Design Factors and Functionality Matching in Sustainability Products:A study of eco-showerheads

The Demystifying the Shower Experience research project is a comprehensive multi-stage study aimed at understanding the multi-dimensional aspects of the shower, including; showering products, habits, behaviour and perceptions. The objective was to determine: if a functionality mismatch occurs between the design and desired functionality of the product, and what specific factors contribute to this mismatch. To achieve the aim, simple heuristic trials packaged as a 12 showerheads in 12 weeks Challenge were conducted involving 12 participants - 6 male and 6 female. It was found that showerhead design factors such as colour, shape and size are inconclusive in determining the water efficient use, and perception of a positive shower experience. However, factors such as the number of function inform user choice and preference of which showerhead to choose and use. Further, sprout type and mode of operation both influence user perception of the performance factors such as feel, pleasantness, enjoyability, time taken and effectiveness of clean. And these factors in turn significantly affect the user perception of what constitutes a ‘good' shower experience. It was also found that a functionality mismatch does occur in sustainability products if performance, and not design factors, fail to meet with user expectations. This work is novel because few, if any, studies of this nature have specifically been undertaken outside of the laboratory environment, and significant because the findings highlight the importance and influence of the physical design and performance-informing features on the user perception of the product itself. And for showerheads, this affects the satisfaction with the resulting showering experience and, therefore the propensity to use less water in the shower for an effective clean

Free Convective Heat Transfer in a Closed Gap between Concentric Semi-Hemispheres

Free convective heat transfer in the closed gap between concentric semi-hemispheres is quantified by means of a numerical approach based on the volume control method using the SIMPLE algorithm. The average Nusselt number is determined for several configurations obtained by varying the cavity’s aspect ratio between 0.15 and 1.5, while the Rayleigh number varies within the 5.33 × 103–4.50 × 108 range. The results show that the correlations available in the literature dealing with concentric whole spheres cannot be used for the configuration treated here. The new correlation between the Nusselt and Rayleigh numbers proposed in this work can be applied in various engineering sectors, such as in the electronic packaging considered in this present work, buildings, and architecture

Improving Energy Performance of Historic Buildings through Hygrothermal Assessment of the Envelope

The intervention on historic buildings through building energy retrofitting has become one of the current challenges of improving energy efficiency. Nonetheless, this building typology presents certain complexities. Among them, one of the most relevant is the protection on their façades due to the historical and/or artistic values of a given façade and, therefore, the addition of external thermal insulation is restricted. However, at the same time, in several of those buildings indoor surfaces do not present that architectural value, and then internal thermal insulation becomes a promising strategy for improving their thermal performance. Nevertheless, its application must be carefully evaluated to avoid possible pathologies caused by moisture problems. This paper aims to identify constructive solutions for interior insulation of walls free from moisture problems. For this purpose, a comprehensive analysis of a series of constructive solutions based on internal insulation has been carried out through hygrothermal simulations. The results show how the application of water-repellent impregnation becomes essential to guaranteeing the integrity of the envelope. In addition, the combination of insulations with or without inner membranes, such as smart vapor retarders or vapor diffusion barriers, has been evaluated detecting the solutions that best fit the objective. Finally, taking advantage of the great potential of 2D simulation tools, the post-processing of the data has been performed to apply the wood decay model, and thus assess the behavior of a very conflictive point in this type of intervention, i.e., the wooden beam-ends. The results in this critical point have shown how the application of the proposed constructive solutions becomes essential to guarantee the integrity of the element and how the application of traditional solutions could lead to a hazard that must be avoided.This research was funded by Hezkuntza, Hizkuntza Politika Eta Kultura Saila, Eusko Jaurlaritza (PRE_2016_2_0178)

Airtightness Analysis of the Built Heritage–Field Measurements of Nineteenth Century Buildings through Blower Door Tests

