The Energy Implications of Air-Side Fouling in Constant Air Volume HVAC Systems

This thesis examines the effect of air-side fouling on the energy consumption of constant air volume (CAV) heating, ventilating, and air conditioning (HVAC) systems in residential and small commercial buildings. There is a particular focus on evaluating the potential energy savings that may result from the remediation of such fouling from coils, filters, and other air system components. A computer model was constructed to simulate the behavior of a building and its duct system under various levels of fouling. The model was verified through laboratory and field testing and then used to run parametric simulations to examine the range of energy impacts for various climates and duct system characteristics. A sensitivity analysis was conducted to determine the impact of parameters like duct insulation, duct leakage, duct location, and duct design on savings potential. Duct system pressures, temperatures, and energy consumption for two houses were monitored for one month. The houses' duct systems, which were both in conditioned space, were given a full cleaning, and were then monitored for another month. The flow rates at the houses improved by 10% and 6%. The improvements were primarily due to installing a new filter, as both houses had only light coil fouling. The results indicate that there was negligible change in heating energy efficiency due to the system cleaning. The parametric simulation results are in agreement with the field experiment: for systems in all eight climates, with flowrates degraded by 20% or less, if ducts are located within the thermal zone, HVAC source energy savings from cleaning are negligible or even slightly negative. However, if ducts are outside the thermal zone, savings are in the 1 to 5% range. For systems with flowrates degraded by 40%, if ducts are within the thermal zone, savings from cleaning occurs only for air conditioning energy, up to 8% in climates like Miami, FL. If ducts are outside the thermal zone, savings occurs with both heating and cooling energy, and ranges from 7% in Los Angeles, CA to 13% in Fairbanks, AK. These results assume a leaky and uninsulated duct system. The potential for savings from cleaning decreases if duct insulation is in place or sealing has been performed. The potential for energy savings is directly related to the distribution system's thermal efficiency, with air conditioner performance also playing a minor role. Results for small commercial buildings with constant air volume HVAC systems and leaky and uninsulated duct systems span a wider range: from -12% in Miami, FL to 30% in Minneapolis, MN. However, for improved ducts or ducts in the conditioned space, small commercial HVAC source energy savings is always negative (down to -17%) for flowrates degradation in the 0-40% range. The sensitivity of these results to duct characteristics (location, leakage, and insulation) and the after- cleaning flowrate, as it varies from an ideal flowrate, was also evaluated. Energy savings can reach up to 80% for some scenarios where clean airflow is severely restricted down to 20% of ideal by poor duct layout or other obstructions not removable by cleaning. In addition, a simplified spreadsheet tool was developed for technicians to use in the field to estimate potential savings resulting from a system cleaning. Measuring the temperature rise across the furnace was found to give less uncertainty than measuring the pressure rise and assuming a fan curve. Despite the uncertainty, the tool can give a general idea of the range of savings possible under various conditions

A new Euclidean tight 6-design

We give a new example of Euclidean tight 6-design in $\mathbb R^{22}$.Comment: 9 page

Further Comparison between ATNoSFERES and XCSM

International audienceIn this paper we present ATNoSFERES, a new framework based on an indirect encoding Genetic Algorithm which builds finite-state automata controllers able to deal with perceptual aliazing. In the context of our ongoing line of research, we compare it with XCSM, a memory-based extension of the most studied Learning Classifier System, XCS, through two benchmark experiments. We focus in particular on internal state generalization, and add special purpose features to ATNoSFERES to fulfill that comparison. We then discuss the role played by internal state generalization in the experiments studied

Using tourism free-choice learning experiences to promote environmentally sustainable behaviour: The role of post-visit ‘action resources’

