Search

Energy consumed by the water industry is not negligible and improvements on energy efficiency in water distribution networks are still needed. This work aims to provide a new approach to design tailored torpedo shaped in-pipe axial pico-hydraulic turbines for the recovery of energy in water distribution networks. Simple straight untwisted blades with arc of circles profiles are imposed to simplify manufacturing. Ideal flow bi-dimensional cascade theory with Weinel isolated airfoil to cascade correlations are used as compromise between accuracy and simplicity. From it, a dimensionless design chart is build. A novel flow-to-head factor is chosen as main dimensionless factor to simplify stator analysis and obtain a more compact chart. From five usual input design parameters, choosing the value of three, and letting two of them to vary allows the trace of a space of all optimal designs. From this space, a turbine or family of turbines can be obtained. A design example on the same conditions as a experimentally tested turbine found in the literature was carried over and simulated with OpenFOAM open source library. A mesh parametric study for numerical validation purposes is realized. Discretization uncertainty found for the selected mesh was about one point for the hydraulic efficiency. The designed and simulated turbine showed a maximum hydraulic efficiency of . The presented non-dimensional approach proved to be useful to design efficient tailored simple pico-hydraulic turbines for energy recovery in distribution water networks, relaying on one design chart. This work have been supported by Fundación Séneca (Murcia, Spain)[Grant No. 20352/FPI/17].

Este documento es el resultado de una reflexión sobre las posibilidades y dificultades de la observación social empírica en la cárcel, desde la preocupación por la enseñanza de la metodología sociológica aplicada a las titulaciones universitarias de criminología. Lo aquí expuesto se apoya en la experiencia práctica que los autores han acumulado a través de múltiples estudios realizados en España y en distintos países de Iberoamérica. Una primera versión del texto fue creada para ser utilizada como apuntes prácticos de investigación para estudiantes de criminología que comenzaban su formación y no tenían por tanto experiencia profesional en este campo de estudio. A esa versión se le han introducido las adaptaciones oportunas para que pueda ser utilizado de manera más general por investigadores y estudiantes de ciencias sociales que necesiten una guía básica de diseño y ejecución de proyectos de investigación social en cárceles. El texto tiene una orientación didáctica, es una propuesta que ofrece claves para mejorar la enseñanza y aplicación de la metodología de investigación en los sistemas penitenciarios.This article is the result of a reflection on the possibilities and difficulties of empirical social observation in prison, from the perspective of sociological methodology teaching applied to university degrees in criminology. What is here exposed is based on the practical experience accumulated by the authors via multiple studies carried out in Spain and in different Ibero-American countries. A first draft of this text was created with the purpose of being used as practical research notes for students of criminology who began their training and had no professional experience in this field of study. This version has been adapted, so that it may be used generally by researchers and students of social sciences who need a basic guide to the design and execution of social research projects in prisons. The paper assumes a didactic orientation; it is a proposal that offers guidelines to improve the teaching and application of the research methodology in the penitentiary systems.

The heat transfer process to a non-Newtonian pseudoplastic fluid inside a scraped surface heat exchanger has been experimentally analysed. The scraping device consists of a rod with semicircular pieces mounted on it, which are in contact with the inner surface of the pipe. The whole moves axially and thus, the pieces scrape the inner surface of the pipe, in order to avoid fouling formation and enhance heat transfer. Pressure drop, heat transfer and power consumption measurements, using non-Newtonian pseudoplastic fluids, have been carried out in static and dynamic conditions of the scraper. Four flow regions have been identified: attached laminar, detached laminar, transitional and turbulent flow regions. A generalization method for the fluid viscosity that includes the effects of the non-Newtonian behaviour has been used. Friction factor and Nusselt number have been successfully correlated by employing the generalized viscosity on pressure drop and heat transfer results, both in static and dynamic conditions, for three of the four identified flow regions (it was not possible to get correlations in the transition to turbulent flow region). The study shows that, despite the high power consumption of the scraping movement, the device is suitable for an industrial process using non-Newtonian fluids, since it prevents fouling, increases heat transfer, provides flexibility and enhances the final product quality. Furthermore, the obtained correlations are a valuable tool in the design of heat exchangers.

