Academic literature on the topic 'Cooling energy need'

Energy prices are constantly rising and that ́s why people are always looking for new ways to reduce energy costs. The main trend is to eliminate heat losses to the maximum extent. The demands for more sophisticated outer insulation for building still envelope (roofs, floors, walls, doors, and windows) are growing. Increased demands are evident also in the standards used in this area. Buildings with nearly zero energy (nZEB) become not only a vision but reality. Several ways for reduction of the energy needs are offered. The application of various colour adjustments of the building facade is one of the options. The impact of colour on the demand for heating and cooling at different thermal insulation capability is analyzed from the thermo - technical point of view. However, the question is whether it is possible to influence the annual costs for heating and cooling through the selection of facade colour (respectively through the absorption of solar radiation). We can say that today's architecture tries to use the structure of the building as some kind of thermal radiation (or rather solar energy) accumulator. In such a way we can characterize the majority of the structural designs for energy low cost buildings, where the main aim of such a solution is to reduce the energy need for heating and cooling.

The value of the external surface resistance on the outside of the structure in the summer season affects the energy need for cooling buildings. The paper analyzes the convection and radiation in the external environment for the current climate conditions of Slovakia in terms of their impact on the value of the external surface resistance to heat transfer in the months when it is expected cooling of buildings. Analysis of the external surface resistance to heat transfer on the outside of the structure for the monthly method of calculating the energy need for heating and cooling.

Counterbalancing climate change is one of the biggest challenges for engineers around the world. One of the areas in which optimization techniques can be used to reduce energy needs, and with that the pollution derived from its production, is building design. With this study of a generic office located both in a northern country and in a temperate/Mediterranean site, we want to introduce a coding approach to dynamic energy simulation, able to suggest, from the early-design phases when the main building forms are defined, optimal configurations considering the energy needs for heating, cooling and lighting. Generally, early-design considerations of energy need reduction focus on the winter season only, in line with the current regulations; nevertheless a more holistic approach is needed to include other high consumption voices, e.g., for space cooling and lighting. The main considered design parameter is the WWR (window-to-wall ratio), even if further variables are considered in a set of parallel analyses (level of insulation, orientation, activation of low-cooling strategies including shading devices and ventilative cooling). Finally, the effect of different levels of occupancy was included in the analysis to regress results and compare the WWR with corresponding heating and cooling needs. This approach is adapted to Passivhaus design optimization, working on energy need minimisation acting on envelope design choices. The results demonstrate that it is essential to include, from the early-design configurations, a larger set of variables in order to optimize the expected energy needs on the basis of different aspects (cooling, heating, lighting, design choices). Coding is performed using Python scripting, while dynamic energy simulations are based on EnergyPlus.

In district energy systems planning, the calculation of energy needs is a crucial step in making the investment profitable. Although several computational approaches exist for estimating the thermal energy need of individual buildings, this is challenging at the district level due to the amount of data needed, the diversity of building types, and the uncertainty of connections. The aim of this paper is to present a simplified measurement-based methodology for estimating the cooling energy needs at the district level, which can be employed in the preliminary sizing and design of a district cooling network. The methodology proposed is suitable for tertiary buildings and is based on building electricity bills as historical data to calculate the yearly cooling demand. Then, the developed method is applied to a real case study: the feasibility analysis of a sustainable district cooling network for a hotel district in the city of Marrakech. The designed system foresees a 23-MWcold district cooling network that is 4 km long, supplying 26 GWh of cooling to the tourist area. The results show that the proposed methodology for cooling demand estimation is coherent with the other existing methods in the literature.

The use of mobile data has increased and will continue to increase in the future, because more data is moving to wireless networks such as 5G. Cooling energy need is also expected to increase in indoor telecom rooms, and can be as high as the equipment’s own power consumption. The world’s first liquid Base Transceiver Station (BTS) was adopted into commercial use in 2018, in Helsinki, Finland. Conventional air-cooled BTS hardware was converted into liquid-cooled BTS equipment. Heat from the BTS was pumped out of the site room, and thus ventilation or air conditioning was not needed for the heat load from the BTS. Heat stored in the liquid was released into the ventilation duct of the building, still providing annual cooling energy savings of 70%, when compared to air cooling. In the future, 80% of the total dissipated energy, 13450 kWh/a in total, can potentially be used for heating purposes. In terms of CO2 emissions, adapting liquid cooling showed an 80% reduction potential when compared to air cooling.

Cooling of air in buildings has a significant effect on thermal comfort and, consequently, productivity of office occupants. This study presents a state of the art review of energy efficient cooling systems that will provide occupants in buildings with satisfying thermal comfort. Using high-temperature cooling systems combined with renewable energy sources increases the energy efficiency in buildings. Latent heat thermal energy storage (LHTES) using Phase Change Materials (PCM) is a renewable energy source implemented in space cooling applications due to its high energy storage density. Since the share of commercial buildings in need of cooling is increasing, there is a need for developing new technical solutions in order to reduce the energy use without compromising thermal comfort. To this end, a proposed ventilation system, preliminarily analyzed in this paper, is expected to reduce further the energy use. The ventilation system is composed of an air handling unit, a 2-pipe active chilled beam system, and a cooling system including a LHTES using PCM. Few researchers have investigated chilled water air-conditioning systems that integrate a LHTES using PCM. In this review, function characteristics, possibilities and limitations of existing systems are discussed.

To date, very little attention has been devoted to the scales and turbulence energy spectra of coolant exiting from film cooling holes. Length-scale documentation and spectral measurements have primarily been concerned with the free-stream flow with which the coolant interacts. Documentation of scales and energy decomposition of the coolant flow leads to more complete understanding of this important flow and the mechanisms by which it disperses and mixes with the free stream. CFD modeling of the emerging flow can use these data as verification that flow computations are accurate. To address this need, spectral measurements were taken with single-sensor, hot-wire anemometry at the exit plane of film cooling holes. Energy spectral distributions and length scales calculated from these distributions are presented for film cooling holes of different lengths and for coolant supply plenums of different geometries. Measurements are presented on the hole streamwise centerline at the center of the hole, one-half diameter upstream of center, and one-half diameter downstream of center. The data highlight some fundamental differences in energy content, dominant frequencies, and scales with changes in the hole and plenum geometries. Coolant flowing through long holes exhibits smoothly distributed spectra as might be anticipated in fully developed tube flows. Spectra from short-hole flows, however, show dominant frequencies.

This article discusses the need for new technologies to address emerging energy and water challenges. The demand for both energy and water is expected to grow with growth in global economy and population. Therefore, there is a need to minimize future conflicts between energy and water development and to foster more reliable and sustainable use of these two very important natural resources. Several renewable energy technologies and alternative cooling approaches for thermoelectric power plants exist that could reduce water consumption for electric power generation. Improving dry, hybrid, and other alternative cooling technologies and carbon sequestration approaches could help lower future water consumption and reduce the water footprint of power plants. Likewise, research to address the issues that are limiting the implementation of low-water-use renewable energy technologies could accelerate their use, reducing both water consumption and carbon emissions. Any major scale-up of alternative transportation fuels must consider approaches that use less fresh water than current methods, and must improve water use efficiency in mining, processing, and refining future fuel resources.

