Technical and Cost-optimal Evaluation of Thermal Plants for Energy Retrofitting of a Residential Building

Abstract With the adoption of the recast EPBD in 2010, EU Member States faced new tough challenges, moving towards new and retrofitted nearly-zero energy buildings by 2020 and the application of a cost-optimal methodology for setting minimum requirements for both the envelope and the technical systems. Attention often is focused on building envelope technologies however nowadays technical systems can be a powerful instrumental factor in achieving high levels of energy efficiency. Thermal systems producing heating and cooling have higher investment costs but it is possible to demonstrate that in a long term they are cost effective related with traditional high efficient technologies. Refurbishment and energy retrofitting in residential buildings is frequently approached with standard and traditional technologies preventing the penetration of different but already consolidated solutions. The paper shows the technical and economical comparison between three technical systems (gas boiler, ASHP and GSHP) as option to replace an oil boiler after a whole refurbishment of an apartment residential building in Milan, Italy. The retrofitting of the envelope was standard nevertheless the most innovative choice was on thermal system

Solar Heating and Air-Conditioning by GSHP Coupled to PV System for a Cost Effective High Energy Performance Building

Abstract Energy requirements for new buildings show the strong direction given by UE Directives to improve energy performance in buildings according to economic feasibility. Nowadays it is possibile to const ruct new buildings reaching a substancial reduction in energy consumption containing prices and time for the construction. In architectural competitions are always included architectural, energy and economic parameters of quality which are decisive in the success of the project design. A Housing Contest to collect projects with high performance and low cost for residential buildings for the Municipality of Comune di Milano, Italy, and the future construtions in the local area was launched by the to involve architects and professionals on the future development of the urban landscape giving specific requirements to achieve high performance. These requirements were focused on energy quality, acoustic quality, quality of the building site, guaranteed time schedule, prefabrication, economic affordability in comparison with the market trend of costs. The project presented in the paper is one of the chosen building by the Municipality to represent a pilot project for possible future constructions. In the Contest all the design group were in team with a builder to verify and guarantee the costs of the construction. The high energy performance required coupled to the low cost assured by the projects gave the Municipality a good example of how is possible to fulfill quality levels recommended by EU Directives and national regulations. In the Contest a high energy performance for heating was compulsory. The project described in the following paragraphs not only fulfill this energy requirement but also is almost self-sufficiency since it provides the energy for heating, cooling and common electrical demand

Development and testing of a multi-fuel micro-CHP conversion kit

This paper describes the development of a kit for converting a spark-ignition engine installed on small-size generators in order to allow their functioning with multiple fuels, with particular reference to low-boiling-point fuels. The kit can be easily added to technological systems which have been on the market for a long time. In addition, depending on the local conditions of use, operation in cogeneration is also possible, which increases the total efficiency of such generators. The solution developed is technically simple, robust, reliable and versatile, since it can be fed with different fuels, and it can be used both for grid-connected and off-grid applications, with particular reference to the developing Countries. The results of the first phase of technical development of the system and the experimental tests carried out with LPG and bioethanol are hereby presented. They attest the feasibility of using the conversion kit in a commercial power unit and they demonstrate that the actual performances are broadly consistent with the calculated results. The overall efficiency (electric and thermal) of the prototype system reaches a value close to 40% in conditions of rated load, almost doubling the generation efficiency of the system before its conversion. Any further developments of the research will be dedicated to better investigate also the environmental and economic aspects of the kit in different operating contexts, as well as to test other suitable fuels

Highlights of recent SPIDER results and improvements

Three years of experiments on SPIDER allowed characterization of the main features of the source plasma and of the negative ion beam, in the original design configuration. For the large dimensions of the source chamber, and of the extraction area, the investigation of the single-beamlet currents and of the source plasma uniformity had to be carried out to extend the knowledge gained in smaller prototype sources. The configuration of the multiple RF drivers and filter field topologies were found to cause a peculiar behavior in the plasma confinement in the drivers, creating left-right asymmetries which were also visible in the extracted negative ion currents, even after the early implementation of a new scheme of plasma-grid current send and return busbars that greatly improved performance at high filter fields. The plasma properties in the driver and expansion region as well as the positive ion energy at the extraction region were studied in different experimental conditions, and interpreted also with the support of numerical models, suggesting that an improved plasma confinement could contribute to the increase of the plasma density, and to a certain extent to a lowering of the plasma potential profile; both effects shall contribute to increase the presence of cold negative ions for the formation of low-divergence beamlets. Early results related to unwanted RF discharges on the back of the plasma source and the gas conductance of the beam source suggested the reduction of the vessel pressure as mitigation, leading to the definition of a new pumping system. The difficulties related to the simultaneous operation, stable control and high-power operation of multiple RF self-oscillating vacuum tube based RF generators were an unambiguous obstruction to the experimentation, calling for the implementation of RF solid-state amplifiers. The initial tests related to caesium management, the non-uniform plasma properties at different locations across the plasma grid, and the challenges in the measurement of the current and divergence of the accelerated beamlet, unambiguously resulted in the need of new diagnostic systems to investigate with better resolution the spatial uniformities. This contribution summarises how the main experimental findings in the previous experimental campaigns are driving modifications to the SPIDER experiment, during the present shut down, in view of future operations

SPIDER, the Negative Ion Source Prototype for ITER: Overview of Operations and Cesium Injection