Heating and cooling processes involving viscous fluids, crystallization processes or with fouling tendency require often the employment of scraped surface heat exchangers to enhance the heat transfer. In these cases, obtaining the heat transfer coefficient is complex due to the difficulty of measuring the wall temperature. The present work introduces an innovative measurement technique to retrieve the scraped wall temperature based on embedded thermocouples, welded directly into the wall plate. The thermocouple wires were introduced into a knockout and welded with a filler material. Once welded, the entire set was calibrated in a cold room at controlled temperature. A total of 26 T-type thermocouples were welded to a stainless steel wall substrate, tested later in a rotating scraped surface heat exchanger employed in the ice slurry production. The thermocouples presented a variance of 0.3 °C and an accuracy after calibration of 0.2 °C. The deviation between the scraped wall temperature and the thermocouple measurement was assessed by 2D numerical simulations of the transient heat conduction across the wall substrate. The influence of the wall substrate thickness, thermocouple location and scraping velocity has been considered.

En este documento se aborda el caso específico de las mujeres privadas de libertad, sin olvidar la posible extensión de las medidas alternativas a otros grupos que se hallan en una situación de vulnerabilidad. En el texto se fundamenta primero la necesidad de integrar la perspectiva de género en la creación de sistemas de control y ejecución de penas y medidas alternativas a la privación de libertad en la prisión. A continuación, se analiza cómo esta integración y una buena ejecución de las medidas puede favorecer los procesos de inserción y abandono del delito de estas mujeres. Seguidamente, se revisan las mejores prácticas de medidas alternativas que se están llevando a cabo en América Latina, El Caribe y la Unión Europea, considerando con más detenimiento las que mejor se adaptan a las necesidades de este grupo de mujeres. Y, por último, se concluye con unas mínimas recomendaciones para su implantación considerando la perspectiva de género.

Cooling towers, among other equipment, could have an important atmospheric impact, becoming a source of pollutants or biological agents. The most important, due to its frequency and importance of the outbreaks, is Legionella. Since its discovery in 1976 in Philadelphia, PA, several outbreaks have been reported causing tens of deaths. The most important one took place in the city of Murcia, Spain, in 2001, with more than 600 cases. In the present work, a validated numerical model using the computational fluid dynamics code ANSYS Fluent is employed to simulate the dispersion of the drift from the cooling tower causative of the outbreak in the urban environment of Murcia in the days of highest emissions. The results of the model are compared with the results of the epidemiological investigation carried out by the Epidemiology Service (Consejeria de Sanidad, Murcia, Spain). The main objective of this model is to predict a cooling tower influence area, and what will help to reduce environmental and per...

The flow pattern of a pseudoplastic fluid inside a scraped surface heat exchanger has been obtained by means of Particle Image Velocimetry. The scraping device consists of a rod with semicircular pieces mounted on it, which are in contact with the inner surface of the pipe. The whole moves axially and thus the pieces scrape the inner surface of the pipe, in order to avoid fouling formation and enhance heat transfer. The aim of this work is to obtain the influence on the flow pattern of the significant parameters of the problem: the Reynolds number, the scraping velocity and the non-Newtonian behaviour of the fluid. In order to achieve this, a numerical model has been created. This model provides the velocity profile of non-Newtonian fluids in a concentric annulus, which has been used as start point for the study of the flow in the pipe with the insert device. Finally, PIV experiments have been carried out in the geometry under study, covering the representative ranges of the mentioned variables. The results provide a deeper knowledge of the flow, allowing for a better understanding of the flow structures, as well as of the consequences they can have on linear pressure drop and heat transfer and on their study. Furthermore, the possibility of applying a suitable generalization method for the viscosity in this device has been analysed.

Adiabatic cooling pads are mostly used as a previous step for cooling systems, they cause the raise of the cooling system global efficiency. In this study, several types of pads have been analysed regarding on its compactness and thickness. The problem is addressed from an experimental, analytical and numerical point of view.vThe validation of the temperature drop and cooling efficiency of the cooling pad numerical model is the main objective of this paper, and, in order to get this goal, Discrete Phase Model (DPM) of ANSYS Fluent software is used to calculate how water droplets, injected over the pad to cool the air, evaporate and how the continuous phase affect them. The results of this paper, focused to be a part of a complete cooling system analysis carried out by the research group, show the performance of an adiabatic cooling pad varying its width and compactness. The authors acknowledge the financial support received from the Spanish Government, through Projects ENE2013-48696-C2-1-R and C2-2-R as well as by the FEDER (Fondo Europeo de Desarrollo Regional).

