Lillo, Gianluca
(2020)
Compressor and hybrid ejector systems: assessment of performance and costs based on current technology via experiments and models.
[Tesi di dottorato]
| Tipologia del documento: |
Tesi di dottorato
|
| Lingua: |
English |
| Titolo: |
Compressor and hybrid ejector systems: assessment of performance and costs based on current technology via experiments and models |
| Autori: |
| Autore | Email |
|---|
| Lillo, Gianluca | gianluca.lillo@unina.it |
|
| Data: |
2020 |
| Istituzione: |
Università degli Studi di Napoli Federico II |
| Dipartimento: |
Ingegneria Industriale |
| Dottorato: |
Ingegneria industriale |
| Ciclo di dottorato: |
32 |
| Coordinatore del Corso di dottorato: |
| nome | email |
|---|
| Grassi, Michele | michele.grassi@unina.it |
|
| Tutor: |
| nome | email |
|---|
| Mastrullo, Rita | [non definito] | | Mauro, Alfonso William | [non definito] |
|
| Data: |
2020 |
| Parole chiave: |
Two-phase ejector, Transcritical cycle, Thermo-economic analysis, Waste heat recovery ejector cooling cycle, Two-phase heat transfer. |
| Settori scientifico-disciplinari del MIUR: |
Area 09 - Ingegneria industriale e dell'informazione > ING-IND/10 - Fisica tecnica industriale |
[error in script]
[error in script]
| Depositato il: |
02 Apr 2020 07:55 |
| Ultima modifica: |
10 Nov 2021 11:43 |
| URI: |
http://www.fedoa.unina.it/id/eprint/13035 |
Abstract
The fast growth of the world population leads to an increase of the global energy demand and carbon dioxide emissions, with an increase of the worldwide average temperature. Residential and commercial buildings represent the most energy-consuming sector with an electricity consumption approximately equal to 60% of the worldwide one. In particular, over 70% of the residential energy requests are due to air-conditioning systems. The reduction of the primary energy consumption related to the residential sector can be obtained by acting on the building envelope as well as by using more efficient heating and cooling systems.
According to this scenario, electrical heat pump technology represents a very efficient solution and their adoption is expected to be much larger into the energy transition to renewable energy sources. The recent regulations imposed two opposite targets: the introduction of new eco-friendly refrigerants and the improvement of performance, with the adoption of new technologies/plant schemes. However, the use of new refrigerants does not imply the increase of the performances. In this thesis two heat pump types will be investigated, one driven by electricity and the other one by heat (waste heat or produced by renewable energies) both using a technology not so common in the market, the ejector.
The first case study concerns the experimental evaluation of the benefits related to the use of a multi-ejector expansion device in a prototype of an air-to-water carbon dioxide heat pump for sanitary hot water production. The effects of the ejector geometry and the operating conditions on the system as well as on the ejector performance are analysed. The sizing of the ejector represents one of the main technical issues in order to maximize the benefits in the use of the ejector with respect to a conventional vapor compression cycle: from this point of view, a comparison between the experimental data and predictive methods by the literature is carried-out. Furthermore, a new correlation calibrated on experimental data is proposed.
The second case study investigates the possible technical and economical convenience in the use of a hybrid ejector cooling system powered by an heat source, where the ejector realizes the expansion of the high pressure fluid from the direct cycle and drives the low pressure flow from the inverse cycle to produce cooling effect. In this analysis different working fluids are considered, paying more attention to eco-friendly solutions such as hydrocarbons, HFOs and natural fluids (R717, R600, R600a, R290, R1233zd, R1234ze). The HFC R134a is considered due to its wide usage in vapor compression cycles, despite its high GWP. Costs functions for each component are considered to estimate the investment costs and to compare the hybrid ejector cycle with the current heat driven technology on the market.
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