Search results for "energy engineering and power technology"

Investigation on Ash Slagging Characteristics During Combustion of Biomass Pellets and Effect of Additives

2017

This study reports a systematic investigation into ash slagging behavior during combustion of barley straw and barley husk pellets with or without additives in a residential pellet burner. The slagging tendencies of the pellets were evaluated based on the amount, chemistry, mineralogy, and morphology of inlet ash formed as slag and sintering degrees of residual ash. The barley straw and husk pellets showed high slagging tendencies with 39 and 54 wt % ingoing ash formed as slag. Analyses using X-ray fluorescence and scanning electron microcopy combined with energy-dispersive X-ray spectroscopy revealed high concentrations of K, Si, and Ca but a minor amount of P in barley straw slag. The sla…

Cover Feature: Controlling the Formation of Sodium/Black Phosphorus IntercalationCompounds Towards High Sodium Content (8/2021)

2021

Naturally occurring polyphenols as building blocks for supramolecular liquid crystals – substitution pattern dominates mesomorphism

2021

A modular supramolecular approach towards hydrogen-bonded liquid crystalline assemblies based on naturally occurring polyphenols is reported. The combination of experimental observations, crystallographic studies and semi-empirical analyses of the assemblies provides insight into the structure–property relationships of these materials. Here a direct correlation of the number of donor OH-groups as well as their orientation with the mesomorphic behavior is reported. We discovered that the number and orientation of the OH-groups have a stronger influence on the mesomorphic behavior of the supramolecular assemblies than the connectivity (e.g. stilbenoid or chalconoid) of the hydrogen bond donor…

Spray Atomization Models in Engine Applications, from Correlations to Direct Numerical Simulations

2011

Sprays are among the very main factors of mixture formation and combustion quality in almost every (IC) engine. They are of great importance in pollutant formation and energy efficiency although adequate modeling is still on development. For many applications, validation and calibration of models are still an open question. Therefore, we present an overview of existing models and propose some trends of improvement. Models are classified in zero dimensional and dimensional classes ranging from simple formulations aimed at close-to-real-time applications to complete detailed description of early atomization stages.

Assessing the Energy-Saving Potential of a Dish-Stirling Concentrator Integrated into Energy Plants in the Tertiary Sector

2021

Energy consumed for air conditioning in residential and tertiary sectors accounts for a large share of global use. To reduce the environmental impacts burdening the covering of such demands, the adoption of renewable energy technologies is increasing. In this regard, this paper evaluates the energy and environmental benefits achievable by integrating a dish-Stirling concentrator into energy systems used for meeting the air conditioning demand of an office building. Two typical reference energy plants are assumed: (i) a natural gas boiler for heating purposes and air-cooled chillers for the cooling periods, and (ii) a reversible heat pump for both heating and cooling. For both systems, a dis…

A Validation Methodology for a Combined Heating Cooling and Power (CHCP) Pilot Plant

2004

A great number of variables significantly influence the energetic, environmental and economic results of CHP (Combined Heating and Power) and CHCP (Combined Heating Cooling and Power) plants operation, and as a consequence their project activity is rather complex. In order to select the best layout and properly size the machines, detailed data on hourly electric, thermal, and cooling demand are necessary, so that a series of plant life cycle simulations may have to be carried out. Unfortunately, such detailed data are rarely available, because energy consumptions data for existing buildings are usually derived from aggregated monthly or bimonthly gas and electricity bills. Even more difficu…

A methodology for sizing a trigeneration plant in mediterranean areas

2003

Combined heat and power production is an old and well-known technique for the rational use of energy and, thanks to more than fifty years of experience, the state of art can be considered very advanced from a technological point of view. Trigeneration, that is combined electric, heat and cooling energy production, is however a quite recent technology and is becoming economically viable thanks to the commercial spread of absorption chillers. In fact, a well-projected trigeneration plant can achieve better results than a cogenerative one. The CHCP plant benefits over CHP will be underlined, showing the effects of regularisation of annual thermal load curves generated by consumption for feedin…

Exergoeconomic analysis as support in decision-making for the design and operation of multiple chiller systems in air conditioning applications

2020

Abstract Multiple-chillers systems represent viable solutions for medium/large-scale air conditioning applications characterized by variable cooling demand. The energy efficiency of such systems is influenced by the number of chillers, the combination of cooling capacities, and the load-sharing among the units. Large efforts have been devoted to developing efficient operation strategies for these systems, but rules of thumb are usually adopted for selecting cooling capacities thus leaving room for energy and economic savings. In this paper, exergoeconomic analysis is proposed as a promising method to identify near-optimal design and operation strategies, due to the capability of exergoecono…

The Place of Energy Security in the National Security Framework: An Assessment Approach

2022

The term “energy security” is used almost everywhere in economic and political discussions related to energy supply. However, different authors use different meanings to express the concept of energy security. Quite often, this term is used to give more importance or relevance to issues that are often not inherently related to energy security. Attempts to define the essence of the concept of “energy security” have hitherto not been systematic and are characterized by a variety of approaches, and some insufficient justification especially in the aspect of state national security is notable. Our contribution to the discourse development is the consideration of energy s…

Influence of synthesis conditions on the performance of chitosan–Heteropolyacid complexes as membranes for low temperature H2–O2 fuel cell

2015

Flat, free-standing chitosan/phosphotungstic acid (PTA) polyelectrolyte membranes were prepared by in-situ ionotropic gelation process at room temperature on porous alumina support firstly impregnated by H3PW12O40. Scanning electron microscopy revealed the formation of compact and homogeneous membranes, whose thickness resulted to be dependent on chitosan concentration and reticulation time. X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) evidenced the formation of almost amorphous membrane without appreciable concentration of not protonated NH2 groups and PTA3- ions with preserved Keggin structure. Membranes were tested as proton conductor in low temperature H2-O2 fuel…