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The electrochemical reforming of ethanol to H2 is achieved at 150 °C in an autoclave electrochemical cell that allows the safe pressurization of the H2 produced as no O2 is evolved. The alkaline conditions are very aggressive to catalysts including noble metals like Pt and Pd. We report a highly active ethanol oxidation catalyst (PdCoNifoam) composed of Pd nanoparticles supported on nanostructured Co oxide structures grown on nickel foam. Treatment with phosphorous vapors at high temperature yields a thin coating of phosphate that confers enhanced stability to the electrode operating in an electrolysis cell at 150 °C. A combination of scanning electron microscopy (energy dispersive X-ray spectroscopy) and X-ray photoelectron spectroscopy reveal a 3D nano-flake surface with an external layer of phosphates that prevents Pd dissolution. The PdCoP@Nifoam catalyst was successfully used for ethanol electrochemical reforming at 150 °C with self-pressurization of the H2 produced by the electrochemical reaction.

The paper provides results from a hardware-in-the-loop experimental campaign on the operation of an air-source heat pump (HP) for heating a reference dwelling in Pisa, Italy. The system performances suffer from typical oversizing of heat emission devices and high water-supply temperature, resulting in HP inefficiencies, frequent on-off cycles, and relevant thermal losses on the hydronic loop. An experimentally validated HP model under different supply temperatures and part-load conditions is used to simulate the installation of a thermal storage between heat generator and emitters, in both series and parallel arrangements. Results relative to a typical residential apartment show that the presence of the thermal storage in series configuration ensures smoother heat pump operation and energy performance improvement. The number of daily on-off cycles can be reduced from 40 to 10, also saving one-third of electric energy with the same building loads. Preliminary guidelines are proposed for correctly sizing the tank in relation to the HP capacity and the average daily heating load of the building. A storage volume of about 70 L for each kilowatt of nominal heating capacity is suggested.

The aim of this paper is to expose the main involved physical phenomena underlying the alteration of convective heat transfer in a heat exchanger subjected to imposed vibrations. This technique seems to have interesting features and industrial applications, such as for efficiency increases, heat transfer rate control and cleanliness action. However, a clear description and comprehension of how vibrations may alter the convective heat transfer coefficient in a heat exchanger has still not been reached due to the complexity of the involved physical mechanisms. For this reason, after a presentation and a schematization of the analyzed thermodynamic system, the fundamental alterations of the thermo-fluid dynamics fields are described. Then, the main involved physical phenomena are exposed for the three cases of gaseous, monophasic liquid and boiling liquid mediums. Finally, on the basis of the characteristics of these described phenomena, some considerations and indications of general validity are presented.

We present an experimental investigation of the effect of ultrasound application to increase the heat-transfer coefficient for natural convection of a dielectric fluid. An experimental analysis is carried out to estimate the increase of the convective heat-transfer coefficient between an electronic board and a refrigerant fluid, the Fluorinert Electronic Fluid FC-72. For this purpose, an experimental apparatus composed of an electronic board, its electronic control circuit, and data acquisition systems have been designed and implemented. The data collected appear to confirm in some situations of practical interest the enhancement effect of the convective heat-transfer coefficient in connection with the use of ultrasound. The most favorable condition was observed with the fluid in quite low subcooled conditions.

The COVID-19 pandemic is changing the way individuals, worldwide, feel about staying in public indoor spaces A strict control of indoor air quality and of people's presence in buildings will be the new normal, to ensure a healthy and safe environment Higher ventilation rates with fresh air are expected to be a requirement, especially in educational buildings, due to their high crowding index and social importance Yet, in this framework, an increased use of primary energy may be overlooked This paper offers a methodology to efficiently manage complex HVAC systems in educational buildings, concurrently considering the fundamental goals of occupants' health and energy sustainability The proposed fourstep procedure includes: dynamic simulation of the building, to generate synthetic energy loads;clustering of the energy data, to identify and predict typical building use profiles;day-ahead planning of energy dispatch, to optimize energy efficiency;dynamic adjustment of air changes, to guarantee a safe indoor air quality Clustering and forecasting energy needs are expected to become particularly effective in a highly regulated context The technique has been tested on two university classroom buildings, considering pre-lockdown attendance This notwithstanding, quality and significance of the obtained thermal energy clusters push towards a benchmark post-pandemic application © 2020 The Authors, published by EDP Sciences

