Results 1 - 10 of 68
Results 1 - 10 of 68. Search took: 0.021 seconds
|Sort by: date | relevance|
[en] An experimental investigation to develop and test a burner and a heat recovery system for thermophotovoltaic (TPV) applications is presented. Experimental data have been compared with theoretical calculations and considerations in the pre-design and design phases of the project to find the weakest point of the concept and to validate the expected performance. The TPV generator has been designed as a compact module in order to be used as a range extender in an electric car. The heat recovery system is the key element to increase the efficiency of the system. The heat recovery system presented in this paper is a rotary type regenerator that is very compact and has higher effectiveness in comparison with other types of regenerators with the same number of transfer units (NTU). The experimental data have been used to verify the numerical models used in the calculations for design of the regenerator matrix. A new version of the numerical model has been developed to take into account the variation of the thermal properties of the system with the temperature. Dimensions, weight, efficiency, emissions and high working temperatures have been the most important competitive constraints to observe for design of the system
[en] Highlights: • Internal Combustion Engine (ICE) dynamical and static models. • Organization of ICE model using Energetic Macroscopic Representation. • Description of the distribution of the chemical, thermal and mechanical power. • Implementation of the ICE model in a global vehicle model. - Abstract: In the simulation of new vehicles, the Internal Combustion Engine (ICE) is generally modeled by a static map. This model yields the mechanical power and the fuel consumption. But some studies require the heat energy from the ICE to be considered (i.e. waste heat recovery, thermal regulation of the cabin). A dynamical multi-physical model of a diesel engine is developed to consider its heat energy. This model is organized using Energetic Macroscopic Representation (EMR) in order to be interconnected to other various models of vehicle subsystems. An experimental validation is provided. Moreover a multi-physical quasi-static model is also derived. According to different modeling aims, a comparison of the dynamical and the quasi-static model is discussed in the case of the simulation of a thermal vehicle. These multi-physical models with different simulation time consumption provide good basis for studying the effects of the thermal energy on the vehicle behaviors, including the possibilities of waste heat recovery
[en] A model for a building with ventilated façade was created using the software tool TRNSYS, version 17, and airflow parameters were simulated using TRNFlow. The results obtained with the model are compared and validated with experimental data. The temperature distribution along the air cavity was analysed and a chimney effect was observed, which produced the highest temperature gradient on the first floor. The heat flux of the external wall was analysed, and greater temperatures were observed on the external layer and inside the cavity. The model allows to calculate the energy demand of the building façade proposing and evaluating passive strategies. The corresponding office building for computer laboratories located in Valencia (Spain), was monitored for a year. The thermal behaviour of the floating external sheet was analysed using an electronic panel designed for the reading and storage of data. A feasibility study of the recovery of hot air inside the façade into the building was performed. The results obtained showed a lower heating demand when hot air is introduced inside the building, increasing the efficiency of heat recovery equipment. - Highlights: •An existing office building was monitored for a year. •A model of a ventilated façade by TRNSYS simulation tool was validated. •Air flow parameters inside the ventilated façade were identified. •Recovery of the hot air inside the façade for input into the building was studied
[en] Description and basic physical characteristics of fast neutron source (FNS) on the base of multiplying electron linear accelerator 'Fackel' are presented. The FNS wide experimental possibilities making it possible alongside with radiation studies of superconducting materials at cryogenic temperatures to conduct traditional material radiation tests and accomplish production of short-lived radionuclides widely applied in nuclear medicine, biology and technology. FNS experimental facilities are described, in particular, low-temperature irradiation channel, equipped with systems enabling observation of changes in electrodynamic properties of superconductors at cryogenic temperatures in the course of fast neutron fluence increase
[en] In this research paper, a comprehensive thermodynamic model of a thermal system in a dual pressure heat recovery steam generator during cold start-up operation is presented. The model consists of unknown parameters identified by two parameter identification techniques. The first algorithm is an online adaptive parameter identification algorithm which is based on gradient algorithm with integral cost function and forgetting factor. Second algorithm is a designed parameter identification algorithm based on the genetic algorithm method. Results are compared with a broad set of actual data taken from one of the Iranian power plants during cold start-up. Simulation results represent the effectiveness and reliability of the developed model and each of two parameter identification techniques. A comprehensive study is carried out in order to compare two applied techniques. The first technique leads to time-varying parameters and the second reaches the constant parameters with a piecewise model. In order to achieve a simulated model for heat recovery steam generator cold start-up, the costs of the modeling and identification process, and the concepts of the optimization lead to the designed algorithm based on genetic algorithm. - Highlights: • A comprehensive model for thermal systems in HRSGs, cold start-up is presented. •Two parameter identification algorithms are applied to the model. •A designed parameter identification algorithm based on GA is presented. •The aspects of the model and proposed parameter identification algorithm are studied. •Application of experimental data in order to modeling and validation experiments
[en] Highlights: •Determination of the conditions that challenge control design in ORC systems. •Development of an adaptive predictive strategy to maximize ORC power generation. •Comparison to the performance achieved by a gain-scheduled PID control strategy. •Procedure to build an optimizer for evaporating temperature from experimental data. •Experimental validation of the proposed control strategies on a 11 kW ORC unit. -- Abstract: Increasing the energy efficiency of industrial processes is a challenge that involves, not only improving the methodologies for design and manufacturing, but optimizing performance during part-load operation and transient conditions. A well-adopted solution consists of developing waste heat recovery (WHR) systems based on Organic Rankine Cycle (ORC) power units. The highest efficiency for such cycle is obtained at low superheating values, corresponding to the situation where the system exhibits time-varying nonlinear dynamics, triggered by the fluctuating nature of the waste heat source. In this paper, an adaptive control law using the Model Predictive Control (MPC) framework is proposed. This work goes a step beyond most of the existing scientific works in the field of ORC power systems, since the MPC controller is implemented in a lab-scale prototype, and its performance compared against a gain-scheduled PID strategy. The experimental results show that the adaptive MPC outperforms the gain-scheduled PID based strategy, as it allows to accurately regulate the evaporating temperature, while keeping vapor condition at the inlet of the expander i.e., the superheating, in a safe operating range, thus increasing the net power generation.
