183 research outputs found
Multiple Shots Averaging in Laser Flash Measurement
No full textThe knowledge of the thermal properties of materials is a key resource for the correct design of industrial components. The laser flash method is a well-known procedure to determine the thermal diffusivity of a wide range of materials. However, in some cases there is the need of limiting the input power, or measuring materials with high thermal capacity, or investigating thick samples. Under these circumstances, the expected signal-to-noise ratio can reach extremely low values. To solve this issue, the existing laser flash apparatus has been improved, creating a new control and data acquisition system that is able to repeat multiple times the emission of the laser impulse and the measurement of the thermal response of the specimen. This gives the possibility of averaging several measurements, leading to a decrease of the noise. The experimental validation on different samples shows the feasibility of the proposed setup, that makes it possible to work with low power inputs
Primary Health Care and Disasters: Applying a “Whole-of-Health System” Approach through Reverse Triage in Mass-Casualty Management
No full textIntroduction: In 2019, the World Health Organization (WHO) published the Health Emergency and Disaster Risk Management (H-EDRM) framework detailing how effective management of disasters, including mass-casualty incidents (MCIs), can be achieved through a whole-of-health system approach where each level of the health care system is involved in all phases of the disaster cycle. In light of this, a primary health care (PHC) approach can contribute to reducing negative health outcomes of disasters, since it encompasses the critical roles that primary care services can play during crises. Hospitals can divert non-severe MCI victims to primary care services by applying reverse triage (RT), thereby preventing hospital overloading and ensuring continuity of care for those who do not require hospital services during the incident. Study Objective: This study explores the topic by reviewing the literature published on early discharge of MCI victims through RT criteria and existing referral pathways to primary care services. Methods: A scoping literature review was performed and a total of ten studies were analyzed. Results: The results showed that integrating primary care facilities into disaster management (DM) through the use of RT may be an effective strategy to create surge during MCIs, provided that clear referral protocols exist between hospitals and primary care services to ensure continuity of care. Furthermore, adequate training should be provided to primary care professionals to be prepared and be able to provide quality care to MCI victims. Conclusion: The results of this current review can serve as groundwork upon which to design further research studies or to help devise strategies and policies for the integration of PHC in MCI management
Condensation of steam over nano-engineered surfaces, 9th International Conference on Boiling and Condensation Heat Transfer
No full textNano-engineered surfaces have recently been studied as a promising solution for several heat transfer applications. In particular, modification of surface wetting properties for achieving enhanced condensation heat transfer coefficients is an extremely interesting field of research. Superhydrophilic surfaces can be obtained by properly roughening the surface to a micro-/ nano- scale, while hydrophobic ones are obtained by lowering the surface free energy.
In the present work, chemical procedures to obtain a modification of the wetting properties over aluminum substrates are presented. Moreover, the influence of such properties on condensation heat transfer applications is investigated. A new thermosyphon test loop for the analysis of pure steam flow condensation, at different vapor velocities, is described. Heat transfer data measured during condensation in the new apparatus over untreated, superhydrophilic and hydrophobic surfaces are hereinafter presented and discussed.
It is shown that condensation is negatively affected by rough surfaces presenting superhydrophilic properties, because of condensate adhesion to the substrate which leads to an enhancement of the liquid film thickness. On the contrary, condensation over hydrophobic treated surfaces leads to an augmentation of the two-phase heat transfer coefficient when compared to the one on the untreated surface. This may be due to the presence of a non-zero slip velocity condition at the solid-liquid interface, due to the water repellency properties of the surface, which leads to a reduction of the condensate film thickness. Thinning the condensate thickness means a reduction of the driving thermal resistance, and thus an enhancement of the condensation heat transfer coefficient
Experiments of dropwise condensation on wettability controlled surfaces
No full textDuring filmwise condensation, the liquid layer adjacent to the wall introduces a thermal resistance that adversely affects the heat transfer. On the contrary, the dropwise condensation mode leads to higher thermal performance by inducing the breakage of the liquid film and replacing it with a big amount of randomly distributed droplets. The potential of dropwise condensation is based on the increase of the condensation heat transfer coefficients by several times compared to those measured during filmwise condensation. The surface properties, and in particular the surface wettability, play a crucial role in determining the condensation mode (e.g. hydrophobic surfaces are expected to promote dropwise condensation). The present paper aims to present and discuss experimental data taken during filmwise and dropwise condensation of pure steam over vertical surfaces. Surfaces with different wettability have been realized on aluminum substrates and then characterized by means of contact angle measurements using the standard sessile drop method. The test rig used for the experimental campaign is a two-phase thermosyphon loop that allows measurement of heat transfer coefficients and simultaneous visualization of the condensation process. Heat transfer coefficients have been measured at around 107°C saturation temperature with three different aluminum samples. A high-speed camera has been used to analyze the condensation regimes
Periodic thermal behavior of walls: an experimental approach
No full textThe need for testing methods that could verify the performance of building components is continuously
increasing, as it is mandatory to reduce the overall energy need of the buildings. This work provides a method that
determines the dynamic behavior of walls. The time-shift due to the thermal and physical properties of the component is
measured using infrared thermography. A case study on a typical wall sample is proposed, validating the technique
Bioinspired silica-based sol–gel micropatterns on aluminium for humid air condensation
No full textSeveral patterned coatings with a hybrid organic-inorganic nature were deposited on metallic substrates by exploiting the
dewetting of a sol–gel bilayer. The hybrid coatings, inspired by the exoskeleton of a desert beetle, consisted of hydrophilic
silica droplets on a hydrophobic CH3-silica bottom layer. The patterned morphology was tuned by changing the initial
solution concentration, which resulted in substantial changes in the size and the density of distribution of the hydrophilic
droplets. The reproducibility of the dewetting process on metallic substrates was confirmed, together with its scalability over
large area substrates. The real-life application of the patterned coating for atmospheric water harvesting was tested in a
custom-made apparatus, which demonstrated that the patterned coating led to a higher collected mass during condensation
from humid air compared to the bare aluminium substrate. The patterned coating was proven to maintain its structure after
the humid air exposure, confirming the robustness of the sol–gel-based materials
Numerical Model and Experimental Analysis of the Thermal Behavior of Electric Radiant Heating Panels
No full textElectric radiant heating panels are frequently selected during the design phase of residential and industrial heating systems, especially for retrofit of existing buildings, as an alternative to other common heating systems, such as radiators or air conditioners. The possibility of saving living and working space and the ease of installation are the main advantages of electric radiant solutions. This paper investigates the thermal performance of a typical electric radiant panel. A climatic room was equipped with temperature sensors and heat flow meters to perform a steady state experimental analysis. For the dynamic behavior, a mathematical model was created and compared to a thermographic measurement procedure. The results showed for the steady state an efficiency of energy transformation close to one, while in a transient thermal regime the time constant to reach the steady state condition was slightly faster than the typical ones of hydronic systems
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