Design and development of a hydronic system for temperature regulation and heat harvesting in a building integrated photovoltaic thermal panel

In recent years, solar energy has drawn vast attention as an abundant source of clean renewable energy. However, a common issue with the solar panels is the reduction of their efficiency and the output power with increased temperature of the panel’s surface. For every degree rise in temperature, the efficiency decreases by about 0.40 – 0.50%. In addition, the absorbed heat accelerates the aging of the cells and shortens their lifespan. Herein, a novel design is presented to reduce the temperature of the cells by means of a hydronic loop system integrated on the backside of the panel. In this design, aluminum tubes that are cast inside a foamed aluminum layer are integrated on the backside of the solar panel and a fluid with high heat capacity circulates inside the tubes in a closed loop. The fluid absorbs the heat when it comes in contact with the panels and thus, reduces the surface temperature of the cells and makes them cooler. Therefore, the water is acted as both a heat sink and a heat collector. The heated fluid is then transferred to the facility room of the building via a pump to heat a water tank indirectly. As a result, the temperature of the panel can be regulated during the operation time, and the harvested heat could be used for warm water applications in the building. This system not only maintains the efficiency of the solar panels at its feasible peak but also harvests heat and reduces the total energy consumption of the building. Please click Additional Files below to see the full abstract

Activation of Right Ventral Prefrontal Cortex Using a Predictive Cue during Visual Spatial Orienting of Attentional Processes: An fMRI Study

Visual spatial orienting of attention can be investigated with location-cueing paradigms in which a cue provides correct information about the location of the upcoming target. Target detection is facilitated when the target appears at the expected cued location. In this study, we examined the brain activation of the spatial orienting response based on attentional “benefits.” During an fMRI experiment, two types of attentional tasks were used. Both predictive and nonpredictive cues were used and followed by an upcoming target. Behavioral data showed a faster reaction time with the predictive cue when compared with that of the nonpredictive cue. The fMRI results of these two tasks were compared, whereby isolated brain areas activated when the targets appeared at the attended position after a specific spatial expectation was induced by the cue were compared with when equivalent targets appeared after no spatial expectation was induced by the cue. The results showed that the right ventral prefrontal cortex was activated to a similar degree as the dorsal frontoparietal spatial attentional network

VISVE – A VIScous Vorticity Equation Model Applied to Cylinders, Hydrofoils, Propellers

A newly developed numerical tool for Computational Fluid Dynamics (CFD) computations is presented. This method is designed to be spatially compact and computationally efficient, and meanwhile capable of modeling the dynamics of vortices interacting with solid walls. The vorticity transport equation is solved in the Eulerian frame to model only the vortical regions, where the vorticity is concentrated, in the flow field. Therefore, the computational domain can be made rather small without a loss in accuracy. The small computational domain results in a significantly small number of elements in the grid and considerably less simulation time compared with the velocity based methods, such as the Navier-Stokes methods. The method has a wide range of applications, including the flow past a cylinder, sphere, hydrofoil, and propeller. In addition, both Open-MP and MPI are used to parallel the code to further facilitate its performance. Validations against the experimental results and numerical results from other methods have been conducted to verify the correctness, robustness, and computational efficiency of the current method.Texas Advanced Computing Center (TACC

Inclusion-based boundary element method for design of building envelopes

The energy efficiency of a building envelope can be improved by embedding phase change materials (PCM) due to their high latent heat. However, heat transfer in the PCM-embedded composite can be quite complex due to temperature-dependent thermal properties of paraffin-based PCMs and material mismatch between PCMs and the Metrix, especially in transient heat conduction cases. This research presents an novel numerical method to simulate the transient heat conduction through a concrete wall panel containing PCM using the Green’s function. The pioneer work on simulation of PCM and heat equation applied finite element method (FEM), finite difference method (FDM). FDM discretize the time and space domain instead of taking derivatives, and it is usually applied to solve diffusion equations. However, the solutions of FDM are sensitive to time discretization and discontinuity issues. PCM capsules embedded in the domain of the building envelope serve as multiple inhomogeneities with heat source. To treat inhomogeneity problem, the PCM capsules need to be meshed to elements compatible to the matrix domain, which leads to large number of meshed elements. For inhomogeneity problem, Eshelby proposed equivalent inclusion method (EIM), filling inhomogeneities with the same material with the matrix and fictious heat source, eigen gradient of temperature. The inclusion-based boundary element method (IBEM) combines EIM with boundary element method, which only requires to mesh convex surface. Upon experimental validation, the iBEM model is used for energy efficient building design and energy savings prediction. Please click Additional Files below to see the full abstract

An analysis of the vibrating motion of an axially moving thin plate using the HHT method

Axially moving plates can be found in many industrial applications. Characteristics of the motion of thin moving plates are demonstrated in this paper using real-time signals and the Hilbert-Huang transform method. Ensemble empirical mode decomposition (EEMD) and calculation procedures are used to determine the instantaneous frequency, Hilbert spectrum and marginal spectrum of a moving plate. Some comparisons between different cases are discussed briefly. The motion is sensitive to the velocity, the initial tension of the conveyor strings and the weight of the plate. In addition, to express the motion (including the pitch and roll) of a moving plate quantitatively for field applications, a motion indicator is introduced. The signal processing method used is based on EEMD and time domain filtering. The indicator should be helpful for monitoring or adjusting the motions of axially moving plates