Estimating and optimizing the dynamic performance of a heat pump system coupled to a building is a paramount yet complex task, especially under intermittent conditions. This paper presents the “hardware-in-the-loop” experimental campaign of an air-source heat pump serving a typical dwelling in Pisa (Italy). The experimental apparatus uses real pieces of equipment, together with a thermal load emulator controlled by a full energy dynamic simulation of the considered building. Real weather data are continuously collected and used to run the simulation. The experimental campaign was performed from November 2019 to February 2020, measuring the system performances under real climate and load dynamics. With a water set point equal to 40 °C, the average heat pump coefficient of performance was about 3, while the overall building-plant performance was around 2. The deviation between the two performance indexes can be ascribed to the continuous on-off signals given by the zone thermostat due to the oversized capacity of the heat emission system. The overall performance raised to 2.5 thanks to a smoother operation obtained with reduced supply temperature (35 °C) and fan coil speed. The paper demonstrates the relevance of a dynamic analysis of the building-HVAC system and the potential of the “hardware-in-the-loop” approach in assessing actual part-load heat pump performances with respect to the standard stationary methodology.

The aim of this paper is to expose the main involved physical phenomena underlying the alteration of convective heat transfer in a heat exchanger subjected to imposed vibrations. This technique seems to have interesting features and industrial applications, such as efficiency increase, heat transfer rate control and cleanliness action. However, a clear description and comprehension of how vibrations may alter the convective heat transfer coefficient in a heat exchanger is no still reached due to the complexity of the involved physical mechanisms. For this reason, after a presentation and a schematisation of the analyzed thermodynamic system, the fundamental alterations of the thermo-fluid dynamics fields are described. Then, the main involved physical phenomena are exposed for the three cases of gaseous, monophasic liquid and boiling liquid mediums. Finally, on the basis of the characteristics of these described phenomena, some considerations and indications of general validity are presented.

Numerical results are presented for flow evolution, mass transfer and evaluation of the turbulent Schmidt number in a turbulent submerged free jet of air with small laminar Schmidt number (Sc = 0.1). A series of Large Eddy Simulation (LES) are carried on in the Reynolds number range from 5000 to 40,000. The numerical results are reported in terms of instantaneous and mean velocities, static pressure, passive scalar fields and turbulent Schmidt number. The numerical results show that the instantaneous cross-stream velocity and the static pressure are null in the Negligible Disturbance Flow (NDF) and the Small Disturbance Flow (SDF) of the instantaneous jet evolution, allowing a new definition of NDF and SDF. Similarly, the numerical mean static pressure is null in the Undisturbed Region of Flow (URF) of the mean evolution, allowing a new definition of URF. The turbulent Schmidt number shows differences at the two smallest Reynolds numbers, Re = 5000 and 10,000, in comparison to the previous numerical results, obtained with a laminar Schmidt number equal to Sc = 1. A theoretical model is proposed for the passive scalar diffusion in the Undisturbed Region of Flow (URF) and the Potential Core Region (PCR), under the hypotheses of self-similarity, according to the Tollmien and Gortler approaches. The solutions of the present theoretical models, at Sc = 0.1, are self-similar in the PCR and in good agreement with the LES numerical results of the passive scalar, while the passive scalar profiles are not self-similar in the URF at the smaller Reynolds numbers, differently from what happens with a laminar Schmidt number in the range 1–100. The theoretical model assumes a turbulent Schmidt number inversely proportional to the mean velocity gradient in the PCR, as suggested by the LES results. The numerical results of the ScT in the URF are variable in the range 0–0.85, which is a value commonly suggested in the literature. In the PCR the values of ScT are variable between zero and a maximum which is one order of magnitude greater than in the URF.

A large tube may still behave, to a certain extent, as a capillary in a micro-gravity environment. This very basic concept is here applied to a two-phase passive heat transfer device to obtain a new family of hybrid wickless heat pipes. Indeed, a Loop Thermosyphon, which usually consists of a large tube, closed end to end in a loop, evacuated and partially filled with a working fluid and intrinsically gravity assisted, may become a capillary tube in space condition and turn its thermo-fluidic behavior into a Pulsating Heat Pipe. This work presents the results obtained on such a hybrid device heated at 200 W both on board a sounding rocket (ESA REXUS 22, microgravity period ~120 s), and on ground in vertical and anti-gravity orientation. Since no steady state occurred in microgravity conditions, the comparison between flight and ground data focuses on the startup phenomenon, whereas the thorough ground test campaign describes the limits and performances of the device working in thermosyphon mode. The expected thermal behavior in microgravity conditions is between that of a purely conductive tube in anti-gravity conditions on ground and that of a gravity assisted thermosyphon. Since a microgravity period of approximately 120 s is not enough to reach a pseudo steady state regime, further investigation on a longer-term weightless condition is mandatory.

