Tommaso Toppi

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• Ph.D. in Energy Engineering
• Professor (Associate) at Politecnico di Milano

The decarbonization process of the industry and the heating sector, underway in Europe, directly involves heating, cooling, ventilation, and air conditioning systems. In this context, heat pump technologies play a key role in having the ability to be powered by decarbonized energy carriers (i.e., electricity from renewables for vapor compression cy...

PUSH2HEAT is an EU-funded project aimed at scaling up heat upgrading technologies to overcome technical, economic, and regulatory barriers. The project focusses on four different technologies with supply temperatures ranging from 90°C to 160°C, integrating them into the paper and chemical industries. Demonstrations of the four technologies will tak...

The application of life cycle thinking and the life cycle assessment method is becoming increasingly important in Europe, with the decarbonization targets set by the European Commission. Electric heat pumps (vapor compression) are considered one of the most promising solutions for reducing a building’s greenhouse gas emissions. Applying the life cy...

The hydrogen vector stands as a potentially important tool to achieve the decarbonization of the energy sector. It represents an option to store the periodic excesses of energy generation from renewable electrical sources to be used as it is as a substitute for fossil fuels in some applications or reconverted into electricity when needed. In this c...

Gas-driven absorption heat pumps are a valid alternative to condensing boilers for non-insulated buildings with radiators as emission system. In fact, they can provide high supply water temperatures with a limited performance degradation. However, their seasonal performance is often limited by suboptimal operation at partial load conditions, due to...

In this work, the performance of an innovative evaporator based on water falling film was investigated. The studied evaporator has been equipped with a recirculation system to maximise the wetted surface. Tests have been carried out in a lab-scale adsorption unit connected to a test bench recently realised at Politecnico di Milano labs for evaluati...

In this study, the long-term transient response of a single-effect ammonia-water gas-fired absorption heat pump prototype is investigated both numerically and experimentally. For the numerical model, heat and mass transfer components are divided into four groups; (a) tubular heat exchangers comprising condenser, evaporator, absorber, solution and r...

The aim of this paper is to compare energy consumptions, CO 2 emissions, and operative costs of condensing boilers, electric vapour compression heat pumps and gas driven absorption heat pumps to provide space heating and domestic hot water. The analysis is performed for 140 m ² single-family houses in five different Italian cities whose envelope fe...

Gas absorption heat pumps represent an alternative to condensing boilers for space heating and domestic hot water production in existing buildings. In particular, they enable fuel saving and the exploitation of renewable energy even in heating systems based on radiators, which require high supply temperature. However, in order to provide useful ind...

Adsorption chillers can provide energy efficient cooling and have large potential for performance increase and cost reduction compared to conventional chillers. Among the different R&D activities currently in progress in the field, the development of advanced cascading adsorption cycles is an effective way to improve the performance of standard ads...

Multiple-lift absorption cycles are an interesting option for cooling and refrigeration driven by waste or renewable heat. Compared with single effect cycles, they allow higher thermal lift or lower thrust, but they often require the use of controlled valves, which can cause stability and control issues. The self-adapting concept, firstly introduce...

When designing a gas driven heat pump, the selection of the cycle impacts both on complexity and efficiency. Among absorption cycles, the nominal efficiency usually increases with complexity. However, heat pumps are required to operate over a wide range of conditions, of different temperatures and capacity. In this research, three alternative cycle...

-The environmental concerns related to global warming and ozone layer depletion along with the growing worldwide demand for heating and cooling have brought an increasing attention toward ecological and efficient Heating, Ventilation, and Air Conditioning (HVAC) systems. Furthermore, since space heating accounts for a considerable part of the Europ...

The steady-state mathematical modelling of advanced absorption cycles can be time-consuming and error-prone. In this work, a computer tool based on a modular approach and supported by a comprehensive methodology is described. The solver automatically eliminates redundant mass and species balance equations, detects the existence of paired interconne...

The selection of the proper device for space heating and domestic hot water for a building is crucial to achieve good energy and economic performances. For a single-family house, the most common heating device is the condensing boiler. Solar systems, electric heat pumps and gas driven sorption heat pumps represent suitable alternatives for improvin...