Water droplets emitted from cooling towers must be prevented for several reasons, human health hazards are the most important ones. The generation and control of these droplets are the main tasks for drift eliminators: devices installed inside mechanical draft cooling towers useful to prevent water droplets, originated by the crossflow between air and water inside the tower, from being released into the environment. This is the phenomenon called ‘drift’. In this paper, the operating conditions of a type of drift eliminator placed in a cooling tower are studied. This work is focused on the numerical and experimental characterization of the multiphase flow taking place when water droplets, drifted by the airstream, impact on the water film formed over the drift eliminators plates. The problem of these drop impacts has been studied throughout an experimental installation and a numerical model has been developed throughout the ANSYS software and several VOF multiphase flow simulations have been carried out showing a good agreement with experimental data.

En este documento se aborda el caso específico de las mujeres privadas de libertad, sin olvidar la posible extensión de las medidas alternativas a otros grupos que se hallan en una situación de vulnerabilidad. En el texto se fundamenta primero la necesidad de integrar la perspectiva de género en la creación de sistemas de control y ejecución de penas y medidas alternativas a la privación de libertad en la prisión. A continuación, se analiza cómo esta integración y una buena ejecución de las medidas puede favorecer los procesos de inserción y abandono del delito de estas mujeres. Seguidamente, se revisan las mejores prácticas de medidas alternativas que se están llevando a cabo en América Latina, El Caribe y la Unión Europea, considerando con más detenimiento las que mejor se adaptan a las necesidades de este grupo de mujeres. Y, por último, se concluye con unas mínimas recomendaciones para su implantación considerando la perspectiva de género.

The vacuum infusion is a process usually applied to manufacture large structures of composite materials, such as wind turbine blades. The specific stiffness and weight ratio required by these structures can be achieved by manufacturing sandwich composites. The forecast by numerical simulation of the resin infusion flow is an indispensable tool to design and optimize the manufacturing process of composite. Present work analyzes by numerical simulation the mold filling process of a sandwich composites, performed by fiberglass plies with different fiber orientations and a perforated core. The flow through a single perforation of the core is analyzed and the influence of the permeability values of fiberglass on the volume flow through core perforations is determined. In order to reduce the computing costs, a transfer function to simulate the flow through the perforations is developed and integrated in the numerical code by computational subroutines. A 3D numerical modeling of a sandwich composite, in which the flow through the core perforations is simulated via computational subroutines, is carried out and experimentally validated. The research work presented in this paper has been carried out under the project "Automation of the global manufacturing process for wind turbine blades (AQ–BLADE)" IDI‐20110154, financially supported by Centro para el Desarrollo Tecnológico Industrial (CDTI) from the Spanish Government.

This work presents and experimental study of the generalization method of the Reynolds number and the viscosity of pseudoplastic fluid flow in ducts of non-uniform cross-section. This method will permit to reduce 1 degree of freedom of hydrodynamical and thermal problems in those ducts. A review of the state of the art has been undertaken and the generalization equation proposed for ducts of uniform cross section has been used as a starting point. The results obtained with this equation have not been found satisfactory and a new one has been proposed. Specifically, the procedure has been developed for two models of scraped surface heat exchanger with reciprocating scrapers. For both models, the scraper consists of a concentric rod inserted in each tube of the heat ex- changer, mounting an array of plugs that fit the inner tube wall. The two models studied differ in the design of the plug. The procedure to perform the generalization method out of experimental data is accurately detailed in the present document. The first author thanks Mr. Martínez and Dr. Solano for their invaluable contribution to the project and their advise. He also thanks the Spanish Government, Ministry of Education for the FPU scholarship referenced as AP2007-03429 which covered the expenses of a 4-year research at Universidad Politécnica de Cartagena.

