Design and Experimental Testing of a Solar Box Cooker with Paraffin Wax as Thermal Energy Storage Using Maiduguri Weather Condition

The performance of paraffin wax as phase change material (PCM) for thermal energy storage (TES) was investigated using a Solar Box Cooker (SBC) exposed to Maiduguri weather condition. Temperature and energy generated by SBC were experimentally established. The result shows tremendous improvement in energy storage compared to SBCs without TES in existence within Maiduguri and environs. The measured temperature and energy generated by the PCM in the experiment were 118oC and 4164.5KJ respectively, an adequate temperature and energy for cooking during off-sunshine hours and beyond. First figure of merit (F1) and second figure of merit (F2) were deduced to be 0.13 and 0.44 with overall SBC efficiency (ɳ) of 63% qualifying the SBC to grade A based on the Bureau of Indian Standards (BIS

Application of Stearic Acid for Solar Thermal Energy Storage in a Double Compartment Solar Box Cooker

Energy storage in some form is the need of the hour to even out the mismatch between energy supply and demand. Thermal Energy Storage (TES) system employing a phase change material (PCM) has been widely considered as an effective way to store and retrieve energy due to its high heat storage capacity at almost constant temperature during the phase change. In this work, an energy storage system was designed to study the heat transfer characteristics of stearic acid (as a phase change material in a double compartment solar box cooker (DCSBC) fabricated using wooden materials with high thermal energy storage system. In order to analyze the various characteristics of the PCM, the Bureau of Indian Standards (BIS) was used throughout the experiment. Investigations were performed to determine the first and second figure of merits (F1 and F2) of compartments 1 and 2 (C1 and C2) simultaneously. The results for F1 were found to be (C1= 0.14 and C2= 0.15) and F2 were (C1=0.47 and C2= 0.4) while the overall thermal efficiency of the cooker after water boiling test for C1 with 2.5kg and C2 with 3kg of water were deduced to be 77% for C1 and 92% for C2 after six hours of the load test, showing considerable temperature increase and extension of heat retention making possible to cook the dinner and even breakfast the next day

Maritime Carrier's Liability for Loss of or Damage to Goods under the Hague Rules, Visby Rules and the Hamburg Rules, Compared with His Liability as an Operator under the Relevant Rules of the International Multimodal Transport Convention

The system of the carrier's liability, in respect of carriage of goods, is a very controversial issue which raises many difficulties in solving the problems thereto related, whether in national laws or in international Conventions. The present thesis, dealing with the carrier's liability, consists of five chapters and final conclusions. The first four chapters concentrate, theoretically, practically and in detail on analysing and comparing the liability regimes in relation to the carrier's liability under the Hague/Visby Rules and the Hamburg Rules, in order to ascertain which is more conducive to international certainty and uniformity. The Hague/Visby Rules and the Hamburg Rules have played a vital role in the international transport industry. They are correspondingly discussed in the thesis. Chapter five is devoted to discussion of the liability of the multimodal transport operator as one of the most important parts of the International Multimodal Transport Convention (1980). The chapter also evaluates the situation when, in the future, the Convention comes into force. In its structure the thesis is divided as follows; chapter one deals with a brief history and the scope of application of the Rules. The liability of the carrier and the limitation of the carrier's liability are considered in chapters two and three. Chapter four deals with the procedures of action for lost or damaged cargo. The liability of the multimodal transport operator for loss or damage to the goods under the 1980 United Nations Multimodal Transport of Goods Convention is dealt with in chapter five

Combustion Modeling of a Fixed Bed Downdraft Biomass Gasifier Using Computational Fluid Dynamics Design

Thermochemical conversion of biomass in a gasifier for the production of syngas provides the enabling technology for efficient biomass resource utilization. Gasification is a complex process involving the interactions of numerous parameters, hence CFD tool is usually utilized to numerically optimize the design and operation of the gasifier reactor for improved performance. The gasification of multiple biomass usually requires a complex set of facilities for experimental set up in order to determine the optimum operating conditions for maximum gas yield. When this is not available, it can pose a bottle-neck to process development and optimization.  In this study, the GAMBIT and FLUENT were used to model and simulate the gasifier reactor with emphasis on the combustion and gasification (reduction) zones in order to maximize the thermal output of the combustor by an optimization of biomass fuel types. Model validation was achieved by showing a close agreement between numerical and experimental results within the same configuration, particularly to show the effect of temperature on the gasification of Fixed Bed Downdraft gasifier. The fraction of initial moisture content, air flow rate, temperature of the pyrolysis zone, and chemical composition of the biomass were the required input data for the model to predict the gasification temperature. Computations were carried out for rice husk, saw dust and corn cobs as gasifier fuels, whereby air was used as the oxidizing agent. The porosity and oxidizer velocity were varied between 0.1 – 0.5 and 5 – 15 m/s respectively. The predicted results compared with experimental data showed good agreement. The simulated temperature gradient also indicated that rich fuel combustion zone was greater for rice husk - corn cobs, an indication that improved gasification and pyrolysis were present