This paper argues the need for the providers of ecotourism and other free‐choice environmental learning experiences to promote the adoption of environmentally sustainable actions beyond their own sites, when visitors return to their home environments. Previous research indicates that although visitors often leave such experiences with a heightened awareness of conservation issues and intentions to adopt environmentally responsible behaviours, only a minority translate these intentions into real actions. Building on research and theory in relation to visitor experiences in free‐choice learning environments, the paper identifies three different stages in the educational process and proposes a strategy for facilitating the translation of visitors' behavioural intentions into the adoption of sustainable actions through the provision of post‐visit action resources

On the Relationship between the Uniqueness of the Moonshine Module and Monstrous Moonshine

We consider the relationship between the conjectured uniqueness of the Moonshine Module, ${\cal V}^\natural$, and Monstrous Moonshine, the genus zero property of the modular invariance group for each Monster group Thompson series. We first discuss a family of possible $Z_n$ meromorphic orbifold constructions of ${\cal V}^\natural$ based on automorphisms of the Leech lattice compactified bosonic string. We reproduce the Thompson series for all 51 non-Fricke classes of the Monster group $M$ together with a new relationship between the centralisers of these classes and 51 corresponding Conway group centralisers (generalising a well-known relationship for 5 such classes). Assuming that ${\cal V}^\natural$ is unique, we then consider meromorphic orbifoldings of ${\cal V}^\natural$ and show that Monstrous Moonshine holds if and only if the only meromorphic orbifoldings of ${\cal V}^\natural$ give ${\cal V}^\natural$ itself or the Leech theory. This constraint on the meromorphic orbifoldings of ${\cal V}^\natural$ therefore relates Monstrous Moonshine to the uniqueness of ${\cal V}^\natural$ in a new way.Comment: 53 pages, PlainTex, DIAS-STP-93-0

Classtalk: A Classroom Communication System for Active Learning

This pdf file is an article describing the advantages of using Classtalk technology in the classroom to enhance classroom communication. Classtalk technology cab facilitate the presentation of questions for small group work, collec the student answers and then display histograms showing how the class answered. This new communication technology can help instructors create a more interactive, student centered classroom, especially when teaching large courses. The article describes Classtalk as a very useful tool not only for engaging students in active learning, but also for enhancing the overall communication within the classroom. This article is a selection from the electronic Journal for Computing in Higher Education. Educational levels: Graduate or professional

Bragg spectroscopy with an accelerating Bose-Einstein condensate

We present the results of Bragg spectroscopy performed on an accelerating Bose-Einstein condensate. The Bose condensate undergoes circular micro-motion in a magnetic TOP trap and the effect of this motion on the Bragg spectrum is analyzed. A simple frequency modulation model is used to interpret the observed complex structure, and broadening effects are considered using numerical solutions to the Gross-Pitaevskii equation.Comment: 5 pages, 3 figures, to appear in PRA. Minor changes to text and fig

Biomassapotentie Rijkswaterstaat : analyse van hoeveelheden en huidige toepassing

Het onderhoud van de terreinen die Rijkswaterstaat beheert kost geld o.a. doordat de geproduceerde biomassa moet worden verwijderd en verwerkt. Afzet naar compostering kost momenteel tot € 30 per ton (nat) aan de poort. Tegelijk is er een toenemende vraag naar biomassa voor de biobased economy waardoor er perspectief is ontstaan om biomassa tegen steeds lagere kosten af te zetten of zelfs een vergoeding te gaan ontvangen. Hiervoor is het eerst nodig inzicht te hebben in de (1) relevante arealen van Rijkswaterstaat voor de productie van biomassa en (2) de huidige potentie van deze arealen voor de productie van biomassa te kennen. Om dit in kaart te brengen zijn de arealen in direct of indirect beheer (vooral uiterwaarden) bij Rijkswaterstaat bepaald op basis van beschikbare bestanden bij Rijkswaterstaat. Daarna is per oppervlaktesoort (en vegetatie) ingeschat wat voor biomassa er geproduceerd wordt en hoeveel de huidige oogstbare biomassaproductie per ha per jaar is