Due to the aeration system, biological reactors are the most energy-consuming facilities of convectional WWTPs. Many biological reactors work under intermittent aeration regime; the optimization of the aeration process (air diffuser layout, air flow rate per diffuser, aeration length …) is necessary to ensure an efficient performance; satisfying the effluent requirements with the minimum energy consumption. This work develops a CFD modelling of an activated sludge reactor (ASR) which works under intermittent aeration regime. The model considers the fluid dynamic and biological processes within the ASR. The biological simulation, which is transient, takes into account the intermittent aeration regime. The CFD modelling is employed for the selection of the aeration system of an ASR. Two different aeration configurations are simulated. The model evaluates the aeration power consumption necessary to satisfy the effluent requirements. An improvement of 2.8% in terms of energy consumption is achieved by modifying the air diffuser layout. An analysis of the influence of the air flow rate per diffuser on the ASR performance is carried out. The results show a reduction of 14.5% in the energy consumption of the aeration system when the air flow rate per diffuser is reduced. The model provides an insight into the aeration inefficiencies produced within ASRs.

The flow pattern inside a scraped surface plate heat exchanger used for ice slurry production is studied both experimentally and numerically. Isothermal planar velocity fields are reported in the range 2.2 · 104⩽Rerot⩽1.7 · 105 using a phase averaged PIV technique. Unsteady RANS modelling of the flow, using the rotating frame methodology is used to obtain a time-averaged description of the flow structure, which was successfully validated against the PIV data. The flow structure is characterized by the presence of a roll-up vortex generated by the scraper blade, which is the main factor for both the radial and vertical displacements of the flow. Increasing the Re rot number leads to a more uniform flow, reducing the presence of stagnant zones. However, the main pattern structure does not change significantly when increasing the scraping velocity.

The flow pattern within an enhanced tubular heat exchanger equipped with a reciprocating scraping device is experimentally analysed. The insert device, specially designed to avoid fouling and to enhance heat transfer, has also been used to produce ice slurry. It consists of several circular perforated scraping discs mounted on a coaxial shaft. The whole is moved alternatively along the axial direction by a hydraulic cylinder. The phase-averaged velocity fields of the turbulent flow have been obtained with PIV technique for both scraping semi-cycles. Special attention has been paid to the effect of the non-dimensional scraping velocity and the Reynolds number in the flow field. CFD simulations provide support for the identification of the flow patterns and the parameter assessment extension. The results show how the scraping parameters affect the turbulence level produced in the flow and therefore the desired heat transfer enhancement.

Background: Levels of bone turnover markers (BTM) might be correlated with outcome in terms of skeletal-related events (SRE), disease progression, and death in patients with bladder cancer (BC) and renal cell carcinoma (RCC) with bone metastases (BM). We try to evaluate this possible correlation in patients who receive treatment with zoledronic acid (ZOL). Methods: This observational, prospective, and multicenter study analysed BTM and clinical outcome in these patients. Serum levels of bone alkaline phosphatase (BALP), procollagen type I amino-terminal propeptide (PINP), and beta-isomer of carboxyterminal telopeptide of type I collagen (beta-CTX) were analysed. Results: Patients with RCC who died or progressed had higher baseline beta-CTX levels and those who experienced SRE during follow-up showed high baseline BALP levels. In BC, a poor rate of survival was related with high baseline beta-CTX and BALP levels, and new SRE with increased PINP levels. Cox univariate analysis showed that beta-CTX levels were associated with higher mortality and disease progression in RCC and higher mortality in BC. Bone alkaline phosphatase was associated with increased risk of premature SRE appearance in RCC and death in BC. Conclusion: Beta-isomer of carboxy-terminal telopeptide of type I collagen and BALP can be considered a complementary tool for prediction of clinical outcomes in patients with BC and RCC with BM treated with ZOL., As this was a multicenter study, Adknoma Health Research (Barcelona, Spain) collected and ordered data throughout the study. We especially thank Margarida Garcia from Adknoma who followed carefully the development of the study. And we thank Novartis Oncology Spain for supporting this study.

