Modular Simulation Code Research Articles

Sensitivity study with a D and B mesons modular simulation code of heavy flavor RAA and azimuthal anisotropies based on beam energy, initial conditions, hadronization, and suppression mechanisms

Heavy flavor probes provide important information about the in-medium properties of the quark-gluon plasma produced in heavy-ion collisions. In this work, we investigate the effects of 2D+1 event-by-event fluctuating hydrodynamic backgrounds on the nuclear suppression factor and momentum anisotropies of heavy flavor mesons and non-photonic electrons. Using the state-of-the-art D and B mesons modular simulation code (called "DAB-MOD"), we perform a systematic comparison of different transport equations in the same background, including a few energy loss models --- with and without energy loss fluctuations --- and a relativistic Langevin model with different drag parametrizations. We present the resulting D and B mesons $R_{AA}$, $v_2$, $v_3$, and $v_4$ as well as multi-particle cumulants, in AuAu collisions at $\sqrt{s_\text{NN}}=200\, \text{GeV}$ and PbPb collisions at $\sqrt{s_\text{NN}}=2.76 \, \text{TeV}$ and $\sqrt{s_\text{NN}}=5.02 \, \text{TeV}$, and compare them to the available experimental data. The $v_2\{4\}/v_2\{2\}$ ratio, which is known to be a powerful probe of the initial conditions and flow fluctuations in the soft sector, is also studied in the context of heavy flavor. We also investigate the correlations between the transverse anisotropies of heavy mesons and all charged particles to better understand how heavy quarks couple to the hydrodynamically expanding quark-gluon plasma. We study the influence that different initial conditions and the implementation of heavy-light quark coalescence has on our results.

Modular simulation of cogeneration system based on absorption heat exchange (Co-ah)

Restricted by the return water temperature of district heating network, conventional cogeneration plants cannot efficiently recover the low-grade waste heat of exhaust steam. A novel cogeneration technology based on absorption heat exchange (Co-ah) has been successfully applied to waste heat recovery of thermal power plants, enlarging the heating capacity of district heating network. In this paper, a modular simulation code is developed to simulate and analyze the complicated Co-ah system. The establishment and solution of system equations are accomplished automatically, so any changes in operating conditions or system configuration can be easily dealt with. The theoretical models are validated by the practical operating data. A comparison between the conventional cogeneration system and Co-ah system is made. With the help of the absorption heat pump, the Co-ah system recovers more waste heat from the exhaust steam and exhibits better exergetic and economic performances than the conventional system. The effects of three key parameters including back pressure, extract flow rate and extract pressure on cogeneration performances are analyzed in details, providing a guide for regulation strategies when operating conditions vary.

Thermoeconomic analysis of a MSF desalination plant

A modular simulation code, CAMEL™, developed by the University of Roma1, has been adapted to include the capability to perform a thermoeconomic analysis of a MSF desalination plant. The existing tool already calculates the exergy losses in each component, and it is endowed with an economic cost utility that makes it a very useful tool in optimising the allocation of energy resources and minimising the product monetary cost. Since the MSF process requires low-temperature steam, it is usually deployed as the bottoming part of a combined power plant. The combined cycle has been also simulated and its thermoeconomic analysis has been performed in order to determine the cost of its products (steam and electricity). A model for the thermoeconomic analysis of a MSF stage has been developed and the results have been compared with existing literature data. Before proceeding with the thermoeconomic analysis, an exergy analysis was performed, to allocate the inefficiencies across the MSF stages. Different MSF plant configurations have been coupled with the same power plant: all of them have the same total heat exchange surface, but they differ as for the number of stages (18, 24, 30 respectively). The distillate cost has been derived and the optimal configuration and operating conditions have been determined. The results show that capital- and steam costs are equally important in determining the optimal operative conditions. For the present analysis, the 24 stages configuration, even if characterized by a sub-optimal efficiency, results to be the most convenient.

