experimental comparison of two heat exchanger concepts for latent heat storage applications

Abstract In the present work, two different types of heat exchangers are experimentally compared, namely a fin-and-tubes custom made HEX and a commercial asymmetric plate heat exchanger, for the application with phase change materials. In particular, the two devices were tested in a specifically designed testing rig located at CNR-ITAE and suitable for the characterization of thermal energy storages. The testing bench allows simulating a heat source up to 100°C (e.g. solar thermal collectors, low-grade waste heat) and to set the desired discharge temperature in the range 20°C-80°C. The phase change material with which the exchangers were filled, is a commercial paraffin (Plus ICE A82), having a nominal melting temperature of 82°C. The experimental results on charge and discharge tests, realized with the same protocol, were used for a comparison of the systems, through the identification of suitable performance figures and Key Performance Indicators, such as material-to-metal ratio, heat storage density, maximum and average power achievable and effectiveness of the system. The results show that, for the tested material, characterised by a very low thermal conductivity (i.e. about 0.2 W/mK), the selected plate heat exchanger allows a better exploitation of the heat stored inside the material, letting at the same time to reach a power output in the range 1-10 kW

A semi-coherent analysis method to search for continuous gravitational waves emitted by ultra-light boson clouds around spinning black holes

As a consequence of superradiant instability induced in Kerr black holes, ultra-light boson clouds can be a source of persistent gravitational waves, potentially detectable by current and future gravitational-wave detectors. These signals have been predicted to be nearly monochromatic, with a small steady frequency increase (spin-up), but given the several assumptions and simplifications done at theoretical level, it is wise to consider, from the data analysis point of view, a broader class of gravitational signals in which the phase (or the frequency) slightly wander in time. Also other types of sources, e.g. neutron stars in which a torque balance equilibrium exists between matter accretion and emission of persistent gravitational waves, would fit in this category. In this paper we present a robust and computationally cheap analysis pipeline devoted to the search of such kind of signals. We provide a full characterization of the method, through both a theoretical sensitivity estimation and through the analysis of syntethic data in which simulated signals have been injected. The search setup for both all-sky searches and higher sensitivity directed searches is discussed.Comment: 13 pages, 13 figure

Ultrafine Magnetite Nanopowder: Synthesis, Characterization, and Preliminary Use as Filler of Polymethylmethacrylate Nanocomposites

Magnetite (Fe3O4) nanoparticles prepared by microwave-assisted hydrothermal synthesis have been characterized in terms of morphological and structural features. Electron micrographs collected in both scanning (SEM) and transmission (TEM) modes and evaluations of X-ray powder diffraction (XRD) patterns have indicated the achievement of a monodispersed crystallite structure with particles having an average size around 15–20 nm. Structural investigations by Micro-Raman spectroscopy highlighted the obtainment of magnetite nanocrystals with a partial surface oxidation to maghemite (γ-Fe3O4). Preliminary attention has been also paid to the use of these magnetite nanoparticles as filler for a commercial polymethylmethacrylate resin. Hybrid formulations containing up to 3 wt% of nanoparticles were prepared by melt blending and characterized by calorimetric and thermogravimetric tests. For sake of comparison, same formulations containing commercial Fe3O4nanoparticles are also reported. Calorimetric characterization indicates an increase of both glass transition temperature and thermal stability of the nanocomposite systems when loaded with the synthesized magnetite nanoparticles rather then loaded with the same amount of commercial Fe3O4. This first observation represents just one aspect of the promising potentiality offered by the novel magnetic nanoparticles when mixed with PMMA

Percutaneous endoscopic jejunostomy (PEJ) in patients with dumping syndrome: Evaluation of our center on a series of clinical cases

Background: The Dumping syndrome occurs in a variable percentage of subjects undergoing surgery involving the esophageal and gastric district. The treatment makes use of the introduction of dietary measures and arti!cial nutrition, especially the internal one. This study evaluates the experience of a single center regarding the use of percutaneous endoscopic jejunostomy (PEJ) in patients developing the dumping syndrome. Methods: We evaluated the case history of our department, of all patients operated on at the level of the upper gastrointestinal tract, who had manifested symptoms referable to the Dumping syndrome in the postoperative period.We have identi!ed 3, which we have carried out further investigations to con!rm the presence of an accelerated gastric emptying, and given the poor results obtained with dietary modi!cations and drug therapy, we have implemented a feeding through enteral nutrition, through a jejunal probe. PEG/J positioned by Pull technique, and subsequently replaced after 8 months. Results: Clinically, patients did not develop short- or long-term complications, symptoms were signi!cantly reduced, and they gained weight. Psychologically, the anxiety disorders related to nutrition have improved. Conclusions: By means of percutaneous endoscopic jejunostomy, the symptoms related to hypoglycemic crises following the hyperinsulinemic response to the ingestion of carbohydrates in patients with Dumping were attenuated and the anxiety of eating was lessened. Although limited to a few cases, we believe this form of nutrition is the best for patients with dumping

Design of an Innovative Graphite Exchanger for Adsorption Heat Pumps and Chillers