Cooling towers are evaporative heat transfer devices in which atmospheric air cools warm water, with direct contact between the water and the air by evaporating part of the water. The principle of operation of cooling towers requires spraying or distributing water over a heat transfer surface (packing) across or through which a stream of air is passing. As a result, water droplets are incorporated in the air stream and,depending on the velocity of the air, will be taken away from the unit. This is known as drift. Although cooling tower drift is objectionable for several reasons, the most hazardous problem concerning human health is the emission of chemicals or microorganisms into the atmosphere. Undoubtedly, regarding microorganisms, the most well-known pathogens are the multiple species of bacteria collectively known as legionella. The binomial water distribution system-drift eliminator is identified to be that mainly responsible for cooling tower drift. While water distribution systems affect the mechanics of setting up the drops, drift eliminators work by changing the direction of the airflow and separating droplets from the airstream through inertial impact. The drift eliminator’s performance can be quantified mainly by two factors: droplet collection efficiency and the pressure drop across the eliminator. In contrast, water distribution systems are characterized by the pressure drop across itself and the achieved size of the particle spread. Alongside drift, the binomial water distribution system-drift eliminator affects the cooling tower performance. From the reviewed bibliography, some studies assessing the effect of the drift eliminator on cooling tower performance have been found. Nevertheless, no studies regarding the influence of the water distribution system on the cooling tower’s performance have been detected. In this sense, this paper studies the thermal performance of a forced draft counter-flow wet cooling tower fitted with two water distribution systems (the pressure water distribution system (PWDS) and gravity water distribution system (GWDS)) for six drift eliminators for a wide range of air and water mass flow rates. The data registered in the experimental set-up were employed to obtain correlations of the tower characteristic, which defines the cooling tower’s thermal performance. The outlet water temperature predicted by these correlations was compared with the experimentally registered values, obtaining a maximum averaged difference of ±0.95%. The authors wish to acknowledge the collaboration of the Ministerio de Educación y Ciencia (Spanish Education and Science Ministry) for their support of project PN I+D+I 2008-2011 ENE2010-21679-C02- 02.

The existence of cooling towers arises from the need to evacuate power to the environment from engines, refrigeration equipment and industrial processes. Water drift emitted from cooling towers is objectionable for several reasons, mainly due to human health hazards. It is common practice to fit drift eliminators to cooling towers in order to minimise water loss from the system. The presence of the drift eliminator mainly affects two aspects of cooling towers: their thermal performance and the amount of water drift loss. This paper experimentally studies the drift loss emissions from a cooling tower without drift eliminator and fitted with six different drift eliminators. Chemical Balance is the selected method and Australian Standard methodology is taken as a reference. Some modifications are proposed to reduce uncertainty by increasing the duration of the test and the number of water samples. Installation of a drift eliminator, even in the worst case, reduces the water drift level to less than half of the situation without the eliminator. The water drift losses obtained with the different drift eliminators installed at the pilot plant, from 0.0118% to 0.161%, are within the range generally reflected in the literature. Finally, a criterion for designing drift eliminators in order to optimise both the collection efficiency and the cooling tower's thermal performance is proposed. This research has been partially financed by the project DPI2007-66551-C02-01 grant from the “Dirección General de Industria, M. de Ciencia y Tecnología”, the project 2I05SU0029 grant of the “Secretaría General de la Consejerí de Educación y Cultura de la C.A. de la Región de Murcia” and the HRS Spiratube Company, Murcia (Spain).

Resumen Introduccion La medida de la concentracion de las cadenas ligeras libres de inmunoglobulinas en suero proporciona informacion clinicamente relevante en el diagnostico, pronostico y monitorizacion de pacientes con mieloma multiple (MM) y con gammapatias monoclonales de significado incierto (GMSI). En este trabajo se ha calculado el valor predictivo negativo (VPN) del cociente kappa/lambda libres (κ/λ) en un suero incluido dentro del rango diagnostico (0,26-1,65), ademas de establecer unos nuevos valores discriminantes con un VPN del 100% en el grupo de pacientes estudiado. Material y metodos La medida de la concentracion de cadenas ligeras libres en suero se realizo por nefelometria en 157 muestras de pacientes diagnosticados de MM o GMSI y se calculo el cociente κ/λ libres. Resultados El area bajo la curva de rendimiento diagnostico para el cociente κ/λ libres fue de 0,885 en los pacientes con gammapatias con isotipo kappa y 0,879 en pacientes con gammapatias con isotipo lambda. El VPN para un cociente κ/λ libres entre 0,26 y 1,65 fue del 92%. Utilizando un intervalo de 0,36-1,0 se alcanzo un VPN del 100%. Conclusiones La modificacion del rango diagnostico de 0,26-1,65 del cociente κ/λ libres por el comprendido entre 0,36 y 1,0, podria ser util para obviar la realizacion de un aspirado de medula osea en pacientes con criterios clinicos y analiticos de GMSI.

