J.M. Sala

J.M. Sala
Universidad del País Vasco / Euskal Herriko Unibertsitatea | UPV/EHU · Department of Thermal Engineering

Ph D

About

117
Publications
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1,998
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Introduction
Additional affiliations
January 1983 - May 2016

Publications

Publications (117)
Article
Klima-aldaketaren eraginez, tokian-tokiko energia-eskaria aldatzen ari da. Honek, energia-eskaria asetzeko sistemen dimentsionamendu eta operazio moduan eragiten du; batez ere, epe luzerako proiektatzen diren sistemetan. Hala, jatorri berriztagarria duten energia-iturriak ezagutzea, modu jasangarrian ustiatzea eta ustiaketa klima-aldaketaren eskaki...
Article
Full-text available
In this work thermoeconomics is applied to a central thermal system covering three buildings that consists of a cogeneration engine, an aerothermal heat pump and a natural gas condensing boiler. Cogeneration systems integrated with renewable energy technologies are very attractive solutions in the building sector. Nevertheless, the use of cogenerat...
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This work defines and analyzes the performance of a polygeneration system in five different locations in Spain to maintain the thermal comfort and air quality of an office building. The facility is based on a chiller and a CHP engine with PV panels that provide almost all the electricity demand of the chiller. According to the energy performance an...
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This work describes the project submitted to the University-Society-Business 2021 call for proposals whose aim is to integrate the knowledge and university practices in the field of energy in buildings into secondary school students. The aim is to define the energy strategies to be implemented to strengthen the relationship between secondary educat...
Article
Before applying energy improvement strategies to real energy supply facilities, it is necessary to have an accurate model of their dynamic energy behaviour in order to predict and optimize the results. However, contrary to experimental facilities, in real operating facilities, budget constraints and fast access to recorded data limit the number of...
Article
This work develops a software to control and diagnose building thermal facilities based on thermoeconomics. It is tested with the data obtained from three building blocks in the Basque Country (northern Spain) with the aim of detecting the potential energy saving points and mitigating environmental impacts. Some obstacles, solved, are related to th...
Article
The energy performance certificate (EPC) is the core source for the European Union (EU) to obtain information about the efficiency levels of building stock and plan energy target paths. For this reason, and due to its wide variety of applications, it is important to ensure its quality. This study evaluates the quality of a representative EPC sample...
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Thermoeconomics combines the concepts of economics and thermodynamics to assess the cost formation process of thermal systems. It has great applicability in the allocation, optimization and diagnosis of product costs. However, some aspects need to be gathered and solved, to have common criteria for its implementation. That is precisely what happens...
Article
This work tries to present some reflections that help to understand the bases and the interest of the application of the exergetic analysis method and of thermoeconomics in buildings, both in what refers to their envelope and to their facilities. A brief introduction is made to the concept of exergy and the interest in incorporating the exergetic m...
Article
This work analyses deeply and critically the behavior of a heat recovery device of the ventilation system, in a dwelling of the Basque Country, under the energy and the exergy point of view. The aim is to show the different results that come from both perspectives. Heating period was monitored and data of the velocities and temperatures of the extr...
Article
The purpose of this paper is to apply thermoeconomics in a HVAC&R facility in order to implement the dynamic behaviour as well as to solve the direct problem of diagnosis. New methodological aspects of thermoeconomic applications are developed, such as a new method for setting the productive dynamic structure, in particular to define the commonly u...
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In order to achieve a sustainable society, the energy consumption in buildings must be reduced. The first step toward achieving this goal is to detect their weak points and analyze the energy-saving potential. to detect the units with higher consumption and cost. Exergy is very useful for analyzing pieces of equipment, systems or entire buildings....
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This work applies the Dynamic Advanced Exergy Analysis (DAEA) to a heating and domestic hot water (DHW) facility supplied by a Stirling engine and a condensing boiler. For the first time, an advanced exergy analysis using dynamic conditions is applied to a building energy system. DAEA provides insights on the components’ exergy destruction (ED) by...
