a b s t r a c tSimulation results indicate that urban morphology plays an important role in determining the efficacy of rooftop urban cooling strategies for improving pedestrian thermal comfort. Results suggest that a white roof has the greatest effect on near-surface air temperatures within the urban canyon when used on buildings of 1-2 stories height and almost no near-surface effect when applied to 4 story buildings. However, the near-surface effect is more substantial when complex urban morphology introduces enhanced vertical mixing. Of the cases studied the largest near-surface cooling benefit of implementing white roofs was found for the case when a taller building existed downwind from a building with a white roof. Using the Thermal Footprint Ratio it was found that by placing a tall building behind a building with a white roof in an otherwise uniform array of 2 story buildings, the cool roof would be twice as effective at reducing air temperatures at the pedestrian level. Calculations of the volumetric heat removal confirmed this result, indicating that the positioning of the tall building downwind of the modified roof would be 2.6 times as effective at cooling the pedestrian level air volume as compared to the case where all buildings were a uniform height.
Arduino is a compact, inexpensive, open-source electronics prototyping platform built around an Atmel AVR microcontroller. The features, cost, and small size makes Arduino a potent tool teaching as well as practical device use in engineering projects. This paper reports on adapting the Living with the Lab (LWTL) curriculum to the Arduino platform. LWTL was developed with the Boe-Bot mobile robotics platform and the Basic Stamp microcontroller. The Arduino is more modern and has better technical capabilities, but there are fewer educational resources for the Arduino than there are for the Boe-Bot. The updated curriculum was successfully implemented at two universities. End-of-term surveys indicate that students had a positive experience of the course, especially the hands-on exercises. However, students were not as positive about the current state of instructional support for Arduino programming. The Arduino remains a viable and preferable platform. Recommendations for improvement of curricular materials for the Arduino are made.
Results of numerical optimization are reported for a phase change heat sink used to cool electronic equipment in extreme environments. The heat sink consists of a conventional, extruded aluminum sink embedded in a block of phase change material. This type of heat sinkis used ininfraredcamerascaniedby fire fighters into burning buildings.Optimization of the geometry of the heat sink assembly involves determination of the fin length, the fin thichess, and the base thickness that maximizes the time time before the base of the heat sink reaches a critical temperature. The numerical model is briefly described, and representative results of the simulation are presented. The optimum design for a given combination of heat load, conductance to ambient, and phase change material is discussed. The model can easily be applied to other geometries, heat loads, and material properties.
This paper is a report on evidence-based practice in a first year engineering program for Mechanical Engineering Students. We adapted a year-long curriculum called Living with the Lab (LWTL) that uses a project-based, hands-on instruction to introduce students to engineering fundamentals, programming, sensors, controls and engineering design. While adhering to the spirit and much of the content of the original curriculum, we added material, created new hands-on projects, introduced a flipped instructional model for the first course in the sequence, and experimented with an alternative final project model. We briefly describe our key innovations to the LWTL curriculum.Introduction of this curriculum has coincided with a sharp rise in enrollment in our Mechanical Engineering program. Retention at the end of the three-term sequence is approximately 60%. After six years of implementation the curriculum continues to evolve. We report on a survey of student opinion that spans all cohorts of students passing through the program. Overall there is strong student satisfaction with the curriculum, especially the hands-on approach. Students describe the courses as both "fun" and "challenging". Survey responses show female students are more positive than males about the hands-on pedagogy despite having less prior hands-on experience. Both male and female respondents think the pedagogical approach is appropriate for the course material and beneficial to their learning.
Large scale solar farms supply an increasing amount of the worlds electricity supply. However, in order to reach cost parity with fossil fuels, further reductions are necessary. Towards this end, photovoltaic (PV) panel cooling becomes increasingly important; high temperatures both decrease e ciency and panel lifetime. To better understand, characterize, and exploit the natural convective cooling of utility scale solar farms, a model solar farm was created. Using both thermal measurements and particle image velocimetry to characterize heat transfer and velocity fields, wind tunnel experiments were conducted using the model solar farm. Three parameters were examined for their e↵ect on heat transfer and the flow field: Reynolds number, inflow turbulence intensity (TI), and PV inclination angles. Results show that increasing inflow turbulence improved both upper and lower surface heat transfer by 7%, and lower surface increases on order of 100% were demonstrated in both the flow field and heat transfer with changes in angle inclination. Results suggest that significant farm level temperature reductions are possible.
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