U-PHOS (Upgraded PHP Only for Space) is a project developed by a team of students from the University of Pisa with the goal to analyze and characterize the behavior of a Pulsating Heat Pipe (PHP), one of the most attractive two phases passive systems for thermal management in space applications. The PHP consists of a sealed serpentine capillary tube filled with a working fluid. The heat is efficiently transported by means of the combined action of phase change and capillary forces, so no extra equipment is required. The project aims at investigating the thermal response of such a device under a milli-gravity condition, in order to assess its effectiveness in space conditions. U-PHOS is one of the selected experiment of the REXUS/BEXUS programme, which allows European university students to carry out scientific and technical experiments on research rockets and balloons, thanks to a bilateral agency agreement between the German Aerospace Centre (DLR) and the Swedish National Space Board (SNSB) in collaboration with ESA. 19 students from the University of Pisa, with different backgrounds, compose the U-PHOS team. Students had the chance to completely design, build and test the experiment, which will flight up to space in March 2017. This paper intends to describe the work done by the students, their organization and how this experience empowered their careers, from both an academic and professional point of view.

The objective of this work is to study the increase of the convective heat transfer coefficient in the presence of ultrasound waves and, in particular, to find a relationship between the ultrasonic power and the effective pressure of water. The tests have focused on the heat exchange by natural convection, in single-phase conditions, at atmospheric pressure, between a cylinder, heated by means of the Joule effect, and distilled water, with and without the action of ultrasonic waves. The variables involved in the heat exchange have been varied within the range allowed by the experimental apparatus and the convective heat transfer coefficient has been maximized. The specific thermal flow has been chosen in a range compatible with applications in the field of electronics. For the first time the pressure of water at various ultrasonic power levels has been measured, in the vicinity of the cylindrical surface, thanks to the collaboration with the Naval Experimentation and Support Center (CSSN) of the Italian Navy in La Spezia, Italy.

The aim of this paper is to investigate the potential use of ultrasounds for improving the performances of heat exchangers. In a heat exchanger, the effect of ultrasonic vibrations is important both for heat transfer intensification and for the possibility of obtaining fouling reduction: the cumulative effect can determine an interesting advantage in term of overall heat transfer coefficient increase. After a general analysis of the topic, the paper analyse the results recently obtained in the two main fields of analysis, heat transfer coefficient enhancement and fouling reduction. The perspective of the use of acoustic fields and ultrasound for optimization of heat exchangers operation is some particular fields of application are discussed.

This work collects the experimental results obtained in the Thermal Fluid Dynamics Lab at the Department of Energy, Systems, Land and Constructions Engineering at the University of Pisa, concerning a basic physics research on the influence of ultrasounds in single phase free convection and in subcooled boiling, at atmospheric pressure. The ultrasounds are applied at the set frequency of 40 kHz, with a transducer output changing from 300 to 500W, on a circular horizontal cylinder heated by Joule effect, immersed in distilled water. The tests in single phase free convection, without ultrasonic waves, are validated by means of the classical correlations reported in literature, but they do not produce distinctive augmentation of the heat transfer. The enhancement of the heat transfer coefficient is maximum in subcooled boiling conditions (about 57%). In this regime a detailed investigation was performed to optimize the variables involved, such as the ultrasound generator power, the position of the cylinder and, especially, the subcooling degree. This paper, makes clear systematically the effects of ultrasounds on the heat transfer and shows as they could be very useful as cooling system for the last generation electronic components.

New data on the ancient landscape of Naples (southern Italy) during the middle and late Holocene from geo-archaeological excavations associated with public transport works were used to reconstruct the hill and coastal environment to the west of the ancient Graeco-Roman polis, where remains of human settlements date to the late Neolithic. The rich stratigraphic and archaeological records that emerged from the digs and from previous boreholes were measured and analysed by combining sedimentary facies analysis, tephrostratigraphy and archaeological data. Between the 5th and 4th millennia BP, a rocky profile with a wave-cut platform cutting across pyroclastites emplaced from the surrounding volcanoes was predominant in the coastal landscape. During the 3rd millennium BP, this rocky coast was progressively replaced by a sandy littoral environment primarily due to marine deposition, with a coastline located some hundred meters inland with respect to the modern one. The sedimentary record of the Greek and Roman periods indicates short-term fluctuations of the coastline, leading to the establishment of a backshore environment towards the end of the 6th century AD, when prograding river mouths and lobes of debris flows contributed to the advancing trend of the shoreline. The frequent archaeological remains from these periods indicate a stable settled area since Roman times. The shoreline was still subject to short-lived fluctuations between the 12th and 16th centuries, and attained its present position during the modern era with man-made reshaping of its profile. The construction of Relative Sea Level curves for two coastal sites reveals that the persistence of the foreshore environment in the Naples coastal strip during the 5th and 4th millennia BP was controlled by the counterbalancing effect of either the concurrent eustatic sea level rise or subsidence. On the other hand, the morpho-stratigraphic record for the last two millennia shows a significant correlation between sedimentation rate and settlement history, accounting for the dominant role of the anthropogenic forcing-factor in late Holocene landscape history. In particular, land mismanagement during Late Antiquity seems to have triggered a slope disequilibrium phase, exacerbating soil erosion and increasing the sediment accumulation rate in both foothill and coastal areas. Nonetheless, the environmental changes of the Chiaia coast during the last 2000 years clearly show volcanic–tectonic perturbations influencing coastline development up to the modern era.