Airtightness is a major issue in architectural design and it has a significant impact on the energy performance of buildings. Moreover, the energy behaviour of built heritage is due, to its singular characteristics, still a great unknown. The aim of this study is to establish a better knowledge of the airtightness of historical buildings, based on an in depth field study using blower-door tests. A set of 37 enclosures were analyzed inside eight buildings located in historical areas of a Spanish city with a significant built heritage. They were constructed between 1882 and 1919 and include diverse construction typologies applied for many building uses such as residential, cultural, educational, administrative and emblematic. The results indicate lower values compared to other previous airtightness studies of historical buildings. The average air change rate was found to be n50 = 9.03 h−1 and the airtightness of the enclosures presented a wide range of between 0.68 and 37.12 h−1. Three main levels of airtightness were identified with two thirds of the tested samples belonging to the intermediate level between 3–20 h−1. To conclude, several correlations have been developed which provide a method to estimate air leakage and could serve as a basis for energy performance studies of these kinds of building.This work has been funded through the Researcher Training Program of the Department of Education, Language Policy and Culture of the Basque Government (Spain) with the PhD fellowship PRE_2016_2_0178

Aerodynamics in the open channel of the Sistan-type wind-mill with vertical axis wind turbine

International Journal of Numerical Methods for Heat and Fluid FlowThe purpose of this paper is to examine the details of the air mass flow and aerodynamical phenoména across a channel containing a large vertical axis wind turbine. The considered model reproduces as closely as possible the real assembly of the Sistan-type wind-mill whose top is open. The technical results of this work could be used for the restoration and operation of this assembly whose historical and architectural values are recognized.L'objectif de cet article est d’examiner les détails d'un écoulement dans un canal contenant une turbine à axe vertical. Les résultats techniques de ce travail pourront être utilisés pour la restauration et la mise en service de ce dispositif dont la valeur historique et architecturale est reconnue

Temperature Determination of Tilted Electronic Assemblies Equipped with Basic and Wire-Bonded QFN16 and 32 Devices Subjected to Free Convection

International audienceThe correlations proposed in this work allow to calculate the average temperature on different areas of electronic assemblies containing basic QFN16 and QFN32 packages and their wire-bonded versions named QFN16b and QFN32b respectively. The study is based on correlations proposed in recent works allowing calculation of the average natural convective heat transfer coefficient according to the power generated by the package and the tilt angle of the printed circuit board (PCB) on which they are welded. The considered generated power is within the range 0.1–1 W for the QFN16 and 16b models. For the QFN32 and QFN32b, the correlations are extended to lower power ranging from 0 (off) to 0.1 W. These power ranges are associated to an inclination angle of the PCB varying between 0° and 90° (horizontal and vertical positions respectively) corresponding to the operative conditions of these devices increasingly used in electronics. Temperature determination of every part of these assemblies through the proposed correlations easy to use, helps improving their thermal design and reliability

Effects of the Wire-Bonding Technique on the QFN16b's Thermal Performance. New Correlations for the Free Convective Heat Transfer Coefficient

International audienceThe technique of wire-bonding used in electronics is interesting for thermoregulation of the quad flat non-lead (QFN) packages during operation. To properly size these devices in the assemblies, it is necessary to know the surfacic thermal phenomena represented by the convective heat transfer coefficient. This is the objective of this work examining the thermal effects due to installation of wire-bonding on a QFN16. This particular device is named here QFN16b to differentiate it from the basic model without wire-bondings addressed in a previous study. During its actual operation, it generates a power ranging from 0.1 W to 1.0 W and it is welded on a printed circuit board (PCB) which could be inclined at different angles varying between the horizontal and vertical positions, according to the intended application. Calculations corresponding to 6 different areas of the considered assembly have been done by combining 20 powers generated by the QFN and 7 inclination angles. The distribution of the surface temperature and that of the source itself, as well as the free convective power exchanged by every area, are determined. Natural convective heat transfer is quantified by means of correlations which allow calculation of the average convective heat transfer coefficient in each area of the assembly and for all the treated configurations. They improve design, reliability, durability and performance of these conventional assemblies widely used in electronics in many engineering sectors