Analysis of a double source heat pump system in a historical building

This work presents the case study of the retrofitting of a historical building of the University of Padua, equipped with a hybrid heat pump system, which uses as heat source/sink the ground and ambient air. The building is located in Padua (Italy) and it is a historical complex of the late 1800, previously used as a geriatric hospital, in which a retrofit process is occurring in order to build the new humanistic campus of the Padua University reaching the highest energy efficiency. The refurbishment is in progress and regards both the building envelope and the plant-system. The building is equipped with two types of heat pumps: the first one is coupled to the ground with borehole heat exchangers and the second is a common air-to-water heat pump. The entire building plant system has been investigated through integrated computer simulations making use of EnergyPlus Software. A new control strategy in order to manage the two types of the heat pumps has been developed in order to increase the energy efficiency. The results outline the potential of the computer simulations in order to control the hybrid heat pump system. In fact, a suitable switch temperature was found in order to move from ground to air source/sink for the heat pumps. In addition, this strategy allows the control of the thermal drift of the ground temperature throughout the years

Double source heat pump: A case study

The design of a Ground Source Heat Pump (GSHP) system is critical because design choices affect the system's energy performance and operating conditions. If the thermal load profile on the ground side is unbalanced the ground temperature will change throughout the time and, consequently, also the energy efficiency of the heat pump. This phenomenon is known as "ground thermal drift". A possible solution to avoid this inconvenience is the adoption of a hybrid system.In this work a double source heat pump is investigated, i.e. the heat pump can use air or ground as heat source or heat sink. The case study is an office building located in the city of Padova (Italy). The building load profile is cooling dominant and a thermal drift can be observed in the monitoring records. A new water-to-water heat pump coupled to the boreholes and also to an air-cooled condenser was recently installed in order to tackle the thermal drift of the ground.Detailed computer simulations of the system were carried out via EnergyPlus software to investigate the energy performance of the system and the control strategy for switching between the heat sources (air or ground). The study shows the advantages of the double source heat pump

Nuclear fragmentation cross section measurements with the FOOT experiment

FOOT (FragmentatiOn Of Target) is an applied nuclear physics experiment that aims at a full characterization of the nuclear fragmentation processes of interest for Particle Therapy and Radiation Protection in Space. The physics program foresees a set of measurements in direct and inverse kinematics using particle beams and targets with composition similar to human tissues and spacecraft shielding materials. The final goal of the experiment is the measurement of double differential cross sections with respect to angle and fragment energy in the 100-800 MeV/u range with a precision better than 5%. The FOOT Collaboration is currently completing the development of the apparatus and data acquisition campaigns with partial setups have already started. In this paper, an overview of the current status of the experiment is given, together with a summary of the preliminary results obtained from the first measurements with 16O beams

Charge identification of nuclear fragments with the Time-Of-Flight detectors of the FOOT experiment

Charged Particle Therapy (CPT) is an increasingly used technique in the treatment of deep-seated solid tumors. The rationale for this approach is the favorable depth-dose profile of heavy charged particles with respect to conventional X-rays. This is characterized by low energy deposition in the entrance channel, followed by a high energy release at a certain depth: the Bragg Peak. This behavior makes it possible to spare healthy tissues while delivering high dose to the tumor. CPT represents a consolidated treatment procedure in clinical practice. Still, research is ongoing to further improve the accuracy of Treatment Planning Systems, by including advanced Monte Carlo models into the dose calculations. One of the many topics discussed in CPT is the contribution of nuclear fragmentation processes to beam dose profiles in both proton and heavy ion therapy. While in proton therapy the short-range recoil nuclei generated in target fragmentation processes could lead to an increased dose in the entrance channel, in ion therapy projectile fragments generate an additional dose tail behind the Bragg Peak. However, it is difficult to exactly evaluate the contribution of fragmentation products to total dose distributions because of the lack of experimental cross section data in the energy range of CPT. The aim of the FOOT (FragmentatiOn Of Target) experiment is to measure the double differential cross section of nuclear fragmentation processes relevant for CPT. The apparatus will exploit inverse and direct kinematics to accurately characterize both target and projectile fragmentations. To achieve this goal, the system needs to measure the mass, charge, velocity and energy of the nuclear fragments produced by different beams impinging on tissue-like targets. This thesis focuses on the development and validation of the charge (Z) identification procedure, based on energy deposition (∆E) and Time-Of-Flight (T OF ) measurements performed with the Start Counter (STC) and TOF-Wall (TW) of FOOT. The former is a thin foil of plastic scintillator, while the latter is made of two orthogonal layers of 20 scintillating bars each. These two detectors provide the ∆E (TW) and T OF (TW and STC) values needed to calculate the Z of nuclear fragments traveling through FOOT. The data analyzed in this work have been acquired during two test beam data takings performed in early 2019. The first one was carried out at CNAO (Centro Nazionale di Adroterapia Oncologica, Pavia) and was dedicated to energy and T OF calibration measurements with protons (60 MeV) and carbon ions (115, 260, 400 MeV/u). The second data taking was performed at GSI Helmoltz Centre for Heavy Ion Research (Darmstadt, Germany). In this case, an oxygen ion beam (400 MeV/u) was used in different acquisitions to both calibrate the detectors and observe the nuclear fragmentations on a 5 mm graphite target. In this work, data analysis software has been developed to process the raw detector signals. The resulting quantities are then compared to Monte Carlo simulations to calibrate the detectors in terms of both ∆E and T OF . Furthermore, the β of the particles is retrieved from T OF and calibrated data are used to calculate the Z of nuclear fragments through the Bethe-Bloch formula. A direct comparison with Monte Carlo results is also presented as a validation of the procedure. Using the developed reconstruction and analysis framework, the ∆E and TOF measurements have shown energy and time resolution of a few MeV and 50-80 ps respectively. The resulting Z values have been reconstructed with an uncertainty of 2 to 6%, in agreement with the requirements of FOOT