An overview of the recent operations and the main results of cesium injection in the Source for the Production of Ions of Deuterium Extracted from Rf plasma (SPIDER) negative ion source are described in this contribution. In experiments without cesium injection, all SPIDER plants were tested to verify the basic expectations on the operational parameters (e.g., electron cooling effectiveness of magnetic filter field) and to determine its operational region. For beam properties, it was shown that the current density varies across the beam in the vertical direction. In preliminary cesium experiments, the expected increase of negative ion current and simultaneous decrease of co-extracted electrons were found, along with the influence of the control parameters (polarization of the plasma electrodes, magnetic filter field) on the SPIDER beam uniformity in the horizontal and vertical directions. It was shown that non-Gaussian tails can be identified in the angular distribution on the plane perpendicular to the beam propagation direction. Stray particles, nonhomogeneous beam and large divergence might result in unexpected heat and particle loads over ITER neutral beam injector (NBI) accelerator grids; it is the goal of SPIDER to assess and possibly to identify suitable methods for controlling these beam features. A major shutdown, planned for late 2021, to solve the issues identified during the operation and to carry out scheduled modifications, is outlined. Such improvements are expected to allow SPIDER to pursue the ITER requirements in terms of negative ion current, electron-to-ion ratio, and beam duration

Lessons learned after three years of SPIDER operation and the first MITICA integrated tests

ITER envisages the use of two heating neutral beam injectors plus an optional one as part of the auxiliary heating and current drive system, to reach the desired performances during its various phases of operation. The 16.5 MW expected neutral beam power per injector is several notches higher than worldwide existing facilities. In order to enable such development, a Neutral Beam Test Facility (NBTF) was established at Consorzio RFX, exploiting the synergy of two test beds, called SPIDER and MITICA. SPIDER is dedicated developing and characterizing large efficient negative ion sources at relevant parameters in ITER-like conditions: source and accelerator located in the same vacuum where the beam propagates, immunity to electromagnetic interferences of multiple radio-frequency (RF) antennas, avoidance of RF-induced discharges on the outside of the source. Three years of experiments on SPIDER have addressed to the necessary design modifications to enable full performances. The source is presently under a long shut-down phase to incorporate learnings from the experimental campaign, in particular events/issues occurred during operation, which led to the identification of improvement opportunities/necessities (e.g. RF discharges, local burns, water leaks, other damages, configuration/design upgrades to maximize chances/margin to quest target parameters). Parallelly, developments on MITICA, the full-scale prototype of the ITER Neutral Beam Injector (NBI) featuring a 1 MV accelerator and ion neutralization, are underway including manufacturing of the beam source, accelerator and the beam line components, while power supplies and auxiliary plants, already installed, are under final testing and commissioning. Integration, commissioning and tests of the 1 MV power supplies are essential for this first-of-kind system, unparalleled both in research and industry field. 1.2 MV dc insulating tests of high voltage components were successfully completed. The integrated test to confirm 1 MV output by combining invertor systems, DC generators and transmission lines extracted errors/accidents in some components. To realize a concrete system for ITER, said events have been addressed and solutions for the repair and the improvement of the system were developed. Hence, NBTF is emerging as a necessary facility, due to the large gap with existing injectors, effectively dedicated to identify issues and find solutions to enable successful ITER NBI operations in a time bound fashion. The lessons learned during the implementation on NBTF and future perspectives are here discussed

Lessons learned after three years of SPIDER operation and the first MITICA integrated tests

ITER envisages the use of two heating neutral beam injectors plus an optional one as part of the auxiliary heating and current drive system, to reach the desired performances during its various phases of operation. The 16.5 MW expected neutral beam power per injector is several notches higher than worldwide existing facilities. In order to enable such development, a Neutral Beam Test Facility (NBTF) was established at Consorzio RFX, exploiting the synergy of two test beds, called SPIDER and MITICA. SPIDER is dedicated developing and char- acterizing large efficient negative ion sources at relevant parameters in ITER-like conditions: source and accel- erator located in the same vacuum where the beam propagates, immunity to electromagnetic interferences of multiple radio-frequency (RF) antennas, avoidance of RF-induced discharges on the outside of the source. Three years of experiments on SPIDER have addressed to the necessary design modifications to enable full perfor- mances. The source is presently under a long shut-down phase to incorporate learnings from the experimental campaign, in particular events/issues occurred during operation, which led to the identification of improvement opportunities/necessities (e.g. RF discharges, local burns, water leaks, other damages, configuration/design upgrades to maximize chances/margin to quest target parameters). Parallelly, developments on MITICA, the full-scale prototype of the ITER Neutral Beam Injector (NBI) featuring a 1 MV accelerator and ion neutralization, are underway including manufacturing of the beam source, accel- erator and the beam line components, while power supplies and auxiliary plants, already installed, are under final testing and commissioning. Integration, commissioning and tests of the 1 MV power supplies are essential for this first-of-kind system, unparalleled both in research and industry field. 1.2 MV dc insulating tests of high voltage components were successfully completed. The integrated test to confirm 1 MV output by combining invertor systems, DC gener- ators and transmission lines extracted errors/accidents in some components. To realize a concrete system for ITER, said events have been addressed and solutions for the repair and the improvement of the system were developed. Hence, NBTF is emerging as a necessary facility, due to the large gap with existing injectors, effectively dedicated to identify issues and find solutions to enable successful ITER NBI operations in a time bound fashion. The lessons learned during the implementation on NBTF and future perspectives are here discussed