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The fluid mixing process is a common supportive phenomenon that often occurs in a large number of industrial systems. This phenomenon is the subject of many numerical and experimental analysis. The mixing process effectiveness depends on: mixing tank construction, mixing phases viscosity, temperature, density of liquids and, what is crucial, the impeller shape. The optimal design of impeller geometry is still an open issue. In this research work, the main objective is experimental investigations of the influence of the newly constructed impeller type on the fluid flow motion phenomena and energy consumption. Flow field values were evaluated using PIV measurement and the power consumption using precise torquemeter. The comparison between the Rushton turbine and a novel impeller is presented and discussed. The basis for the assessment of the intensity degree and efficiency of mixing was the analysis of velocity vectors distribution and power number. Results show that the power number for both impellers are similar but the fluid motion is quite different. The pumping capacity Qz for the novel impeller in reference to the Rushton turbine is for many cases at least one order of magnitude higher. This shows that the proposed impeller can be a very promising alternative to the classic blades and non-blades based impeller types.

In the present paper, results for fluid flow, temperature and air humidity experimental measurements for innovative energy recovery counterflow air-to-air heat exchanger have been shown. For the low outdoor air temperatures case, frost formation is also observed and analysed. Base on the results of analysis the temperature, humidity and total efficiency of the exchanger are presented. The analysis showed that fluid flow rate, humidity and system efficiency significantly drop down under unfavourable conditions in the winter period when the outdoor temperature decrease below -5oC. In the present system, the heat exchanger equipped with a set of opposing air dampers can use intake air to absorb the moisture from the exhaust air. This solution has the advantage to prevent the exchanger frosting as well as melt ice layer if any growth on heat exchanger walls.

The airflow in the room or any space has a significant impact on the proper operation of the entire ventilation system. An appropriate field of air velocity flowing through the entire room allows for climate comfort. That is why it is so important proper selection as well as proper arrangement for the air-supply and air-exhaust elements in the ventilation system. This research study presents an isothermal air stream flowing from two different slot diffusers. The supply airstream was analysed at various volumetric flow rates and the velocity of the supply air stream was measured in accordance with the PN-EN 12238: 2002 standard. In order to evaluate the optimal measuring points and to create an appropriate grid, before starting the experimental measurement smoke tests were carried out which determine the scope and shape of the supply stream. All experimental measurements were performed up-to the location where the supply air stream reaches the limiting speed of 0.2 m/s. As a result of the analysis, the obtained characteristics of two types of slot diffusers were discussed and compared.

Ventilation systems are responsible for a large part of total energy consumption in operated buildings. The possibility of significant energy savings has been noticed when using mechanical ventilation. In order to decrease energy consumption, devices called recuperators are used and their main element responsible for heat recovery is the heat exchanger. In this work, thermal efficiency and pressure drop at individual heat exchangers designed for recuperators were examined. The results of the analysis and the influence of parameters on the device operation are presented. Finally, the thermal efficiency of the entire unit was evaluated. The results were compared and the phenomena occurring in the device itself affecting the differences in calculated efficiency were described.

The earth natural carrying capacity is being surpassed, and there is an urgent need to develop new alternatives, notably in regards to energy supplies, carbon dioxide emissions, and nitrogen supplies to the ecosystem. Hydrogen gas, produced from renewable energy by water electrolysis, may serve as a platform molecule for the 21st century low-carbon economy and electrification. The ability to utilise hydrogen metabolic processes is quite diverse, and this offers up a vast array of avenues for innovative biotechnological advancements and applications. A strategy focusing on the major role of hydrogen throughout the production of bio-based foundational element compounds through the hydrocarbon pathway would avoid the inherent low economic value of hydrocarbons in favour of products with greater value. Furthermore, hydrogen could serve as a crucial carbon-neutral source for the manufacture of third-generation proteins while allowing carbon capture and nutritional recovery immediately at the site of emission. Using these methods to deal with the seasonal changes in renewable energy sources makes the use of alternative energy as efficient as possible. The outcomes demonstrated the production technologies of bio-hydrogen is a good way to make renewable hydrogen that is both cost-effective and good for the environment compared to other ways of making hydrogen. [ABSTRACT FROM AUTHOR]

