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Air Conditioning: The maintenance of certain aspects of the environment within a defined space to facilitate the function of that space; aspects controlled include air temperature and motion, radiant heat level, moisture, and concentration of pollutants such as dust, microorganisms, and gases. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Heat Exchanger Analysis

JoVE 10391

Source: Alexander S Rattner and Christopher J Greer; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA

Heat exchangers transfer thermal energy between two fluid streams, and are ubiquitous in energy systems. Common applications include car radiators (heat transfer from hot engine coolant to surrounding air), refrigerator evaporators (air inside refrigerator compartment to evaporating refrigerant), and cooling towers in power plants (condensing steam to evaporating water and ambient air). The objective of this experiment is to introduce experimental measurement (rating) and modeling procedures for heat exchangers. In this experiment, a water-to-water tube-in-tube heat exchanger will be constructed, and evaluated. Temperature and flow rate measurements will be employed to determine the heat transfer rate (Q) and overall conductance (UA). The measured heat exchanger UA will be compared with predicted values for the geometry and operating conditions.

 Mechanical Engineering

Human Brown Adipose Tissue Depots Automatically Segmented by Positron Emission Tomography/Computed Tomography and Registered Magnetic Resonance Images

1Chemical and Physical Biology Program, Vanderbilt University, 2Department of Physical Medicine and Rehabilitation, Vanderbilt University School of Medicine, 3Radiology & Radiological Sciences, Vanderbilt University Medical Center, 4Department of Pharmacology, Vanderbilt University

JoVE 52415


Introduction to Refrigeration

JoVE 10387

Source: Alexander S Rattner and Christopher J Greer; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA

This experiment demonstrates the principles of vapor compression refrigeration. The vapor compression cycle is the dominant refrigeration technology, found in most refrigerators, freezers, air-conditioning systems, and heat pumps. In this cycle, cooling (heat acquisition) is achieved with low-pressure evaporation of refrigerant. Thermal energy absorbed in evaporation is rejected to the surroundings through high-pressure refrigerant condensation. Mechanical work is applied in the compressor to raise the working fluid from low to high pressure. While refrigeration technology is ubiquitous, the concealing packaging and autonomous operation of most refrigerators makes it difficult to appreciate the operating principles and function of key components. In this experiment, a rudimentary vapor compression refrigerator is constructed. The compressor is manually actuated with a bicycle pump, allowing intuitive appreciation of cycle operation as the experimenter becomes part of the system. Resulting component pressures and temperatures can be interpreted in terms of the thermodynamic T-s and P-h diagrams, which captu

 Mechanical Engineering

Testing the Heat Transfer Efficiency of a Finned-tube Heat Exchanger

JoVE 10437

Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA

Heat exchangers transfer heat from one fluid to another fluid. Multiple classes of heat exchangers exist to fill different needs. Some of the most common types are shell and tube exchangers and plate exchangers1. Shell and tube heat exchangers use a system of tubes through which fluid flows1. One set of tubes contains the liquid to be cooled or heated, while the second set contains the liquid that will either absorb heat or transmit it1. Plate heat exchangers use a similar concept, in which plates are closely joined together with a small gap between each for liquid to flow1. The fluid flowing between the plates alternates between hot and cold so that heat will move into or out of the necessary streams1. These exchangers have large surface areas, so they are usually more efficient1. The goal for this experiment is to test the heat transfer efficiency of a finned-tube heat exchanger (Figure 1) and compare it to the theoretical efficiency of a heat exchanger without fins. The experimental data will be measured for three diffe

 Chemical Engineering

Measuring Turbulent Flows

JoVE 10450

Source: Ricardo Mejia-Alvarez and Hussam Hikmat Jabbar, Department of Mechanical Engineering, Michigan State University, East Lansing, MI

Turbulent flows exhibit very high frequency fluctuations that require instruments with high time-resolution for their appropriate characterization. Hot-wire anemometers have a short enough time-response to fulfill this requirement. The purpose of this experiment is to demonstrate the use of hot-wire anemometry to characterize a turbulent jet. In this experiment, a previously calibrated hot-wire probe will be used to obtain velocity measurements at different positions within the jet. Finally, we will demonstrate a basic statistical analysis of the data to characterize the turbulent field.

 Mechanical Engineering

A Rapid Laser Probing Method Facilitates the Non-invasive and Contact-free Determination of Leaf Thermal Properties

1Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V., 2Institute for Molecular Biotechnology, RWTH Aachen University, 3Fraunhofer Institute for Laser Technology ILT, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V.

JoVE 54835


The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight

1School of Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, 2BlueScope Steel Research, 3Infrared Microspectroscopy Beamline, Australian Synchrotron, 4School of Science, College of Science, Engineering and Health, RMIT University

JoVE 54309


Contractility Measurements of Human Uterine Smooth Muscle to Aid Drug Development

1Harris-Wellbeing Preterm Birth Research Centre, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, 2School of Biomedical Sciences, The University of Queensland, 3Faculty of Chemistry, Institute of Biological Chemistry, University of Vienna, 4Institute for Molecular Bioscience, University of Queensland, 5Center for Physiology and Pharmacology, Medical University of Vienna

JoVE 56639


Intravital Microscopy of Monocyte Homing and Tumor-Related Angiogenesis in a Murine Model of Peripheral Arterial Disease

1Department of Cardiology and Angiology, University of Magdeburg, 2Leibniz Institute for Neurobiology, 3Institute of Molecular and Clinical Immunology, University of Magdeburg, 4Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School

JoVE 56290


VFD-fed AC Induction Machine

JoVE 10165

Source: Ali Bazzi, Department of Electrical Engineering, University of Connecticut, Storrs, CT.

Variable frequency drives (VFDs) are a type of adjustable speed drive, which are becoming standard equipment to power most AC induction motors. VFDs are common in industrial and automation applications and typically provide robust control of the motor in speed, torque, or position modes. The VFDs tested and simulated in this experiment focus on speed and open-loop control with constant voltage to frequency ratio (V/f) control. The induction motor typically operates at a rated stator flux, and this flux is approximately proportional to the V/f ratio. To maintain constant stator flux, the voltage and frequency applied to the stator are maintained at a constant ratio, which is the V/f ratio. The VFD used in this experiment is a 1 hp Yaskawa V1000 drive, but the procedure applies to most commercially available general purpose drives.

 Electrical Engineering

Evaluating the Heat Transfer of a Spin-and-Chill

JoVE 10440

Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA

The Spin-and-Chill uses heat transfer and fluid flow fundamentals to chill beverages from room temperature to 38 °F in as little as 2 min. It would take a refrigerator approximately 240 min and an ice chest approximately 40 min to achieve an equivalent temperature change. This is accomplished Spin and Chill by spinning a can or bottle at up to 500 rpm, which creates little or no foaming. In this experiment, the efficacy of spinning a cylinder (i.e., soda can) at high speeds to cool a soft drink will be evaluated. Operational parameters, such as rpm and spin time, will be varied to assess their effect on heat transfer, and the heat transfer coefficient will be calculated using a lumped parameter model.

 Chemical Engineering

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