José Simões-Moreira - Academia.edu (original) (raw)

Papers by José Simões-Moreira

Applied Thermal Engineering, Aug 1, 2012

Trigeneration systems have been used with advantage in the last years in distributed electricity ... more Trigeneration systems have been used with advantage in the last years in distributed electricity generation systems as a function of a growth of natural gas pipeline network distribution system, tax incentives, and energy regulation policies. Typically, a trigeneration system is used to produce electrical power simultaneously with supplying heating and cooling load by recovering the combustion products thermal power content that otherwise would be driven to atmosphere. Concerning that, two small scale trigeneration plants have been tested for overall efficiency evaluation and operational comparison. The first system is based on a 30 kW (ISO) natural gas powered microturbine, and the second one uses a 26 kW natural gas powered internal combustion engine coupled to an electrical generator as a prime mover. The stack gases from both machines were directed to a 17.6 kW ammoniaewater absorption refrigeration chiller for producing chilled water first and next to a water heat recovery boiler in order to produce hot water. Experimental results are presented along with relevant system operational parameters for appropriate operation including natural gas consumption, net electrical and thermal power production, i.e., hot and cold water production rates, primary energy saving index, and the energy utilization factor over total and partial electrical load operational conditions.

Fuel, Mar 1, 2005

A simple electric impedance sensor embedded in ethanol and regular gasoline blends for determinin... more A simple electric impedance sensor embedded in ethanol and regular gasoline blends for determining mass ratios was built and tested in the present work. It was carried out a quantitative evaluation of mixtures for several fuel mass ratios in the temperature range of K10 to 40 8C. A non-linear dimensionless electrical conductivity-fuel mass ratio correlation was obtained for a 0-100% ethanol mass content in gasoline. Tests at different temperatures showed that the temperature had an important influence over the mixture bulk conductivity and sensor signal. This work was carried out following the Brazilian automotive industry trend of using ethanol-gasoline mixtures at any proportion to power passenger automobile engines.

Proceedings of the 25^th IIR International Congress of Refrigeration: Montréal , Canada, August 24-30, 2019., Aug 24, 2019

SAE Technical Paper Series, Nov 18, 2003

Abstract In this work is presented an electric impedance sensor for measurement of the mass ratio... more Abstract In this work is presented an electric impedance sensor for measurement of the mass ratio of ethanol and regular gasoline blends. It was carried out a quantitative evaluation of the electric bulk conductivity of mixtures at several liquid-liquid mass ratios, ...

Journal of Fluid Mechanics, Nov 3, 2022

Viscous effects on an ideal gas flow in a supersonic convergent–divergent nozzle are a well-studi... more Viscous effects on an ideal gas flow in a supersonic convergent–divergent nozzle are a well-studied subject in classical gas dynamics. However, the ideal assumption fails on fluids that exhibit complex behaviours such as near-critical-region and non-ideal dense vapours. Under those conditions, a realistic equation of state (EOS) plays a vital role for a precise and realistic computation. This work examines the problem for solving the quasi-one-dimensional viscous compressible flow using a realistic EOS. The governing equations are discretised and solved using the fourth-order Runge–Kutta method coupled with a state-of-the-art EOS to calculate the thermodynamic properties. The role of the Grüneisen parameter along with viscous and real gas effects and their influence on the sonic point formation are discussed. The study shows that the flow may not achieve the supersonic regime for any pressure ratio depending on the combination of that parameter and the normalised friction factor. In addition, the analysis yields the discharge coefficient and the isentropic nozzle efficiency, which may achieve maximum values as a function of the stagnation conditions. Finally, the study also evaluates the formation and intensity of normal shock waves by using the Rankine–Hugoniot relations, which now depend on the real gas and viscous effects in opposition to the inviscid solution. Moreover, the methodology used captures the sonic point and shock wave position by a space marching algorithm using the Brent method for scalar minimisation. Experimental data available in the open literature corroborate the approach.

Engenharia térmica, Oct 9, 2022

The air conditioning system of a Data Center is a great challenge for mechanical engineers. At th... more The air conditioning system of a Data Center is a great challenge for mechanical engineers. At the same time, it is fundamental for computer safety, it is a great energy consumer. Considering that, the present work carried out an analysis in which a solar-powered absorption refrigeration cycle system is combined with a conventional electrical chiller system. The proposed system also introduces the use of PV panels to generate electricity to power the electric chiller. A decision algorithm was developed based on local solar parametric data and cooling demand. A case study was analyzed for a typical data center located in the city of São Paulo, Brazil. Electrical specific installed power demands of 0.5, 1.0, 2.0, 4.0, and 8.0 kW/m² at half and total load were studied. Local solar irradiation and temperature indexes were based on the data obtained from ASHRAE [1]. The results show that, for a typical year, the absorption solar system performs better than the photovoltaic system in most cases (0.5, 1.0, 4.0, and 8.0 kW/m²), except when the baseline of the installation operates near the optimum point of the consumption curve of the chiller, which occurs at 2 kW/m². Finally, the study shows that air conditioning systems powered by solar energy are a great alternative to reduce the energy consumption and operational costs of a Data Center.