The research study provides a techno-economic analysis for the green hydrogen generation based solar radiation data for both the single and hybrid alkaline water electrolyzer and energy storage system systems. In addition, a carbon footprint study is conducted to estimate the developed system carbon dioxide emissions. The optimal size of the alkaline water electrolyzer and energy storage system is determined by a genetic algorithm that takes into account a carbon tax on carbon emissions. Based on itemized cost estimating findings, unit hydrogen production costs for a single system and a hybrid system were $6.88/kg and $8.32/kg respectively. Furthermore, capital cost it has been found as a key element in determining the optimal scale of the alkaline water electrolyzer and energy storage system, which are essential for minimizing the unit hydrogen production cost. Lastly, an effort to minimize the capital cost of producing green hydrogen is required when the rising trend of the carbon dioxide tax is taken into account. [ABSTRACT FROM AUTHOR]

The study examines the methods for producing hydrogen using solar energy as a catalyst. The two commonly recognised categories of processes are direct and indirect. Due to the indirect processes low efficiency, excessive heat dissipation, and dearth of readily available heat-resistant materials, they are ranked lower than the direct procedures despite the direct procedures superior thermal performance. Electrolysis, bio photosynthesis, and thermoelectric photodegradation are a few examples of indirect approaches. It appears that indirect approaches have certain advantages. The heterogeneous photocatalytic process minimises the quantity of emissions released into the environment; thermochemical reactions stand out for having low energy requirements due to the high temperatures generated; and electrolysis is efficient while having very little pollution created. Electrolysis has the highest exergy and energy efficiency when compared to other methods of creating hydrogen, according to the evaluation. [ABSTRACT FROM AUTHOR]

In the article, the viability of adopting photovoltaic energy systems to convert solar energy into hydrogen in Iraqi four main cities are examined. A 22 kWp off-grid solar system, an 8 kW alkaline electrolyzer, a hydrogen compressor, and a hydrogen tank were modeled for an entire year in order to produce hydrogen. Using hourly experimental weather data from 2021 to 2030, MATLAB/Simulink is used to create a mathematical model of the recommended system behavior. The results revealed a range of annual hydrogen production from 1713.92 to 1891.12 kg, annual oxygen production from 1199.74 to 1323.78 kg, and annual water consumption from 7139.91 to 7877.29 L. Each kilogram of hydrogen costs $3.79. The results indicate that the optimal location for solar hydrogen production systems might be constructed in the central region of Iraq and in other regions with comparable climatic characteristics, particularly those with high radiation levels. [ABSTRACT FROM AUTHOR]

This research established the technoeconomic feasibility of an on-grid hybrid renewable energy system for delivering electricity to the deanery building of the Engineering College at the University of Diyala, Iraq. The most cost-effective system design was discovered by modeling and optimization, with an average daily load of 25.0 kWh and total cost and energy cost of $5142 and $0.05/kWh, respectively. In relation to the energy generated by conventional resources, the designed system is more cost-effective and has a lower carbon footprint of about 13,052 kg/year of CO2 emissions avoided. According to the research, using a hybrid power system to electrify and decarbonize the electrical energy supply could be a reliable and economical way to do both at the same time. Innovation is in integrating the suggested hybrid system so that the use of electricity can effectively be decreased to meet the load. As a result, the system components are not oversized, which reduces system costs and reduces emissions. [ABSTRACT FROM AUTHOR]

The present paper examines one of the most popular anti-icing solutions on the system performance. Different ratios of flowing fresh air to exhaust air were applied in order to heat the exchanger’s iced surface with warm air. The analysed system demonstrated that the system efficiency significantly dropped down under unfavourable conditions in winter. The results show that this type of solution is insufficient and should not be applied. A long operation with the iced surface can cause irreversible permanent damage to the heat exchanger unit and a serious system failure.

The air swirl diffusers are popular for the ceiling level air supply system and have been widely used for Indoor Air Quality. They are nowadays one of the most popular diffusers commonly used in airconditioning systems [1, 2]. The swirl diffusers are intended to use in low- and medium-pressure ventilation systems. They allow for obtaining the swirl airflow and are especially recommended to use in spaces with the height from 3m up to 12m, where heating and cooling is performed by the ventilation system and where the exact setting of supply air velocity is important [3-6]. In the case of swirl diffusers,fluid flow is usually significantly influenced by the characteristics of different diffuser designs. In the ventilation system design phase, a typically focus on ventilation effectiveness and takes into account a large number of parameter. However, the discrepancy between design and practice are often experienced mainly because operating conditions don’t correspond to the designing conditions [7-9]. Inthis work, the airflow of swirl diffuser has been studied using Particle Image Velocimetry (PIV) method to analyse the mean airflow and geometry influence on the results. The paper presents a comparison of the results of velocity field measurements using the PIV method and the results obtained by means ofnumerical analysis CFD. Based on the analysis the velocity flow field was evaluated and the range of effective operation of the diffuser have been determined [10].