One of the most crucial factors for energy transition and the incorporation of renewable energy sources into the existing energy map is citizen engagement. Local energy communities (LECs), which are cooperative-based coalitions aimed at reducing the carbon footprint of the residential building sector, have received increasing attention in the past decade. This is because residential buildings account for almost half of the total energy consumed worldwide. A resounding 75% of it is used for thermal energy consumption, heating and cooling, cooking and bathing. However, the main focus of the literature worldwide is explicitly on electrical LECs, despite the fact that the significant increase in natural gas and oil prices, creates instability in the heating and cooling prices. The scope of this study is to provide an overview of the research field regarding Thermal LECs, using both a thorough literature review as well as bibliometric analysis (VOSviewer software), in order to validate the findings of the review. The results indicate a collective scarcity of literature in the field of thermal/cooling energy communities, despite their proven value to the energy transition. A significant lack of directives, research background and state initiatives in the context of LECs incorporating thermal/cooling energy production, storage and distribution systems, was also observed. Case studies and the applications of such systems are scarce in the available literature, while published studies need further feasibility assessments.

Energy dispersive x-ray fluorescence (XRF) spectrometry has been used extensively for some time now to do accurate and rapid analysis of a variety of samples. Most XRF Systems today use cryogenically cooled Si(Li) detectors to obtain the resolution needed for analysis of samples containing several elements. The need for the cryogenic coolant results in these XRP systems being rather large and not readily adaptable to portable devices. Detectors that require no cooling, or at least require only cooling obtainable by electrical weans, offer a definite advantage over cryogenically cooled detectors for use in portable devices. Mercuric iodide (HgI2) detectors are one type of such room-temperature detectors. The major disadvantage of any room-temperature detector has been the poor eneygy resolution associated with them.

Since twenty years European Union produces Directive to decrease energy consumption. The building sector is one of the most affected, since the buildings we live and work are responsible of about one third of global European energy consumption. Heating, Ventilation and air conditioning systems (HVAC systems) are often unknown by end-users. Also building owner and manager do not know deeply how the systems is composed. In the present work the writer found numerous specific diagnosis and intervention on HVAC system to dramatically decrease energy consumption. Incredible energy savings are possible by simply check and set up the right schedule and set up of HVAC system. Numerous European funded project demonstrated the effectiveness of such approach. Two European project results are described: Harmonac and iSERVcmb. Harmonac set up standards for HVAC systems inspections, the main findings are related to: general lack of information about system/components effectively installed in a building, HVAC inspections needing of a specific knowledge, not available in the market, lack of knowledge on control system by maintenance service companies, general over sizing of Heating power, Cooling power and water flow, scarce availability of logged data concerning energy consumption. BMS (Building Management System), if properly designed and installed could decrease inspection time and increase energy efficiency. Nevertheless, the inspections carried out in those years show that few BMS were able to log energy data. With a correctly installed BMS data of consumption the strategy and schedule of HVAC system should be understand, and also pointed the major energy savings opportunities. Buildings long term metering shown that HVAC inspection is fundamental to ensure efficiency of systems and, as a result, the best performance in terms of energy savings and comfort. BMS system should help in this issue, but they have to be originally designed for this purpose. Short term metering demonstrated that such approach could be a low cost solution to understand system behaviour and potential improvement. Building owner approach to system inspection shown clearly that there is a common under estimation of energy savings that could be reached by simply control strategy management. Since is necessary to demonstrate to building owner how much energy (and money) is possible to save with metering and operation control, the writer believe that the next step is to provide robust benchmark for the most common activities. With benchmark data will be easier to understand the potential of energy savings that is possible to achieve in buildings. That will convince building owner and/or financial bodies and ESCO to invest in big refurbishment of existent building stock, that are just operated “as usual.”

