S. Lazzari, A. Priarone,
DIN, University of Bologna, Bologna, Italy
DIME-TEC, University of Genova, Genova, Italy
The transient behavior of the thermal resistance of single and double U-tube borehole heat exchangers (BHEs) is investigated numerically by means of COMSOL Multiphysics® software with reference to the 2D cross section of usually employed BHEs. The study is performed in a dimensionless parametrical form, the parameters being the ratio between the thermal conductivities of grout and ground, the ...
Heat Loss Evaluation of an Experimental Set-up for Predicting the Initial Stage of the Boiling Curve for Water at low Pressure
K. T. Witte, F. Dammel, L. Schnabel, and P. Stephan
Fraunhofer Institut Solare Energiesysteme - Department of Thermal Systems and Buildings, Freiburg, Germany
Technische Universität Darmstadt - Institute of Technical Thermodynamics, Darmstadt, Germany
In this paper heat losses and gains are assessed for a specific measuring set-up improving the validity of performance data to accurately predict the initial stage of a boiling curve. Simulation focus on achieving results predicting real measuring data of a plain surface structure. Therefore, the relevant components of the measuring set-up have been implemented in a 2-D axisymmetric model ...
B. Chinè , M. Monno
Laboratorio MUSP, Macchine Utensili e Sistemi di Produzione, Piacenza, Italy
Politecnico di Milano, Dipartimento di Meccanica, Milano, Italy
Instituto Tecnologico de Costa Rica, Cartago, Costa Rica
Introduction: In metal foams production, nucleated gas bubbles expand in a heated metal in a mold, then the foam cool and solidify. Thereby energy, mass and momentum transfer mechanisms are present simultaneously in the system and must be taken into account. Metal foam (Figure 1) can be obtained by foaming a precursor, i.e. a mixing of aluminum (Al) powders with the blowing agent TiH2, placing ...
University of Hartford, Hartford, CT, USA
Laser percussion drilling is widely used in the aerospace industry to produce cooling holes in jet engine components. This process is a thermal, contact-free process which involves firing a sequence of focused optical pulses onto a target material [1-4]. During each optical pulse, the central portion of the target area heats to a liquid then vapor state where the expanding gas produces a recoil ...
M. Bottarelli, M. Bortoloni
Università degli Studi di Ferrara, Dipartimento di Architettura, Ferrara, Italia
Ground Heat Exchangers (GHXs) are rarely installed horizontally in linked ground source heat pumps used for space conditioning, because their energetic performance is lower than in the vertical solution. However, the horizontal one holds several advantages: it is easy to carry out and upkeep, it is more compliant with environmental regulations, and interferes marginally with groundwater systems. ...
K. O. Lund , S. M. Lord ,
 Kurt Lund Consulting (COMSOL Certified Consultant), Del Mar, CA, USA
 SML Associates, Encinitas, CA, USA
A frequently occurring geometry for heat exchangers is that of a long tube wound into a helix or spiral around a core volume. There is to be heat exchange between the tube and the gases (or solids) in the core. However, the length scales of these two parts of the geometry are very different, thus complicating the interface between the tube and the core processes. Usually, the tube is too ...
D. Testi, P. Conti
University of Pisa, Department of Energy and Systems Engineering, Pisa, Italy
The use of foundation piles as ground heat exchangers coupled to a geothermal heat pump is considered of interest for possible savings in installation costs, compared to conventional borehole heat exchangers. We refer to them as “geothermal piles” or “energy piles”. The main purpose of the foundation structure is to transmit the load of the building to the lower layers of the soil, best suited ...
J. v. Schijndel , S. Goesten , H. Schellen ,
 Eindhoven University of Technology, Eindhoven, Netherlands
Benchmarks are important tools to verify computational models. In the research area of building physics, the so-called HAMSTAD (Heat, Air and Moisture STAnDardization) project is a very well known benchmark for the testing of simulation tools. In this paper we revisit this benchmark by modeling all five subtasks using the COMSOL Multiphysics® software. Again we conclude that the COMSOL® software ...
S. Birla ,
 ConAgra Foods, Omaha, NE, USA
Scraped surface heat exchangers (SSHEs) are commonly used in the food, chemical, and pharmaceutical industries for heat transfer, crystallization, and other continuous processes. One of the factor posing difficulties to heat transfer is viscosity. Highly viscous fluids tend to generate deep laminar flow, a condition with very poor heat transfer rates and high pressure losses involving a ...
A. Warning, A. K. Datta, A. Dhall, and D. Mitrea
Department of Biological and Environmental Engineering
A multiphase porous media model involving heat and mass transfer within a potato chip was implemented in COMSOL 3.5a. The diffusive flux in oil and liquid water was modeled from capillary driven flow while the gas phase was modeled using binary diffusion. A non-equilibrium water evaporation rate was used and Darcy's law for the momentum equation to solve for the convection of each species. ...