The increase in global energy consumption and the expected exhaustion of traditional energy sources, especially in the last century, led to an increased search for alternative sources of energy.The use of renewable energy sources has become extremely important to reduce dependence on fossil fuels. Due to the stochastic nature of the renewable energy sources such as the wind speed fluctuation and the intensity of solar radiation the stable operation of the systems base single renewable source can be problematic. But the using two or more of these sources results in higher stability than relying on a single source. For this reason, hybrid renewable energy systems have become an attractive solution in thefield of renewable energy. A hybrid energy system is a combination of two or more renewable energy sources that can enhance each another to increase the reliability of the supplied energy. The objective of this paper is investigation about the energy supplying improvement and the energy efficiency utilisation by hybridisation using two renewable energy resources: wind energy and solar energy with respect two different optimisation objectives: economical to reduce the net present cost and ecological to reduce CO2 emissions. Presented system has been implemented to supply a single household with an electric load.

In this work, we focus on utilization of hybrid renewable energy system for a residential load based in two different optimisation criteria. The presented system utilises photovoltaic modules wind turbines and batteries as energy storage. The analyses were carried out based on experimental measurements, for the electrical load, local solar radiation, wind speed and other environmental parameters. The optimisation process has been performed based on two aspects economic and ecological. The novelty of this work to find the relationship between two optimisation objectives.

Future development of the energy conversion systems will be based on second and third generation technology. Additionally, modern power plants are expected to be able to work in a very wide range of power output. At the same time, frequent and rapid changes in generated power reduce systems lifetime, their average efficiency, and in the case of nuclear energy, introduce additional issues related to nuclear safety. The hybrid energy systems can give at least a partial solution to such challenges. In the present work, a thermodynamic analysis of a hybrid system consisting of a nuclear block powered by Small Modular Reactor (SMR) and a gas-steam block Gas Turbine Combined Cycle (GTCC) was performed. The coupling was made by means of a compressor in a gas block powered by an electric motor and using steam from a nuclear block in the Gas Turbine Combined Cycle steam power plant block. Some promising and challenging results are shown and discussed.

The recently a large number of various companies from the energy sector have to follow new very restrictive regulations which protect the natural environment against pollution and degradation. At the same time, the efficiency of energy conversion and the cost of energy remain important economic aspects. One of the solutions for today's challenges can be power generation based on Gas Turbine Combined Cycle proposed in this paper which is the most efficient and environmentally friendly cycle. What is more important this solution can be easily integrated with a High-Temperature nuclear Reactor. The proposed in this work systems consist of the reactor combined with a gas turbine as well as steam turbine. The results show that it is possible to obtain for proposed cycle an efficiency higher than 50% which is not only more than could be offered by traditional coal power plant but much more than can be proposed by any other nuclear technology.

Ceiling diffusers are one of the most important elements of ventilation and air-conditioning installations. They have a significant impact on the speed and temperature distribution of air. The basic task of these devices is to provide the required air stream while maintaining its appropriate parameters in the occupied zone and low noise levels in the room. Square ceiling diffusers are designed for use in low- and medium-pressure ventilation systems. The diffusers allow obtaining 1, 2, 3 or 4-way air supply. Knowledge of the airflow formed by the diffuser is essential in order to ensure the comfort of people staying in a ventilated room. Designers of the diffusers nowadays mainly use advanced software and CFD (Computational Fluid Dynamics) modelling technique. CFD methods allow to quickly analyse the fluid flow. However, an very important problem is the consistency of the results obtained by numerical methods with the results obtained on an experimental way. The work presents a laboratory stand designed to test ceiling diffusers. In this research study the single square ceiling diffuser was experimentally and numerically analysed.