ABSTRACT Current national standards for determining the energy performance of buildings, are four parts of UNI TS 11300, which provide the calculation procedures in order to determine the thermal and primary energy and the use of renewable energy for air conditioning in winter and summer , as well as for the production of domestic hot water. In UNI TS 11300-1:2008. Energy performance of buildings - Part 1: Determination of thermal energy demand for air conditioning in winter and summer , and in the document CTI 010200043. DRAFT, Revision of the technical specification UNI / TS 11300-1, of 20/03/2012, the calculation of the thermal energy demand in the cooling operation, is carried out by the monthly quasi-steady state method, in which the utilization factor of the dispersions is used to take into account the dynamic effects. The literature regarding the energy performance of buildings, counts among recent works, many papers concerning the comparison of methods of dynamic simulation, and many developed that aim to verify the basic assumptions of the simplified methods for the determination of cooling energy demand . In the present work, an exhibition of classic theories and studies is provided in Chapter IV. At the same time, the Building simulation fundamentals are analyzed (Chapter V). The specific field of reference is that of validation procedures, in the sense and in terms of Chapter VII of the calculation method of monthly cooling demand, through the utilization factor of the dispersions. Based on the analysis of the calculated values with the software adopted in the guidelines for the energy certification of buildings throughout the country, and analyzing in detail the procedure for calculating the national and European standards for the determination of the cooling energy demand , and the significance and determination of dynamic parameters, the validation procedure is analyzed, evaluating the internal temperature, on which is based the utilization factor of the dispersions for the calculation of the thermal energy, which is necessary to maintain within a thermal zone of predetermined conditions of temperature. The thermal zone of UNI EN 15265:2008 has been considered, , which was worked in the process of method validation monthly UNI EN ISO 13790: 2008, Calculation of energy use for heating and cooling; moreover the test conditions Test 1 and Test 4 of the same Standard have been applied,. The weather data, provided by the Italian Thermotechnical Committee in the draft UNI 10349: 2012, Climatic data, have been used; furthermore these data have been properly processed with the code TRNSYS to be compatible with the chosen code to perform dynamic simulations, Energy Plus, because there was a significant difference (Chapter VI) with climate data provided by the US Department of Energy (DOE), that are climate data "G. De Giorgio, usually used in dynamic simulations. The results of obtained internal temperature do not justify the adoption of the coefficient of utilization of dispersions, because the value of internal temperature does not presents the changes that would lead to calculate a greater heat exchange than real case, by referring to the value of the control temperature. Another important issue is related to the weather data used for building simulation. To this purpose, using the approach of "black box", present in the UNI EN ISO 13790: 2008, in relation to the first two calculations listed therein, the needs of thermal energy in cooling mode were compared. In detail a thermal zone residential has been simulated in conditions of climate data "G. De Giorgio, and then in the conditions, referred to as " type CTI Year ", highlighting the significant differences for each location and special look. The results obtained by studying the operative temperature, in Chapter VII, have further confirmed the idea to determine and compare the various terms entering the monthly heat balance, to identify problems and then search for the key parameters on which to make the necessary processing to get an agreement between the energy needs by a dynamic simulation method and by a calculation based on a stationary or semi-stationary method. To this purpose, for a thermal zone of residential type, and for eleven national weather climates, suitably chosen to represent the usual national meteorological conditions, the energy demand has been determined the terms of exchange and the terms arising from the contributions, by the dynamic method, and with the quasi-stationary method,. These, however, are the first step in research that must be done, and that in dynamic simulations, using the new values of outdoor temperature, relative humidity, solar radiation and wind speed which have been developed to identify the test reference year. Chapter II reports the study carried out as part of the review of UNI TS 11300-1 and 11300-2 (draft) Determination of primary energy demand and yields for winter heating and production of hot water, for ventilation and lighting. This study involves a more correct way to evaluate the primary energy rate of the ventilation by means of a suitable evaluation of the thermal energy need.
Le norme nazionali vigenti per la determinazione della prestazione energetica degli edifici, sono le quattro parti della serie delle UNI TS 11300, che forniscono le procedure di calcolo per la determinazione dell’energia termica e primaria e per l’utilizzo delle energie rinnovabili per la climatizzazione estiva ed invernale, nonché per la produzione di acqua calda sanitaria. Nella UNI TS 11300-1:2008. “Prestazioni energetiche degli edifici - Parte 1: Determinazione del fabbisogno di energia termica per la climatizzazione estiva ed invernale”, e nel documento CTI 010200043. DRAFT , “Revisione della specifica tecnica UNI/TS 11300-1”, del 20/03/2012, il calcolo del fabbisogno di energia termica in modalità di raffrescamento, viene effettuato mediante il metodo mensile quasi-stazionario, in cui il fattore di utilizzazione delle dispersioni, consente di tenere conto degli effetti dinamici. La letteratura che riguarda la prestazione energetica degli edifici, annovera tra gli ultimi lavori, numerosi scritti inerenti il confronto dei metodi di simulazione dinamica, ed altrettanti elaborati che mirano a verificare le ipotesi fondamentali dei metodi semplificati per la determinazione del fabbisogno di energia termica in modalità di raffrescamento. Nel presente lavoro, una esposizione classica delle teorie e degli studi che si sono avvicendati, si trova nel capitolo IV. Contemporaneamente, ha avuto un notevole impulso la Building simulation, di cui si sono evidenziati ( capitolo V ) i fondamenti e la modellazione energetica dell’ambiente confinato mediante il bilancio sull’aria, di massa e di energia, indicando i termini e le equazioni fondamentali. L’ ambito specifico di riferimento è quello delle procedure di validazione, nel senso e nei termini del capitolo VII, del metodo di calcolo mensile del fabbisogno termico per raffrescamento, attraverso il fattore di utilizzazione delle dispersioni. Partendo dall’analisi dei valori calcolati con il software adottato nelle linee guida per la certificazione energetica degli edifici sul territorio nazionale, e analizzando in dettaglio la procedura di calcolo delle norme nazionali ed europee ai fini della determinazione del fabbisogno di energia termica per il raffrescamento, nonché il significato e la determinazione dei parametri dinamici, ci si é inseriti nel solco della validazione, andando a valutare le effettive condizioni di temperatura interna, che sono alla base del significato attribuito al fattore di utilizzazione delle dispersioni per il calcolo dell’energia termica, che é necessaria per mantenere all’interno di una zona termica delle prefissate condizioni di temperatura. La zona termica considerata nelle simulazioni è quella della UNI EN 15265:2008, “Calcolo del fabbisogno di energia per il riscaldamento e il raffrescamento degli ambienti mediante metodi dinamici” , e le condizioni di prova sono il “Test 1” e il “Test 4” della medesima norma, che è stata adoperata nel procedimento di validazione del metodo mensile della UNI EN ISO 13790 : 2008, “Calcolo del fabbisogno di energia per il riscaldamento e il raffrescamento”. Le condizioni meteoclimatiche , sono quelle attualmente disponibili, fornite dal Comitato Termotecnico Italiano nella bozza della UNI 10349 : 2012, “ Riscaldamento e raffrescamento degli edifici. Dati climatici”, opportunamente elaborate con il codice TRNSYS ed ulteriormente sviluppate per renderle compatibili con il codice scelto per effettuare le simulazioni dinamiche , Energy Plus , perché si è rilevata una notevole differenza ( capitolo VI ) con i dati climatici forniti dal Ministero dell’ Energia statunitense ( Department of Energy , DOE ), che per l’ ITALIA sono sostanzialmente basati sui dati “ G. De Giorgio ”, con cui, finora, si conducono le simulazioni dinamiche. I risultati ottenuti, riguardo le condizioni di temperatura interna, non giustificano l’adozione del coefficiente di utilizzazione delle dispersioni, perché il valore di temperatura interna non presenta le variazioni che porterebbero a calcolare uno scambio termico superiore a quello che realmente si realizza, facendo riferimento al valore della temperatura di regolazione. Un alto aspetto importante, da tenere in considerazione nelle valutazioni energetiche di cui si tratta, è quello della congruenza dei dati climatici posti a base dei calcoli. A tal fine, utilizzando l’approccio “ black box ” , presente nella UNI EN ISO 13790: 2008, relativamente ai primi due calcoli in esso elencati, si sono confrontati i fabbisogni di energia termica in modalità di raffrescamento, per una zona termica di tipo residenziale, simulata nelle condizioni dei dati climatici “ G. De Giorgio” , e nelle condizioni, indicate come “ Anno tipo CTI “ , mettendo in evidenza le notevoli differenze riscontrate per ogni località e le particolarità osservate. I risultati ottenuti studiando la temperatura operativa, nel capitolo VII, hanno ulteriormente confermato l’idea di determinare e confrontare i vari termini che entrano nel bilancio termico mensile, per identificare le criticità e successivamente ricercare i parametri fondamentali su cui poter fare le elaborazioni necessarie per ottenere un adeguato accordo tra i valori di fabbisogno energetico ricavati con un metodo di simulazione dinamica e quelli ricavati con un metodo di calcolo stazionario o semi-stazionario. A tal proposito, per una zona termica di tipo residenziale, e per undici contesti meteo climatici nazionali, opportunamente scelti per rappresentare le usuali condizioni meteoclimatiche nazionali, si sono determinati i termini di scambio e i termini che derivano dagli apporti, calcolati con un metodo di simulazione dinamica, e con un metodo quasi stazionario, sul quale però non è stato possibile apportare le correzioni che impongono i nuovi dati climatici, ottenendo, pertanto, risultati di natura orientativa. Questi, comunque, rappresentano il primo passo nel campo della ricerca che si deve compiere, e che nelle simulazioni dinamiche, utilizza, i nuovi valori di temperatura esterna, umidità relativa, irradiazione e velocità del vento che sono stati elaborati per identificare l’anno tipo dei capoluoghi delle province nazionali. Un ulteriore aspetto importante è quello legato alla determinazione dei fabbisogni energetici per la valutazione degli edifici. Nel capitolo II si riporta il contributo fornito nell’ambito della revisione delle UNI TS 11300-1 e 11300-2, ( draft ) “Determinazione del fabbisogno di energia primaria e dei rendimenti per la climatizzazione invernale e per la produzione di acqua calda sanitaria, per la ventilazione e per l’illuminazione”, che ha messo in evidenza una modalità più corretta per la valutazione della quota parte di fabbisogno di energia primaria dovuta alla ventilazione, attraverso una appropriata valutazione del fabbisogno di energia termica.

