77 research outputs found
Gifts of the Desert: The Forgotten Path of Christian Spirituality
No full textIn Kyriacos C. Markides’s newest book, Eastern Orthodox mysticism meets Western Christianity as the internationally renowned author takes readers on a deep journey back in time to unveil the very roots of authentic spirituality. In his previous book The Mountain of Silence, Markides introduced us to the essential spiritual nature of Eastern Orthodoxy in a series of lively conversations with Father Maximos, the widely revered charismatic Orthodox bishop and former abbot of the isolated monastery on Mount Athos. In Gifts of the Desert, Markides continues his examination of Easter Orthodox mystical teachings and practices and captures its living expression through visits to monasteries and hermitages in Greece and America and interviews with contemporary charismatic elders, both male and female.Markides’s pursuit of a deeper understanding of Orthodoxy takes him to the deserts of Arizona and a stay at a new monastery in Sedona; to the island of Cyprus and a reunion with Father Maximos; on a pilgrimage to holy shrines aboard a cruise ship in the Aegean Sea; and finally to the legendary Mount Athos, home to more than two thousand Orthodox monks. Markides relates his journey and reflections in a captivating style while providing important background material and information on historical events to give readers a highly accessible, in-depth portrait of a tradition little known in the West.https://digitalcommons.library.umaine.edu/fac_monographs/1124/thumbnail.jp
Inner River: A Pilgrimage to the Heart of Christian Spirituality
No full textIn Markides\u27 latest work, Eastern Orthodox mysticism once again meets Western Christianity as the internationally renowned author takes readers on a mind-expanding, soul deepening journey to the very roots of an authentic spirituality as in his best-selling book, The Mountain of Silence. In an engaging combination of dialogues with Fr. Maximos, reflections, conversations, history, and travelogue he poses and answers questions about life, near death experiences, consciousness beyond the grave, and the struggles of a purely material existence.https://digitalcommons.library.umaine.edu/fac_monographs/1256/thumbnail.jp
Thermoeconomic assessment of a PV/T combined heating and power system for University Sport Centre of Bari
No full textThis paper presents a thermoeconomic analysis of a solar combined heating and power (S-CHP) system based on hybrid photovoltaic-thermal (PV/T) collectors for the University Sport Centre (USC) of Bari, Italy. Hourly demand data for space heating, swimming pool heating, hot water and electricity provision as well as the local weather data are used as inputs to a transient model developed in TRNSYS. Economic performance is evaluated by considering the investment costs and the cost savings due to the reduced electricity and natural gas consumptions. The results show that 38.2% of the electricity demand can be satisfied by the PV/T S-CHP system based on an installation area of 4,000 m2. The coverage increases to 81.3% if the excess electricity is fed to the grid. In addition, the system can cover 23.7% of the space heating demand and 53.8% of the demand for the swimming pool and hot water heating. A comparison with an equivalent gas-fired internal combustion engine (ICE) CHP system shows that the PV/T system has a longer payback time, i.e., 11.6 years vs. 3 years, but significantly outperforms the ICE solution in terms of CO2 emission reduction, i.e., 435 tons CO2/year vs. 164 tons CO2/year. These findings suggest that even though the economic competitiveness of the proposed PV/T S-CHP system is not yet favourable when compared to the alternative gas-fired ICE-based system, the S-CHP solution has an excellent decarbonisation potential, and that if this is of importance in the wider sense of energy-system decarbonisation, it is necessary to consider how the higher upfront costs can be addressed
Intermittent waste heat recovery via ORC in coffee torrefaction
No full textCoffee torrefaction is carried out by means of hot air at average temperature of 200-240°C and with intermittent cycles where a lot of heat is discharged from the stack. CHP systems have been investigated to provide heat to the process. However, much of the heat released in the process is from the afterburner that heats up the flue gas to higher temperatures to remove volatile organic compounds and other pollutants. In this paper, the techno-economic feasibility of utilising waste heat from a rotating drum coffee roasting with partial hot gas recycling is assessed. A cost analysis is adopted to compare the profitability of two systems configurations integrated into the process. The case study of a major coffee torrefaction firm with 500 kg/hr production capacity in the Italian energy framework is taken. The CHP options under investigation are: (i) regenerative topping micro gas turbine (MGT) coupled to the existing modulating gas burner to generate hot air for the roasting process; (ii) intermittent waste heat recovery from the hot flue gas through an organic Rankine cycle (ORC) coupled to a thermal storage buffer. The results show that the profitability of these investments is highly influenced by the natural gas/electricity cost ratio, by the coffee torrefaction production capacity and intermittency level of discharged heat. In this case study, MGT seems to be more profitable than waste heat recovery via ORC due to the intermittency of the heat source and the relatively high electricity/heat cost ratio
Effect of working-fluid mixtures on organic Rankine cycle system performance : heat transfer and cost analysis
No full textPapers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.A thermodynamic limitation of single-component working fluids in organic Rankine cycles (ORCs) is the large exergy destruction (and, consequently, useful power loss) associated with evaporation and condensation. Due to their non-isothermal phase-change behaviour, non-azeotropic working-fluid mixtures have shown reduced exergy losses, leading to improved cycle efficiencies and power outputs. These benefits are exclusively observed from a thermodynamic perspective. The present paper considers the effects of selecting such working-fluid mixtures on heat transfer performance, component sizing and system costs compared with those of pure fluids; a mixture of n-pentane and n-hexane is selected. While the fluid-mixture cycles do indeed allow higher efficiencies and the generation of higher power outputs, they require larger evaporators, condensers and expanders; thus, the resulting ORC systems are more expensive than those based on the pure fluids. While a working-fluid mixture (60% n-pentane + 40% n-hexane) leads to the thermodynamically optimal cycle, a pure n-pentane ORC system has reduced costs of 37% per unit power output over the thermodynamic optimum.am201