Experimental data about the heat transfer from a heated 0.25 mm in diameter nickel wire to a submerged upward flow slot jet of distilled water are reported. The tests are carried on in forced convection regime, in sub-cooled and saturated boiling conditions. The influence on the heat transfer rate of different parameters is investigated, such as the jet exit velocity, the distance between the slot exit and the wire and the heat transfer regime, in particular the sub-cooling degree. The choice of the nickel is due to the opportunity to operate in a wide range of the jet exit velocity, thanks to its mechanical and thermometric characteristics. The main aim of this research was to find out the optimal conditions, in order to maximize the heat transfer coefficient enhancement, and moreover, to make a comparison between other results obtained in the 1990s by the same authors on horizontal circular cylinders, with the diameter one size order bigger than the present wire.

In this paper are reported the results of an experimental investigation about the heat transfer enhancement from vertical and downward inclined wall to air, in natural convection, by means of expired jets. The air was maintained at room temperature and the wall is heated by Joule effect. The temperature difference between the wall and the air was prefixed at 25 K and the wall placement had been varied from the vertical to different downward inclined positions (5°, 10°, 15°, 20°, 25° and 30°). The experimental results had shown an increase in the heat transfer coefficient, at the different wall inclinations, due to the jets; actually they had induced turbulence in the dynamic field, by interrupting the laminar flow. Our aim was to optimize the variables involved in the phenomenon, in order to find out the highest enhancement of the heat transfer coefficient values, caused by the jets. The variables were the number of active horizontal lines of jets, their activity and the inactivity time and their velocity. We had also investigated the conditions without jets and we found out that the heat transfer coefficient trend versus the downward inclination angles, could not be described by correlations present in literature. In fact, in the investigated range of the downward wall inclinations, the heat transfer coefficient did not may be simply correlated with the cosine of the angle, but it increased up to a maximum value, reached at 15°, and then decreased. The visualization by smoke had confirmed these results: the boundary layer thickness had followed this trend. In correspondence to the wall inclination equal to 15°, it reached its minimum value. Finally, to the purpose to link the experimental data, we had proposed a numerical correlation. The values calculated thanks to this one reported differences much lower than the computed experimental error.

This article describes the development of a high power density Direct Formate Fuel Cell (DFFC) fed with potassium formate (KCOOH). The membrane electrode assembly (MEA) contains no platinum metal. The cathode catalyst is FeCo/C combined with a commercial anion exchange membrane (AEM). To enhance the power output and energy efficiency we have employed a nanostructured Pd/C-CeO2 anode catalyst. The activity for the formate oxidation reaction (FOR) is enhanced when compared to a Pd/C catalyst with the same Pd loading. Fuel cell tests at 60 °C show a peak power density of almost 250 mW cm−2. The discharge energy (14 kJ), faradic efficiency (89%) and energy efficiency (46%) were determined for a single fuel charge (30 mL of 4 M KCOOH and 4 M KOH). Energy analysis demonstrates that removal of the expensive KOH electrolyte is essential for the future development of these devices. To compensate we apply for the first time a polymeric ionomer in the catalyst layer of the anode electrode. A homopolymer is synthesized by the radical polymerization of vinyl benzene chloride followed by amination with 1,4-diazabicyclo[2.2.2]octane (DABCO). The energy delivered, energy efficiency and fuel consumption efficiency of DFFCs fed with 4 M KCOOH are doubled with the use of the ionomer.

