Search results for "air conditioning"
showing 10 items of 67 documents
A generalized model of human body radiative heat exchanges for optimal design of indoor thermal comfort conditions
2018
Abstract Human thermal sensation depends heavily on radiative exchanges between the human body and the surrounding environment. Because these exchanges play a crucial role in the thermal balance of the human body, about 35% of the process, human thermal sensation should draw the attention of planners when designing both indoor environments and equipment. The present study aims to contribute to this field by proposing a procedure for delineating the optimal comfort conditions for occupants in most of the articulate and realistic configurations of actual indoor environments. Specifically, this procedure enables accurate assessment of the radiant field surrounding a subject in a given indoor r…
Wireless Sensor Network for Monitoring Thermal Evolution of the Fluid Traveling inside Ground Heat Exchangers
2011
Ground-Coupled Heat Pump (GCHP) systems are an attractive choice of system for heating and cooling buildings (Genchi, 2002; Sanner, 2003; Omer, 2008; Urchueguia, 2008). By comparison with standard technologies, these heat pumps offer competitive levels of comfort, reduced noise levels, lower greenhouse gas emissions, and reasonable environmental safety. Furthermore, their electrical consumption and maintenance requirements are lower than those required by conventional systems and, consequently, they have a lower annual operating cost (Lund, 2000). Ground source systems are recognized by the U.S. Environmental Protection Agency as being among the most efficient and comfortable heating and co…
Cold recovery during regasification of LNG part one: Cold utilization far from the regasification facility
2010
The paper deals with cold recovery during LNG regasification. The applications analyzed pertain to the use in deep freezing agro food industry and in space air conditioning facilities in commercial sector (Supermarkets and Hypermarkets) of cold recovered from the regasification process. A modular LNG regasification unit is proposed having the regasification capacity of 2 billion standard cubic meters/year of gas and it is based on use of a Power Cycle working with Ethane, this unit allows operation of cold energy transfer, contained in LNG to be regasified, in a range of temperatures suitable for multipurpose use of cold, reducing regasification process irreversibility. Some electric energy…
Materiali e Tecniche Innovative per l'Edilizia Sostenibile
2021
Il cambiamento climatico e la necessità di ridurre il consumo energetico degli edifici sono argomenti chiave del dibattito politico, scientifico, economico e culturale. Un dibattito al quale si è voluto dare il proprio contributo sin dall’anno accademico 2010-2011 con la prima edizione del Master in Materiali e Tecniche Innovative per l’Edilizia Sostenibile (MeTIES) dell’Università degli Studi di Palermo insieme al Consorzio Universitario per l’Ateneo della Sicilia Occidentale e del Bacino del Mediterraneo (UNISOM), perseguendo il preciso obiettivo di formare una generazione di professionisti che sappiano padroneggiare le nuove tecnologie per ripensare il modo di “costruire”. Tutti gli stud…
Exergoeconomic analysis as a tool for supporting the design and operation of multiple chiller systems in air conditioning applications.
2019
Multiple-Chillers systems represent viable solutions for medium/large-scale air conditioning applications. In these systems, however, design and energy savings are highly affected by the configuration and operation strategies adopted. For instance, when considering multiple chillers of same size, “symmetric” or “sequential” load sharing strategies are two viable options. Conversely, when considering chillers of different sizes, a wide combination of chillers cooling capacities may be adopted. It is apparent that an integrated analysis of the design and operation of these systems should be carried out in order to achieve profitable energy saving. With this respect, Exergoeconomics, which res…
Development of “Design of Experiments” for modelling direct expansion air-conditioning systems under variable cooling loads and faulty operating cond…
2019
Air conditioning systems are widely adopted in the building sector and are generally responsible for high energy consumption. Part of this consumption is related to the poor maintenance adopted by plant owner over time, which causes energy performance degradation. Typical faults, such as fouling or improper refrigerant charge have been shown to heavily impact on energy consumption of these systems. In order to support cost-effective maintenance schedule, Fault Detection and Diagnosis Technique are under investigation in the world. However, in order to devise a diagnostic method a preliminary modelling of air conditioning system is due. To this aim, a test procedure which requires the least …
On the reliability of thermoeconomic diagnosis of fouled evaporators: assessing the influence of geometries, operating conditions and reference state
2015
Thermoeconomic diagnosis of refrigeration systems is a pioneeristic approach, which has been proven to achieve good performances (under favorable conditions) for the detection of specific faults such as condenser and evaporator fouling and compressor valve leakage. In this paper the sensitivity of performance in detecting fouled Direct Expansion (DX) coils is investigated; the examined parameters are the temperature and relative humidity of coil inlet air and the sensible/latent heat ratio of the coil (varied by considering different numbers of rows). As the thermoeconomic model requires splitting the specific exergy of cooling air into “mechanical”, “thermal” and “chemical” fractions, and …
Multi-Objective Building Envelope Optimization through a Life Cycle Assessment Approach
2019
This work describes a methodology for the identification of the optimal features for the envelope of a residential building. The optimization process allows minimizing operating energy consumption, investment costs and life cycle energy and environmental embodied impacts. A dynamic model for the estimation of building energy consumption during its use phase has been employed, while literature data were adopted for embodied energy and global warming potential impacts. The considered variables refer to the envelope of the building, i.e. external walls and roof insulation and external walls thermal mass. The model was obtained combining EnergyPlus building energy simulator and MOBO, a versatil…
Electrical hybrid heat pumps assisted by natural gas boilers: a review
2022
In this paper, a comprehensive review is performed on hybrid systems using electrical Heat Pumps for Heating, Ventilation & Air Conditioning systems and Domestic Hot Water production using case studies from 2016 to 2022. This work particularly focuses on studies that investigated systems with electrical Heat Pumps assisted by a gas boiler. Some studies that considered the exploitation of renewable energy sources, but not as a whole sub-stitute for fossil sources, have also been included. In particular, the analysis investigated the layouts of the systems by considering the type and the size of the components, the control methods applied (by distinguishing rule-based control methods and …
Thermo-hygrometric comfort in hospital rooms conditioned by means of a primary air system and ceiling radiant panels
2008
In this work the first results of experimental research are described, which began in the 2006 summer season and is still underway, on the performance of a primary air system integrated with radiant ceiling panels that runs in the hospital rooms in the maternity ward of the Maggiore Hospital of Bologna. The choice of this kind of environment is based the fact that there is more and more attention toward literature on comfort standards that must be guaranteed in the hospital environment, due to the presence of typically weak users, both from the clinical and psychological point of view. The performance of the air conditioning system is taken into account in relation to the conditions of comf…