Heating, ventilation and air conditioning systems (HVAC) are widely present in industry. They permit to maintain strict environmental conditions such as in clean room in pharmaceutical and aerospace industries. They also permit to maintain personal health and comfort (e.g., in offices). This article is a case study in an industrial pharmaceutical site in France. HVAC systems represent 57% of siteâs carbon emissions because air must be transported and undergo several different treatments: heating, cooling, dehumidification, and Filtration. Moreover, those systems are generally overdesigned, operate very far to the specification limits and/or regulation are not optimized. To minimize carbon emissions, a specific methodology has been developed for ensuring to make the right choices when implementing a new HVAC or modifying an existing one. This methodology contains 4 steps: reduce quantity of air, reduce air treatment periods, efficient air treatment by design and efficient air treatment by management. Each step includes complex, simple and innovative actions such as electronically commutated motor in place of conventional motor. The methodology developed does not degrade global performance and thermal efficiency of systems and answer to quality, environment, health, and safety requirements. The application of this methodology has permitted to reduce carbon emissions of HVAC systems by 24% in less than 3 years.
This work deals with determining the characteristics of the flow through the penstock of the Three Gorges dam in China. It also allows us to understand the influence of the diameter of the water duct on the modification of the flow structure in the penstock. To achieve our goals, the Eulerian resolution of the Navier-Stokes equations is done by a RANS approach using the FLUENT calculation code. The turbulence model applied is that with two k-ɛ equations. The results show constant velocities upstream of the dam until approaching the water intake at a distance of about 15m upstream, keeping an asymmetric shape in the different sections constituting the penstock. The maximum velocities are observed on the innerside of the various elbow. Layers of positive pressure are also visible in the penstock away from the walls; suggesting substantially coaxial and positive iso-pressures in high velocity zones, with a maximum directed towards the center of the penstock. This phenomenon thus goes against the high velocity-low pressure hypothesis, and may be justified by the geographical arrangement of the penstock, associated with its large diameter.
Crude Distillation Unit often produces gasoline of low Research Octane Number (RON). For efficient engine performance, high RON-gasoline is required. Refiners resort to the use of different chemical compounds called additives to improve the RON of gasoline. One group of these additives is fuel oxygenates, oxygen-containing hydrocarbons. In this study, experimental results of the effect of two fuel oxygenates, Methyl tertiary Butyl Ether (MTBE) and Ethyl tertiary Butyl Ether (ETBE) on the RON, RVP, Distillation, Density, Oxidation Stability (Induction Period), Washed Gum and Copper corrosion were examined and compared. The results showed that ETBE improves the RON of gasoline slightly better than MTBE. The increase in RVP of the gasoline was higher with MTBE than ETBE. Distillation curves were not significantly different from each other and other properties such as oxidation stability and copper corrosion were the same for the blends used.
With the increasing demand for electrical energy worldwide and the proportionate inflation of natural resources, it is important to predict the electrical power output from baseload combined cycle power plants and the factors affecting the yield per hour. Finding reliable factors not only improves the performance of the power plant in terms of production or distribution but also ensures the proper utilization of natural resources (or fuels) with minimal effect on the environment and effective cost management. Though there are sophisticated machine learning models for predicting full load electrical power output, often these deployed models are unable to draw inferences. Thermodynamic models on the other hand are oftentimes too complex, are valid only under a set of assumptions, and are generally non-linear in nature adding to the computation time. Keeping these limitations in mind, the objectives of this study are to find potential predictor variables that affect the power output yield per hour and then use these inferences to construct a simple yet effective model to predict the electrical power output in combined cycle power plants. The dataset used for this study is from a combined cycle power plant over a span of six years (2006-2011), with the power plant operating in a full load. A combined cycle power plant is composed of gas turbines, steam turbines, and heat recovery steam generators. The gas and steam turbines generate the electricity which is combined in one cycle and is transferred from one turbine to another. The input features of the dataset considered for this study consist of average ambient variables: ambient temperature, ambient pressure, relative humidity, and exhaust vacuum which are used to predict the average hourly electrical power output.
