A. James Clark School of Engineering

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

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    Evaluating the Effects of Different Improvement Strategies for the Outdoor Thermal Environment at a University Campus in the Summer: A Case Study in Northern China
    (MDPI, 2022-12-17) Yang, Lina; Liu, Jiying; Zhu, Shengwei
    A lack of consideration of outdoor spaces of universities has resulted in lower outdoor thermal comfort in summer. This study investigates the thermal comfort of outdoor spaces of a university in summer and proposes the model’s accuracy and optimization strategies to improve the outdoor thermal environment, including vegetation greening, building morphology, and surface albedo. The ENVI-met program was used for the simulation. The measured data were utilized to verify the accuracy of the simulation model. The typical meteorological year data were applied as the inlet boundary condition of the optimized case. The simulation results show that vegetation greening has the most significant effect on improving the outdoor thermal environment. At a greening rate of 45%, the air temperature (Ta), mean radiant temperature (Tmrt), and physiological equivalent temperature (PET) in the study area were 3.2 °C, 14.4 °C, and 6.9 °C lower, respectively, than that in the base case. In areas shaded by building, the Ta, Tmrt, and PET were 2 °C, 8.7 °C, and 5.5 °C lower, respectively, than that in the base case. Increasing the height of buildings did not significantly improve thermal comfort when the height-to-width ratio (H/W) exceeded 1.0. Increasing the ground albedo from 0.2 (base case) to 0.6 can reduce the Ta by 1.44 °C but increase the Tmrt by 3.7 °C and the PET by 4.3 °C. These findings can be used by urban planners to develop sustainable cities and improve thermal comfort on university campuses.
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    SYSTEM PERFORMANCE ENHANCEMENT OF MOBILE COOLING SYSTEM WITH THERMAL BATTERY AND THERMOSIPHON RECHARGE
    (2018) Key, Darren Thomas; Hwang, Yunho; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    A personalized mobile cooling device was modified and tested with different components to deliver better system performance. The device uses a miniaturized vapor compression cycle (VCC) to deliver approximately 165 W of cooling to an individual. The device stores the waste heat from the VCC condenser in a phase change material (PCM) carried on-board the device. The PCM is then recharged by rejecting heat stored in the PCM with a thermosiphon recharge cycle. The PCM was enhanced with copper and graphite matrices. The system was tested with the goal of increasing the coefficient of performance (COP) of the VCC and decreasing the PCM recharge time. This study found that a copper enhancement provided the highest COP at 4.43, an improvement over the baseline COP of 2.41.