Dissertação de mestrado integrado em Engenharia Civil
Os edifícios são responsáveis por uma parte importante do consumo de energia em Portugal, sendo por isso necessário dar especial atenção às medidas de melhoramento da sua eficiência energética. As condições de conforto e bem-estar dos ocupantes são muitas vezes atingidas apenas com o recurso a sistemas mecânicos de climatização, tendo por isso o desempenho térmico dos edifícios de uma relevância significativa no consumo de energia dos edifícios. Devido às alterações climáticas, as temperaturas tendem a sofrer um significativo aumento, o que poderá corresponder a verões mais quentes e longos e consequentemente a maiores gastos de energia para arrefecimento ambiente. O presente estudo visa avaliar a influência de algumas medidas passivas de utilização corrente, tais como a variação do coeficiente de transmissão térmica na cobertura, paredes exteriores e pavimentos e a introdução e dimensionamento de elementos de sombreamento no desempenho energético dos edifícios na estação de arrefecimento, de forma a quantificar as necessidades energéticas de arrefecimento e procurar a eliminação das mesmas. O presente trabalho utiliza um mecanismo de avaliação dos riscos de sobreaquecimento existente do regulamento nacional relativo ao desempenho energético dos edifícios (REH), nomeadamente o fator de utilização de ganhos, que pode variar entre 0 e 1 no arrefecimento, e que toma o valor de 0 sempre que o fator de utilização de ganhos seja superior ao respetivo fator de referência. Esta situação representa as condições em que o risco de sobreaquecimento se encontra minimizado, sendo dispensável a utilização de sistemas ativos para arrefecimento. Posto isto, pretende-se indicar estratégias construtivas para as diferentes zonas climáticas para que seja possível identificar as medidas que maior potencial apresentam para a eliminação da energia de arrefecimento nos edifícios.
Buildings are responsible for an important part of the energy consumption in Portugal, therefore it is necessary to give special attention to energy efficiency improvements. The comfort conditions and welfare of the occupants, many times, are only fulfilled with resource to active systems, and because of that, the thermal performance of the buildings have a huge relevance in the building’s energy consumption. Due to climate changes, the temperatures tend to suffer a significant increase which will correspond to hotter and longer summers, and consequently to a bigger energy consumption for cooling purposes. The present study evaluates the influence of certain parameters such as the increase or decrease of the thermal transmission coefficient on the roof, external walls, pavement or the introduction and dimensioning of shading devices on the thermal performance of the buildings during the cooling season, quantifying the cooling energy needs and potential to eliminate the need of cooling active systems. The present work uses a mechanism for the evaluation of risks of the overheating that exists in the national regulation related to the energy performance of the buildings (REH), namely the gain usage factor which can vary between 0 and 1 in the cooling season, assuming the 0 value every time the gain usage factor is superior to the reference factor. This represents conditions in which the risk of overheating is minimized, making the use of active cooling systems unnecessary. Hereupon this, it is intended to indicate the constructive strategies for the different climate zones so that it is possible to identify the measures which present the higher potential for eliminating the building’s cooling energy.

Dissertação de Mestrado Integrado em Engenharia do Ambiente apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Atualmente, o paradigma energético traduz-se num aumento constante da procura de energia elétrica e também por um constante aumento da fatura energética que leva a que se tornasse urgente a necessidade de adotar medidas eficazes para a redução destes custos, no sentido de promover a racionalização da energia e a utilização sustentável das diferentes formas de energia. Na Europa, os edifícios residenciais representam uma grande fatia da energia consumida, assim sendo, é nestes edifícios que se torna pertinente intervir. Por vezes, pequenas mudanças podem contribuir significativamente para o aumento da poupança e da eficiência energética. A implementação de sistemas de climatização, nos últimos anos, têm aumentado nos edifícios residenciais com o intuito de melhorar as condições de conforto térmico do edifício. Neste âmbito, a presente dissertação pretende estudar a influência de certos parâmetros na otimização de sistemas de climatização. O dimensionamento de sistemas de climatização é feito, regra geral e especialmente no setor residencial, de forma expedita, conduzindo a um sobredimensionamento dos sistemas. Neste sentido, é necessário ter um conhecimento mais próximo da realidade das potências de aquecimento e de arrefecimento a adquirir num determinado edifício residencial, reconhece-se a importância de ter ferramentas que permitam aos projetistas obter um dimensionamento mais realista e em tempo útil. Este estudo consiste na avaliação das potências de climatização que permitirá efetuar um dimensionamento adequado dos sistemas de climatização a instalar, verificando a influência da localização do edifício, a zona climática em que se insere, a sua orientação, a área de cada espaço a climatizar e as características construtivas do edifício. Para isso, foram elaboradas diversas simulações dinâmicas com o recurso ao programa EnergyPlus integrado no DesignBuilder, conjugando todos estes parâmetros em estudo
Currently, the energy paradigm is reflected in a steady increase in electricity demand and also by a steady increase in the energy bill that leads to become an urgent need to take effective measures to reduce these costs, in order to promote the rationalization energy and the sustainable use of different forms of energy. In Europe, residential buildings account for a large slice of energy consumed, therefore, it is in these buildings that is pertinent to intervene. Sometimes small changes can significantly contribute to increased savings and energy efficiency. Implementation of HVAC systems, in recent years, have increased in residential buildings in order to improve the thermal comfort of the building. In this context, the present work aims to study the influence of certain parameters in HVAC systems optimization. The HVAC system design is done generally and especially in the residential sector, expeditiously, leading to oversizing of the systems. Thus, it is necessary to have a closer knowledge of the reality of the heating and cooling powers to acquire on a particular residential building, it is recognized the importance of having tools that enable designers to get a more realistic and in good time. This study consists of the evaluation of HVAC powers that will allow make a proper sizing of HVAC systems to be installed by checking the influence of the building location, the climate zone in which it operates, its orientation, the area of each room to be conditioned and constructive characteristics of the building. For this, we have been prepared various dynamics simulations with the use of integrated EnergyPlus program DesignBuilder, combining all these parameters under study.