This work analyzes the thermal–hydraulic behaviour of three types of enhancement technique based on artificial roughness: corrugated tubes, dimpled tubes and wire coils. The comparison has been performed from the three best specimens selected among the wide range of geometries investigated by the authors in previous works. Heat transfer and pressure drop experimental data in laminar, transition and turbulent regimes are used in this investigation. Results show that the shape of the artificial roughness exerts a greater influence on the pressure drop characteristics than on the heat transfer augmentation. Likewise, this shape strongly affects the advance of the transition to turbulence and its characteristics: smooth or sudden. The study concludes that for Reynolds numbers lower than 200, the use of smooth tubes is recommended. For Reynolds numbers between 200 and 2000, the employment of wire coils is more advantageous, while for Reynolds numbers higher than 2000, the use of corrugated and dimpled tubes is favoured over the wire coils because of the lower pressure drop encountered for similar heat transfer coefficient levels.

Flow pattern and thermal-hydraulic characteristics in an innovative tube insert have been experimentally and numerically investigated. The insert device is a concept envisioned for reciprocating scraped surface heat exchangers. It consists of a concentric rod, that mounts an array of semicircular plugs fitted to the inner tube wall. In motionless conditions, the insert works as a turbulence promoter, enhancing heat transfer in laminar regime. Fundamental flow features in the symmetry plane of the tube have been assessed with Particle Image Velocimetry technique. A general model of the flow mechanism has been defined, identifying three regions along a geometrical pitch: recirculation bubbles, flow acceleration and transverse vortex. Results have been complemented with experimental data on pressure drop and heat transfer. The transition onset is clearly identified, and the mechanisms that promote turbulence at low Reynolds number are investigated and discussed. CFD simulations for different Reynolds numbers provide a further insight into the relation of the flow structures with wall shear stress, and their role on the local heat transfer augmentation.

Resumen La medicion del filtrado glomerular es el mejor indice de valoracion de la funcion renal. La creatinina serica es el marcador de filtrado glomerular mas utilizado, a pesar de estar sometido a diferentes fuentes de variabilidad. La cistatina C es una proteina de bajo peso molecular propuesta como marcador de funcion renal mas sensible que la creatinina al detectar de forma precoz alteraciones en la funcion renal. La medida de cistatina C en suero en determinados grupos de pacientes como ancianos, ninos o diabeticos parece aportar mayor informacion que la creatinina. Sin embargo, presenta alteraciones en su concentracion serica por factores diferentes al filtrado glomerular. Actualmente no hay evidencia cientifica suficiente que justifique el cambio de las ecuaciones de estimacion del filtrado glomerular basadas en la concentracion serica de creatinina por la medida de la concentracion serica de cistatina C en la evaluacion de la funcion renal.

A new coefficient to characterize the global behaviour of adiabatic compressible flow at T-junctions is proposed. The new coefficient is defined according to the conclusions derived from the uncertainty propagation analysis of the total pressure loss coefficient defined by Miller for compressible flow. The numerical results obtained using the new linking between branches coefficient definition, K ∧ , show a logarithmic relationship with mass flow rate ratio between branches, q, and the extrapolated Mach number in the common branch, M 3 ∗ , for all flow types studied in a 90° T-junction. Reliable and practical two parameters or global correlations, K ∧ = K ∧ ( M 3 ∗ , q ) , have been obtained. These correlations can be easily implemented as boundary conditions into 1D global simulation codes.