In an era saddled by mounting energy dependency and insecurity, some are not only turning to renewable geothermal energy to ensure access, but it is growing in usage in the Western region of the United States of America. Notwithstanding the United States role as a major producer of geothermal resources globally, geothermal energy has over the last several years found ample use in various spheres of daily endeavors within communities. The surging demand is much so that, it now contributes quite significantly in the generation of electricity to power households and farming activities and to sustain domestic supplies essential to segments of the economy for communities from California to Nevada. With much of the production levels, installations and plant capacities of geothermal power fully entrenched in the western region of the country considering the geologic and physical attributes, California stands out as the largest producer of geothermal power compared to its neighbors in the western region. For that, the demand for geothermal resource has been recurrent in quite a few counties over the years on the California side of the US Western region. In the face of widespread demands in the region, geothermal energy infrastructure in the form of new plants has gradually penetrated different states under varying level of production and installed capacities to boost energy security and sustain development of the areas. Even at that, very little has been done in the literature to undertake a regional assessment of the potentials of geothermal energy using a mix scale approach of spatial analysis anchored in Geographic Information Systems (GIS). Accordingly, this study will fill that void in research by utilizing mix scale tools of GIS and descriptive states in analyzing the geothermal energy potentials of states in the Western region of the United States. Emphasizing the issues, trends, impacts, production, factors and future efforts through recommendations, the results point to growing usage and changes in a whole set of energy indicators ranging from production and demands, installed capacity to others over time in the region with much of that in California coupled with an uptick in geothermal portfolio. Additionally, the GIS mapping of the trends highlights gradual dispersion of changing patterns in consumption and presence of infrastructural facilities visibly concentrated in a cluster of areas located in the western region. With all these attributed to a host of socio-economic and physical factors, the paper proposed suggestions ranging from the design of a regional geothermal energy information system, the education of the public and more infrastructural development in the sector.
TGA measurements have been known to provide valuable information that can be used to select materials for certain applications and to predict product performance giving way for possible improvement. Polymeric cable wires were exposed to TGA analysis (after subjecting them different preheating treatments) which leads to determining their thermal stability through comparative analysis between the fingerprints of the preheated and the non-preheated samples obtained. Very reliable and valuable information was obtained which would help in predicting the product performance giving way for possible improvement of the materials.
Carbon capture is immensely articulated as a technology that is centred on limiting the emission of CO2, which is linked to global climate change. Moreover, the need to attain a sustainable energy supply is viewed as being one of positive ways that will help to react with the increasing global national and local environmental issues. Likewise, Biogas being a renewable energy purifying it is both beneficial to the environment and society as a whole. The goal of this research is to develop a system that can scrub carbon dioxide as well as analyse, assess different materials used to capture CO2. Biogas is a gaseous mixture of approximately 45%-75% methane, 25%-55% carbon dioxide and 2000 PPM hydrogen sulphide depending on the biomass used. The biogas performance is seemingly affected by increasing CO2; thus it has to be removed before it causes more harm to the quality of Biogas produced. Besides it leads to lowering methane combustion performance, difficulties in biogas storage and transportation and reduction in calorific value of the biogas. In this work chemical absorption method was used to remove CO2 from biogas by using sodium hydroxide solution. Different concentrations of sodium hydroxide were used in cleaning biogas the concentrations include; 0.5molar, 1molar, 1.5molar and 2molar. Results showed that as molarities of NAOH were increased reduction of CO2 also increased. Experiments revealed the highest removal efficiency had been achieved at 2molar of NaOH absorbent solution reduction of CO2 achieved was 27.26% from 33.90% as initial value and maximum absorption was achieved when methane increment was about 30.85% from its 65.10% initial value. Gas obtained after removing CO2 from biogas resulted into increased methane content nearer to natural gas. Future works ought to centre their focus on the possibility of converting the sought residue and all the spent solutions in gaining all the value added products for small scale production of biogas.
Coal is still used in various industries with certain specifications, such as caloric value, ash content, sulfur content (Total Sulfur), flying substances (Volatile Matter) and water content (Total Moisture). Because the availability of coal with a variety of qualities is certainly not possible to meet the specification criteria that can be used by industry. Therefore we need a coal mixing system that can provide the quality desired by the industry or Market. In mixing coal there are several methods which are carried out and have different homogeneity. Coal blending using the chevron stockpile method and the windrow stockpile method were tested 5 times. Then the preparation of process was carried out using method of proximate analysis was carried out on the coal. The analysis results were then processed using the exel application. In the chevron stockpile method, the fluctuation value of coal quality analysis was as follows: total moisture had a range of 10.90, inherent moisture had a range of 14.58, ash content had a range of 39.76, votalite matter had a range of 4.71, fixed carbon had a range of 10.14, total sulfur had a range of 72.72 and calorie value had a range of 5.15. In the windrow stockpile method, coal quality fluctuation values were as follows: total moisture had a range of 6.84, inherent moisture had a range of 8.6, ash content had a range of 22.28, votalite matter had a range of 4.24, fixed carbon had a range of 8.18, total sulfur had a range of 31.82 and calorie value had a range of 1.61.
