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.

Retracted: “Residential Energy Efficiency Improvement Using Solar Heating of Water and Air: A Computational Study” [ASME 2017 International Mechanical Engineering Congress and Exposition, Volume 6: Energy, Tampa, Florida, USA, November 3–9, 2017, Conference Sponsors: ASME, ISBN: 978-0-7918-5841-7, Copyright © 2017 by ASME. Paper No. IMECE2017-70041, pp. V006T08A037; 7 pages; doi: 10.1115/IMECE2017-70041]

The above referenced paper has been removed from publication. (March 10, 2020) Copyright © 2020 by ASME

Thermal Energy Recovery From Small Sewage Treatment Plants in Northern Canadian Communities

This paper presents feasibility study and concept design of a thermal energy recovery system with an adsorption heat pump integrated with a small sewage treatment plant in northern Newfoundland communities. Treated fluids from the sewage treatment systems are quite warm even in winter. For example measured fluids temperature is averaged at 17 °C when air temperature is at −10 °C in the town of Whitbourne. This provides an attractive heat source particularly for winter seasons. Four heat pump concepts, i.e., vapour compression, absorption, adsorption and chemical heat pumps, were reviewed and compared. The results show that the adsorption system best fits the sewage treatment plants with minimum power requirements. Thermal fluidic parameters of the key components were designed with fluid flow and heat transfer analysis. A brief economic and environmental analysis showed that the integrated energy recovery unit would lead to a net reduction of CO2 emission and feasible payback time.

Thermal Foundation Benefits and Efficiency

In this paper, a novel type of ground heat exchanger for geothermal applications is introduced. This heat exchanger is installed in the foundations of a commercial and residential building that has piles and diaphragm walls. This dramatically reduces the cost of the ground heat exchanger and makes the application more cost efficient with a payback period of 1–2 years compared to 10 years with the conventional vertical loops. The system will be detailed and its basic operation will be explained. In addition, test results of an in-situ thermal test response of a loop that is already installed in a foundation of a building in Beirut, Lebanon will also be presented. This test allows the approximation of the thermal conductivity of the ground and the amount of heat that is absorbed and extracted from and to the ground. The preliminary tests have given very promising results, since the ground is water dense and has a high thermal conductivity which increases the heat transfer between our heat exchanger installed in the foundation and the ground. In addition, in the current application, and around the foundation, there exists a lot of circulating water. This renders the application more and more efficient since the ground temperature will not fluctuate in the next 10 years.

Parametric Analysis of the Thermal Components of an Alpha-Stirling Engine for Cogeneration Applications

Stirling engines efficiency, the increased maintenance interval periods, the variety of energy sources and the relatively low gas emissions makes Stirling technology an interesting choice as prime mover for cogeneration applications. These are some of the reasons that justify the attention received from researchers in the last years, focused in its modelling, optimization and its application in the suppression of buildings energy needs. In this study, an alpha-Stirling engine was numerically modelled. At this configuration, the working fluid flows between expansion and compression spaces by alternate crossing of, a high temperature heat exchanger (heater), a regenerator and a low temperature heat exchanger (cooler). Thus, the engine is considered as a set of five components connected in series. MatLab® environment was used to implement a software-code to model the thermodynamic cycle of the Stirling engine. The modular code allows investigating the influence of different geometrical and thermal parameters of all the engine components that affects its power production and the efficiency, the effectiveness of heat exchangers and the design itself of the power plant. This parametric analysis helps finding some restriction values for geometrical parameters that cannot be solved through the optimization procedures. For instance, at some point, there is a geometrical limit for which the increase in heat transfer is overlapped by the void volume or pumping losses increase. The parametric analysis led to an enhanced configuration of the numerical model, which resulted in the increase of engine thermal efficiency (about 13.4%), with a power production close to 5 kW.