This research study focuses its attention on the local and temporal distribution of the entropy production generated by thermal irreversibilities as well as on the fact that they contribute, together with the entropy flow through the frontier, towards raising the solid entropy, under situations of thermal transient. For simplicity, a simple unidimensional model, the semi-infinite solid, for which several solutions depending on the Fourier equation time are well known, is investigated; they are here discussed with respect to their aspects of second principle. Moreover, it should be noticed that both entropy and entropy production are not linear in temperature. The principle of superposition is, therefore, not valid for them; this gets the remarks expounded in this paper to be considered as an exemplification of the entropic problems in simple cases, rather than a method for working out entropic solutions in more complex cases.

U-PHOS Project aims at analysing and characterising the behaviour of a large diameter Pulsating Heat Pipe (PHP) on board REXUS 22 sounding rocket. A PHP is a passive thermal control device where the heat is efficiently transported by means of the self-sustained oscillatory fluid motion driven by the phase change phenomena. Since, in milli-gravity conditions, buoyancy forces become less intense, the PHP diameter may be increased still maintaining the slug/plug typical flow pattern. Consequently, the PHP heat power capability may be increased too. U-PHOS aims at proving that a large diameter PHP effectively works in milli-g conditions by characterizing its thermal response during a sounding rocket flight. The actual PHP tube is made of aluminum (3 mm inner diameter, filled with FC-72), heated at the evaporator by a compact electrical resistance, cooled at the condenser by a Phase Change Material (PCM) embedded in a metallic foam. The tube wall temperatures are recorded by means of Fibre Bragg Grating (FBG) sensors; the local fluid pressure is acquired by means of a pressure transducer. The present work intends to report the actual status of the project, focusing in particular on the experiment improvements with respect to the previous campaign.

Background/Aims: The hepatotropic conjugate of adenine arabinoside monophosphate with lactosaminated poly-l-lysine (l-Poly(Lys)) must have a high solubility in order to be injected in a small volume compatible with the intramuscular route. In this paper the molecular weights of Poly(Lys) which allowed the synthesis of conjugates with the properties of high solubility and limited loss by the kidney were determined and a procedure for obtaining Poly(Lys) preparations with the required range of polymerization has been described. Methods: Conjugates were prepared using Poly(Lys) of different molecular weights obtained by the procedure described here or purchased from a commercial source. Their solubility and renal loss in mice was determined. Results: Poly(Lys) with molecular weights ranging from 45000 and 65000 Da guarantees high solubility and low renal elimination of the conjugates. Conjugate preparations with these properties, intramuscularly administered to woodchuch hepatitis virus-infected woodchucks for 37 days at a daily dose of 5.8 mg/kg exerted a strong antiviral activity. These preparations were devoid of acute toxicity in rat and caused no toxic effects when injected intramuscularly daily for 28 days at a dose ten times higher than that active in woodchucks. Conclusions: The results support the possibility of a clinical use of l-Poly(Lys) to obtain liver targeting of adenine arabinoside monophosphate for the treatment of chronic hepatitis B virus infection.

This paper collects the experimental results obtained in the Thermal Fluid Dynamics Lab at the Department of Energy and Engineering Systems at the University of Pisa, concerning the influence of ultrasounds in single phase free convection and in pool saturated boiling, at atmospheric pressure. The authors have just reported in previous papers their results about the enhancement induced by the presence of ultrasonic waves in subcooled boiling conditions. The ultrasounds are applied at the set frequency of 40 kHz, with a transducer output changing from 300 to 500 W, on a circular horizontal cylinder heated by Joule effect, immersed in distilled water. The tests in single phase free convection, without ultrasonic waves, are validated by means of the classical correlations reported in literature. Moreover, the authors managed to correlate the data also in presence of ultrasounds. The enhancement of the heat transfer coefficient is lower than the one obtained in subcooled boiling and with regards to the saturated pool boiling conditions, as far as for subcooling degrees very close to the saturation, the ultrasounds cause a decrease of the heat transfer. At the same time, the ultrasounds induce the critical heat flux (CHF) at higher heat flux compared with the case without ultrasounds. Also in saturated pool boiling, without ultrasonic waves, the experimental value of the CHF is compared with the one obtained by equations reported in the literature. This paper, joined to the others published by the authors, makes clear systematically the effects of ultrasounds on the heat transfer and shows as they could be very useful in the last generation electronic components cooling.