AbstractData centres are complex energy demanding environments. The number of data centres and thereby their energy consumption around the world is growing at a rapid rate. Cooling the servers in the form of air conditioning forms a major part of the total energy consumption in data centres and thus there is an urgent need to develop alternative energy efficient cooling technologies. Liquid cooling systems are one such solution which are in their early developmental stage. In this article, the use of Computational Fluid Dynamics (CFD) to further improve the design of liquid-cooled systems is discussed by predicting temperature distribution and heat exchanger performance. A typical 40 kW rack cabinet with rear door fans and an intermediate air–liquid heat exchanger is used in the CFD simulations. Steady state Reynolds-Averaged Navier–Stokes modelling approach with the RNG K-epsilon turbulence model and the Radiator boundary conditions were used in the simulations. Results predict that heat exchanger effectiveness and uniform airflow across the cabinet are key factors to achieve efficient cooling and to avoid hot spots. The fundamental advantages and limitations of CFD modelling in liquid-cooled data centre racks were also discussed. In additional, emerging technologies for data centre cooling have also been discussed.

AbstractThe chapter describes several climate-correlated variables and suitable key performance indicators (KPIs) to define the local ventilative cooling potential. Furthermore, a methodology is presented to verify potential correlations between climate KPIs and indoor comfort parameters. The latter values are calculated by adopting dynamic energy simulations (EnergyPlus) and comfort models – both Fanger (ISO 7730) and the recently updated EU adaptive comfort approach (EN 16798-1) – considering a sample building unit. Simulations are run by using a parametric-enabling tool developed by the research unit to check correlations and is part of work performed for the PRELUDE project, co-funded by the EU, Horizon 2020 research and innovation programme under grant agreement No 958345. The approach is applied to the whole Italian territory considering typical yearly (hourly defined) meteorological conditions for all municipalities (about 8000 data points). Strong connections between climate and building KPIs are underlined together with the high potential of ventilative cooling in reducing discomfort and energy needs in the Italian territory.

AbstractPortuguese programs aimed at fostering Energy Efficiency (EE) measures often rely on cost–benefit approaches only considering the use phase and neglecting other potential impacts generated. Therefore, this work suggests a novel methodological framework by combining Hybrid Input–Output Lifecycle Analysis (HIO-LCA) with the Portuguese seasonal method for computing the households’ energy needs. A holistic assessment of the energy, economic, environmental, and social impacts connected with the adoption of EE solutions is conducted aimed at supporting decision-makers (DMs) in the design of suitable funding policies. For this purpose, 109,553 EE packages have been created by combining distinct thermal insulation options for roofs and façades, with the replacement of windows, also considering the use of space heating and cooling and domestic heating water systems. The findings indicate that it is possible to confirm that various energy efficiency packages can be used to achieve the best performance for most of the impacts considered. Specifically, savings-to-investment ratio (SIR), Greenhouse gases (GHG), and energy payback times (GPBT and EPBT) present the best performances for packages that exclusively employ extruded polystyrene (XPS) for roof insulation (packages 151 and 265). However, considering the remaining impacts created by the investment in energy efficiency measures, their best performances are obtained when roof and façades insulation is combined with the use of space heating and cooling and DHW systems to replace the existing equipment. If biomass is assumed to be carbon–neutral, solution 18,254 yields the greatest reduction in GHG emissions. Given these trade-offs, it is evident that multiobjective optimization methods employing the impacts and benefits assessed are crucial for helping DMs design future EE programs following their preferences.

I gazed over the railing into the crystal clear cooling pool glowing with blue Cherenkov light caused by particulate radiation traveling faster than the speed of light in water. I can see a matrix of square objects through the water, filling more than half of the pool. It looks like you could take a quick dip into the water, like an indoor swimming pool, but that would not be a good idea! It is amazing to think that this pool, about the size of a ranch house, is holding all of the spent fuel from powering the Wolf Creek nuclear reactor in Burlington, Kansas, for 27 years. The reactor was just refueled about a month before my visit, so 80 of the used fuel rod assemblies were removed from the reactor and replaced with new ones. The used fuel rods were moved underwater into the cooling pool, joining the approximately 1,500 already there. There is sufficient space for the next 15 years of reactor operation. There is no danger from standing at the edge of this pool looking in, though the levels of radon tend to be somewhat elevated and may electrostatically attach to my hard hat, as indeed some did. What I am gazing at is what has stirred much of the controversy over nuclear power and is what must ultimately be dealt with if nuclear power is to grow in the future—the spent nuclear fuel waste associated with nuclear power. What is the hidden danger that I am staring at? Am I looking at the unleashed power of Hephaestus, the mythical Greek god of fi re and metallurgy? Or is this a more benign product of energy production that can be managed safely? What exactly is in this waste? And is it really waste, or is it a resource? To answer that question, we have to understand the fuel that reactors burn. The fuel rods that provide the heat from nuclear fission in a nuclear reactor contain fuel pellets of uranium, an element that has an atomic number of 92 (the number of protons and also the number of electrons).

Considering the 2021 IPCC report that justly attributes our deteriorating climatic condition to human doing, the need to develop nearly zero energy building (nZEB) practices is gaining urgency. However, rather than the typical focus on developing greenfield net-zero initiatives, retrofitting underperforming buildings could create significant scale climate positive impacts faster. The chapter accordingly discusses energy-efficient retrofitting methods under three categorical sectors—visual comfort (daylight-based zoning, shadings); thermal comfort and ventilation (solar radiation-based zoning, central atrium plus interior openings, insulation, and window replacement); energy consumption (efficient lighting system, and controllers, material and HVAC system optimization, PV panels as the renewable energy source). This chapter further substantiates these theoretical underpinnings with an implemented design scheme—an educational building within a cold semiarid climatic condition—to showcase the on-ground impact of these retrofitting strategies in reducing the energy used for heating and cooling and lighting purposes.

The purpose of this study is to identify the technology for next generation aero combustors, and to propose totally new combustor design approaches. Next generation aero combustors need very high combustion air fraction, that brings idle lean blow out (LBO) problem. The present study suggests several measures to solve this problem, including: pilot and main two concentric combustion zones with separation, aerodynamic design to have main air slipping by pilot combustion zones, etc. For high fuel air ratio (FAR) combustor, the present authors propose using angled main fuel co-axial air plain jet injection. Make use of different penetration to meet the need for low power and high power conditions. For low emissions combustor, the present authors use small scale close contact fuel-air mixing with fuel staging to have low emissions at the same time to have good idle, good high altitude ignition, etc. Brand new cooling designs are proposed for outliner and inner liner. This chapter is mainly a survey of present author’s own research. The results of this study will provide guideline for the development of next generation aero combustors.