There is a huge gap between demand and supply of energy carriers, which needs to be met through increased production of biodiesel using non-edible oil plants, without jeopardizing national food security. The study was conducted to investigate the fuel properties of desert-date (Balanites aegyptiaca)-based biodiesel for possible use as fuel for internal combustion engines. Biodiesel was produced from Balanites aegyptiaca oil using alkali catalyzed trans-esterification method. The fuel properties were determined in accordance with the Association of Official Analytical Chemists (AOAC 1990), American Society for Testing and Material (ASTM D6751) and European standard methods. The average oil yield was 396 g/kg, while the oil extraction efficiency was 88%. Trans-esterification of Balanites aegyptiaca oil revealed high biodiesel yield of 82.7%, 15.9% glycerol with 1.4% stir loss. Analysis of biodiesel fuel properties revealed a kinematic viscosity of 4.7mm2/s at 40°C, higher heating value of 37.5 MJ/kg, acid value of 0.11mgKOH/g, peroxide value of 1.4mEq/kg, iodine number of 68.53 gI2/100g, saponification number of 216 mgKOH/g, density of 886.79 kg/m3 at 15°C and cetane number of 50.42. These results are in accordance with the ASTM and European standard for biodiesel except its higher heating value. The findings from the study suggest Balanites aegyptiaca as a raw material for biodiesel production and its biodiesel as suitable alternative fuel for communities in dryland areas of Nigeria.
Landfills near communities place a significant burden on residents that are exposed to the environmental hazards and health risks, especially in locations where land is limited. The paper explores how Plasma Arc Gasification (PAG) can be applied to the City and County of Honolulu in the State of Hawaii, where construction of a new landfill is currently necessary in the coming decade, restricting the already strained land. Potential economic and environmental impacts of PAG with the City and County of Honolulu’s current waste-to-energy program are explored to find a conceivable solution to an ongoing problem. It is seen that PAG technology can reasonably reduce the landfill footprint in Honolulu down to 2%, consume existing landfill waste for fuel thus increasing the longevity of a landfill, and produce 56.65 MWh electricity and 91,000 tons of aggregates as a byproduct for use in concrete and asphalt. The pollution generated by PAG is lower than the minimum permitted, and far lower than existing H-Power plants that burn waste for electricity. Having two PAG plants, instead of one, in conjunction with the already established H-Power is the more optimal explored solution.
To enhance the performance and energy utilization of photovoltaic (PV) systems, efficient maximum power point tracking (MPPT) algorithms are required. The algorithms must be basically evaluated and their performances should be investigated before being implemented in actual systems. In order to experimentally evaluate the performance of MPPT algorithms, many PV testing systems have been designed, however, a low cost and simple experimental system is missing in the literature. In this paper, an efficient and simple PV testing system has been designed and the performances of two well-known MPPT algorithms such as perturb and observe (P&O) and incremental conductance (IC) algorithms have been investigated in real time. The evaluation is conducted under both stable and variable environmental conditions using a 180 W PV module. The system behavior is also challenged and investigated by changing the algorithm parameters such as step size and perturbation frequency and the optimized parameters are used for this application. The results show that the developed experimental testing system is a flexible and low-cost system, which aims to easily embed and simulate MPPT algorithms and evaluate them in various environmental conditions.
Historical wildfire patterns have experienced a recent shift in terms of its scale and intensity. Through the continuing advancements in electrical protection technology, statistical forecasting methodologies, availability of meteorological field data, and regional risk-modelling, wildfire management practices can be made more proactive in the United States and around the globe. To create a comprehensive and practical operating framework, an advanced seasonal autoregressive integrated moving average time series modelling technique for wildfire forecasting is explored. These regressive models, due to their mathematical accuracy has been used in many engineering and scientific applications. The study presented here was done using a qualitative investigation approach to wildfire data. Computer automated grid search techniques were developed to determine suitable seasonal regressive model hyper-parameters. With the usage of power transforms to fit skewed statistical models under study, it is found that a much more accurate and computationally efficient model can be generated. Statistical forecasts and regional risk mapping techniques can influence strategic operational practices for regional and local fire authorities. Concepts that can enhance power system protection and electrical grid hardening are explored and practical guidelines to help electrical utilities improve electrical grid operations are provided. Many benefits of using distributed energy resources are discussed and an optimal power flow involving these resources is formulated to help grid operators preserve system stability under these wildfire scenarios.