In this work a numerical study is carried out on the addition of the VX concept to the GAX cycle implemented in a commercial gas driven absorption heat pump (GAHP). The performance of the two cycles are compared in terms of Gas Utilization Efficiency (GUE) over a wide range of water temperature and for air temperature ranging from -10°C to 10 °C. T...

Based on recently obtained experimental data, a thermodynamic model for a water-ammonia heat transformer is developed. To conform the model to the real behaviour of the prototype, we called into question a few commonly used assumptions and replaced them with empirical correlations. The result is a tuned model effectively able to give an accurate pi...

A prototype water-ammonia absorption heat transformer has been built and thoroughly tested. Compared to water-salts mixtures, water-ammonia allows operating the machine in a lower temperature range, fostering recover of low-grade heat. Driving temperatures between 60 °C and 64 °C were tested, with condenser temperatures of 8–16 °C. The unit proved...

In the present study, a numerical model of a vertical in-tube falling film absorption heat exchanger utilizing NH3−H2O pair as working fluid is developed. At first, the results of the simulations are validated with experimental data obtained from the absorber of an Absorption Heat Transformer (AHT). Then, in order to comprehend the effect of measur...

This work investigates the use of a water-ammonia double-lift absorption cycle for low temperature refrigeration driven by low-grade heat, as waste-heat or solar energy. Among the various double-lift cycles, the investigation focuses on the self-adapting two-pump series cycle, using water-ammonia as working pair. At first, by means of a numerical i...

The experimental analysis of a gas-driven NH3-H2O heat pump whose cycle approaches the GAX concept is carried out. Full load operation is investigated by varying hot water temperatures and partial load operation is investigated by decreasing gas input down to 50% of the full load value. Numerical simulations bolster measurements accuracy and provid...

Double-lift absorption cycles represent a suitable solution for air-cooled thermally driven cooling applications. Among the several existing double-lift configurations, semi-GAX cycles are known as the most promising in terms of efficiency. These cycles incorporate the GAX effect in a pressure staged cycle, by means of a split on the solution leavi...

This paper presents a model to simulate the combined heat and mass transfer processes that occur in a gas-fired generator of an ammonia water absorption heat pump. The model comprises three interconnected components: the gas furnace, the distillation column and the rectifier. The furnace is modeled like a well-stirred single volume. The distillatio...

A model for predicting heat and mass transfer and pressure drops occurring inside a tube-in-tube refrigerant cooled absorber (RCA) is developed. This heat exchanger is used as a low pressure absorber in a half-effect water-ammonia absorption chiller. The two-phase stream, resulting from the mixing at low pressure of the weak solution coming from th...

The prototype of an air-cooled double-lift NH3-H2O absorption chiller driven by hot water at low temperature is presented. The main objective of the study is to illustrate the experimental performances of the prototype under different operating conditions. A mathematical model of the cycle is developed, along with a procedure for the identification...

Composite materials containing phase change materials (PCMs) are obtained by mixing PCM microcapsules with traditional construction materials. The composite materials thermal properties, which depend on the composition, are required when dynamic simulations of building structures containing composite material with PCM are performed. In order to avo...

The paper presents the analysis made to support an Architect Studio (Richard Meier, NY) in the process of designing a large office and laboratory building (6 400 m2 above ground and 10 600 m2 under ground) that will be constructed in 2008 in the new technology area near Bergamo. The building, following the design style of Meier (see for example the...

In Germania e negli altri Paesi del Centro e Nord Europa (Austria, Belgio, Svizzera, Svezia, ecc.) sono state finora costruite più di 8 000 abitazioni conformi all’attuale Standard Passivhaus. Mentre in Germania i professionisti del settore e larga parte dei consumatori riconoscono come “casa passiva” un edificio certificato Passivhaus ed è stato s...

Sono stati sviluppati da eERG, e affinati per questa pubblicazione, modelli di Passivhaus ottimizzati per tre climi italiani (Milano, Roma e Palermo) che forniscono un esempio di un insieme di soluzioni progettuali capaci di soddisfare i criteri energetici e di comfort del nuovo standard Passivhaus esteso. Queste soluzioni se confrontate alla loro...