Green energy paradigm has been gaining popularity in the computing system from the software, hardware, infrastructure and application perspectives. Within that concept, data center greening is of utmost importance at the moment since data centers are one of the most energy conserving elements. Data centers are seen as the technology era's black energy-swallowing secret. Reducing energy consumption at data centers can reduce carbon footprint effect tremendously. Not addressing the issue immediately will lead to significant energy usage by data centers and will hinder the growth of data centers. The call for sustainable energy efficient data center leads to venturing into data center green computing. The green computing concept can be achieved by using several methods adopted by researchers including renewable energy, virtualization through cloud computing, proper cooling system, identifying suitable location to harvest energy whilst reducing the need for air-conditioning and employing suitable networking and information technology infrastructure. This paper focuses into several approaches used by researches to reduce energy consumption at data centers while deploying efficient database management system. This paper differs from others in the literature by giving some suitable solutions by looking into a hybrid model for green computing in data centers.

Net-zero energy buildings (NetZEBs) are of a building typology designed to combine energy efficiency and renewable energy generation to consume only as much energy as produced onsite through renewable resources over a specified time. The successful creation of NetZEBs is crucial to combating the current climate crisis. Water flow glazing (WFG) is a key technology that will assist in achieving this goal. Several experimental facilities have been designed and constructed to collect data based on WFG technology. These experimental facilities demonstrate that the successful implementation of WFG will allow reducing heating and cooling loads, primary energy consumption, and CO2 emissions. However, a wrong WFG selection can lead to failure in NetZEBs design. The goal of this text was to assess WFG performance through key performance indicators to understand the need of other renewable energies so that the construction of NetZEBs becomes a realistic target.

Energy saving and environmental protection are topics of growing interest. In the light of these aspects alternative refrigeration principles become increasingly important. Shape memory alloys (SMA), especially NiTi alloys, generate a large amount of latent heat during solid state phase transformations, which can lead to a significant cooling effect in the material. These materials do not only provide the potential for an energy-efficient cooling process, they also minimize the impact on the environment by reducing the need for conventional ozone-depleting refrigerants. Our paper, presenting first results obtained in a project within the DFG Priority Program SPP 1599 “Ferroic Cooling”, focuses on the thermodynamic analysis of a NiTi-based cooling system. We first introduce a suitable cooling process and subsequently illustrate the underlying mechanisms of the process in comparison with the conventional compression refrigeration system. We further introduce a graphical solution to calculate the energy efficiency ratio of the system. This thermodynamic analysis method shows the necessary work input and the heat absorption of the SMA in stress/strain- or temperature/entropy-diagrams, respectively. The results of the calculations underline the high potential of this solid-state cooling methodology.

Potable water is becoming scarce in many areas of the planet as the human population pushes past 7 billion. There is an increasing need for electric power since electricity is essential for modern development and progress. Traditionally, condenser cooling systems for power plants use seawater or freshwater in conjunction with cooling tower technology. Seawater is used in plants near the sea or ocean, and seawater condenser cooling systems are typically open systems. More recently, air-cooling has been implemented and undergoing evaluations. Predictably, during the summer season in hot, semi-desert and desert areas, air-cooling would not prove very efficient. Ironically, these areas would require the most fresh, potable water if the population and/or population density is large. The need for additional power generation units to satisfy consumer demands, and hence more cooling capacities, creates a problem for utilities. The current work researches the feasibility of using seawater cooling systems in the USA that are far from the sea. Five such locations have been identified as possibilities. Such a system has proven successful in South Florida. This system utilizes a series of cooling canals, used to dissipate the condenser heat to the surroundings. Relevant statistics of such a canal include water flow rate, total capacity, and MW of generators (both fossil-fueled and nuclear steam generators) the system is designed to cool. Additional statistics include the possible need to top-up (both amount and frequency of water required to maintain canal surface levels) or whether local natural rain water is adequate to replace evaporation and loss. Logistical information includes the estimated size of land required to accommodate the cooling canals. In estimating the canal system size and concomitantly the land required in other parts of the country, there is the tacit assumption that the thermal capacity of the surrounding land is about the same, and that the thermal conductivities of the different types of soil, and the heat transfer coefficients between the seawater and the canal are similar.

Exergy is destroyed when work is degraded by friction and turbulence and when heat is transferred through finite temperature differences. Typical HVAC systems use a combination of high quality energy from combustion and electricity to overcome relatively small temperature differences between the building and the environment. It is possible to achieve the heating/cooling necessary to maintain comfort in a building without these high quality energy sources and their high potential-energy destruction. A low-exergy heating and cooling system seeks to better match the quality of energy to the loads of the building and thus to minimize exergy destruction and increase the exergetic efficiency of the building’s heating and cooling system. The method described here for low exergy building system design begins by minimizing overall heating and cooling loads using a tight, highly-insulated envelope and passive solar design strategies. Next a low-exergy heating and cooling system is designed that uses hydronic radiant heating and cooling in floors, along with high thermal mass. The large surface area of the floors enable low fluid flow rates and relatively small temperature differences to achieve heat transfer rates that would traditionally be driven by high temperature differentials and flows. The building uses a solar wall to passively drive ventilation requirements and earth tubes to condition the ventilation air. High thermal mass in the floor reduces peak loads and eliminates the need for solar thermal storage tanks. Thus, this paper begins to explore the practical limits of low-exergy design.

There is a strong need to improve our current capabilities in thermal management and electronic cooling, since estimates indicate that IC power density level could reach 500 W/cm2 in near future. This paper presents several possible closed and open loop cooling schemes for thermal management of electronic equipment in data centers. To be able to identify the overall energy consumption impact, a thermodynamics coefficient of performance (COP) analysis for a data center under each one of the proposed schemes is presented. A limited condition condition 2nd law of thermodynamics thermal efficiency (ηII) analysis of the proposed open-loop schemes is also presented. Using available performance data, the overall data center COP of open and closed-loop cooling schemes is evaluated. Also, the 2nd law efficiency of open-loop schemes is evaluated. To properly design and size the components of a liquid or refrigeration-assisted open or closed-loop cooling scheme requires heat exchanger modeling that need to be incorporated in existing CFD simulation models. For that, analytical modeling of two kinds of direct expansion refrigeration cooling evaporator and a secondary liquid cooling fan coil heat exchanger in conjunction with a computational fluid dynamics (CFD) model to analyze a refrigeration cooled high heat density electronic and computer data center installed on a raised floor is presented. Both models incorporate an accurate tube-by-tube thermal hydraulic modeling of the heat exchanger. The refrigeration coil analysis incorporates a multi region heat exchanger analysis for a more precise modeling of two phase refrigerant flow in the evaporator. The single phase secondary loop fan coil heat exchanger modeling uses an effectiveness method for regional modeling of the spot-cooling coil. Using an iterative method, results of the heat exchanger modeling is simultaneously incorporated in the CFD model and an optimal design of spot cooling heat exchanger is developed. The presented cooling schemes, theoretical thermodynamics analysis along with the detailed thermal-hydraulic heat exchanger simulation in conjunction with the state-of-the-art CFD simulation code should enable data center designers to be able to handle expected increased in heat density of the future data centers.