This paper provides with a set of full-scale experimental data of atrium fires. These data could be used as benchmarks for future numerical validation studies. In particular, the influence of the make-up air velocity as well as the position and area of the vents in an atrium is assessed both experimentally and numerically. Experimentally, the effect of different make-up air supply positions and inlet area on the fire-induced inner conditions and smoke layer descent was studied by means of three full-scale fire tests conducted in a 20 m cubic atrium. Detailed transient measurements of gas and wall temperatures, as well as pressure drop through the exhaust fans and airflow at the inlets were recorded. Later computational fluid dynamics (CFD) simulations of these tests were performed with the code Fire Dynamics Simulator (FDS). Experimentally, the lack of symmetry in make-up air vents and the large inlet area turn the flame and plume into more sensitive to outer effects. However, no significant difference has been observed between the make-up air topologies assessed. Even make-up velocities higher than 1 m/s, with symmetric venting topology, have not induced important flame or plume perturbations. Numerically, the simulations agree well with the experiments for the cases with make-up air velocities lower than 1 m/s. Poor agreement has been found for the case with inlet velocities higher than 1 m/s.

Water drift emitted from cooling towers is objectionable for several reasons, mainly due to human health reasons. A numerical model to study the influence of sychrometric ambient conditions on cooling tower drift deposition was developed. The mathematical model presented, consisting of two coupled sets of conservation equations for the continuous and discrete phases, was incorporated in the general purpose CFD code Fluent. Both experimental plume performance and drift deposition were employed to validate the numerical results. This study shows the influence of variables like ambient dry bulb temperature, ambient absolute humidity and droplet exit temperature from cooling tower on the drift evaporation (and therefore deposition) and on the zone affected by the cooling tower. The stronger effect detected corresponds to the ambient dry bulb temperature. When a higher ambient temperature was present, deposition was lower (evaporation was therefore higher) and the zone affected by the cooling tower was smaller. The influence of the other two variables included in the study was weaker than the one corresponding to the dry bulb ambient temperature. A high level of ambient absolute humidity increased drift deposition and also the size of the zone affected by the cooling tower. Finally, a high level of droplet exit temperature decreased deposition and increased the zone affected by the cooling tower.

This paper investigates the correlation between the frequency components of the wind speed Power Spectral Density. The results extend an already existing power fluctuation model that can simulate power fluctuations of wind power on areas up to several kilometers and for time scales up to a couple of hours, taking into account the spectral correlation between different wind turbines. The modelling is supported by measurements from two large wind farms, namely Nysted and Horns Rev. Measurements from individual wind turbines and meteorological masts are used. Finally, the models are integrated into an aggregated model which is used for estimating some electrical parameters as power ramps and reserves requirements, showing a quite good agreement between simulations and measurement. The comparison with measurements generally show that the inclusion of the correlation between low frequency components is an improvement, but the effect is relatively small. The effect of including the low frequency components in the model is much more significant. Therefore, that aggregated model is useful in the power system planning and operation, e.g. regarding load following and regulation. Copyright © 2009 John Wiley & Sons, Ltd.

A commercial fan coil has been experimentally studied in this work in order to assess its behaviour when ice slurry is used as secondary refrigerant. Experimentally obtained results have been compared to theoretical prediction obtained using the correlations proposed in previous papers in order to verify them. Several reasons have been reported to explain the deviation of fan coil behaviour from that expected and which make the direct application of ice slurry inappropriate in the fan coil studied. In order to avoid those problems and to establish a comparison between two secondary refrigerants with similar cold storage capacity, ice slurry direct application has been compared to ice slurry indirect application – only carrier fluid, without ice particles, flowing through the fan coil. The most remarkable conclusion obtained is that indirect application improves the behaviour of the fan coil studied for all the cases analysed, overcoming the problems reported for direct application.

Research paper published in the peer-reviewed journal Building and Environment. Atria and large spaces are common architectonical features in modern buildings such as high rises, auditoria, warehouses, airports and mass transport stations among others. There is currently an international trend towards the performance-based design for fire safety of these building elements. This design process relies heavily on fire modelling but the knowledge in fire dynamics and the movement of smoke in atria and large spaces still presents some gaps. This paper aims at contributing to close these gaps and reports the three Murcia Atrium Fire Tests conducted in a 20 m cubic enclosure using pools of 1.3 and 2.3 MW. Detailed transient measurements of gas and wall temperatures, as well as pressure drop through the exhaust fans and airflow at the inlets were recorded. The study also includes the effect of the mechanical exhaust ventilation. Results have been compared with those predicted by the computational fluid dynamics (CFD) model Fire Dynamics Simulator FDSv4. In general terms, the comparisons between experiments and simulations show good agreement, especially in the far field of the plume, but the accuracy is poor at the lower plume region and near the flame.

