RefLab DIMEC University of Salerno Via Ponte Don Melillo 1 84084 Fisciano (SA) ITALY
amaiorino@unisa.it
Angelo Maiorino, Ph. D.
Biographical Notes
Degree cum laude in Mechanical Engineering at University of Salerno on 2004
PhD in Mechanical Engineering at the University of Salerno on 2008
Research activity His research activities are focused on thermodynamic applied, especially on the refrigeration systems. He is working on the innovation of the refrigeration technology in order to find an environmental friendly solution. In this way he is investigating into magnetic refrigeration and into using carbon dioxide as refrigerating fluid. Until now he developed an analytical and numerical study of magnetic refrigeration at room temperature and an analytical and experimental study of vapour compression refrigeration plant with carbon dioxide as working fluid. The results of his research activities are demonstrated from his publications.
Abstract: In this paper the experimental results of an autocascade
refrigeration system for achieving ultra low temperature are
presented. The plant is used to preserve tissue and cells. When
the air temperature is equal to -150°C in 0.25 m3 space, the
required refrigeration power is about 250W. The influence of the
most meaningful variables is discussed with regard to the design
of the plant. The experimental results show an acceptable time
to reach the steady-state in dependence of the finality of the
plant. The working substance is a non-azeotropic mixture
consisting of HFC (hydrofluorocarbon) refrigerants in addition
to argon and methane.
Abstract: The classical substances as Hydrochlorofluorocarbons (HCFCs) used as
working fluids in the vapour compression plants have to be replaced by new
substances because of their ozone depletion potential and their greenhouse
effect. Carbon dioxide (CO2) is non-toxic, non-flammable, has zero ozone
depletion potential and negligible global warming potential as refrigerant.
Referring to a transcritical CO2 cycle working as a classical "split-system" to
cool air in residential applications, the aim of this paper is the evaluation of
the energy performances using an internal heat exchanger. The experimental plant
employs a semi-hermetic compressor, plate-finned tube type heat exchangers, a
back-pressure valve electronically controlled and an expansion valve. Besides it
is possible to control the flash gas produced in the liquid receiver thanks to
another semi-hermetic compressor linked to an inverter. An increase of the
coefficient of performance has been found using the internal heat exchanger. The
comparison of the coefficients of performance of two cycles, working with and
without the internal heat exchanger, is discussed.
Abstract: As CFC (clorofluorocarbon) and HCFC (hydrochlorofluorocarbon) refrigerants which have been used as refrigerants in a vapour
compression refrigeration system were know to provide a principal cause to ozone depletion and global warming, production and use
of these refrigerants have been restricted. Therefore, new alternative refrigerants should be searched for, which fit to the requirements
in an air conditioner or a heat pump, and refrigerant mixtures which are composed of HFC (hydrofluorocarbon) refrigerants having
zero ODP (ozone depletion potential) are now being suggested as drop-in or mid-term replacement. However also these refrigerants,
as the CFC and HCFC refrigerants, present a greenhouse effect.
The zeotropic mixture designated as R407C (R32/R125/R134a 23/25/52% in mass) represents a substitute of the HCFC22 for high
evaporation temperature applications as the air-conditioning.
Aim of the paper is a numerical–experimental analysis for an air condenser working with the non azeotropic mixture R407C in steadystate conditions. A homogeneous model for the condensing refrigerant is considered to forecast the performances of the condenser; this model is capable of predicting the distributions of the refrigerant temperature, the velocity, the void fraction, the tube wall temperature and the air temperature along the test condenser. Obviously in the refrigerant de-superheating phase the numerical analysis becomes very simple. A comparison with the measurements on an air condenser mounted in an air channel linked to a vapour compression plant is discussed. The results show that the simplified model provides a reasonable estimation of the steady-state response and that this model is useful to design purposes.
Abstract: In this paper, a numerical model of an Active Magnetic Regenerator
(AMR) for refrigeration at room temperature has been evaluated. The model is
based on the equation of state of a homogeneous ferromagnetic with reference
to the gadolinium used as magnetocaloric substance. In this way the curves of
the magnetisation and of the specific heat at constant magnetic field and of the
adiabatic temperature variation for the gadolinium subject to a variable
magnetic field have been obtained using the Brillouin function.
Abstract: Magnetic refrigeration is an emerging technology based on the magneto-caloric
effect in solid-state refrigerants.
The Active Magnetic Regenerative Refrigeration (AMRR) cycle is a special kind
of regenerator for the magnetic refrigerator, in which the magnetic material matrix works
both as a refrigerating medium and as a heat regenerating medium, while the fluid
flowing in the porous matrix works as a heat transfer medium. The performance of an
AMRR cycle depends strongly on the behaviour of the adiabatic magnetization
temperature change as a function of material temperature in the flow direction of the
regenerator.
In the present paper, a practical model for predicting the performance and
efficiency of an AMRR cycle has been developed. The model simulates both the
ferromagnetic material and the entire cycle of an AMR operating in conformity with a
Brayton regenerative cycle. The model simulates different kinds of layered regenerators
operating at their optimal operation point. The program study the Gdx Tb1- x alloys as
constituent materials for the regenerator over the temperature range 275 – 295 K, and
GdxDy1-x alloys in the temperature range 260 – 280 K. The heat transfer medium is a
water-glycol mixture (50% by weight). With this model, the refrigeration capacity, the
power consumption and consequently the coefficient of performance can be predicted.
The results show a greater COP for the refrigerator based on the magnetocaloric
technology compared with the COP of a classical vapour compression plant working
between the same thermal levels.
Abstract: Room temperature magnetic refrigeration is an emerging green technology with environmentally desirable characteristics.
Magnetic refrigeration is an emerging technology based on the magneto-caloric effect in solid-state refrigerants.
The Active Magnetic Regenerative Refrigeration (AMRR) cycle is a special kind of regenerator for the magnetic refrigerator, in which the magnetic material matrix works both as a refrigerating medium and as a heat regenerating medium, while the fluid flowing in the porous matrix works as a heat transfer medium. An active magnetic regenerator can provide larger temperature spans with adequate heat transfer between the regenerator matrix and fluid.
In the present paper, a practical model for predicting the performance and efficiency of an AMRR cycle has been developed. The model simulates both the ferromagnetic material and the entire cycle of an AMR operating in conformity with a Brayton regenerative cycle. The ferromagnetic material is the gadolinium studied as a porous matrix. The heat transfer mediumis liquid water. With this model, the refrigeration capacity, the power consumption and consequently the coefficient of performance can be predicted. The results show a greater COP when compared toa classical vapour compression plant working between the same thermal levels.
Abstract: Chlorofluorocarbons (CFCs) have been phased out and hydroclorofluorocarbons (HCFCs) are in
process of being phased out as refrigerants due to their potential to destroy the ozone layer of the
earth’s atmosphere. Carbon dioxide (CO2) is non-toxic, non-flammable, has zero ozone depletion
potential and negligible global warming potential as a refrigerant.
The main purpose of this study is to investigate about the energetic performances of a transcritical
CO2 refrigerator working as a classical “split-systems” to cool air in residential applications.
The design and construction of the refrigerator is shown and experimental results of investigations
carried out are presented. The CO2 system utilizes aluminium heat exchangers, a semi-hermetic
compressor, an expansion valve and a suction line heat exchangers.
The performances measured in terms of Coefficient of Performances show a decrease respect to the
“split-system” working with the HCFCs at the same external ed internal conditions. Further
improvements regarding the components of the cycle are necessary to use in large scale the “splitsystems”
working with the carbon dioxide.
1. INTRODUCTION
