Design, Implementation, and Evaluation of Thermal Performance of a Thermosiphon Flat-Plate Solar Collector for Water Heating in Ecuadorian Coastal Region

Passive solar water heating (SWH) is a convenient method to meet domestic hot water requirements in rural areas, where electricity may not be available or fuel supply might be limited due to difficult access. In this work, a low-cost thermosiphon flat-plate solar collector alternative is presented. The design was purposely limited to materials and recyclable products widely available in the local market, such as Tetra Pak, plastic bottles, and polypropylene (PP) fittings and pipes. Since PP is a thermoplastic polymer, a poor heat conductor, it was necessary to ensure a suitable system isolation to obtain an optimum thermal performance, comparable to commercial solar collectors. The design was built and tested in Guayaquil, Ecuadorian coastal city. Six inexpensive temperature sensors were placed at the entrance and exit of the collector, on the flat-plate and inside the hot water storage tank. Data was recorded using an Arduino single-board computer and later analyzed with the data gathered via weather station. The implementation costs of the system are approximately US$300, the overall performance during January 2017 fluctuated between 54% and 23%, and the storage tank temperature range varied from to 46°C to 33°C. Due to its reliability and affordable cost, the SWH system is an attractive alternative to an Ecuadorian commercial solar flat plate collector, which price is set between US$600 and US$700, it has an efficiency around 60%, and the average annual storage tank temperature is 62°C.

Silica Nanocomposite Membrane for Dehumidification

Various designs of novel membrane (silica nanocomposite polyurethane membrane) were tested for its optimal configuration in a membrane-based dehumidification system. This membrane was designed with a hydrophobic polymer matrix with hydrophilic silica nanochains. In this dehumidification process, two driving forces were suggested: concentration gradient of water vapor in the atmospheric air channel due to sweep gas and pressure gradient due to vacuum. This paper describes validation of the model configurations using the finite element method software (COMSOL Multiphysics) with experiments. Pressurized air enters an air duct at 1–5 liters per minute flow rate. Air is then humidified using a misting nozzle until saturation. Then the humid air passes by the membrane with a vacuum pump connected vertically to the duct to maximize the dehumidification rate. A novel design showed water vapor reduction from 19.4 grams of water vapor per kilogram of dry air to 16.9 grams of water vapor per kilogram of dry air for the 1 liter per minute flow rate of the 47 mm diameter membrane.

Repurposing of a Hybrid Vehicle Nickel Metal Hydride Battery Pack for Electrical Grid Storage

Climate change concerns are driving incentives to increase the fuel economy of passenger vehicles. Consequently, this has resulted in a growing prevalence of electrified vehicles (EVs) consisting of hybrid, plug-in hybrid, and fully electric vehicles. Unfortunately, EVs are often removed from the road when 70 to 80% of the original energy capacity remains in their battery pack. In order to maintain or increase the value of EV battery packs in an end-of-vehicle life scenario, there are three potential solutions: remanufacturing for re-use, recycling, or repurposing. However, the complexity of handling dissimilar battery chemistries makes both remanufacturing and recycling a significant challenge. Hence, repurposing may prove to be a more viable short-term goal of the industry. In order to explore this potential outcome, a team of undergraduate students studied the continuous cycling effects of used and refurbished Toyota® Prius nickel metal hydride battery packs. A Raspberry Pi 2 Model B microcomputer recorded relevant data, including battery pack voltage, energy input, and energy output. In combination, a Laboratory Virtual Instrument Engineering Workbench (LabVIEW™) control system used this logged information to regulate charging and discharging of the battery pack. In addition, to enhance the environmental sustainability of the project, this control system acquired solar information from a nearby weather station, subsequently ensuring that the battery pack only recharged during times of peak solar radiation. Analysis of the pack’s energy balance helped to characterize the cycle life of the pack and its potential in repurposing. Others can emulate the methodology employed as a way to instruct students about the potential left in used vehicular battery packs and their possible integration with the electrical grid.

Design and Potential Application of Small Scale Wave Energy Converter

Although theoretical available wave energy is higher than most of ocean energy sources, the commercial utilization of wave energy is much slower than other ocean energy sources. The difficulty of integration with the electrical grid system and the challenges of the installation, operation and maintenance of large energy generation and transmission systems are the major reasons. Even though there are successfully tested models of wave energy converters, the fact that wave energy is directly affected by wave height and wave period makes the actual wave energy output with high variation and difficult to be predicted. And most of the previous studies on wave energy and its utilization have focused on the large scale energy production that can be integrated into a power grid system. In this paper, the authors identify and discuss stand-alone wave energy converter systems and facilities that are not connected to the electricity grid with focus on small scale wave energy systems as potential source of energy. For the proper identification, qualification and quantification of wave energy resource potential, wave properties such as wave height and period need to be characterized. This is used to properly determine and predict the probability of the occurrence of these wave properties at particular locations, which enables the choice of product design, installation, operation and maintenance to effectively capture wave energy. Meanwhile, the present technologies available for wave energy converters can be limited by location (offshore, nearshore or shoreline). Therefore, the potential applications of small scale stand-alone wave energy converter are influenced by the demand, location of the need and the appropriate technology to meet the identified needs. The paper discusses the identification of wave energy resource potentials, the location and appropriate technology suitable for small scale wave energy converter. Two simplified wave energy converter designs are created and simulated under real wave condition in order to estimate the energy production of each design.