The work presented concerns the modelling of the greenhouse effect in solar thermal collectors with W-shape cover. A mathematical model was used to evaluate the net infrared radiation absorbed, the radiation lost by the absorber and the radiation pathways in the collector. A comparison was made between the three collector configurations: the double-glassed flat collector, semi W-shape collector and W-shape collector. The cover of the W-shape collector has double glass whereby the upper glass is flat, and the lower glass is w-shape. The absorber is also W-shape. The results show that at the maximum of solar radiation, the adsorbed infrared radiation is 678 W.m-2, 620 W.m-2 and 433.2 W.m-2 respectively for the double-glassed flat collector, semi W-shape collector and W-shape collector. The radiation losses are smaller in the W-shape collector (234.3 W.m-2) wherever when the absorber is flat, the radiation lost is greater: 250 W.m-2 and 265 W.m-2 respectively for the double-glazed flat collector, semi W-shape collector. Analysis of the angle factors of the transparent cover and the absorber showed a significant influence on the greenhouse effect in the W-shape collector, when the angle of the W-shape cover increases, the absorbed IR radiation also increases as the radiation losses decrease. This result is validated when the W angle of the absorber is constant. We also saw that, the absorbed IR radiation and the radiation lost at the absorber level grow with the W angle of the absorber.
Chemical Looping Reaction is a key strategy to achieve both emission reduction and carbon utilization while producing various value-added chemicals, through redox reactions. Here we study the effect of nanoshape ceria supported Ru catalysts for plasma assisted Chemical Looping Reforming reduction step coupled with water splitting oxidation step reactions in the temperature range 150°C to 400°C at 1 atm pressure. The oxygen carrier/catalyst combination materials used are Ru/CeO2 nanorods (NR), Ru/CeO2 nanocubes (NC), Ru/SiO2 nanospheres (NS), and Ni-based perovskite mixed with CeO2. NRs and NCs showed the best catalytic performance followed by Ni-based perovskite and NS. Differences in the selectivity and reactivity for the NRs and NCs were noticed. The NCs showed slightly higher selectivity towards H2 formation during reduction step and lesser carbon deposition. From the analysis of data and literature, it is proposed that the spillover of species such as H adatoms and CHx radicals after activation at Ru sites into the CeO2 supports and lattice O mobility may be slightly faster in the case of NCs. During the oxidation step, the NR and NC materials showed increased H2 production by a factor of more than 4 when compared to Ni based perovskite material.
A static aerated Compost Reactor (CR) was developed in Kitele, Kenya, and used for evaluating the efficacy of generating, extraction, and utilization of compost heat as a source of clean energy. A Compost Heat Exchanger (COHE), hydronically operated, was developed in order to extract and transfer the heat. Energy generated by the compost reactor was calculated, using temperature profiles, captured by the TC-08 data loggers via the K type (PTFE) thermocouples. Heated water to 55°C was obtainable. The total extracted energy from compost was and 174 kWh.
The objective of the present work is to analyse numerically the effect of embedding a porous matrix (PMX) of high thermal conductivity within a phase change material (PCM) on the heat energy storage and recovery during the melting and solidification of a PCM. Most of the previous work put the insight mainly on the charging process during melting. The present study focuses on both charging and discharging during melting and solidification. Constant heat flux is applied through the left wall of a rectangular storage unit. The other walls are kept thermally insulated. At the end of the heating period, a cooling stage starts to extract the heat through the same wall. The ratio of thermal conductivities of the porous matrix and the PCM will be taken as a parameter to study the efficiency of the thermal storage. Results are presented in terms of temperature fields, liquid-solid interface progress and plots of latent, and sensible heat storage. The study shows that a significant improvement in the heat storage/recovery can be achieved. For better efficiency, a compromise should be established between the ratio of thermal conductivity and the heating period.