One of the several challenges of the oil and natural gas offshore extraction in pre-salt reserves... more One of the several challenges of the oil and natural gas offshore extraction in pre-salt reserves in Brazil, is the high content of carbon dioxide inside the wells, reaching values close to 80% in a molar fraction. This issue has a big impact on the crude extraction, due to the necessity of further expensive equipment occupying considerable deck space in platforms. Therefore, it is necessary to research and find new technologies, which allow separating high contents of carbon dioxide at low energy consumption and low maintenance. The supersonic separation concept fulfils all these requirements due to the absence of moving parts and simple operation, because its working principle is based on the strong temperature drop of gas mixtures at supersonic expansion as it occurs in de Laval nozzles. Eventually, at the right operating conditions, the mixture starts to nucleate and, therefore, it will drive the phase change. Nevertheless, the physical phenomena involved in this device is complex, because it involves phase change at supersonic speeds, which comprise compressible, multispecies, and multiphase flow. This paper analyses the threshold of the phase change at supersonic speeds. The objective of this work is to calculate the influence of operation conditions (pressure, temperature and composition) in the phase change performance in supersonic separators. The phase change was modelled using the classical theory of homogeneous nucleation. In this approach allows to estimate the phase change inside the supersonic flow for different operating conditions and allows to establish operating strategies to ensure low Mach numbers (M < 1.5) in the phase change region, allowing a further pressure recovery.

experimental de um destilador por filme descendente para um ciclo de refrigeração por absorção de... more experimental de um destilador por filme descendente para um ciclo de refrigeração por absorção de amônia-água em um banco de tubos horizontais. 2015. 197 f. Tese

Revista Brasileira de Ciências Mecânicas, 1994

Heat transfer research, 2020

Springer eBooks, 2012

In this chapter it is reviewed the fundamental principles of Thermodynamics aiming at its applica... more In this chapter it is reviewed the fundamental principles of Thermodynamics aiming at its application to power plants cycle analysis. The three most common thermodynamic cycles are studied starting with the Brayton cycle, the Diesel Cycle, and the Rankine cycle. These ideal cycles are thermodynamic operating models for gas turbines, diesel engines, and steam turbines, respectively. Thermal efficiencies, operating conditions and cycle variations are also analyzed. The last issue studied is the combined Brayton-Rankine cycle, which is a trend in industry due to its higher overall efficiency.

Thermal science and engineering progress, Aug 1, 2021

Abstract This work aims at developing a working algorithm to evaluate the necessary parabolic-tro... more Abstract This work aims at developing a working algorithm to evaluate the necessary parabolic-trough solar collectors (PTCs) sizing for any application, basically, as a function of the thermal load and the demanded operating temperature. Energy balance and heat transfer accurate estimations were applied to the PTC parts resulting in a set of non-linear equations, which were solved by a commercial software. Result analyses showed that a maximum relative error of 5.9% in PTCs lengthwise sizing and 6.1% in the thermal efficiency were achieved when compared to available data in the literature (experimental and theoretical ones), demonstrating that the algorithm is suitable for dimensioning both evacuated and not evacuated PTCs. Also, the PTC geometry and thermal efficiency sensitivity were analyzed as a function of relevant parameters, showing the required PTC length increased and the thermal efficiency decreased as either the following parameters were reduced: the direct solar irradiation, the PTC width, the receiver absorptivity and the heat transfer fluid (HTF) mass flow rate (in laminar and transitional flow regime) or the following parameters were increased: the receiver emissivity, the useful heat and the HTF outlet temperature. Also, three commercial thermal fluids were analyzed along with pressurized water. It was shown that water had a superior performance up to an outlet temperature of 300 °C. For temperatures above 400 °C, the required PTC length increased rapidly. The use of an evacuated receiver can reduce the PTC length between 9% up to 160% depending on the analyzed variable.

Energy, Nov 1, 2019

Single and combined steam cycle thermal power plants consume high amounts of water due to condens... more Single and combined steam cycle thermal power plants consume high amounts of water due to condenser cooling and steam generation operations. At the same time, there have been reductions in the supply of this important resource in many regions around the World. This fact has brought technical and environmental discussions along with research on the development of technologies in order to set new strategies to mitigate the problem, such as reutilizing and recovering water from processes. Although thermal power plants consume water intensively in its cooling process and vapor production, they also produce water from the combustion process of hydrocarbon fuels; the water vapor produced is released to the atmosphere. In this sense, this work aims at estimating the amount of water vapor present in the flue gas. For that, a data basis having the operational parameters of thirty-six Brazilian thermal power plants has been used, of which twenty-two are powered by natural gas (single and combined cycles) and fourteen powered by mineral coal (single cycles). The study also considers environmental conditions of the operation site, typical cycle efficiency, and fuel composition employed.