Modelling, Analyses and Optimization for Exergy Performance of an Irreversible Intercooled Regenerated Brayton CHP Plant: Part 1 — Thermodynamic Modelling and Parametric Analyses

A variable-temperature heat reservoir irreversible intercooling regenerated Brayton combined heat and power (CHP) plant model is set up in this paper. The model considers the heat transfer losses in all the heat exchangers, the working substance pressure drop loss in the piping, and the expansion and compression losses in turbine and compressor. Exergy output rate and exergy efficiency are considered as the research targets, and their analytical formulae are obtained. The optimal performances are gotten by optimizing the intercooled pressure ratio and total pressure ratio. The influences of some important parameters on the performances are studied in detail. Besides, the relation of exergy output rate versus exergy efficiency is investigated, and the curve is loop-shaped one. The results indicate that optimum heat capacity rate matching between the heat reservoir and working substance, and optimum heat consumer required temperature exist respectively, which generate double-maximal exergy output rate and double-maximal exergy efficiency, respectively. The heat conductance allocation optimization of all the heat exchangers will be carried out in Part 2 of this paper.

Geometrical Effects of Channel Configuration on the Performance of Membraneless Fuel Cells

In this study, numerical simulations were performed to find the current-voltage distribution for a laminar flow-based membraneless fuel cell (LFFC). The system uses formic acid and oxygen as the fuel and oxidant, respectively, and has a Y-shaped geometry with two separate inlets that merge into a single channel. The main objective of this work is to analyze the impact of geometry and operating conditions on the performance of these devices. This is done by proposing a novel wavy-channel-based geometry for the side walls, along with planar top and bottom walls, and comparing the behavior of the corresponding system to that of LFFCs based on straight-channel walls. Special attention is placed on the effect of both the amplitude of the sinusoid and its wavelength on the performance of the device. The effect of flow rates — in the range of [200, 350] μL/min — is also studied. The mathematical model is formulated by considering the Navier-Stokes equations along with Butler-Volmer and Fick’s law. For each fuel-cell configuration, the governing equations are discretized and solved using finite elements, and the solutions given in terms of the polarization curves. The model was first verified using published numerical data for a straight-channel-based LFFC. The simulations show that the performance achieved by the device, based on the proposed wavy channel geometry, is slightly better than that of the LFFC with straight channel walls. On the other hand, higher flowrates significantly improve the power density of the device. Although the current mathematical model may be useful in a variety of applications, improvements on it are currently underway to account for the effects of potential distributions on ions within the flow channel, and results from it will be reported in the future.

Design and Analysis of Small Scale Horizontal Archimedean Screw for Electric Power Generation

A small scale horizontal Archimedean screw was designed, built, and tested for small-scale electric power generation. The small-scale device is suitable for deployment in shallow waterways and rivers. The design of the screw is environmentally friendly and allows for fish and other aquatic life to pass through harmlessly. A series of horizontal screws were designed over a range of blade pitch and tip conditions to determine the most efficient configuration of the device. The tip conditions included straight, flanged, and open. The device was placed both inside and outside of a duct to control tip conditions. The flanged condition added material to the tip of the device to simulate a partially ducted screw. Preliminary studies have shown that the straight bladed screw is the most efficient design. Preliminary data also show that the addition of a duct reduced the overall efficiency of the device. The flange feature on the screw was shown to be ineffective as well. However, the design was environmentally friendly and would provide electric power on a small scale without harm to local aquatic environments.

Comparison and Evaluation of Engine Performance, Emission, Noise and Wear of Diesel and Karanja Oil Methyl Ester Biodiesel in a 980HP Military Turbo Charged CIDI Engine

Global warming due to engine exhaust pollution and rapid depletion of petroleum oil reserves, has given us the opportunity to find bio fuels as alternative to diesel fuel. Biodiesel is an oxygenated, sulphur free, non-toxic, biogradable and renewable fuel. Karanja biodiesel is prepared using Karanja oil and methanol by the process of transesterification. In the present study, a military 720 kW turbo charged, compression ignition diesel injection (CIDI) engine was fuelled with diesel and Karanja oil methyl ester (KOME) biodiesel respectively. These were subjected to 100 hours long term endurance tests. The performances of fuels were evaluated in terms of brake horse power (kW), torque, heat release rates and specific fuel consumption. The emission of carbon monoxide (CO), unburnt hydrocarbon (UHC), oxides of nitrogen NOx and smoke opacity with both fuels were also compared. Lubricating oil samples, drawn from the engine after 100 hours long term endurance tests, were subjected to elemental analysis. Atomic absorption spectroscopy (AAS) was done for quantification of various metal debris concentrations. Use of Karanja oil methyl ester (KOME) biodiesel in a turbo charged CIDI engine was found compatible with engine performance along with lower emission characteristics (UHC 70%, CO 85.6%), and exhaust noise 11.9% but 13.7% higher NOx emissions. Engine metals wear were found 32% lower for a KOME biodiesel operated engine.

Environmental Impact of an Industrial Kitchen: A Case Study

The large number of industrial kitchens and their energy-intense characteristics provides opportunities for pollution prevention. Life cycle assessment (LCA) is a proper tool not only for unitizing the environmental impact of the complex system of an industrial kitchen, but also for making environmental food labels for the foods produced in the same industrial kitchen. In this study, a gate-to-gate LCA of 11 types of food was conducted to evaluate the environmental impact of a typical industrial kitchen, Villanova University’s Donahue Hall. First, material and energy flow data, including cold storage, food preparation, food display, lighting, heating, ventilation, and air conditioning (HVAC), and dish washing were collected. This data, along with standard data on energy generation and transmission, were used in the LCA. The results show that global warming, fossil fuel depletion and ecotoxicity are the main environmental impact categories. Furthermore, HVAC, cold storage and cooking are the three largest contributors of environmental burden. Using the metrics developed, tuna salad, tomato soup and pasta are the most environmental friendly foods of the 11 sampled food types, while pizza and cheese quesadillas have the worst environmental performance. Energy saving measures for HVAC, cold storage and cooking are proposed.