Intermittent waste heat recovery: Investment profitability of ORC cogeneration for batch, gas-fired coffee roasting
No full textCoffee roasting is a highly energy intensive process with much of the energy being lost in intermittent cycles as discharged heat
from the stack. In this work, combined heat and power (CHP) systems based on micro gas-turbines (MGT) are investigated for
providing heat to the roasting process. Much of the heat released in a coffee roaster is from the afterburner that heats up the flue
gases to high temperatures in order to remove volatile organic compounds (VOCs) and other pollutants. An interesting solution
for utilizing waste heat is assessed through energy and material balances of a rotating drum coffee roasting with partial hot gas
recycling. A cost assessment methodology is adopted to compare the profitability of three proposed system configurations
integrated into the process. The case study of a major coffee torrefaction plant with 500 kg/h production capacity is assumed to
carry out the thermo-economic assessment, under the Italian energy framework. The CHP options under investigation are:
(i) regenerative topping MGT coupled to the existing modulating gas burner to generate hot air for the roasting process;
(ii) intermittent waste-heat recovery from the hot flue-gases through an organic Rankine cycle (ORC) engine coupled to a
thermal storage buffer; and (iii) non-regenerative topping MGT with direct recovery of turbine outlet air for the roasting process
by means of an afterburner that modulates the heat demand of the roasting process. The results show that the profitability of these
investments is highly influenced by the natural gas/electricity cost ratio, by the coffee torrefaction production capacity and by the
intermittency level of discharged heat. The MGT appears as a more profitable option than waste-heat recovery via the ORC
engine due to the intermittency of the heat source and the relatively high electricity/heat cost ratio
Crossing the Chasm: How to Convert Relevant Research Into Managerially Useful Research
No full text There is growing concern within the Academy of Management that a big and growing gap exists between management research and practice. The persistence of this gap is a mystery! Over the past 20 years, literally hundreds of ideas have been proposed to close it. Yet nothing seems to work and according to some, the gap continues to grow. Why is that? Is it that all the ideas proposed are bad or are we simply guilty of not implementing our own ideas in a manifestation of the “knowledge—doing gap”? In this article, the author proposes that a much more serious issue may be at work. Specifically, the author argues that our research is (sufficiently) relevant but still not what our customers (i.e., the managers) want or need. The gap that exists is not between rigorous and relevant research; it is between relevant and useful knowledge. For our (relevant) research to become managerially useful, it still needs to go through a transformation. Unfortunately, academics are not good at this transformation process. This has a serious implication on what we actually need to do to make our research more managerially useful. </jats:p
Magnetic-Cell-Delivery-Simulations
No full textSupplementary material for paper: Experimental and mathematical modelling of magnetically labelled mesenchymal stromal cell delivery (2021) Author: E. Yeo, H. Markides, A.T. Schade, A.J. Studd, J.M. Oliver, S.L. Waters, A.J. El Haj, Royal Society Interface. Code to run moving boundary growth in channel fluid dynamics simulations
Thermo-economic analysis of a low-cost greenhouse thermal solar plant with seasonal energy storage
No full textReduction of greenhouse gas emissions is today mandatory to limit the increase of ambient temperature. This paper provides a numerical study of a thermal solar plant using a seasonal dual-media sensible heat thermal energy storage system for supplying the total energy demand of a greenhouse located in the South of Italy, avoiding the use of the gas boiler. The aim of the work is to assess the technical and economic performance of a low-cost pit storage system, made of gravel and water, placed under the greenhouse to save surface. The study provides an original analysis of the charging and discharging phases during one year of operation on the basis of the real hourly heating demand and on real weather data. A sensitivity analysis of the levelized cost of heat is carried on with respect to the solar-collector area and to the storage-pit volume. The analysis shows that a minimum-cost design solution exists to cover 100% of the heat demand with an estimated levelized cost of heat of 153.3 EUR/MWh. The results demonstrate that dual-media thermal energy storage systems with solar thermal collectors represent a viable solution for reducing the environmental impact of greenhouses
A coupled thermal and electrical model of a sheet-and-tube hybrid photovoltaic/thermal (PV/T) collector
No full textPapers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.The goal of this paper is to obtain the (pair of) efficiency curves of a hybrid PV/T collector with a sheet-and-tube design and to evaluate the effect of a non-uniform temperature distribution on the surface of the solar cell on its electrical power output. A 3-dimensional numerical model is developed to estimate the performance of such a collector. The model allows various design parameters of the PV/T to be varied so that the influence of each of these parameters can be studied on the overall system performance both at steady-state and at varying atmospheric conditions. The main parameters considered are the number of glass covers, ranging from an unglazed collector configuration to a double-glazed collector configuration, and the width-to-pipe diameter (W/D) ratio. The results show that, while the thermal efficiency increases with the additional glazing, the electrical efficiency deteriorates due to the higher temperature of the fluid and due to increased optical losses, as expected. The dynamic performance of the PV/T collector and system are also investigated. Results from the dynamic model and also from a simplified quasi-steady state model are reported. The results show that in the case of highly fluctuating incident radiation, e.g. from clouds, the quasi-steady solution can deviate by up to 20% from the dynamic solution in the evaluation of the thermal energy output in the case of low incident radiation with large fluctuations.am201
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