Abstract In this work, an innovative adsorber for application in adsorption heat pumps and chillers is presented. The adsorber consists of several assembled graphite plates and the flow path of heat transfer fluid. Each plate consists of a process side (where zeolite is deposited onto) and a heat transfer fluid (HTF) side where liquid water flows. The resulting adsorbent heat exchanger is able to deliver about 0.5-1 kW cooling power and possesses attractive thermo physical properties, especially in term of low weight, volume and thermal capacity. Experimental testing of the full-scale adsorber by a testing station available at CNR ITAE is currently ongoing

A method to search for long duration gravitational wave transients from isolated neutron stars using the generalized FrequencyHough

We describe a method to detect gravitational waves lasting $O(hours-days)$ emitted by young, isolated neutron stars, such as those that could form after a supernova or a binary neutron star merger, using advanced LIGO/Virgo data. The method is based on a generalization of the FrequencyHough (FH), a pipeline that performs hierarchical searches for continuous gravitational waves by mapping points in the time/frequency plane of the detector to lines in the frequency/spindown plane of the source. We show that signals whose spindowns are related to their frequencies by a power law can be transformed to coordinates where the behavior of these signals is always linear, and can therefore be searched for by the FH. We estimate the sensitivity of our search across different braking indices, and describe the portion of the parameter space we could explore in a search using varying fast Fourier Transform (FFT) lengths.Comment: 15 figure

Non-motor impairments affect walking kinematics in Parkinson disease patients: A cross-sectional study

Background: In patients with Parkinson disease (PD), severe postural and gait impairments are rarely observed in early stage of disease and non-motor symptoms (NMS) are often overlooked. Objective: This observational study aimed to characterize the impact of non-motor impairments on walking kinematics in early stages PD patients, and to assess the differences of gait parameters and NMS between PD patients with and without mild cognitive impairment (MCI). Methods: Twenty-six patients with Modified Hoehn and Yahr Scale score≤2 were evaluated for NMS using Kings Parkinson's Pain Scale, Parkinson Fatigue Severity scale, Parkinson Anxiety Scale, Beck Depression Inventory and Epworth Sleepiness Scale, kinematic parameters through an inertial sensor and cognitive performance by a comprehensive neuropsychological battery. Results: Fatigue had a moderate negative correlation with step cadence, and a moderate to strong positive correlation with gait duration, Timed Up and Go (TUG) and TUG Dual Task (p < 0.01). Pain showed positive moderate correlation with gait duration (p < 0.01). Twelve patients resulted affected by MCI and reported significantly worse scores in gait duration, pain and fatigue (p < 0.05). According to cognitive z scores, PD-MCI group showed a moderate negative correlation between visuospatial abilities and fatigue (p < 0.05). Conclusions: NMS significantly affect walking kinematics whereas a limited role of cognitive status on motor performance occur in the early PD stages

Combined Administration of Oxycodone/Naloxone in Chronic Osteo-Articular Diseases Pain Therapy

The aim of this study is the analysis of the beneficial impact of using opioid receptor antagonist associated to opioid analgesic on the quality of life in patients suffering from chronic non-cancer pain. We recruited 60 patients suffering from osteo-articular diseases who were randomized into two groups of treatment. The group A was treated with the association of opioid receptor antagonist and opioid agonist, represented by Oxycodone. The group B was treated with the opioid analgesics Oxycodone, transdermal Fentanil, and Hidromorphone, without the opioid antagonist. The end-points assessed were the duration of titration, the average reached dosage, the duration of the stability of dosage and the opioid–induced constipation (OIC) using the BFI

Economic evaluation of “pulse dose” radiofrequency in the treatment of occipital neuralgia headache

Headache occipital neuralgia is an example of pain-disease for which treatment both pharmacological protocols and invasive methods are used. Among the latter, the RF (Radiofrequency) pulse-dose has been of interest for the prospects of analgesic efficacy, safety and patient compliance, although at the moment only data concerning the pulsed RF and not the RF pulse-dose, that represents its evolution, are discussed in scientific literature. The purpose of this study is a "simple" economic evaluation of this method in headache occipital neuralgia

Pain treatment with high-dose, controlled-release oxycodone: an Italian perspective

To investigate the possible role and tolerability of high-dose (>160 mg/day) oxycodone controlled release (CR) for the treatment of cancer and non-cancer pain. 227 patients with cancer or non-cancer pain were enrolled in an open-label, multi-center, Italian study in order to assess the adequacy of their existing pain management (using a numerical rating scale [NRS]) and the possible benefit high-dose oxycodone CR may offer patients experiencing uncontrolled pain. Results: Pain was poorly controlled at baseline, with only 18.1% of patients reporting adequate pain relief (NRS <3.5). All other patients reported uncontrolled pain, with an average NRS of 7.81. At baseline assessment, 47.89% of patients had been in pain for up to 3 months, 32.82% for 3–6 months, and 19.19% for more than 6 months. After baseline assessment, patients were switched to oxycodone CR monotherapy. The starting dose was individualized to each patient and titrated up over a 3- to 4-day period until effective pain management was achieved. Treatment was continued for an average of 37.24 days during the study. Pain control (final mean NRS of 2.85) was attained with an average dose of oxycodone CR 221.84 mg/day. Standard adverse events (including constipations, nausea, and vomiting) were recorded in 39.64% of patients receiving high-dose oxycodone CR monotherapy. Side-effects tended to subside after the initial week of treatment and did not result in any participants leaving the study. High-dose oxycodone CR can achieve rapid and effective management of moderate to severe cancer and non-cancer pain with minimum side-effects