Citarella, Biagio (2022) Experimental and numerical analysis about new control, layout and low-GWP refrigerant options for the commercial refrigeration. [Tesi di dottorato]

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Item Type:	Tesi di dottorato
Resource language:	English
Title:	Experimental and numerical analysis about new control, layout and low-GWP refrigerant options for the commercial refrigeration
Creators:	Creators Email Citarella, Biagio biagio.citarella@unina.it
Date:	7 March 2022
Number of Pages:	172
Institution:	Università degli Studi di Napoli Federico II
Department:	Ingegneria Industriale
Dottorato:	Ingegneria industriale
Ciclo di dottorato:	34
Coordinatore del Corso di dottorato:	nome email Grassi, Michele michele.grassi@unina.it
Tutor:	nome email Mauro, Alfonso William UNSPECIFIED Mochizuki, Katsuki UNSPECIFIED
Date:	7 March 2022
Number of Pages:	172
Keywords:	commercial refrigeration, R744, low-GWP refrigerants, defrost optimization, energy consumption reduction
Settori scientifico-disciplinari del MIUR:	Area 09 - Ingegneria industriale e dell'informazione > ING-IND/10 - Fisica tecnica industriale
Date Deposited:	30 Mar 2022 11:59
Last Modified:	28 Feb 2024 13:59
URI:	http://www.fedoa.unina.it/id/eprint/14557

Collection description

Commercial refrigeration appliances play a fundamental role in modern life to ensure healthy and quality food to be sold in supermarkets, restaurants and grocery stores. They are responsible of a huge energetic and environmental impact in terms of greenhouse gases emissions. Due to the main regulations and provisions emended worldwide and in Europe, the principal countermeasures to be pursued by refrigerator manufacturers as Zanotti SpA are to shift from high to low-GWP refrigerants and to pursue the reduction of the energy consumption. Within this framework, two topics are developed in this thesis. The first is focused on the research of low-GWP refrigerants and is carried-out with experimental and numerical activities. The latter is a thermo-economic and environmental analysis of synthetic blends and propane in small commercial refrigeration units. The experimental analysis is instead carried-out on a condensing unit prototype using R744 as working fluid. The main results of the numerical analysis show that R454C is a suitable blend for small commercial refrigeration appliances as long-term replacement of conventional refrigerants, whereas propane is currently penalized due to high set-up costs and low efficiencies. Finally, R744 requires a more complex and expensive architecture to be competitive in terms of performance with the HFCs, but it has more longevity. The second topic of the thesis is focused on the development of a new method to calculate the optimal time to trigger a defrost cycle aiming at both energy consumption reduction and at the minimization of the compressor duty cycles to preserve its lifetime. The assessment of commercial defrosting systems based on temperature difference or pressure drop thresholds shows that they do not guarantee the minimization of the duty cycles or the required capacity ratio (CR) value in all operating conditions.

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