Jony M. Zangari

Bio: Jony M. Zangari is an academic researcher. The author has contributed to research in topics: Heat exchanger & Subcooling. The author has an hindex of 4, co-authored 5 publications receiving 43 citations.

EXPERIMENTAL STUDIES ON NON-ADIABATIC FLOW OF HFC-134a THROUGH CAPILLARY TUBES

Abstract: This paper discusses results from an experimental work on concentric capillary tube-suction line heat exchangers commonly used as refrigerant control devices in household refrigerators and freezers Heat exchanger performance with the hydrofluorcarbon R-134a was experimentally evaluated for a range of heat exchanger geometries (diameter and length of the capillary tube, length and position of the heat exchanger) and operating boundary conditions (condensing pressure and subcooling) The results provided enough data to study the influence of the independent variables (geometry and operating conditions) on the dependent variables (refrigerant mass flow rate and temperature profiles)

Modular refrigeration unit

Abstract: A modular refrigeration unit (12) for use in an accessible compartment (37) of a cooler. The modular refrigeration unit (12) includes a wire-frame support (50) , a dividing wall (42) mounted to the wire-frame support (50) , a condenser assembly (48) mounted to the wire­frame support (50) on one side of the dividing wall (42) , and an evaporator assembly (46) mounted to the opposite side of the dividing wall (42).

Cooling apparatus and releasing system for beverages in containers

Abstract: Cooling apparatus and releasing system for beverages in containers, by which beverages in containers may be withdrew from the refrigeration with no need to open the front door, having wired vertical devices inside the refrigerated apparatus set, wired devices being able to comprise beverage cans, which are released for consumption through a by-hand operating lever, being conducted by gravity to a front tray, inferior and horizontal; the beverage in containers is kept entirely cooled all the time, not having thermal exchange between the refrigerator inside and the environment because there is not an accessing door with wide opening, which brings high electrical energy saves for the location, as well as minor maintenance services of the apparatus and of the compressor.

Heat exchanger coil with wing tube profile for a refrigerated merchandiser

Abstract: A heat exchanger coil for a heat exchanger assembly that has a housing defining at least one airflow path and that is adapted to receive an airflow for heating or cooling refrigerant in the heat exchanger coil. The heat exchanger coil includes a substantially cylindrical tube for receiving the refrigerant, and at least one plate coupled to the tube and oriented so that the direction of the airflow adapted to enter the housing is non-orthogonal relative to the orientation of the plate.

Flow characteristics of refrigerants flowing through capillary tubes : A review

Abstract: A comprehensive review of the literature on the flow of various refrigerants through the capillary tubes of different geometries viz. straight and coiled and flow configurations viz. adiabatic and diabatic, has been discussed in this paper. The paper presents in chronological order the experimental and numerical investigations systematically under different categories. Flow aspects like effect of coiling and effect of oil in the refrigerants on the mass flow rate through the capillary tube have been discussed. Furthermore, the phenomenon of metastability and the correlations to predict the underpressure of vaporization have also been discussed. The paper provides key information about the range of input parameters viz. tube diameter, tube length, surface roughness, coil pitch and coil diameter, inlet subcooling and condensing pressure or temperature. Other information includes type of refrigerants used, correlations proposed and methodology adopted in the analysis of flow through the capillary tubes of different geometries operating under adiabatic and diabatic flow conditions. It has been found from the review of the literature that there is a lot more to investigate for the flow of various refrigerants through different capillary tube geometries.

Modeling of non-adiabatic capillary tube flows : A simplified approach and comprehensive experimental validation

Abstract: A simplified computational model for simulating refrigerant flow through capillary tubes is proposed and validated using a dataset composed of more than 1400 experimental data points, including adiabatic flows of refrigerants CFC-12, HCFC-22, HFC-134a, HC-600a, R-404A, R-407C and R-507A, and non-adiabatic flows of refrigerants HFC-134a and HC-600a, in both concentric and lateral capillary tube–suction line heat exchanger configurations. The model is based on the mass, energy and momentum conservation equations written according to their one-dimensional differential formulation. Some simplifications were added to the model in order to improve both numerical stability and computational performance. It was found that the model predicts 91.5% of the measured refrigerant mass flow rate for adiabatic and 79.3% for non-adiabatic flows within an error band of ±10%. Also, the model solves non-adiabatic flows as fast as adiabatic ones.

Non-adiabatic capillary tube flow with isobutane

Abstract: This work reports the results of an experimental study on concentric capillary tube–suction line heat exchangers commonly used as expansion devices in household refrigerators and freezers. Heat exchanger performance (mass flow rate and suction line outlet temperature) with the hydrocarbon HC-600a was experimentally evaluated for a range of heat exchanger geometries and operating conditions. The tests were planned and performed following a statistically based methodology. Based on the resulting database empirical correlations were developed to predict the refrigerant mass flow rate and the suction line outlet temperature.

Numerical simulation of non-adiabatic capillary tubes considering metastable region. Part I: Mathematical formulation and numerical model

Abstract: A detailed one-dimensional steady and transient numerical simulation of the thermal and fluid-dynamic behavior of capillary tube–suction line heat exchangers has been carried out. The governing equations (continuity, momentum, energy and entropy) for fluid flows, together with the energy equation in solids, are solved iteratively in a segregated manner. The discretized governing equations in the zones with fluid flow are coupled using a fully implicit step-by-step method. An implicit central difference numerical scheme and a line-by-line solver were used in solids. A special treatment has been implemented in order to consider transitions (subcooled liquid region, metastable liquid region, metastable two-phase region and equilibrium two-phase region). All the flow variables (enthalpies, temperatures, pressures, mass fractions, heat fluxes, etc.) together with the thermophysical and transport properties are evaluated at each point of the grid in which the domain is discretized. The numerical model allows analysis of aspects such as geometry, type of fluid, critical or non-critical flow conditions, metastable regions and transient cases. Comparison of the numerical simulation with experimental data presented in the technical literature will be shown in Part II of the present paper.

Numerical investigation of refrigerant flow through non-adiabatic capillary tubes

Abstract: A mathematical model is developed to study flow characteristics in non-adiabatic capillary tubes. The theoretical model is based on conservation of mass, energy and momentum of fluids in the capillary tube and suction line. The mathematical model is categorized into three different cases, depending on the position of the heat exchange process. The first case is considered when the heat exchange process starts in the single-phase flow region, the second case is determined when the heat exchange process starts at the end of the single-phase flow region, and the last case is considered when the heat exchange process takes place in the two-phase flow region. A set of differential equations is solved by the explicit method of finite-difference scheme. The model is validated by comparing with the experimental data obtained from previous works. The results obtained from the present model show reasonable agreement with the experimental data. The present non-adiabatic capillary tube model can be used to integrate with system models working with alternative refrigerants for design and optimization.