In the European Union by 2050, more than 80% of electricity should be generated using nongreenhousegases energy technology. Nuclear power systems share at present about 15% of the power market and thistechnology can be the backbone of a carbon-free European power system. Energy market transitions are similar to global pathways were analysed in the Intergovernmental Panel on Climate Change report. From a practical point of view currently, the most advanced and most effective technology for electricity generation is based on a gas turbine combined cycle. This technology in a normal way uses natural gas, synthesis gas from the coal gasification or crude oil processing products as the energy carriers but at the same time, such system emits sulphur oxides, nitrogen oxides, and CO2 to the environment. In thepresent paper, a thermodynamic analysis of environmentally friendly power plant with a high–temperature gas nuclear reactor and advanced configuration of gas turbine combined cycle technology is investigated. The presented analysis shows that it is possible to obtain for proposed thermalcycles an efficiency higher than 50% which is not only more than could be offered by traditional coal power plant but much more than can be proposed by any other nuclear technology.

The mixing process is a widespread phenomenon, which plays an essential role among a large number of industrial processes. The effectiveness of mixing depends on the state of mixed phases, temperature, viscosity and density of liquids, mutual solubility of mixed fluids, type of stirrer, a what is the most critical - the shape of the impeller. In the present research, the objective is to analyse the process of the fluid flow in the mechanically agitated vessel with new impeller type. Velocity field values were determined using computer simulation and experimental particle image velocimetry method. The basis for the assessment of the intensity degree and efficiency of mixing was the analysis of velocity vectors distribution and power number. An experimental and numerical study was carried out for various stirred process parameters to determine optimal conditions for the mixing process.

Ventilation systems are used to provide ventilation for covered car parks and to control the smoke in the event of fire. In this paper the interaction between the fire ceiling jet and the flow driven by jet-fans is studied using CFD simulations. There is a number of parameters that can affect the flow of smoke that need to be considered. To avoid mistakes, fluid flow visualisation is highly required as well as in order to directly compare the different design variants. One of the best option to make flow analysis is to performed Computational Fluid Dynamics simulations (CFD). By CFD it is possible to detailed analyse and keep control of the flow of fluid, heat transfer and other related phenomena. It also helps predict the contamination level of Carbon Monoxide, heat and smoke intensity and distribution. In this study, CFD simulations were used to design, test and compare different design of a fire ventilation system. The research drew attention to the location of jet-fan type fans. The main objective of the study was to assess the impact of jet-fans on fire and to check if it is possible to evacuate people from the garage in less than 10 minutes. The simulation results emphasize the important location of the different elements on the functionality and efficiency of a fire protection system. Due to the evacuation of people from the garage, the simulation results suggest a 10 minute safety time for evacuation. During this period, high visibility and oxygen concentration, as well as low temperature allow for rapid evacuation.

The article presents the analysis of signals from a radiometric system consisting of two scintillation probes and two gamma radiation sealed sources. Calculations and interpretation were carried out for the bubble flow of the water-air mixture in the horizontal pipeline. The analysis of the obtained signals was done in time and frequency domain. In the frequency domain, a range of usable frequencies was identified, which were associated with changes in gamma-ray intensity recorded in the time domain. The gas phase velocity, void fraction and statistical parameters of the signal were also calculated.

Knowledge of the structure of a flow is significant for the proper conduct of a number of industrial processes. In this case, a description of a two-phase flow regimes is possible by use of the time-series analysis in time, frequency and state-space domain. In this article the Discrete Wavelet Transform (DWT) is applied for analysis of signals obtained for water-air flow using gamma ray absorption. The presented method was illustrated by use data collected in experiments carried out on the laboratory hydraulic installation with a horizontal pipe, equipped with two Am-241 radioactive sources and scintillation probes with NaI(Tl) crystals. Signals obtained from detectors for slug, plug, bubble, and transitional plug – bubble flows were considered in this work. The recorded raw signals were analyzed and wavelet energy was extracted using multiresolution analysis. It was found that energies of wavelet approximation at 1-5 levels are useful to recognize the structure of the flow.

