An Experimental and Numerical Approach to Multifunctional Urban Surfaces through Blue Roofs

Uncontrolled urban growth causes a number of problems associated with land use, stormwater management and energy generation. Sustainable Urban Drainage Systems (SUDS) are positioned as an alternative to traditional constructive solutions, contributing towards the generation of multifunctional urban spaces for efficient stormwater management and energy consumption reduction. Nevertheless, this combined goal calls for a deeper understanding of the heat transfer processes that govern the temperature performance in SUDS in order to be further validated as infrastructure to house renewable energy elements. This study intends to determine the thermal properties of two types of blue roofs under extreme conditions of performance (wet and dry), depicting the operation features of their layers and comparing their performances based on the materials used. With this aim, a hybrid experimental methodology, combining laboratory and numerical modelling, was designed using standardized equipment (ISO 8990:1994 and ASTM C1363-05), improving previous methods proposed in the study of the thermal properties of SUDS. The section with expanded clay improved the hydraulic capacity by 4.8%. The section without expanded clay increased its thermal transmittance value by 64.9% under wet conditions. It was also found that the presence of water increased the equivalent thermal conductivity in both sections by 60%

Fast Quality Control of Natural Gas for Commercial Supply and Transport Utilities

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Quality control of natural gas frequently relies on off-line slow standardized chromatographic techniques. Previous implementations of new measurement approaches focused of synthetic mixtures without extensive industrial validation. Here, a fast alternative based on infrared spectra is presented to predict the gas constituents and a physical parameter, the Wobbe index. Commercial samples instead of synthetic mixtures were used to develop predictive models. Method performance parameters were calculated and ca. 100 % of the sample-specific confidence intervals for the predictions overlapped with those of the reference values and the approach was unbiased and precise. The limits of detection and quantification (classical and considering errors of type I and II) outperformed other approaches. Validation included commercial samples and primary mixtures. Furthermore, prediction models considering reduced sets of variables were sought for using Markov-chain Monte Carlo guided searches (uninformative variable elimination and random frog) and common (iPLS, UVE and SR) approaches. The prediction errors and limits of detection of these ‘reduced’ models outperformed those from other approaches. The methodology takes only minutes to analyse a sample, requires few sample and no reagents (only some argon), making this approach cost-effective and environmentally-friendly.Xunta de Galicia; ED431C-2017/2

Descriptive Analysis of the Performance of a Vegetated Swale through Long-Term Hydrological Monitoring: A Case Study from Coventry, UK

Vegetated swales are a popular sustainable drainage system (SuDS) used in a wide range of environments from urban areas and transport infrastructure, to rural environments, sub-urban and natural catchments. Despite the fact that vegetated swales, also known as grassed swales, have received scientific attention over recent years, especially from a hydrological perspective, there is a need for further research in the field, with long-term monitoring. In addition, vegetated swales introduce further difficulties, such as the biological growth occurring in their surface layer, as well as the biological evolution taking place in them. New developments, such as the implementation of thermal devices within the cross-section of green SuDS for energy saving purposes, require a better understanding of the long-term performance of the surface temperature of swales. This research aims to contribute to a better understanding of these knowledge gaps through a descriptive analysis of a vegetated swale in Ryton, Coventry, UK, under a Cfb Köppen climatic classification and a mixed rural and peri-urban scenario. Precipitation and temperature patterns associated with seasonality effects were identified. Furthermore, a level of biological evolution was described due to the lack of periodical and planned maintenance activities, reporting the presence of both plant species and pollinators. Only one event of flooding was identified during the three hydrological years monitored in this research study, showing a robust performance

Development of a Multicriteria Scheme for the Identification of Strategic Areas for SUDS Implementation:A Case Study from Gijón, Spain

Spain has been pinpointed as one of the European countries at major risk of extreme urban events. Thus, Spanish cities pursue new urban plans to increase their resilience. In this scenario, experiences in the implementation of Sustainable Urban Drainage Systems (SUDS) have increased substantially. Nevertheless, few cities have developed a global urban strategy for SUDS, lacking, in many cases, a method to identify strategic areas to maximize their synergetic benefits. Furthermore, there is still a need for a holistic Multicriteria Decision Analysis (MCDA) framework that considers the four pillars of SUDS design. The city of Gijón, NW Spain, has been selected as a case study due to its environmental and climatic stresses. This research presents the methodology developed for this city, which aims to analyze the need for SUDS implementation throughout the identification of strategic areas. With this aim, a combination of Geographic Information System (GIS) software and the MCDA Analytical Hierarchical Process (AHP) were proposed. The results show the potential for SUDS’ implementation, according to nine criteria related to the SUDS’ design pillars. We found that the areas where the implementation of SUDS would bring the greatest functional, environmental and social benefits are mainly located in consolidated urban areas