This work focuses on the use of ultrasounds in heat transfer fields. Under particular conditions, ultrasonic waves induce a convection coefficient increase. This initial research work, indicates that there are some practical applications in the cooling of the latest generation electronic components. In the first part of this paper, some background on this subject is reported. The ultrasound's influence on heat transfer rate has been observed since the 60's: different authors studied the cooling effect due to ultrasonic waves from different heat transfer regimes. The most investigated configuration was a thin platinum wire immersed in water. Later, a bibliographic research on possible practical applications of ultrasounds was carried out. This research focused in particular on the issue for 3D highly integrated electronic components. For these systems the thermal problem is a major challenge, because they cannot exceed critical temperatures, after which they could be damaged irreversibly. On the basis of our experimental results, ultrasounds could represent a valid means to overcome these thermal problems. Finally, the paper presents a series of experiments performed in the Thermal-Fluid- Dynamic Lab at the Energy and Engineering Systems Department of the University of Pisa. The experiments provide systematic evidence of ultrasonic waves effects, on free convection heat transfer, from a heated circular cylinder to sub-cooled water, at atmospheric pressure. Many variables involved in the heat transfer rise were tested, for example: the ultrasonic generator's power, the position of the heater inside the ultrasonic tank, the variation of the water sub-cooling degree, as function of the heat flux needed dissipating. The aim of the experiment was to find out the set of optimal conditions, in order to successively apply all the results to real packaging systems, as mentioned before. The maximum increase in the heat transfer coefficient, due to ultrasonic waves, was 57%.

The main aim of this work is to investigate experimentally the influence of ultrasonic waves, on the heat transfer enhancement, from a stainless steel circular cylinder to distilled water, in subcooled boiling conditions. This study has carried on for a few years at the Department of Energetics “L.Poggi.” The effect was observed since the 1960s: Different authors had investigated the cooling effect due to the ultrasonic waves at different heat transfer regimes, especially from a thin platinum wire to water. They had found out that the highest heat transfer coefficient enhancement was in subcooled boiling conditions. So this paper has the purpose to clarify the physical phenomenon and optimize a large range of variables involved in the mechanism. It reports the experimental results obtained with ultrasound at the frequency of 38 kHz, at two different subcooling degrees, ΔTsub=25°C and 35°C. The heat fluxes applied on the cylinder, the ultrasonic generator power Pgen, and also the placement of the heater inside the ultrasonic generator tank were varied. The ultrasonic waves seem to be very useful for a practical application in the last generation electronic components’ cooling: They need dissipating huge heat fluxes and avoiding high temperatures (≈150°C), after that they could damage themselves.

This work represents an experimental basic research aimed to investigate the influence on the heat transfer rate of the ultrasounds, in free convection and in presence of liquid. In fact the ultrasonic waves induce, thanks to vibrations, turbulence on the dynamic field, and so an increase of the convection coefficient. The heater is a circular cylinder, immersed in distilled water, and warmed up by Joule effect. This study has carried on for 1 year at Energetics Department “L. Poggi”. The effect was observed since 1960s: different authors had studied the cooling effect due to the ultrasonic waves at different heat transfer regimes, especially from a thin platinum wire to water. We have chosen to investigate the subcooled boiling regime, because this one is the best condition for the heat transfer enhancement, according to the scientific literature. We have carried out a wide experimental study, varying the different water subcooling degrees, the ultrasonic generator power, the ultrasound frequency and the placement of the heater inside the ultrasonic tank, in function of the range of the values of heat flux per unit surface needed dissipating. These values were supplied us by a possible practical application of the ultrasonic streaming: the cooling of 3D highly integrated electronic components. These packaging systems should have to provide all future devices, such as electronics, actuators, sensors and antenna. In fact, for these systems the thermal problem is a critical challenge, because they do not have to overtake critical temperature, after that they could damage irreversibly. Moreover, the traditional cooling systems used in electronic do not seem to be useful for them. On the contrary, the results obtained with ultrasounds, allow heat transfer coefficient enhancement of about 50% to be reached. The purpose is to find out the set of optimal conditions, in order to apply successively all the results to a real packaging system.

This paper aims to determine the heat transfer enhancement in natural convection between a downward-facing inclined wall, heated by Joule effect, and air in the presence of small air pulsating expired jets, in conditions of medium temperature difference between wall and air, namely 40 K. Experimental measurements have been taken both with and without pulsating expired jets. The wall is kept in condition of uniform temperature. The expired jets blow out perpendicularly from the wall surface. An infrared thermo-camera was used to check the wall temperature uniformity. Hot-wire anemometer and visualization with smoke were used to find information on the air velocity field. The wall inclination angle which maximizes the convective heat exchange near the leading edge has been investigated too.