[en] A flow sheeting programme, SHPUMP, was developed for simulating different absorption heat cycles. The programme consists of ten different modules which allow the user to construct his own absorption cycle. The ten modules configurate evaporators, absorbers, generators, rectifiers, condensers, solution heat exchangers, pumps, valves, mixers and splitters. Seven basic and well established absorption cycles are available in the configuration data base of the programme. A new Carnot model is proposed heat cycles. Together with exergy analysis, general equations for the Carnot coefficient of performance and equations for thermodynamic efficiency, exergetic efficiency and exergy index, are derived, discussed and compared for both absorption heat pumps and absorption heat transformers. Utilizing SHPUMP, simulation results are presented for different configurations where absorption heat cycles are suggested to be incorporated in three different unit operations within both pulp and paper and oleochemical industries. One of the application studies reveled that an absorption heat transformer incorporated with an evaporation plant in a major pulp and paper industry, would save 18% of the total prime energy consumption in one of the evaporation plants. It was also concluded that installing an absorption heat pump in a paper drying plant would result in steam savings equivalent to 12 MW. An experimental absorption heat transformer unit operating with self-circulation has been modified and thoroughly tested. A reference heat transformer plant has been designed and installed in a major pulp and paper mill where it is directly incorporated with one of the evaporation plants. Preliminary plant operation data are presented. 72 refs, 63 figs, 33 tabs
[en] Japan Atomic Energy Agency began design and development of the Gas Turbine High Temperature Reactor of 300MWe nominal output (GTHTR300) in 2001. The reactor baseline design completed three years later was based on 850 °C core outlet temperature and a direct cycle gas turbine balance of plant. It attained 45.6% net power generation efficiency and 3.5 US¢/kW h cost of electricity. The cost was estimated 20% lower than LWR. The latest design upgrade has incorporated several major technological advances made in the past ten years to both reactor and balance of plant. As described in this paper, these advances have enabled raising the design basis reactor core outlet temperature to 950 °C and increasing power generating efficiency by nearly 5% point. Further implementation of seawater desalination cogeneration is made through employing a newly-proposed multi-stage flash process. Through efficient waste heat recovery of the reactor gas turbine power conversion cycle, a large cost credit is obtained against the conventionally produced water prices. Together, the design upgrade and the cogeneration are shown to reduce the GTHTR300 cost of electricity to under 2.7 US¢/kW h.
[en] Study about the recovering of irradiated JFET transistors has been reported. The JFETs were damaged totally or partially by exposition to Gamma ray and neutrons. Electronics noise has used to evaluate the effect of radiation and the recovery. The study focused on the recovery by thermal annealing, where samples have been heated gradually until 140 centigrade degree (410 K). The recovery ratio given by this method was higher than that resulted from the relaxation method (time recovery) carried out in the room temperature (300 K), especially for Gamma irradiated samples.(author)
[en] This study proposes and investigates a novel VCES (Vehicle power and cooling/heating Cogeneration Energy System), including a topping vehicle engine subsystem, and a bottoming waste-heat recovery subsystem which uses the zeotropic working fluid. The various grade exhaust and coolant waste-heat of the topping subsystem are cascade recovered by the bottoming subsystem, and slide-temperature thermal match in waste heat recovery heat exchangers and the condenser is considered also, obtaining power output and cooling/heating capacity. Based on the experimental data from an actual vehicle's energy demands and its waste-heat characteristics, the proposed VCES (vehicle cogeneration energy system) model is built and verified. Using ammonia-water as working fluid of the bottoming subsystem, integrated thermodynamic performances of the VCES are discussed through introducing three variables: an ambient temperature, the vehicle's velocity and the number of seated occupants. The influence of above three variables on the proposed VCES′ overall thermodynamic performance is analyzed by comparing it to a conventional VCES, and suitable operation conditions are recommended under cooling and heating conditions. - Highlights: • A novel vehicle cogeneration energy system is proposed. • Slide-temperature thermal match at two levels are considered. • Integration of the topping vehicle engine and bottoming waste heat recovery cycle is designed. • The cogeneration system model is built and verified based on experimental data. • Energy-saving potential of the proposed system is investigated