$Research paper thumbnail of Capacitance sensor for void fraction measurement in water/steam flows$

Flow Measurement and Instrumentation, 2004

Natural circulation is widely used in nuclear reactors for residual heat refrigeration. In this w... more Natural circulation is widely used in nuclear reactors for residual heat refrigeration. In this work, a conductance probe is designed and constructed to measure the instantaneous bulk void fraction in a vertical tube section. This probe is installed in a natural circulation refrigeration loop designed to simulate a nuclear reactor primary refrigeration circuit. During the operation of the natural circulation loop several gas-liquid flow patterns are observed, including oscillatory flow. The instantaneous signal generated by the capacitance probe allows the calculation of the two-phase flow void fraction. The void fraction obtained by the probe will be compared with the theoretical void fraction calculated by the computational program RELAP5/MOD3.2.2 gama. The probe design and electronics, as well as the previous results obtained are presented and discussed.

International Journal for Numerical Methods in Fluids, 2009

This paper presents a study of the stationary phenomenon of superheated or metastable liquid jets... more This paper presents a study of the stationary phenomenon of superheated or metastable liquid jets, flashing into a two-dimensional axisymmetric domain, while in the two-phase region. In general, the phenomenon starts off when a high-pressure, high-temperature liquid jet emerges from a small nozzle or orifice expanding into a low-pressure chamber, below its saturation pressure taken at the injection temperature. As the process evolves, crossing the saturation curve, one observes that the fluid remains in the liquid phase reaching a superheated condition. Then, the liquid undergoes an abrupt phase change by means of an oblique evaporation wave. Across this phase change the superheated liquid becomes a two-phase high-speed mixture in various directions, expanding to supersonic velocities. In order to reach the downstream pressure, the supersonic fluid continues to expand, crossing a complex bow shock wave. The balance equations that govern the phenomenon are mass conservation, momentum conservation, and energy conservation, plus an equation-of-state for the substance. A false-transient model is implemented using the shock capturing scheme: dispersion-controlled dissipative (DCD), which was used to calculate the flow conditions as the steady-state condition is reached. Numerical results with computational code DCD-2D v1 have been analyzed.

Heat Transfer Engineering, Sep 14, 2016

ABSTRACT This paper presents an experimental study of heat transfer and film thickness behavior i... more ABSTRACT This paper presents an experimental study of heat transfer and film thickness behavior in falling liquid water film evaporation technology over horizontal tubes. Liquid distribution systems have also been evaluated. The experimental setup consisted of two horizontal 0.019-m OD stainless-steel tubes, 0.194 m in length. Reynolds numbers in the 160–940 range were tested in both subcooled and saturated liquid regimes. For the liquid distribution system study, several distributor geometries were tested in order to develop the least disturbed film over the tubes. An intrusive method was used for measuring the liquid film thickness in the laminar regime and the measured values were compared with the theoretical prediction computed from the Nusselt equation. An experimental heat transfer correlation was obtained and compared with previous ones obtained by other authors. In addition, the local heat transfer coefficient was observed to be always higher at the horizontal tube top region for all operational conditions (on the order of 14 kW/m2-°C). Finally, the use of a liquid storage distribution system along with the installation of a wire mesh to obtain an uniform liquid distribution for all Reynolds numbers tested.

Journal of The Brazilian Society of Mechanical Sciences and Engineering, Apr 25, 2020

Nowadays, data processing is a fundamental operation for modern businesses such as banks, technol... more Nowadays, data processing is a fundamental operation for modern businesses such as banks, technology companies, and factories, among others. However, computers dissipate significant amounts of heat yielding to an operational temperature rise. Considering that these machines cannot operate properly in inappropriate temperatures or at extreme conditions, they can come to a stop due to overheating. Consequently, cooling and airconditioning systems are necessary to keep the proper operating temperature as well as the room temperature itself. On the other hand, a data center airconditioning system drains a large amount of electrical power. Based on this, this paper evaluates a solar-powered absorption cooling system to assist the traditional electric chiller system resulting in energy saving, an advantage over conventional cooling, and day availability for this system. A case study is analyzed in a conventional data center located in the city of São Paulo, Brazil. First, the electric power density consumed by computers is 2.0 kW/m 2 , which represents a typical power load of an IT room. In addition, some other power density cases are also analyzed, namely: 0.5, 1.0, 4.0, and 8.0 kW/m 2 ; these would occur at partial or at high operational loads. Local solar irradiation indexes are based on ASHRAE temperature and solar data for that city. The results are valid for a typical year and are compared to (1) a conventional data center and (2) the event combined with the solar-powered cooling system. Keywords Airconditioning • Absorption refrigeration cycle • Data center • Solar cooling List of symbols A U Solar collectors' area C 0 Constants for evacuated tube collectors (-) C 1 , C 2 Constants for evacuated tube collectors (kW °C −1) COP Coefficient of performance COP AB Absorption chiller coefficient of performance (-) COP E Electrical chiller coefficient of performance (-) C T Thermal load (kW) I n Global irradiance (kW) Losses Percentual losses of installation PV Photovoltaic panel Q G Absorption chiller vapor generator heat input rate (kW) Q E Absorption system cooling load (kW) R E Residual thermal load (kW) t Measurement time (h) W c Electrical power of chiller (kW) W c R Electrical energy of chiller to cooling the residual thermal load (kWh) W C R Electrical power of chiller to cooling the residual thermal load (kW) cins Yield of evacuated tube installation (-) sol_heat Evacuated tube collector's efficiency (-)