The impact of rising household energy demands on the development of various regions in Kenya is not clearly understood due to lack of energy consumption behavior data among rural and urban households. The purpose of the study was to investigate households’ energy consumption behavior and examine factors that influence this behavior among households in rural and peri-urban areas in Western Kenya. Stratified random sampling technique was used to select a sample of 560 households in the counties of Bungoma and Uasin Gishu. Results showed that rural households are dependent largely on kerosene and electricity for lighting purposes and majorly firewood for cooking, while electricity and charcoal form a major source of energy for lighting and cooking in peri-urban households respectively. Also, a small fraction of households uses solar panels as their source of energy for lighting among other uses. Further, results shows that household energy utilization is characterized by multiple fuels use, conforming to energy stacking theory rather than energy ladder hypothesis. Generalized linear model (GLM) results on household energy utilization supported the energy ladder model which showed income level as the most influencing factor. Renewable energy use for cooking showed a reduction of firewood and charcoal as household energy sources. The research findings offer insights to enhance household energy policy making in Kenya and countries alike.
The increasing cost of energy has caused the energy intensive industries to examine means of reducing energy consumption in processing in order to remain competitive both in local and global markets. This paper presents a method for modeling and optimizing energy use in textile manufacturing using linear programming (LP). A linear programming model has been developed which meets the finished product requirements at a minimum cost of energy used in the process subject to different operational constraints. To develop the model, data required were collected through energy audit of the plant. It is through energy audit that constraints and products manufactured were identified and used in the development of the model. Constraints come in the form of system material balance equations and output production demands. Material balance equations and energy balance are the main features of the model. The model will determine optimum values for the process design variables, so as to achieve minimum cost. Sensitivity analysis of the model determines how the optimal production values (optimal solution) are affected by changes in prices of the resources (objective function coefficients).
Biodiesel from waste frying oil is an effective alternative fuel for conventional diesel and can be directly used as fuel in a diesel engine without any modifications to the engine. It has many positives like high biodegradability, reduction in greenhouse gas emissions, non-sulfur emissions, non-particulate matter pollutants, low toxicity, and excellent lubricity and is obtained from renewable source like vegetable oils, animal fat, etc. The major objectives of this work were to produce and compare the biodiesel yield from Waste Frying Vegetable Oil (WFVO) and Waste Frying Palm Oil (WFPO) using transesterification process. The physicochemical characterization of the biodiesel, as well as the effects of process variables on biodiesel yield, were evaluated. Also, optimum levels of process conditions for optimum production of biodiesel were determined. The WFVO and WFPO with methanol and catalyst were heated in a hot plate-magnetic stirrer at a temperature of 60°C and operated at 300 rpm. Potassium hydroxide (KOH) was used as catalyst. The one-factor-at-a-time method was used to select the optimum levels of process variable that gives high biodiesel yield. The results showed that the physicochemical characteristics (acid value, free fatty acid, density, kinematic viscosity, pour point and flash point) of the biodiesel obtained from WFVO and WFPO were within the standard value of EN14214 and ASTMD-6751.From the results, the possible optimum conditions of the process variables for transesterification process using KOH catalyst were found to be as follows: reaction time of 90 min, methanol to oil molar ratio of 12:1 and the catalyst loading of 1.5 wt%. At these optimum conditions, the optimum yield of biodiesel obtained from transesterification of WFVO and WFPO were found to be 97% and 90%, respectively. Thus, in comparison, the transesterification of WFVO resulted in higher biodiesel yield than WFPO. Conclusively, both WFVO and WFPO has good potential to be used for bio-diesel production.
Sheikhan crude oil faces obstacles during transportation from production wellsite to processing facilities due to high viscosity. To enhance the flowability, reducing the sheikhan crude oil viscosity is a promising approach. For this purpose, a heavy crude oil sample from Sheikhan oilfield was blended with various rate of industrial polar solvents such as (Toluene, methanol) and gas condensate at different temperatures. This experimental study shows that mixing sheikhan heavy crude oil with toluene have a good reduction in the crude oil viscosity since this polar tends to interface between asphaltene sheets and dissociation of asphaltene aggregates. However, the impact of methanol on viscosity is less where this solvent tends to forming hydrogen bond between asphaltene sheets and methanol molecules. Finally, the gas condensate reduced the crude oil viscosity but its impact reduced at higher temperature.
