Flow Patterns and Temperature Distribution in an Underground Metro Station

Accurate control of thermal conditions in large space buildings like an underground metro station is a significant issue because passengers’ thermal comfort must be maintained at a satisfactory level. The large eddy simulation (LES) model was adopted while using the computational fluid dynamics (CFD) software “STAR CCM+” to set up a CFD station model to predict static air temperature, velocity, relative humidity and predicted mean vote (PMV), which indicates the passengers’ thermal comfort. The increase in the number of passengers using the model station is taken into consideration. The studied cases covered all the possible modes of the station box, these modes are (1) the station box is empty of trains, (2) the presence of one train inside the station box, (3) the presence of two trains inside the station box. The objective is to bring the passengers’ thermal comfort in all modes to the acceptable level. The operation of under platform exhaust (UPE) system is considered in case of train presence inside the station box. The use of UPE is more energy efficient than depending entirely on the air conditioning system to maintain the thermal conditions comfortable.

Quasi-Solid Graphite Anode for Flexible Lithium-Ion Battery

Flexible Li-ion batteries (LIBs) have a strong oncoming consumer market demand for use in wearable electronic devices, flexible smart electronics, roll-up displays, electronic shelf labels, active radio-frequency identification tags, and implantable medical devices. This market demand necessitates research and development of flexible LIBs in order to fulfill the power requirements of these next-generation devices. This study investigated the performance of quasi-solid anode — the active and conductive additive materials suspended in liquid electrolyte — for flexible lithium-ion batteries (LIB). A quasi-solid graphite anode was fabricated and tested using different material ratios and compositions, showing an acceptable performance. Furthermore, this study looked into the effect of graphite powder ratios in battery performance. A ratio of over 65% of the specific discharge capacity to the theoretical capacity was achieved maintaining the capacity retention of more than 74% after the second cycle.

100% Test Burn of Torrefied Wood Pellets at a Full-Scale Pulverized Coal Fired Utility Steam Generator

Portland General Electric’s (PGE) Boardman plant is a nominal 600 megawatt (MW) coal fired unit that burns sub-bituminous Powder River Basin (PRB) coal from Wyoming. This paper will cover the experience and results of PGE’s Boardman plant operating on 100% torrefied wood (TW) pellets at 255 MW consuming almost 5000 tons of pellets. Results were positive and include suitable handing after inclement weathering for months. Pulverizers were able to handle the TW pellets with adjustments, resulting in near 100% combustion efficiency. Particulates were controlled with an electrostatic precipitator (ESP). Topics investigated include torrefied wood production, fuel handling and storage on the front end of the test. Fuel handling, pulverization, combustion, emissions, and ESP performance were monitored during the test and are reported here. Several one mill tests were conducted prior to the 100% test to evaluate and improve mill performance. This test showed that a pulverized coal (PC) boiler can operate on 100% TW fuel with minimal operational changes.

Experimental Investigation of a Flat Plate Photovoltaic/Thermal Collector

Photovoltaic thermal collectors (PVT) combines technologies of photovoltaic panels and solar thermal collectors into a hybrid system by attaching an absorber to the back surface of a PV panel. PVT collectors have gained a lot of attention recently due to the high energy output per unit area compared to a standalone system of PV panels and solar thermal collectors. In this study, performance of a liquid cooled flat PVT collector under the climatic conditions of Abu Dhabi, United Arab Emirates was experimentally investigated. The electrical performances of the PVT collector was compared to that of a standalone PV panel. Moreover, effect of sand accumulation on performance of PVT collectors was examined. Additionally, effect of mass flow rate on thermal and electrical output of PVT collector was studied. Electrical power output is slightly affected by changes in mass flow rate. However, thermal energy increased by 22% with increasing flow rate. Electrical power output of a PV panel was found to be 38% lower compared to electrical output of PVT collectors. Dust accumulation on PVT surface reduced electrical power output up to 7% compared with a reference PVT collector.

The Impact of Lack of Clean Cooking Fuels on Sustainable Development in Developing Countries

Access to energy is crucial in tackling many of the current global development challenges that impact on people’s economic, health and social well-being as well as the ability to meet the commitments of reducing carbon emissions through clean energy use. Despite increased attention from multiple governments and agencies, energy poverty remains a serious sustainable development issue in many developing countries. To date, most research have focused on general access to electricity and the generation of clean energy to replace fossil fuels, failing to address the lack of basic access to clean energy for cooking and heating. More people in the world lack access to clean cooking fuels than to electricity. This issue is one aspect of a broader research which investigates the impacts of optimized energy policy and energy business models on sustainable development in developing countries.

Cooling of Concentrator Photovoltaic Cells Using Mini-Scale Jet Impingement Heat Sinks

In this study, an efficient cooling technique for concentrator photovoltaic (CPV) cells is proposed to enhance the system electrical efficiency and extend its lifetime. To do this, a comprehensive three-dimensional conjugate heat transfer model of CPV cells layers coupled with the heat transfer and fluid flow model inside jet impingement heat sink is developed. Four different jet impingement designs are compared. The investigated designs are (A) central inlet jet, (B) Hypotenuse inlet jet, (C) staggered inlet jet, and (D) conventional jet impingement design with side drainage. The effect of coolant flowrate on the CPV/T system performance is investigated. The model is numerically simulated and validated using the available experiments. The performance of CPV system is investigated at solar concentration ratios of 20 and coolant flowrate up to 6000g/min. It is found that increasing the flowrate from 60 g/min to 600 g/min decrease the maximum cell temperature by 31°C for the configuration D while increasing the flowrate from 600 g/min to 6000 g/min reduce the cell temperature by 20.2°C. It is also concluded that at a higher flowrate of 6000g/min, all the investigated configurations relatively achieve better temperature uniformity with maximum temperature differences of 0.9 °C, 2.1 °C, 3.6 °C, and 3.9 °C for configurations A, B, C, and D respectively.

