Search results for "thermal [correlation function]"
showing 10 items of 1923 documents
Thermal characterization of insulating materials
2018
Abstract The strict energy saving standards are based on the declared values of the materials, i.e. U-value, thermal conductivity or thermal capacity. To this end, proper knowledge of the thermophysical properties of the wall components is needed, especially with regard to new lightweight technologies that are being used in building construction/refurbishment, under the dynamic conditions of the Mediterranean climate, where one of most important parameters of building materials is their heat capacity because of the influence of solar radiation energy. With this regard, the actual heat capacity value, obtained in laboratory tests, is typically quite different from the nominal one. So, this p…
Life Cycle Assessment of Solar Technologies
2015
This chapter analyses the most common solar technologies and assesses their energy and environmental performance, based on a life cycle perspective. After a preliminary description of the main technologies, the chapter presents a review of studies on solar plants, as published in scientific journals in the past decade. Successively, the chapter assesses solar plants in comparison to other renewable and non-renewable based technologies, including a discussion of uncertainties and criticalities in the assessment
A criterion for the assessment of the reliability of ASHRAE conduction transfer function coefficients
2010
This paper presents a new mathematical approach, which, when applied to conduction transfer functions (CTFs) of a multi-layered wall, is able to predict the reliability of building simulations. This new procedure can be used to identify the best set of CTF coefficients, which are a critical point at the core of the ASHRAE calculation methodology founded on the transfer function method. To evaluate the performance of different CTF coefficient sets, the authors performed a large number of thermal simulations on the multi-layered walls included in the ASHRAE Handbook, volume fundamentals, and on other walls typical of Mediterranean building heritage. Those data were employed to test an algorit…
Energy and environmental impacts of Energy related products (ErP): a case study of biomass-fuelled systems
2014
Abstract Energy-related Products (ErP) account for a large proportion of European energy and natural resource consumption. In 2007, ErP were responsible for the consumption of about 239 Mtoe of electricity and about 555 Mtoe of fuels. In order to reduce the energy and environmental impacts of these products, the European Commission published the Directive 2009/125/EC on the eco-design of ErP. This Directive represents a key component of European policy for improving the energy and environmental performances of products in the internal market. In this context, it is important to develop scientific research aimed at assessing the energy and environmental impacts of ErP, and at defining their …
Annual heating energy requirements of office buildings in a European climate
2016
Abstract The concept of implementing energy savings to reduce greenhouse gas emissions has become a key element of energy policies of any industrialized country. In the civil sector and specifically, energy savings for office buildings, there are still opportunities for further enhancements related to correctly determining the air conditioning thermal requirements. However, there is a lack of simple correlations that allow a preliminary assessment for a single building or correlations that can be quickly applied at the district level. This paper proposes several simple correlations that determine the heating loads of a typical office building by only knowing the Degree-Days of a specific Eu…
Comparing different control strategies for indoor thermal comfort aimed at the evaluation of the energy cost of quality of building
2010
Abstract The rapid improvement in the standard of living requires more detailed and sophisticated methods of evaluating comfort conditions. But, maintaining thermal comfort conditions in confined environments may require complex regulation procedures and the proper management of heating, ventilating and air conditioning (HVAC) systems. In turn, the requirements for indoor thermal comfort do not necessarily coincide with those of energy saving purposes, which in the last years are becoming a crucial issue owing to the enactment of the European Energy Performance of Buildings Directive (EPBD). The aim of this work is to compare different indoor control thermal comfort strategies in view of th…
Membrane distillation: Solar and waste heat driven demonstration plants for desalination
2013
Abstract The development of small to medium size, autonomous and robust desalination units is needed to establish an independent water supply in remote areas. This is the motivation for research on alternative desalination processes. Membrane distillation (MD) seems to meet the specific requirements very well. This work is focused on experimental studies on full scale demonstration systems, utilizing a parallel multi MD-module setup. Three different plant concepts are introduced, one of them is waste heat driven and two of them are powered by solar thermal collectors. Design parameters and system design are presented. After the analysis of plant operation a comparison among the plants as we…
Design of a power conditioning unit for a Stirling generator in space applications
2012
The Free-Piston Stirling Generator (FPSG) is a thermal to electrical energy conversion system, based upon the thermal engine of the same name. Intensive research concerning the feasibility of the engine for its application in deep space and planetary missions has been conducted, primarily due to the potential increase in efficiency (−30%) over the currently used Radio-isotope Generators (RTGs). On the other hand, less attention has been paid to the power conditioning requirements and alternatives. The present work has investigated on the dynamics governing the FPSGs in order to assess the design requirements for the subsequent power-conditioning unit (PCU). Thereafter, two alternatives of A…
Thermo acoustic - MHD electrical Generator
2011
Abstract The thermo-acoustic generators offer a unique means of converting thermal energy into mechanical energy without any moving parts and without fluid circulation. They are comparable to the Stirling engine with the advantage of much greater simplicity. They are therefore natural candidates for special uses where interventions are limited. The problem to solve is transforming the mechanical energy into electrical energy. MHD generators offer excellent opportunities in this area, particularly by using the mechanisms of induction. The work concerns the combination of a thermo-acoustic generator with an induction generator of a new concept for obtaining electric current with adjustable vo…
Optimization of a thermoelectric system for power generation realized by ‘‘hidden’’ components
2014
Abstract Today the utilization of renewable energy sources is very important to support the traditional ones, and also in order to reach the objectives fixed by the Kyoto Protocol. In this context, also well-known technologies related to the electric energy production, formerly not suitable – due to the poor technological level of the components or due to the high costs linked to the system efficiency – may now find a suitable collocation. Among these technologies, the thermoelectric effect may be very advantageous in some particular applications of small power. A power generation system utilizing this technology has been studied by the authors. This system utilizes the thermal difference b…