Occurrence of Similar Periods in Geomagnetic Field Variations and Solar Activity

The periodicities associated with some geomagnetic field parameters under quiet and disturbed solar conditions have been examined using a set of data spanning through five years obtained courtesy of INTERMAGNET network. Hourly values of the Horizontal component of the geomagnetic field simultaneously obtained at seven INTERMAGNET stations were engaged in the study. The stations were well distributed across the latitudes, viz: Bangui, 4.4°N; Kourou, 5.1°N; Alibag, 18.6°N; San Juan18.1°N; Crozet, 46.4°S; Barrow, 71.3°N; Scott  Base, 77.9°S). Solar quiet daily variation Sq, Superposed Magnetic field SPMF and Solar disturbance daily variation SD in the horizontal magnetic field component were evaluated and studied for their spectral characteristics. The spectral analysis revealed the periods of 6 hours, 12 hours, 24 hours, 3 months, 6 months, 12 months and 16 months in the geomagnetic field variations. The observed periodicities were explained in terms of associated solar terrestrial processes. This clearly shows the influence of an extra terrestrial source (the Sun) on terrestrial processes. Sun is the undisputable driver of space weathe

Physical And Mechanical Characteristics Of Charcoal, Sawdust And Sugarcane Bagasse As Solid Fuel Materials

This paper reports on the physical and mechanical characteristics of briquettes produced from charcoal, sawdust and sugarcane bagasse using molasses with sodium silicate as binders. Charcoal, sawdust and sugarcane bagasse were mixed in respective ratio of 20:20:60, 20:30:50, 20:40:40, 20:50:30 and 20:60:20. The briquettes were produced using Budenberg dial gauge compression machine, with pressure of 64 MPa at 120 seconds dwell time. Physical properties (relaxation ratio, compaction ratio and shattering index) and mechanical property (compressive strength) of the produced briquettes were investigated. Results show that briquette with sample composition of 20:30:50 has better physical properties with relaxation ratio of 1.562, compaction ratio of 7.573 and shatter index of 99.6%, while sample with ratio 20:40:40 has highest compressive strength of 55.43 kN/m2

Protective Roles of Adansonia digitata (African Baobab), Cucumeropsis mannii (Melon), and Abelmoschus esculentus (Okro) Supplemented Diets against Cadmium-Induced Lipotoxicity, Bone Demineralization, and Cytotoxicity in Rabbits

The present study was undertaken to investigate the protective roles of Adansonia digitata (African baobab) Cucumeropsis mannii (Melon), Abelmoschus esculentus (Okro),  on lipid profile, bone health, and selected organs (liver, kidney, brain, and testis) against cadmium-induced toxicity in rabbits. Twenty male rabbits were grouped into five with four rabbits in each group. Group 1 served as positive control and received standard feed and 1.5 mg/kg body weight normal saline, group 2 served as negative control and were exposed to 1.5 mg/kg body weight cadmium chloride, group 3 received 1.5 mg/kg body weight cadmium Adansonia digitata supplemented feed, group 4 received 1.5 mg/kg body weight cadmium chloride and Citrullus lanatus supplemented feed, while group 5 were given 1.5 mg/kg body weight cadmium chloride and Abelmoschus esculentus supplemented feed. All administrations were orally and lasted for 28 days. At the end of the administration, blood, liver, kidney, brain, and testes were harvested from the rabbits for biochemical and histological analysis. One-way analysis of variance followed by Turkey’s test was used to analyze the results with p < 0.05 considered significant. The results revealed that cadmium exposure caused a significant increase in serum total cholesterol, triacylglycerol, low density lipoprotein cholesterol concentration, and atherogenic index in rabbits exposed to cadmium. Cadmium exposure also reduced bone calcium concentration. Adansonia digitata maintained the atherogenic index of plasma at 2.67 compared with the positive control group (2.66). The three vegetables reversed the cadmium-induced up-regulation of total cholesterol and triacylglycerol in the liver, kidney, and brain but not in the testis. All the vegetables also restored bone calcium. Citrullus lanatus and Abelmoschus esculentus prevented organ damage induced by cadmium exposure. These vegetables however play different protective roles against cadmium exposed rabbits

Fixed-wing MAV attitude stability in atmospheric turbulence, part 1: Suitability of conventional sensors

Fixed-wing Micro-Aerial Vehicles (MAVs) need effective sensors that can rapidly detect turbulence induced motion perturbations. Current MAV attitude control systems rely on inertial sensors. These systems can be described as reactive; detecting the disturbance only after the aircraft has responded to the disturbing phenomena. In this part of the paper, the current state of the art in reactive attitude sensing for fixed-wing MAVs are reviewed. A scheme for classifying the range of existing and emerging sensing techniques is presented. The features and performance of the sensing approaches are discussed in the context of their application to MAV attitude control systems in turbulent environments. It is found that the use of single sensors is insufficient for MAV control in the presence of turbulence and that potential gains can be realised from multi-sensor systems. A successive paper to be published in this journal will investigate novel attitude sensors which have the potential to improve attitude control of MAVs in Turbulenc

Fixed-wing MAV attitude stability in atmospheric turbulence-part 2: Investigating biologically-inspired sensors

Challenges associated with flight control of agile fixed-wing Micro Air Vehicles (MAVs) operating in complex environments is significantly different to any larger scale vehicle. The micro-scale of MAVs can make them particularly sensitive to atmospheric disturbances thus limiting their operation. As described in Part 1, current conventional reactive attitude sensing systems lack the necessary response times for attitude control in high turbulence environments. This paper reviews in greater detail novel and emerging biologically inspired sensors, which can sense the disturbances before a perturbation is induced. A number of biological mechanoreceptors used by flying animals are explored for their utility in MAVs. Man-made attempts of replicating mechanoreceptors have thus been reviewed. Bio-inspired flow and pressure-based sensors were found to be the most promising for complementing or replacing current inertial-based reactive attitude sensors. Achieving practical implementations that meet the size, weight and power constraints of MAVs remains a significant challenge. Biological systems were found to rely on multiple sensors, potentially implying a number of research opportunities in the exploration of heterogeneous bio-inspired sensing solution