Evaluating the thermal performance of Wet Swales housing Ground Source Heat Pump elements through laboratory modelling

The authors wish to acknowledge the CAWR, Coventry University, for the administrative support; and the GITECO Research Group, University of Cantabria, for housing the laboratory experiments.Land-use change due to rapid urbanization poses a threat to urban environments, which are in need of multifunctional green solutions to face complex future socio-ecological and climate scenarios. Urban regeneration strategies, bringing green infrastructure, are currently using sustainable urban drainage systems to exploit the provision of ecosystem services and their wider benefits. The link between food, energy and water depicts a technological knowledge gap, represented by previous attempts to investigate the combination between ground source heat pump and permeable pavement systems. This research aims to transfer these concepts into greener sustainable urban drainage systems like wet swales. A 1:2 scaled laboratory models were built and analysed under a range of ground source heat pump temperatures (20–50 ºC). Behavioral models of vertical and inlet/outlet temperature difference within the system were developed, achieving high R2, representing the first attempt to describe the thermal performance of wet swales in literature when designed alongside ground source heat pump elements. Statistical analyses showed the impact of ambient temperature and the heating source at different scales in all layers, as well as, the resilience to heating processes, recovering their initial thermal state within 16 h after the heating stage

Modeling the natural gas knocking behaviour using gas-phase infrared spectra and multivariate calibration

[Abstract] To assess the knocking properties of natural gas (NG) when it is used as fuel for vehicles is vital to optimize the design and functioning of their motors. Analytical efforts in this field are needed as the engines used to define it empirically are not available anymore, and existent mathematical algorithms yield different accuracy. The hybridization of gas-phase infrared spectrometry and partial least squares multivariate regression is presented first time to address the determination of the methane number (MN) of NG samples. It circumvents the need for the previous knowledge of the NG composition required to apply dedicated equations. The use of true NG samples to develop the models is also quite new in the field. Proof-of-concept studies were made with synthetic spectra and, then, a collection of liquefied NG samples for which MN values were computed by the National Physics Laboratory algorithm (NPL) from their sample composition were used to develop operative models. Additional validation was made with a collection of synthetic standard mixtures prepared for two European projects (EMRP LNG II and EMPIR LNG III) whose service methane numbers (SMN) were measured with an engine. The FTIR-PLS approach yielded statistically unbiased predictions with average standard errors around 0.4% MN when compared to the NPL-MN and SMN values, and standard deviations of the means ca. 1% MN. The approach is fast, cost effective as it involves standard instrumentation, and can be considered compliant with the green chemistry principles.This work is part of the EMPIR 16ENG09 project ‘Metrological support for LNG and LBG as transport fuel (LNG III)’. This project has received funding from the EMPIR programme co-financed by the Participant States and from the European Union's Horizon 2020 Research and Innovation programme. The authors from TU Braunschweig would like to thank IAV, Mahle, MAN Truck & Bus and Motortech for their support in preparing the test engine. The Group of Applied Analytical Chemistry of the University of A Coruña acknowledges Mestrelab, Reganosa and Naturgy for hiring its services for FTIR method developmentFinanciado para publicación en acceso aberto: Universidade da Coruña/CISU

Thermal Performance of Wet Swales Designed as Multifunctional Green Infrastructure Systems for Water Management and Energy Saving

Lack of city space and conventional drainage systems failures have derived in the need to implement Green Stormwater Infrastructure (GSI) techniques which provide multifunctional areas capable of managing stormwater, treating the pollutants present in the runoff, bringing back biodiversity to the urban environment, and providing amenity whilst improving livability. In this context, swales were studied as a potential multifunctional GSI for water management and energy saving. This research successfully proposed the combination of a wet swale with a Ground Source Heat Pump (GSHP) system. The materials used within the cross section of a standard wet swale provided good isolation properties within the temperature performance ranges (20–50 °C), showing great potential for a swale to be developed together with GSHP elements, opening a new research area for water management and energy saving