Article
Purpose Understanding the dynamic hygrothermal behavior of building elements is very important to ensure the optimal performance of buildings. The Laboratory for Quality Control in Buildings of the Basque Government tested a flat roof designed by a construction company that developed a building to be constructed using prefabricated modules. This is...
Article
Thermoeconomic analysis allows for a deep understanding of the cost formation process within an energy system, providing insights into the possible routes for improvement. Several thermoeconomic approaches are well-established for application in systems with steady operating conditions, such as power plants, while a limited number of applications t...
Article
Heat transfer during melting and solidifying processes in phase change materials, is a highly non-linear phenomenon. Artificial Neural Networks seem a suitable approach to deal with highly non-linear processes. The present work uses dynamic neural networks to simulate the behavior of a phase change material layer of a building envelope, which typic...
Data
Oral communication presented in the 9th edition of the European Congress on Energy Efficiency and Sustainability in Architecture and Urbanism (EESAP 9), hosted in Bilbao in September, 2018 (In Spanish)
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A study of moisture pathologies in a modern residential multifamily building is presented. The housing block was designed under the regulation NBE-CT of 1979 in northern Spain. After the appearance of some moisture problems in the façades, three complementary studies were conducted to analyze the situation of the envelope and diagnose the best impr...
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Resumen Hoy en día, las ciudades están experimentando radicales cambios operacionales. Estos nuevos modelos conocidos como Smart Cities tienen como objetivo mejorar la calidad de vida de los ciudadanos mediante el uso de datos recopilados sobre el entorno a través del uso de Tecnologías de la Información y la Comunicación (TIC). Además, el Interne...
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Individual metering and charging of heat and domestic hot water is one of the possibilities for reducing the energy consumption in existing multifamily buildings and, with this aim in mind, the EU-directive 2012/27/EU enforced the installation of individual heat consumption meters. Even though some experimental evaluation of energy savings that may...
Article
Microcogeneration systems guarantee the reduction of primary energy consumption and greenhouse gas emissions in residential sector, by reducing fossil fuels demand and grid losses with respect to conventional energy conversion systems. Energy, environmental and economic benefits can be obtained sharing the cogenerated thermal and electric energy am...
Article
Thermoeconomic analysis of building energy supply systems are usually performed following the input-output approach, where the supply chain is divided into several subsystems directly related to each other. However, in this paper Symbolic Thermoeconomics has been applied and a dynamic analysis and comparison has been performed between the old and t...
Article
Minimum airflow rates are either recommended or required based on the number of occupants, the intended use of the space or the floor plan area. This paper focuses on a new proposal for Spanish Technical Building Code based on limitations of the ventilation using the CO2 concentration as an indicator. The aim of the proposal is to introduce indoor...
Article
This paper deals with the design and development of a low cost building environmental monitoring system, and it is based on Open Source Platforms and on the Internet of Things. To achieve this aim, a wireless microcontroller with attached sensors has been used to collect the environmental data. The information obtained from the sensors is collected...
Article
The research in the field of nanofluids has experienced considerable advances from their discovery two decades ago. These liquid mixtures with tiny quantities (< 10% in volume) of nanometric size solid particles (< 100. nm) in suspension have a great potential for thermal management applications due to their excellent thermophysical properties. The...
Article
One of the key factors that currently limit the commercial deployment of latent heat thermal energy storage (LHTES) systems is their complex design procedure. The optimization of such kind of systems requires a compromise between the storage capacity and the charging/discharging power, and therefore, there is a need of modeling tools that allow the...
Conference Paper
Se trata de una instalación de calefacción y producción de ACS a partir del aprovechamiento de la energía geotérmica de muy baja temperatura mediante una bomba de calor BC agua-agua de 68 kW, en un edificio de 26 viviendas en el País Vasco. La generación cuenta con un sistema de apoyo mediante caldera de condensación CC a gas natural para las punta...
Conference Paper
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The building energy performance not only depends on the thermal parameters related to the building’s envelope, but also with the installed services and its intended use. The building’s use is a difficult parameter to control; therefore, to reduce the discrepancies between the designed energy performance and the real one, is critical to correctly ch...
