Search results for "ENERGY BALANCE"
showing 10 items of 135 documents
Closed-form solutions of the energy balance equation for drip laterals under the Darcy-Weisbach resistance formula
2018
Many studies have investigated easy methods to design drip laterals, as well as the best resistance equation to use, which is fundamental to accurately account for friction losses. This paper addresses both the features of lateral design relationships and the influence of the friction-loss equation on the design variables. First, simple closed-form solutions of the energy balance equation for both sloped and horizontal drip laterals are derived with the simplified Darcy-Weisbach resistance formula by assuming the Darcy friction factor as invariant versus the Reynolds number. Second, an error analysis is performed assuming the friction factor as constant in the design, which is compared to u…
Different energy balances for the redesign of nearly net zero energy buildings: An Italian case study
2015
Abstract The currently developing concept of a Net Zero Energy Building introduces new challenges and research problems. The calculation of a net zero energy balance is heavily influenced by the energy carrier weighting factors that are chosen, which can deeply influence the future energy market towards adopting specific energy technologies. The following paper proposes an analysis of different definitions and conventions for Net Zero Energy Buildings that employ different calculation methodologies and apply different weighting factors to an Italian case study. The case study, which is called “the Leaf House”, is one of the first examples of a nearly net zero energy building in Italy. A bui…
Energy, economic and environmental analysis on RET-hydrogen systems in residential buildings
2008
The aim of this study was to analyze energy, economic and environmental performances of a set of scenarios dealing with the production and the use of hydrogen as energy carriers in residential applications in combination with renewable energy (RE). The authors also made an investigation into the required economic conditions necessary for making H2–RE residential systems competitive with conventional ones, which are based on the use of grid electricity and natural gas. A case study was enacted in a small residential district in Palermo (Italy) made by five multi-storey buildings. Many energy systems have been considered according to several fuel-device combinations (electric grid, fuel cell,…
Mixed heuristic-non linear optimization of energy management for hydrogen storage-based multi carrier hubs
2014
In this paper, an heuristic and non-linear programming based algorithm to optimally operate an energy hub plant is proposed. The energy hub plant described in this work is the test system for the European INGRID research project. The Energy Management System defines the optimal energy flows dispatch in order to obtain the energy balance and the maximum profit for the owner of the plant. The problem is highly constrained and non-linear, for this reason the methodology cannot rely on Linear Programming (LP) methods. The Energy Management System manages two energy carriers, electricity and hydrogen, interfacing three distribution networks: the electricity, the hydrogen and the methane networks…
ERCP : Energy-Efficient and Reliable-Aware Clustering Protocol for Wireless Sensor Networks
2022
Wireless Sensor Networks (WSNs) have been around for over a decade and have been used in many important applications. Energy and reliability are two of the major problems with these kinds of applications. Reliable data delivery is an important issue in WSNs because it is a key part of how well data are sent. At the same time, energy consumption in battery-based sensors is another challenge. Therefore, efficient clustering and routing are techniques that can be used to save sensors energy and guarantee reliable message delivery. With this in mind, this paper develops an energy-efficient and reliable clustering protocol (ERCP) for WSNs. First, an efficient clustering technique is proposed for…
An integrated simulation method for building energy performance assessment in urban environments
2012
a b s t r a c t The microclimate around a building, establishing through the interaction with other buildings or the natural environment, is a significant factor in the building energy consumption. This paper presents a method for the quantitative analysis of building energy performance under any given urban contexts by linking the microclimate model ENVI-met to the building energy simulation (BES) program EnergyPlus. The full microclimatic factors such as solar radiation, long wave radiation, air temperature, air humidity, and wind speed have been considered in the proposed scheme. A case study has been conducted to analyze the effects of different microclimatic factors on the energy balan…
Role of Green Coverings in Mitigating Heat Island Effects: An Analysis of Physical Models
2012
Worldwide, governments are introducing several rules and standards in the aim of limiting the quantity of primary energy for air conditioning of buildings and supporting the use of renewable source of energy for generating thermal and electric energy to be utilized in buildings such as the European Directive on the Energy Performance of Buildings [1]. Along with these interventions, another important action takes currently place in the building sector, that is the introduction of passive structural components of the envelope, able to reduce the requirements of energy for air conditioning purposes. Among these building components, the so-called green roofs are becoming more and more interest…
Assessment of organic waste management methods through energy balance
2014
In Italy, the Organic Fraction of Municipal Solid W aste (OFMSW) is nowadays landfilled or processed through aerobic composting. The Italian towns curre ntly support a high cost for OFMSW disposal and cause a high environmental impact, because of long distance s travelled from towns to a few available landfills and fewer treatment places, as well as the used waste m anagement methods. An interesting option for OFMSW is Anaerobic Digestion (AD), producing biogas and “digestate”. In this survey a theoretical biogas plant was placed near a town of Sicily Region (Italy), centra lised with reference to the area considered for pro ducing OFMSW. The distances travelled every year to transport OFMS…
Finite difference thermal model of a latent heat storage system coupled with a photovoltaic device: Description and experimental validation
2014
Abstract The use of photovoltaic (PV) systems has been showing a significant growth trend but for a more effective development of this technology it is essential to have higher energy conversion performances. Producers of PV often declare an higher efficiency respect to real conditions and this deviation is mainly due to the difference between nominal and real temperature conditions of the PV. To improve the solar cell energy conversion efficiency many authors have proposed a methodology to keep lower the temperature of a PV system: a modified PV system built with a normal PV panel coupled with a Phase Change Material (PCM) heat storage device. In this paper is described a thermal model ana…
Life cycle assessment of a solar thermal collector: sensitivity analysis, energy and environmental balances
2005
Abstract Starting from the results of a life cycle assessment of solar thermal collector for sanitary warm water, an energy balance between the employed energy during the collector life cycle and the energy saved thanks to the collector use has been investigated. A sensitivity analysis for estimating the effects of the chosen methods and data on the outcome of the study was carried out. Uncertainties due to the eco-profile of input materials and the initial assumptions have been analysed. Since the study is concerned with a renewable energy system, attention has been focused on the energy indexes and in particular the “global energy consumption”. Following the principles of Kyoto Protocol, …