Modular approach to analysis of chemically recuperated gas turbine cycles

Current research programmes such as the CAGT programme investigate the opportunity for advanced power generation cycles based on state-of-the-art aeroderivative gas turbine technology. Such cycles would be primarily aimed at intermediate duty applications. Compared to industrial gas turbines, aeroderivatives offer high simple cycle efficiency, and the capability to start quickly and frequently without a significant maintenance cost penalty. A key element for high system performance is the development of improved heat recovery systems, leading to advanced cycles such as the humid air turbine (HAT) cycle, the chemically recuperated gas turbine (CRGT) cycle and the Kalina combined cycle. When used in combination with advanced technologies and components, screening studies conducted by research programmes such as the CAGT programme predict that such advanced cycles could theoretically lead to net cycle efficiencies exceeding 60%. In this paper, the authors present the application of the modular approach to cycle simulation and performance predictions of CRGT cycles. The paper first presents the modular simulation code concept and the main characteristics of CRGT cycles. The paper next discusses the development of the methane–steam reformer unit model used for the simulations. The modular code is then used to compute performance characteristics of a simple CRGT cycle and a reheat CRGT cycle, both based on the General Electric LM6000 aeroderivative gas turbine.

A flexible simulation code for microwave curing of polymers

AbstractWe describe a modular simulation code for microwave curing of polymers. The exposed item geometry can be either 3D or 2D (extruded draw pieces), the item can be multi‐component and contain metal insertions as well. The applied microwave field can be either resonant or traveling wave, with or without mode‐stirring. The output of the code is in the form of cross‐linking degree and temperature maps. Utilities are included to input the problem's geometry and to display the outputs.

Depressurization Accidents in a Medium-Sized High-Temperature Gas Reactor: Break Size Parametric Study

The amount of fission product release during a core heatup accident in a medium-sized high-temperature gas reactor depends on the size of the inadvertent opening in the primary circuit; this dependence is assessed. The opening triggers a depressurization event that is assumed to be coupled with the failure of the forced circulation in both decay-heat removal systems. The scenario investigated is a beyond-design-base accident. The DSNP modular simulation code is used. This paper reports that a two-dimensional model is developed to simulate the HTR-500 design. The study shows that the depressurization process does not contribute significantly to the sweeping out (from the primary circuit) of fission products released from the fuel during the core heatup. There is also no significant variation in the results when the opening size is {gt}33 cm{sup 2}, and only a slight sensitivity is found when the rupture size is between 3.3 and 33 cm{sup 2}. The fission product release decreases considerably in the range from 1 to 3.3 cm{sup 2}. The small-sized rupture is of major significance, as the failure of the relief valves to reclose increases the frequency of the event.

Safety Analysis of Depressurization Accidents in a Medium-Sized High-Temperature Gas Reactor

In this paper the potential release of fission products during a beyond-design accident in a medium-sized high-temperature gas reactor (the HTR-500) is investigated. The DSNP modular simulation code is used to simulate a depressurization accident as well as the failure of the forced circulation of the decay heat removal systems to actuate. For such an extreme accident, the calculated maximum localized fuel temperature reaches 3040{degrees} C 43 h after the beginning of the accident. During the heatup, 3.4% of the {sup 137}Cs inventory is found to be released from the fuel elements to the primary circuit, and 4.6 {times} 10{sup {minus}2}% is estimated to be released into the environment. The carbon monoxide and helium releases from the graphite matrix prove to be an important factor in sweeping the fission products from the primary circuit. The comparative consequence analysis indicates a much lower risk than in the analogous light water reactor severe accident. A design-base depressurization accident is also investigated at the beginning of the study and involves the operation of one out of the two redundant decay heat removal systems.

An application of the lego package to pwr power plant modelling

The LEGO package is a modular simulation code particularly oriented to a detailed description of power generation plants for dynamic dimensioning verification, control system design and operational procedures verification. In this paper, after a brief survey of the package features, a PWR power plant model and some significant validation tests are presented. ENEL (the Italian National Electricity Board) is now using this model within the frame of the Italian National Nuclear Energy Program.