Application of Low Temperature Phase Change Materials to Enable the Cold Weather Operability of B100 Biodiesel in Diesel Trucks

The use of pure biodiesel for compression ignition engines during the winter poses a challenge due to gelling and plugging of engine filters and fuel lines. The most common method to prevent this issue is blending with petroleum diesel and many engine manufacturers limit the biodiesel in blends to 20% or less for warrantee purposes; as low as 5% may be set for winter months. In a previous work, the authors proposed a novel fuel tank design that could potentially solve this problem and presented a numerical validation of the concept of using phase change materials (PCM) to enable cold weather operability of 100% biodiesel by maintaining its temperature above a cloud point of 5 degrees Celsius for over 3 days at an ambient temperature of −25 degrees Celsius and initial temperature of 20 degrees Celsius. In this research, an experimental analysis is performed using a scaled model of the fuel tank with canola oil as a test fluid in the tank. The tank is subjected to an ambient temperature of −20 degrees Celsius in an icing tunnel facility with air velocity at 10 m/s. The results show that the time above cloud point was increased from 18.6 hours to 22.5 and 33 hours respectively when 4 and 12 PCM tubes were inserted in the tank containing 33 litres of canola oil. A simple numerical model was formulated to predict the transient temperature of the oil and comparison with experimental results showed excellent agreement.

Deactivation Characteristics of SCR Catalyst at Different Stages in Coal-Fired Flue Gas

Through analyzing the impact of the factors of catalyst deactivation, different factors are classified according to timeliness characteristics. In this research, experiments were made under the condition of coal combustion flue gas on a coal-fired boiler to study the characteristics of the early deactivation of the SCR catalyst. Analysis shows that the main cause of early deactivation of catalyst is chemical poisoning (mainly alkali metal) and pores clogging on the surface of the catalyst. While the main cause of long-term deactivation is deeper chemical poisoning, pores clogging and the chemical form changes of elements on the surface of the catalyst. Through analyzing the influence of the factors of catalyst deactivation, separate factors are classified according to timeliness characteristics. This research provides a strong fundamental support to clear the deactivation mechanism of the SCR catalyst.

Experimental Performance Evaluation of a Rechargeable Lithium-Air Battery With Hyper-Branched Polymer Electrolyte

Synthesis of hyper branched polymer (HBP) based electrolyte has been examined in this study. A real world lithium-air battery cell was fabricated using the developed HBP electrolyte, oxygen permeable air cathode and lithium metal as anode material. Detailed synthesis procedures of hyper branched polymer electrolyte and the effect of different operation conditions on the real-world lithium-air battery cell were discussed in this paper. The fabricated battery cells were tested under dry air with 0.1mA∼0.2mA discharge current to determine the effect of different operation conditions such as carbon source, electrolyte types and cathode processes. It was found that different processes affect the battery cell performance significantly. We developed optimized battery cell materials upon taking into account the effect of different processes. Several battery cells were fabricated using the same optimized anode, cathode and electrolyte materials in order to determine the battery cells performance and reproducibility. Experimental results showed that the optimized battery cells were able to discharge over 55 hours at over 2.5V. It implies that the optimized battery cell can hold charge for more than two days at over 2.5V. It was also shown that the lithium-air battery cell can be reproduced without loss of performance with the optimized battery cell materials.

Comparison of Different Energy Storage Systems for a Small Airport Facility

Airports, one of the important transportation components in this modern age, are under continuous improvement especially in regard to energy sustainability. While most work is concentrated on large airports, smaller airports which are mostly scattered around rural areas seem to be better opportunities for renewable energy utilization. However, while renewable energy has come into use at airports over the past decade, it has been at a slow pace and has not included storage. A reliable storage system can significantly increase the power reliability of a small airport and make a renewable energy system viable. Acquiring the technical requirements of a facility based on its characteristics enables the designer to evaluate the power source options and develop an efficient storage system. The current paper analytically develops a framework to design and integrate an energy storage method for a renewable system into a small airport facility. The framework details include methods for energy storage which are environmentally acceptable in combination with renewable energy sources to produce electrical power for the on-site facilities. The technical analysis which leads to the sizing of the storage unit initiates with categorizing different methods for energy storage and their applicability to an airport facility for off-grid and on-grid modes. Based on the results and conclusions from the first step, the search is narrowed down to mediums for electricity storage for a wind farm or solar power plant. In such a case, the main applications of the storage unit could be either to supply power to the facility during the transition time from the renewable source to the main grid or to regulate the power frequency of the generation unit. Capacitors and batteries were selected as the two options for the given power requirement of the facility. Considering the wide variety of available technologies and lower costs, the appropriate storage system is proposed for both long term and short term applications. A table is presented to compare available battery technologies and their respective storage capacities.