Film cooling has been successfully used in cooling gas turbine components that are exposed to very high temperature environments. One main disadvantage of using film cooling is the aerodynamic losses associated. To address to the needs of obtaining uniform cooling in the downstream regions, backward injection of coolant has proved to be effective. However, there is a need to understand the aerodynamic behaviors of jet and mainstream flows in order to design effective configurations with this scheme of injecting coolant. In this work, the underlying aerodynamic principles of backward injection are studied numerically. All simulations are conducted with Fluent, a commercial CFD software. Results show that the classical counter rotating vortex found in simple cylindrical holes are not seen in the case of backward injections. Backward injection results in reduced coolant requirements and elimination of complex hole designs to avoid jet lift-off.

The design and performance of a triple glass window used as a roof component was analyzed in this paper. A mathematical model was set up for the component and weather data for the Finnish city Helsinki was used to assess its performance. This roof component would act as a passive radiative cooler during the summer and as a thermal insulator during the rest of the year. This versatile usage of the window component would thus decrease the need for traditional air-conditioning during summer and hence save electricity. The triple glass window would consist of one normal silica window and of two High Density Polyethylene (HPDE) windows. The space between the three windows would contain a (pressurized) greenhouse gas that would act as the heat carrier in this system. The heat would be transferred in to the system to the gas by heat radiation, conduction and natural convection through the window facing the room. This heated gas would then rise to the upper vacant space due to a decrease in the gases density caused by the heating. In the upper vacant part, the gas would then be cooled by radiative cooling through the HDPE, and the atmospheric window with colder air masses in the upper atmosphere. When, the greenhouse gas would have cooled down its density would increase and the gas would drop to the lower part of the window component. During times when no cooling would be needed the connection between the two vacant spaces would be cut, thus changing the roof components’ task from a passive radiative cooler to a thermal insulator. The heating of the space due to sunshine is of course evident and lower temperatures would be achieved if no window at all be used, but for places were roof windows are built this component would offer a viable alternative. This paper is a continuation to the paper by Zevenhoven and Fa¨lt submitted to this conference (1).

Abstract City’s electricity power grid is under heavy load during on-peak hours throughout summer cooling season. As the result, many utility companies implemented the time-of-use rate of electricity leading to high electricity cost for customers with significant cooling needs. On the other hand, the need for electricity and/or cooling decreases greatly at night, creating excess electricity capacity for further utilization. An innovative ice energy storage system is being developed leveraging a unique supercooling-based ice production process. During off-peak hours the proposed system stores the low-cost electric energy in the form of ice; during on-peak hours the system releases the stored energy to meet extensive home cooling needs. Thus, it can not only reduce energy and cost of cooling, but also increase the penetration of renewable energies (especially wind energy). In this paper, the working principles of the system is presented along with the modeling details of the overall system and several key components. The Simulink model takes in hourly temperature and peak/off peak electricity cost data to dynamically simulate the amount of energy required and associated cost for cooling an average home. Both energy consumption and cost for homes using the cooling system with ice energy storage in two US cities have been compared with those using conventional HVAC cooling system. According to the model, huge reduction in energy cost (up to 3X) can be achieved over six months of cooling season in regions with high peak electricity rates. While only moderate reduction on energy consumption is predicted for the ice energy storage system, further energy reduction potentials have been identified for future study.

The cooling of portable electronic devices has become paramount in the last number of years due to the simultaneous increase in power consumption and reduction in package size. This has lead to an increase in the amount of heat that needs to be dissipated by these devices. Passive cooling techniques will no longer provide an adequate solution and therefore active cooling solutions need to be implemented. The use of miniature radial fans in conjunction with heatsinks is a possible solution. These types of fans are especially suited as they can be deployed in a low profile format. However, little is known about the aerodynamic effects of reducing the fan scale and therefore Reynolds number to the extent necessary for use in portable electronic device cooling. This paper looks to quantify deviation of aerodynamic performance with Reynolds number from that predicted by the fan laws. Before tests were carried out experimental facilities were calibrated. Four radial fans with diameters of 80, 40, 18.3 and 10mm were then tested at a number of different rotational speeds with measurements of pressure rise and flow rates recorded for each of these speeds. The measurements presented show the need for a homogonous experimental setup with the exact conditions replicated each time a test is carried out. Results also show that there is good correlation between the experimental results for pressure rise and flow rate at high Reynolds numbers in accordance with trends from high Reynolds number theory. However at the lower Reynolds numbers a fundamental change in flow phenomena emerges which alters the maximum pressure and flow characteristics.

Due to serious deterioration of aluminum fins on two dry coolers only 6 years after initial installation, the potential to disrupt operation of the 3,000 tons per day (tpd) Pinellas County Resource Recovery Facility was a real concern. A new system upgrade was required to provide reliable cooling of the glycol liquid system. This system dissipates the heat rejection requirements of the process and instrument air compressors, particularly critical during Florida’s hot summer months. A second issue was the need to provide redundancy, which was not designed into the original installation. The selected system included two plate and frame coolers along with two pumps located next to the existing cooling tower (C.T.) basin. Water from the C.T. basin is pumped through one plate and frame cooler, reducing the temperature of the glycol liquid. The water then flows back to the C.T. basin. The construction work, completed in August 2003, provides in excess of 200% redundancy and has been in successful operation since that date.

While solar energy provides a source for passive space heating across a variety of climates, other ambient energy sources may be more appropriate for passive space cooling. These ambient resources include ambient air at dry-bulb and wet-bulb temperatures, ground temperature at locations where the soil is cooler than the indoor comfort temperature, and night-sky radiant temperature, which is substantially lower than ambient air in most climates. The focus of this study was on comparing these sources to cooling loads across climates in the US. Using a degree-day approach, annual cooling potentials were calculated for over 800 TMY3 locations. Color-themed maps for each ambient source at several indoor comfort temperature ranges were constructed as visual references for design purposes. In addition, eight US cities (Denver, CO, Los Angeles, CA, Louisville, KY, Madison, WI, Miami, FL, New Orleans, LA, Phoenix, AZ and Washington DC) were selected to represent a range of climate characteristics, including seasonal ambient temperature, diurnal temperature swings, humidity and sky clearness. For each city, an ambient potential to cooling load ratio (ALR) was calculated, with the potential based on an indoor comfort temperature range of 68°F – 72°F and the load calculated with a base temperature of 65°F. ALR, which neglects phase lags between source and load and the associated need for thermal storage, exceeded one for dry-bulb air and for ground temperature for all locations except Miami, New Orleans and Phoenix. Wet-bulb ALR exceeded one for all locations except Miami, and sky ALR exceeded one for all locations. Finally, the effect of limited thermal storage was estimated by calculating daily ambient source fraction, fas, which is the daily ambient cooling potential divided by the daily cooling load. fas thus approximates the cooling potential of systems with one day’s worth of thermal storage, and has an upper limit of one. Fas, the annual sum of fas, equaled one for ground temperature for Los Angeles and Madison and for sky temperature for Denver and Los Angeles. Fas for ground temperature was above 0.9 for all locations except Miami, New Orleans and Phoenix. Fas for sky temperature exceeded 0.6 for all locations. By utilizing all possible combinations of ambient sources, half of the selected locations attained Fas equal to one and the minimum for all locations still exceeded 0.65.