Conference Paper
To achieve an efficient use of energy in building energy supply systems not only an adequate design of the equipment is required, but also the detection and immediate determination of the costs of the products through the appropriate sensors. The comparison of these costs with the reference ones will allow us to detect the failures and establish th...
Article
In this paper, a general model for the optimization of the energy supply systems of buildings is proposed. The model is based on a general superstructure that allows to include all the existing and future technologies, covering heating, domestic hot water, cooling and electricity. The model is linked to a Mixed Integer Linear Programming (MILP) pro...
Conference Paper
The paper is based on the exergoeconomic study of an installation which covers the heating and DHW demand of a 176 dwellings nZEB in Vitoria-Gasteiz. It is composed by 2 cogeneration engines, 5’5 kWe and 12’5 kWt each and two 5’5 kWt each auxiliary conventional boilers. The novelty of this paper is that Symbolic Thermoeconomics (ST) is applied in t...
Article
Concerning the building environment HVAC facilities, even if a great effort has been made in developing components and systems with high nominal efficiencies, less attention has been paid to the problem of system maintenance. The main objective of the thermoeconomic diagnosis is to detect possible anomalies and their location inside a component of...
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Full-text available
The two spaces office module is usually considered as a representative case-study to analyse the energetic improvement in office buildings. In this kind of buildings, the use of a model predictive control (MPC) scheme for the climate system control provides energy savings over 15% in comparison to classic control policies. This paper focuses on the...
Article
The present article studies the binary mixture comprised by erythritol and urea for its application as a phase change material (PCM) in latent hat thermal energy storage systems for heating and domestic hot water applications. A sequential methodology was employed to evaluate the suitability of the mixture as a PCM. First, a preliminary evaluation...
Article
Application of Thermoeconomics in the diagnosis of building energy supply systems allows the localization and quantification of an abnormal operation, which can cause significant increase in energy consumption to obtain the same product. To do that, a comparison between the real operation of the energy system and the reference operation must be don...
Conference Paper
In order to improve energetic efficiency and reduce environmental impact (and therefore, improve the sustainability of buildings), new tools are being developing for the building sector, which are commonly used within the industrial field. Thermoeconomics in one of those new science, which is the one that connects the physics of buildings with econ...
Article
The advantages in applying the exergy concept and exergy efficiencies to evaluate the performance of energy systems in the building environment, contributing to the reduction in the use of high quality energy sources is currently known. Although Thermoeconomics has been widely applied in energy systems at building level Symbolic Thermoeconomics has...
Article
This research studies a binary mixture composed of sodium nitrate and urea for use as a phase change material in latent thermal energy storage systems between 75 and 90. °C. This temperature is suitable for heating and domestic hot water applications, such as solar thermal systems and cogeneration devices. This work is divided into two parts. In Pa...
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This work presents the implementation of a Model Predictive Control (MPC) scheme used to study the improvement of the thermal quality in aged residential buildings without any rehabilitation. The controller manages the heating system of an experimentally characterized model of a residential dwelling in a social block built during the decade of the...
Chapter
Cogeneration and trigeneration systems may operate more efficiently if the production of electricity and heat are uncoupled by using thermal energy storage, where heat that is not needed during the production period is stored. A review is made of the different methods that have been developed to size thermal energy storage to maximize benefits in c...
Article
A solution to the finite cylinder-source model for the ground heat exchangers at a different buried depths that takes into account the heat capacity inside them and allows arbitrary heat rate changes is presented. Analytical expressions for the average ground temperature are derived by integrating the exact solutions over the cylinder-source depth...
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The development of mathematical models that can reliably simulate the energy performance of a whole building or a building component with minimal discrepancy between the real and simulated data is a major aim of Building Physics science. In order to create models that accurately represent real physical phenomena it is necessity to perform tests on...
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Experimental work to assess the thermal performance of complex building components often requires testing under real and therefore variable conditions. The PASLINK methodology developed during many years by a European network of outdoor test centres is a dynamic methodology that provides high quality data sets and makes it possible to study the the...