The main aim of this work is to investigate experimentally the influence of ultrasonic waves, on the heat transfer enhancement, from a stainless steel circular cylinder to distilled water, in subcooled boiling conditions. This study has carried on for a few years at the Department of Energetics “L.Poggi”. The effect was observed since ’60s: different authors had investigated the cooling effect due to the ultrasonic waves at different heat transfer regimes, especially from a thin platinum wire to water. They had found out that the highest heat transfer coefficient enhancement was been in subcooled boiling conditions. So this paper has the purpose to clarify the physical phenomenon and optimize a large range of variables involved in the mechanism. It reports the experimental results obtained with ultrasound at the frequency of 38 kHz, at two different subcooling degrees, ΔTSUB = 25 and 35°C. The heat fluxes applied on the cylinder, the ultrasonic generator power, Pgen and also the placement of the heater inside the ultrasonic generator tank, are been varied. The ultrasonic waves seem to be very useful for a practical application in the last generation electronic components cooling: they need dissipating huge heat fluxes and avoiding high temperatures (≈150°C), after that they could damage themselves.

Heat transfer from a platinum wire 0.2 mm. in dia., heated by Joule effect, to an impinging upward flow submerged slot jet of distilled water is studied in two–phase conditions. A new experimental apparatus is built for this experimental activity. Different geometrical configurations were investigated in order to find out which of them could maximize the heat transfer coefficient. Its dependence on some parameters as jet velocity, heat flux and distance between exit jet and wire is also examined. In the future the results of this paper will be compared with the previous ones presented in literature, referred to cylinders of one size order bigger than the platinum wire and the same slot, all parameters being equal.Copyright © 2009 by ASME

The present communication deals with the tests for the validation of the DJOSER steady-state thermal simulation program, purposely designed for power electronic assembling structures and which is based on the resolution of analytical relationships. The validation experiments were carried out theoretically by comparing the thermal maps with those obtained using standard finite-elements programs and yielding temperature accuracy below 1%. Experimental tests were also performed on purposely built multi-layer structures and industrial circuits with power diodes mounted in naked-chip configuration. The simulated maps were compared with accurate thermo-graphic recordings and showed a good agreement, testifying the validity of the mathematical model.

Heparins are useful for the protection of residual renal function in several nephropathies, but the anticoagulant action and the need of parenteral administration are two main drawbacks limiting their use in chronic renal failure patients. Heparan sulphate (HS) is a heparin-like mucopolysaccharide devoid of anticoagulant action and active orally. In this study, the effects of HS oral administration have been evaluated in 18 subtotally nephrectomized rats;18 untreated remnant kidney rats served as control. No mortality was observed in the HS-treated rats, whereas in the control rats the survival rate was 72.2% at 18 weeks. At the end of the study, HS-treated rats showed lower urinary protein excretion (44 ± 22 vs. 80 ± 54 mg/24 h , p < 0.01), lower urea plasma levels (75 ± 34 vs. 134 ± 105 mg/dl, p < 0.01) and higher creatinine clearance (66 ± 15 vs. 47 ± 21 ml/min · 102, p < 0.05) than control rats. Remnant kidney weight (2.3 ± 1.1 vs. 1.3 ± 0.2 g, p < 0.01) and heart weight (1.3 ± 0.2 vs. 1.1 ± 0.1 g, p < 0.05) were greater in the control than in the HS-treated rats, as well as the systemic blood pressure values (167 ± 19 vs. 115 ± 32 mm Hg, respectively, p < 0.001). The remnant kidney histological examination in the HS-treated rats showed a lower prevalence of glomerular sclerosis, mesangial proliferation, and a much less evident tubulointerstitial damage than in controls. The antiproliferative and anti-inflammatory actions of HS together with its protective action on the endothelium are the putative mechanisms that could account for our findings. In conclusion, the present study supports evidence of an antiproteinuric and a renoprotective effect of orally administered HS in subtotally nephrectomized rats. This is in keeping with the well-known effects exerted also by other heparins, but the effectiveness of an orally available heparin-like product in this animal model could suggest the possibility of a clinical use also in progressing chronic renal failure patients.

The results of an experimental investigation concerning the heat transfer from three cylindrical heaters to a water jet are reported in the form of correlating equations, which express the Nusselt number versus the Reynolds, Prandtl and Grashof numbers and some dimensionless ratios characterising the configuration. As the experienced range of the thermal flux is wide (2·104 ≤ q ≤ 6·105 W·m−2), the influence of the free convection, which was shown to be negligible in previous studies, is carefully investigated in the present one. This influence appears still negligible up to the maximum value of q for the heater impinged by the jet; on the contrary it is remarkable for the heaters lying in its wake. Another aspect which is carefully studied is the influence both of the ratios characterising the configuration and of the impingement direction: accordingly the values of these ratios and the kind of impingement which yield the maximum Nusselt number are clearly singled out. The investigation is completed by some visualization experiments which allow us to qualitatively clarify some aspects of the interaction between the dynamic and thermal fields.