IMPRESSÕES DE ESTUDANTES UNIVERSITÁRIOS SOBRE A PRESENÇA DAS MULHERES NA CIÊNCIA

O objetivo deste trabalho é analisar a presença das mulheres nas ciências naturais nos aspectos histórico, social e epistemológico e tem como objetivo esclarecer as formas como esta presença ocorre. É feita uma análise de uma pesquisa realizada com estudantes universitários de um curso de licenciatura em física sobre a relação entre as mulheres e a ciência. São analisadas, também, as estratégias e práticas pedagógicas de educação científica que melhor se adaptem ao perfil feminino para permitir que professores de ciências naturais atuem como agentes de mudanças de modo a atrair mais mulheres para este campo de conhecimento

A comparison of numerical simulation methods analyzing the performance of a ground-coupled heat pump system

Ground-coupled heat pumps are increasingly being utilized to heat and cool buildings. Although it is difficult to size and to predict their behavior and performance, their design can be optimized via simulations. EnergyPlus is a popular energy simulation program for modeling building heating and other energy flows and, since it is organized to consider borehole heat exchangers via the well-known g-functions approach, it can be used advantageously for that purpose. The Capacity Resistance Model is another recent numerical simulation tool devoted to ground and borehole heat exchangers. In this work, two methods to calculate the g-fucntions were analyzed, using as case-study a real office building, whose imbalance between the heat extracted and injected into the ground was found to be appreciable. The energy imbalance involves a ground temperature drift affecting the system efficiency. The results of the EnergyPlus g-functions and the Capacity Resistance Model model approaches were compared. The capacity of the two methodologies to accurately simulate this phenomenon were analysed also with reference to the available building's long-term monitoring data. The analysis showed the importance of using g-functions suitable to reflect the layout of the borehole field, in order to correctly evaluate the energy performance of the entire ground source heat pump system

A simplified model for large spaces

In the last years large spaces have been becoming very diffused in new buildings (atria, show- rooms, etc.). The study of the indoor climate in these spaces is very difficult, due to problems related to air stratification. Generally CFD programs (Computational Fluid Dynamics) are used; they are able to solve air motion in accurate way but steady state simulation or simula-tion of only short time periods can be obtained. Furthermore CFD need surface temperatures as input and thermal behaviour in time domain is difficult to obtain, while for energy purposes the dynamic behaviour of the whole environment is needed. In this paper a simplified model taking into account heat balance and air motion for large spaces is presented; it enables to simulate a large room obtaining information about the air stratification in height. It derives from detailed model DigiThon, which is based on transfer function method, and it allows to simulate all types of radiant systems. The room is divided into n volumes one above the other, as to take into account the possible air stratification. It is possible to consider air inlet/outlet and internal loads. In this way one year dynamic simulation may be carried out, thus allowing to get the temperatures of the n volumes in height. A comparison with CFD program is shown, as test the developed model