Conference Paper
Analytical and simulation models of ground heat exchangers (GHE) are necessary for proper sizing piles with smaller depth to radius ratio than boreholes. Most existing methods of design ignore the transient thermal processes within the piles or boreholes: some software programs are based on the classical “hollow” cylindrical surface source or line-...
Article
Grey box models are a solution for evaluating and quantifying the effect on building thermal performance of different energy saving measures. They are usually used to predict a building thermal performance, and applied to energy systems. This paper presents the application of a grey box model to evaluate the thermal performance of a reference socia...
Article
In this paper an economic analysis of a 1 kWe Stirling engine-based micro-CHP (combined heat and power) residential plant is developed, approaching the case of a Spanish detached house sited in a cold climatic zone. The work focuses on analysing how the latest modifications in the Spanish micro-CHP and renewable energies regulation affect viability...
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In order to reduce the required volume for thermal energy storage, a finned plate latent heat thermal energy storage system for domestic applications is presented in this paper. This innovative design allows the exchanging of energy between water and the RT60, used as the phase change material. The simulation of that system is covered by a validate...
Conference Paper
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Great research effort is currently carried out to develop Energy-efficient Buildings. In particular, the control community is in a privileged position to help new buildings to comply with the European Energy Performance of Buildings Directive obligations and thus meet 'nearly zero-energy'. This work presents energy efficient studies on a dwelling i...
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The objective of this paper is to present a laboratory program designed for the Thermodynamics course offered in the Department of Thermal Engineering at the University of the Basque Country. With reference to one of the examples given in the textbook by Moran, Shapiro, Boettner and Bailey (2012), the balances of mass, energy, entropy and exergy ar...
Article
This paper presents an innovative finned-plate latent heat thermal energy storage system for its integration in cogeneration systems. For optimization purposes it is very important to maximize the efficiency of the computational calculations. Therefore, three approaches are presented for the simulation of the same storage system: a numerical model,...
Article
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In order to evaluate the accuracy and performance of two different heat transfer models for PCM containing systems, a thermal testing has been performed in a conductivimeter. A mixture of PCM and gypsum was submitted to a cyclic surface temperature change inside the conductivimeter, measuring heat fluxes and temperatures. The results of this test w...
Article
Although there are specific rules in the standard ISO 10211 for the characterization of thermal bridges, they are mainly focused on steady state calculations to obtain the linear thermal transmittance (Ψ) or the temperature factor at the internal surface (fRsi). These parameters are respectively indicators of the additional heat flow and the risk o...
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The approval of the Technical Building Code has meant major changes in the construction of multi-storey buildings in Spain. One of the most important revisions, with respect to the buildings erected prior to the Technical Building Code, has been the obligation to ventilate each one of its rooms. Depending on the use and occupancy a minimum flow rat...
Article
Nowadays, several regulations exist covering different general guidelines that must be considered in order to decrease the energy demand in residential buildings. One of the main ones consists in increasing the insulation of the building envelope with the aim of minimizing heat losses or gains. As a result, a proper treatment of thermal bridges and...
Article
The present article evaluates the influence of the experimental conditions in the determination of the subcooling of sodium sulfate decahydrate (Glauber's salt) nucleated with anhydrous and hydrated sodium tetraborate (borax). Experiments have been carried out by means of Differential Scanning Calorimetry (DSC) and by two other custom experimental...
Conference Paper
Full-text available
Thermal characterization of building envelope systems is a complex task requiring both, a level of certainty and realistic prediction models, i.e. dynamic exterior conditions instead of laboratory stationary conditions. Normally in the analysis of hygrothermal performance of envelope systems, especially in the thermal and solar characterization of...
Article
The aim of this research is to quantify the influence of a louvered blind in a double-glazed unit during night-time conditions. First, an analytical study of free convection was conducted to obtain a set of correlations for the Nusselt numbers of the cavity. Second, a parametric study was performed to calculate the total heat transfer (convective a...
Article
This paper considers the effect that different hot water storage tank modelling approaches have on the global simulation of residential CHP plants as well as their impact on their economic feasibility. While a simplified assessment of the heat storage is usually considered in the feasibility studies of CHP plants in buildings, this paper deals with...