Ice slurry performance in a concentric corrugated tube heat exchanger is experimentally studied in this work in order to compare experimental results to theoretical prediction obtained using the correlations proposed in previous papers. Once the validity of those correlations is verified, the behaviour of the studied heat exchanger is analyzed for different ice slurry flow conditions and compared to the results obtained when a heterogeneous storage is used and only carrier fluid flows through the heat exchanger. According to the performance evaluation criterion used – variation in heat transfer rate for equal pressure drop and surface area – the most remarkable conclusion obtained is that slurry improves the behaviour of the heat exchanger studied for all the cases analyzed, although the increase in heat transfer rate is always lower than 15%, being in most cases lower than 5%.

The rheological behaviour of the ice slurry made from 9% NaCl brine has been experimentally studied in this work. Starting from the dimensional analysis of pressure drop and heat transfer processes, the minimum numbers of non-dimensional parameters present in these processes have been determined. Rheological behaviour has been adjusted to the experimental data on ice slurry pressure drop. Two different behaviours were observed depending on the shear rate values, with a clear yield stress recognizable in the low shear rate region and a shear thickening behaviour for high shear rate values. A modified Herschel–Bulkley rheological model has been proposed, which is able to predict ice slurry behaviour in both, low and high shear rate region. The influence of the parameters involved has been determined and an analytical equation for the Darcy friction factor has been obtained from the model proposed and compared to experimental results. The comparison showed a very good agreement between these data.

Ice slurry flow through horizontal pipes is studied experimentally in order to find out its heat transfer and isothermal friction properties. Using 9% NaCl brine as the carrier fluid, different flow conditions are discussed with a view to analyse each involved variable. In this Part I, experimental data are directly correlated and easy-to-use expressions for the Darcy friction factor and the Nusselt number were obtained as functions of non-dimensional parameters expressing flow and geometrical properties. The most remarkable conclusion obtained is a clear influence of the ice particle–pipe diameter ratio in the pressure drop parameters, not previously taken into account, which must be confirmed in heat transfer process. The thermal and hydraulic performance of ice slurry flowing through corrugated pipes is also analysed showing, with regard to smooth pipe, the same behaviour in pressure drop and opposite behaviour in heat transfer.

Cooling towers are equipment devices commonly used to dissipate heat from power generation units, water-cooled refrigeration, air conditioning and industrial processes. Water drift emitted from cooling towers is objectionable for several reasons, mainly due to human health hazards. It is common practice to fit drift eliminators to cooling towers in order to minimize water loss from the system. It is foreseeable that the characteristics of the installed drift eliminators, like their pressure drop, affect the thermal performance of the cooling tower. However, no references regarding this fact have been found in the reviewed bibliography. This paper studies the thermal performance of a forced draft counter-flow wet cooling tower fitted with different drift eliminators for a wide range of air and water mass flow rates. The data registered in the experimental set-up were employed to obtain correlations of the tower characteristic, which defines the cooling tower’s thermal performance. The outlet water temperature predicted by these correlations was compared with the experimentally registered values obtaining a maximum difference of ±3%.

New experimental correlations to characterize energy losses in adiabatic compressible flow at 90-degree T-junctions and their expanded uncertainties are presented. These new correlations are based on a new linking between branches coefficient definition, K ˆ , and show a logarithmic relationship with mass flow rate ratio between branches, q, and the extrapolated Mach number in the common branch, M 3 ∗ , for all the different flow types studied. The extrapolated properties up to the junction are calculated, from measurement sections, subtracting the frictional losses using the Fanno fluid flow model. These two parameters or global correlations, K ˆ = K ˆ ( M 3 ∗ , q ) , can be easily implemented as boundary conditions into 1-D global simulation codes.