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

Taguchi Method for Development of Mass Flow Rate Correlation Using Hydrocarbon Refrigerant Mixture in Capillary Tube

The capillary tube is an important control device used in small vapor compression refrigeration systems such as window air-conditioners, household refrigerators and freezers. This paper develops a non-dimensional correlation based on the test results of the adiabatic capillary tube for the mass flow rate through the tube using a hydrocarbon refrigerant mixture of 89.3% propane and 10.7% butane (HCM). The Taguchi method, a statistical experimental design approach, was employed. This approach explores the economic benefit that lies in studies of this nature, where only a small number of experiments are required and yet valid results are obtained. Considering the effects of the capillary tube geometry and the inlet condition of the tube, dimensionless parameters were chosen. The new correlation was also based on the Buckingham Pi theorem. This correlation predicts 86.67% of the present experimental data within a relative deviation of -10% to +10%. The predictions by this correlation were also compared with results in published literature

Artificial Neural Network Modelling of the Energy Content of Municipal Solid Wastes in Northern Nigeria

The study presents an application of the artificial neural network model using the back propagation learning algorithm to predict the actual calorific value of the municipal solid waste in major cities of the northern part of Nigeria, with high population densities and intense industrial activities. These cities are: Kano, Damaturu, Dutse, Bauchi, Birnin Kebbi, Gusau, Maiduguri, Katsina and Sokoto. Experimental data of the energy content and the physical characterization of the municipal solid waste serve as the input parameter in nature of wood, grass, metal, plastic, food remnants, leaves, glass and paper. Comparative studies were made by using the developed model, the experimental results and a correlation which was earlier developed by the authors to predict the energy content. While predicting the actual calorific value, the maximum error was 0.94% for the artificial neural network model and 5.20% by the statistical correlation. The network with eight neurons and an R2 = 0.96881 in the hidden layer results in a stable and optimum network. This study showed that the artificial neural network approach could successfully be used for energy content predictions from the municipal solid wastes in Northern Nigeria and other areas of similar waste stream and composition

Statistical Modelling of the Energy Content of Municipal Solid Wastes in Northern Nigeria

The ability to predict the quantity of energy to be produced is of paramount importance in every country. It would assist in setting up a waste management plan which will lead to a sustainable energy policy. This paper presents the development of a statistical linear regression mathematical model to predict the amount of energy contained in municipal solid wastes from the knowledge of such characteristics of the wastes as physical composition and/or moisture content. Major cities of Kano, Katsina, Dutse, Damaturu, Maiduguri, Bauchi, Birnin Kebbi, Gusau and Sokoto in Northern Nigeria, with high population densities and intense industrial activities constituted the area of study. Ten kilogram each, of the municipal solid waste was collected from the government designated refuse dumping sites in both highly dense populated low income areas and government residential areas, during the hottest months of February, March and April and during the rainy season in the month of August for three years. The waste material was prepared for the determination of its physical characteristics by sifting through. Proximate, ultimate analyses and calorific values were determined using ASTM analytical techniques and formulas from the literature. An empirical linear regression based mathematical model was developed using statistical methods and experimental data. Comparison between experimental and predicted values of the calorific values showed an agreement of about 70% with an average deviation of 5.03% while the standard deviation was found to be 5.29%

Maximum Power Point Tracking in Partial Shaded Photovoltaic System using Smell Agent Optimization Algorithm

With partial shading conditions, it is essential to acquire Maximum Power Point at which the Photovoltaic systems (PV) operate effectively despite the variation in the cell temperature and incident angle of sunlight rays on the panels. This study explores the use of a Smell Agent Optimization (SAO) algorithm for Maximum Power Point Tracking (MPPT) in partial shaded PV systems. The proposed MPPT system is composed of a PV model, a DC-DC converter model and a control part. The Smell Agent Algorithm (SAA) was adopted in the control part of the MPPT system to implement the optimization algorithm using four different shading patterns (SPs) and to calculate the optimal switching duty cycle of the DC-DC converter. The effectiveness of the proposed system was verified using simulations in the MATLAB/Simulink environment. The SAO respectively track maximum values for Power, Voltage and Current as 845.8476 W, 211.7308 V, 3.99492 A while the maximum values for Power, Voltage and Current for Perturb and Observe (P and O) are 845.0465 W, 211.6305 V, 3.993028 A respectively during SP1. The results showed that the SAO algorithm has excellent tracking results in terms of convergence speed, accuracy, power extracted stability, and dynamic response in reaching the optimum point

Numerical Study of an Ejector as an Expansion Device in Split-type Air Conditioners for Energy Savings

The present study describes a numerical approach for determining both the motive nozzle and constant-area diameters of an ejector as an expansion device, based on the cooling capacity of a split-type air-conditioner using R290 as refrigerant. Previous studies have shown that replacement of HCFC R22 with HC290 (propane) in the air conditioner can improve the coefficient of performance (COP). The purpose of replacing the capillary tube with an ejector as an expansion device in a split-type air conditioner using HC290 is to further improve the COP. In developing the model, conservation laws of mass, momentum and energy equations were applied to each part of the ejector. The numerical results show that the motive nozzle diameter remains constant (1.03 mm) under varying condenser temperatures, whereas the diameter of the constant-area decreases as the condenser temperature increases. It was also found that improvement of the COP can reach 32.90% at a condenser temperature of 55 °C. From the results mentioned above, it can be concluded that the use of an ejector can further improve the COP of a split-type air conditioner using HC290 as working fluid

Experimental investigation of the performance of a household refrigerator using plywood as radiation shield

This research work investigates the performance of domestic refrigerators. Test were carried out on two configurations of household refrigerators; a conventional refrigerator and a refrigerator that was modified by incorporating a radiation shield. In this work, plywood was used as thermal radiation shield placed between the back of the refrigerator and the condenser and compressor. Pressure gauges were welded to the evaporator inlet and condenser outlet. Thermocouples were attached to the compressor inlet and outlet, condenser outlet and evaporator inlet in order to obtain data from the test. The pressure and temperature data obtained was applied to evaluate the performance of the two systems. With further repeated tests, the coefficient of performance (COP) of the refrigeration systems were determined at normal ambient condition. The highest evaporator temperature obtained for the conventional refrigeration system (CRS) and modified refrigerators system (MRS) were -5oC and 0oC respectively. Interestingly, an efficiency improvement of about 10% was achieved for the MRS. The result shows a remarkable improvement in the COP of the MRS. Therefore, for a better performance, thermal radiation shield can be recommended to be incorporated in vapour compression refrigeration system