Heating, ventilation and air conditioning systems are responsible for a nearly 50% of total energy consumption in operated buildings. One of the most important parts of the ventilation system is an air handling unit with a heat exchanger for energy recovery which is responsible for effective and efficient energy recovery from exhaust air. Typically heat exchangers are characterised by the producers by heat and humidity recovery efficiency up to 90% and 75% respectively. But these very high values are usually evaluated under laboratory conditions without taking into account a dynamic change of outdoor and indoor air conditions significantly affecting the recovery efficiency. In this paper, results of thermal, humidity and enthalpy recover efficiency of innovative energy recovery exchanger have been presented. The analysed system allows adjustment of the humidity recovery especially useful in the winter period and forefends energy use for an anti-froze system of energy exchanger. Presented result show that analysed innovative system can achieve the value of thermal efficiency recovery higher than 90% and efficiency of humidity recovery about 80%. This is possible because the analysed system is able to work without the use of any primary source energy or other anti-freeze systems. Presented in this research unique solution is able to work without external anti-freeze systems even in extremely adverse outdoor air conditions such as minus 20°C and humidity 100% RH.

At present many companies from the energy sector have to follow new regulations and concerns three crucial aspects of energy production: the impact on the environment, the efficiency of energy conversion and the cost of energy. From a technical point of view, the most efficient technology available today for electricity generation is based on a gas turbine combined cycle. In the present paper, an analysis of environmentally friendly, high-temperature gas nuclear reactor system coupled with gas turbine combined cycle technology has been investigated. The analysed system is one of the most advanced concepts and allow electricity generation with the higher thermal efficiency than could be offered by any currently existing nuclear power plant technology. The results show that it is possible to achieve thermal efficiency for nuclear power plant higher than 50% which is not only more than could be produced by any modern nuclear plant but it is also more than could be offered by most of the traditional power plants.

The operating temperature of the photovoltaic module is an important issue because it is directly linked with system efficiency. The objective of this work is to evaluate temperature distribution in the photovoltaic module under different environmental conditions. The results shown that photovoltaic module operating temperature depends not only on the ambient temperature or solar radiation dependent but also depends on wind speed and wind direction. It is presented that the mounting conditions which are not taken into consideration by most of the literature models also play a significant role in heat transfer. Depends on mounting type an increase in module operating temperature in the range 10-15oC was observed which cause further PV system efficiency decrease of about 3.8-6.5 %.

The air diffuser is a very important component of any ventilation system, and the comfort level of ventilated space occupants depend among many other factors on properly designed and choice of diffusers. At present a large number of diffusers are produced to meet a different kind of requirements. One of the most efficient and very popular types of the diffuser is the vortex diffuser in which air flow has angular as well as translational velocity components. This paper investigates experimentally airflow characteristics of vortex ceiling diffuser and its effect on airflow in a ventilated space. Two thermal comfort criteria namely: mean age of the air and ventilation effectiveness have been used to predict the comfort zone inside the room. Effect of supply air velocity on the flow field is investigated and hence the on comfort and energy consumption. The results show that significant amount of energy can be saved by using vortex diffuser in reference to the other diffusers type. The values of the velocity decay coefficient were compared for different diameters of vortex diffuser.

In this paper, an investigation of the electrical load temporal resolution on the PV/Grid energy system flows, and self-consumption is done in order to determine the optimum parameters for modelling and simulation. The analysed PV/Grid power systems include a photovoltaic system with the nominal power of Pmax@STC=1.5, 2.5, 3.5 kW without storage unit connected to the grid. The results show that the temporal load resolution may have a high impact on energy flows as well as can be a critical issue for the system analysis accuracy even for the single household. It has been found that the load temporal resolution for energy consumption of 1-min yields reliable results, while data resolutions of 5 and 15 min are still sufficient, however, in that case, the daily electrical energy flows and in consequence energy self-consumption estimation error for selected days may exceed 15%. Acquisition time step longer than 15-minutes may increase error above 20% and from the designer’s point of view should not be used. The high and low temporal resolution experimental data of the electricity consumption (load) for a household are available in digital form on the author’s website http://home.agh.edu.pl/jaszczur.

This work investigates the effect of the dust deposition and temperature on the photovoltaic module working under varying environmental conditions. The impact of the module temperature caused by the dust deposition, as well as direct impact caused by the dust particle absorption, scattering and reflectance on module performance, has been analysed. Presented results showed that dust deposition even in desert free country Poland influences the module temperature and power output significant. The estimated join effect of dust deposition and temperature increase, on power loss after three-four days of natural dust exposure in the city environment, was about 0.32 and 0.37 point of percentage for the selected sunny and cloudy days while evaluated PV system efficiency was in the range 13.37-14.14%.