat extraction are associated with useful mechanical work at high performance. The analysis of the cycle between top working temperatures ranging from 350 to 700 K while botom temperature approaches 300 K has been carried out, corroborated by experimental validation for low temperatures, in the order of 350 degrees Kelvin through a test bench designed specifically for this task. It is also worth noting that the thermal efficiency is independent of the temperature ratio. Therefore the results indicate that for lower temperatures below 690 K, the thermal efficiency of the cycle exceeds the Carnot factor, which is an efficient means of recovering residual or low-grade heat efficiently.