Since the mid-1980s, the international community has controlled refrigerants that may damage the ozone layer and cause climate change based on several international agreements. In particular, the Montreal Protocol contributed to not only solving the ozone layer depletion problem but also limiting global warming. Given that the global demand for cooling would triple by 2050 and this rise would increase global greenhouse gas emissions significantly, the Montreal Protocol has expanded its regulatory scope to decarbonize the cooling sector through the adoption of the Kigali Amendment. Also, increasing interest in low-carbon cooling has driven the launch of various global initiatives to complement the international agreements and accelerate low-carbon cooling in developing countries. The experience of implementing the Montreal Protocol and its amendments suggests some lessons and insights for making the Kigali Amendment work well. First, each country should develop and enforce national policies aligned with international agreements. Second, financial and technical support mechanisms should be strengthened to facilitate developing countries’ compliance with the Kigali Amendment. Third, along with the improving energy efficiency of cooling, the substances that neither harm the ozone layer nor exacerbate climate change should be used as substitutes for hydrofluorocarbons. Last, the monitoring, reporting, and verification of controlled substances need to be strengthened.

Thermosyphons are an artificial ground-freezing technique that has been used to stabilize permafrost since the 1960s. The largest engineered structure that uses thermosyphons to maintain frozen ground is the Trans Alaska Pipeline, and it has over 124,000 thermosyphons along its approximately 1300 km route. In passive mode, thermosyphons extract heat from the soil and transfer it to the environment when the air temperature is colder than the ground temperature. This passive technology can promote ground cooling during cold winter months. To address the growing need for maintaining frozen ground as air temperatures increase, we investigated a solar-powered refrigeration unit that could operate a thermosyphon (nonpassive) during temperatures above freezing. Our tests showed that energy generated from the solar array can operate the refrigeration unit and activate the hybrid thermosyphon to artificially cool the soil when air temperatures are above freezing. This technology can be used to expand the application of thermosyphon technology to freeze ground or maintain permafrost, particularly in locations with limited access to line power.

Heat pumps are an excellent solution to supply heating and cooling for indoor space conditioning and domestic hot water production. Conventional heat pumps are typically electrically driven and operate with a vapour-compression thermodynamic cycle of refrigerant fluid to transfer heat from a cold source to a warmer sink. This mature technology is cost-effective and achieves appreciable coefficients of performance (COP). The heat pump market demand is driven up by the urge to improve the energy efficiency of building heating systems coupled with the increase of global cooling needs for air-conditioning. Unfortunately, the refrigerants used in current conventional heat pumps can have a large greenhouse or ozone-depletion effect. Alternative gaseous refrigerants have been identified but they present some issues regarding toxicity, flammability, explosivity, low energy efficiency or high cost. However, several non-vapour-compression heat pump technologies have been invented and could be promising alternatives to conventional systems, with potential for higher COP and without the aforementioned refrigerant drawbacks. Among those, the systems based on the so-called “caloric effects” of solid-state refrigerants are gaining large attention. These caloric effects are characterized by a phase transition varying entropy in the material, resulting in a large adiabatic temperature change. This phase transition is induced by a variation of a specific external field applied to the solid refrigerant. Therefore, the magnetocaloric, elastocaloric, electrocaloric and barocaloric effects are adiabatic temperature changes in specific materials when varying the magnetic field, uniaxial mechanical stress, electrical field or hydrostatic pressure, respectively. Heat pump cycle can be built from these caloric effects and several heating/cooling prototypes were developed and tested over the last few decades. Although not a mature technology yet, some of these caloric systems are well suited to become new efficient and sustainable solutions for indoor space conditioning and domestic hot water production. This technical report (and the paper to which this report is supplementary materials) aims to raise awareness in the building community about these innovative caloric systems. It sheds some light on the recent progress in that field and compares the performance of caloric systems with that of conventional vapour-compression heat pumps for building applications.

Recent concerns regarding global warming and energy security have accelerated research and developmental efforts to produce biofuels from agricultural and forestry residues, and energy crops. Anaerobic digestion is a promising process for producing biogas-biofuel from biomass feedstocks. However, there is a need for new reactor designs and operating considerations to process fibrous biomass feedstocks. In this research project, the multiphase flow behavior of biomass particles was investigated. The objective was accomplished through both simulation and experimentation. The simulations included both particle-level and bulk flow simulations. Successful computational fluid dynamics (CFD) simulation of multiphase flow in the digester is dependent on the accuracy of constitutive models which describe (1) the particle phase stress due to particle interactions, (2) the particle phase dissipation due to inelastic interactions between particles and (3) the drag force between the fibres and the digester fluid. Discrete Element Method (DEM) simulations of Homogeneous Cooling Systems (HCS) were used to develop a particle phase dissipation rate model for non-spherical particle systems that was incorporated in a two-fluid CFDmultiphase flow model framework. Two types of frictionless, elongated particle models were compared in the HCS simulations: glued-sphere and true cylinder. A new model for drag for elongated fibres was developed which depends on Reynolds number, solids fraction, and fibre aspect ratio. Schulze shear test results could be used to calibrate particle-particle friction for DEM simulations. Several experimental measurements were taken for biomass particles like olive pulp, orange peels, wheat straw, semolina, and wheat grains. Using a compression tester, the breakage force, breakage energy, yield force, elastic stiffness and Young’s modulus were measured. Measurements were made in a shear tester to determine unconfined yield stress, major principal stress, effective angle of internal friction and internal friction angle. A liquid fludized bed system was used to determine critical velocity of fluidization for these materials. Transport measurements for pneumatic conveying were also assessed. Anaerobic digestion experiments were conducted using orange peel waste, olive pulp and wheat straw. Orange peel waste and olive pulp could be anaerobically digested to produce high methane yields. Wheat straw was not digestible. In a packed bed reactor, anaerobic digestion was not initiated above bulk densities of 100 kg/m³ for peel waste and 75 kg/m³ for olive pulp. Interestingly, after the digestion has been initiated and balanced methanogenesis established, the decomposing biomass could be packed to higher densities and successfully digested. These observations provided useful insights for high throughput reactor designs. Another outcome from this project was the development of low cost devices to measure methane content of biogas for off-line (US$37), field (US$50), and online (US$107) applications.