The fibrinolytic and anticoagulant activities of heparan sulphate (HS) and dermatan sulphate (DS) were compared with those of heparin using in vitro tests. Our results demonstrate that HS has higher profibrinolytic activity than heparin and DS. Although 50 times less potent than heparin in inhibiting factor IIa, HS is three times more active than DS. The action of HS resides in HCII-mediated factor IIa inhibition combined with an ATIII-mediated inhibition. DS has no action on ATIII-mediated inhibition of factor IIa. The comparison of the anticoagulant activities of the, three compounds confirmed the very limited anticoagulant effect of both HS and DS in comparison with heparin.

Kappa-carrageenan (kappa-carrageenin; kappa-carragheen) was found to be thrombogenic in rats. After i.p. injection of 3 mg/kg of kappa-carrageenan the thrombosis extended to a maximum 7.5 cm from the tip of the tail. Infarction frequency as well as the extent of infarction were inhibited by oral administration of a new heparan sulphate of low molecular weight (LMW-HS) (alpha-idosane). Mesoglycan and heparin were active when administered by parenteral route, and aspirin showed no effect; mesoglycan was inactive at 50 mg/kg per os. The present data confirm the validity of this experimental model for evaluating the protective effects of antithrombotic drugs and show the activity of oral administration of a new drug endowed with fibrinolytic activity.

An experimental investigation was carried out on the heat transfer due to a submerged slot jet of water impinging on a circular cylinder in crossflow. The cylinder diameter and the slot width are of the same order of magnitude, specifically D s = 2.0 and 3.0 mm and D c = 2.5 and 3.0 mm . The experimental apparatus allowed variation of the slot width, the cylinder diameter, and the distance from nozxle exit to heater. Conditions of impingement from the bottom (ascending flow) were taken into consideration as well as impingement from above (descending flow). The Nusselt number was determined as a function of Reynolds and Prandtl numbers in the range 1.5 × 10 3 4 , 2.7 1.5 ≤ z/D s ≤ 10 . The experimental data were correlated with a simple equation that fits 90% of the data with a precision of 20%.

SUMMARY Over the past few years, numerous pharmacokinetic techniques based on Michaelis-Menten principles have been proposed to individualize PHT dosage and predict plasma levels. The choice of one of these techniques for clinical use depends on the number of steady state concentration-versus-dose (Css-D) data pairs that are known in the patient for whom the predictive technique is to be applied. The most frequent clinical situations in which these predictions are made can be divided into three groups for each patient considered—Case A: only one previous Css-D data pair is known; Case B: two previous Css-D data pairs are known; Case C: three previous Css-D data pairs are known. Of the available techniques that can be applied in case A, we compared the population clearance (PC) method and the Bayesian feedback (BF) method. The procedure for comparing the predictive capabilities of these methods was very similar to that adopted in a recent report by Vozeh et al. Our findings showed that the PC method should be preferred for clinical use under this circumstance. Two predictive techniques suitable for use in Case B (BF and Mullen & Foster methods) were compared. In this case, the BF method was shown to be more accurate. As regards Case C, three pharmacokinetic techniques were compared: the Mullen and Foster method, the iterative least-squares (ILS) technique, and the BF method. The ILS technique was found to be the most accurate in this case. Finally, we describe a programmable calculator procedure which uses the PC, BF or ILS methods in Cases A, B and C respectively. The advantage in using this procedure is that the choice of the method to be used and its subsequent application are made automatically by a unique calculator programme.

A programmable calculator procedure allowing nonlinear least-squares fit to pharmacokinetic data conforming to the Michaelis-Menten model is described. Model parameter estimation is performed according to the iterative Gauss-Newton technique as modified by Hartley. This procedure thus employs the same theoretical approach used by most pharmacokinetic computer programs. No programming skill is needed to run the program described. The proposed procedure is discussed in detail and applied to some sets of pharmacokinetic data.

The paper analyzes the design of a typical solution for a smart energy system. It examines a particular plant, evaluating the integration of a Photovoltaic (PV) system and a Ground-Source Heat Pump (GSHP) for residential building service. The idea is to develop a system that maximizes self-consumption of the renewable energy generated by a small-sized solar array installed on the building. The case is analyzed starting from the results of a long-term experimental analysis of a real plant in Pisa. The analysis concerns the energy balance of the system during a year with a special attention on the operation of the two different systems, PV array and GSHP. Some indications on the possible optimum design of this solution are proposed and discussed and analyzed.