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The quantitative color schlieren technique is renowned for its capacity to convert deflection angles into color ratios. This technique has been instrumental in providing data on 2D flows. The current study delves into assessing how the geometry and optical characteristics of color filters impact the sensitivity of the schlieren system. At present, there are many papers making the assumption that implementing a larger-sized color filter leads to better system sensitivity. However, having more calibration filter positions can lead to measurement errors due to the difficult calibration process. The present investigation focuses on the type of color filters created with a gradual evolution of colors. A turbulent, round water vapor jet serves as the test case. By comparing the results obtained with two different filter sizes, this analysis gives insight into the compromises made between system sensitivity and ease of calibration, helping one to better understand the trade-offs between the above-mentioned parameters. Moreover, the quantitative and qualitative results of the test case are presented to offer more comprehensive insights into quantitative color-calibrated schlieren. [ABSTRACT FROM AUTHOR]

The concept behind this article is an extensive analysis of the most recent findings about free convection thermal flow in an enclosure or cavity, as well as the methods employed to enhance heat transfer (HT). There are different heat transfer enhancers such as (a) nanofluids, (b) porous media, (c) large particle suspensions, (d) phase-change devices, (e) flexible seals, (g) fins and microfins, and (h) ultra high thermal conductivity composite materials. The majority of heat transfer enhancement techniques that use porous media, fins, and nanofluids are reviewed in the literature. In this review, both experiments and theoretical studies on different cavities are highlighted through investigating the subsequent parameters: impacts of the configuration of the cavities, effect of the type of nanoparticles, significance of cavities in nanofluids, effects of the cavities' tilt angle, wave amplitude, the magnetic field's (MF) influence in cavities, and cooler and heater impacts. Through a review of the literature, it was found that the use of nanofluid in all forms of cavities increases its thermal performance. The most used cavity is square, which has many applications. The results obtained from previous studies can be used to improve the design and heat refinement of the geometry applied in diverse energy systems. Additionally, as the Hartmann number rises, there is a rising tendency observed in the average Nusselt number. Furthermore, as the concentration of nanofluid particles and Rayleigh numbers rise, so does the rate of heat transfer. The heat transfer within the cavity is improved by the hybrid nanoparticles. The amount of the augmentation would, however, decrease as the concentration of nanoparticles increased. The lowest volume fraction of nanoparticles, Ø = 0.2 vol.%, showed the greatest increase. Also, the inner wave affects the flow pattern when the wave amplitude rises but the flow strength stays constant. The most important findings showed that the heterogeneous porous medium transfers heat more effectively than the homogeneous porous medium in different enclosures. [ABSTRACT FROM AUTHOR]

Throughout many decades, the Schlieren visualization method has been mainly used as means to visualize transparent flows in a qualitative manner. The images recorded provide data regarding the existence of the flow, or illustrate predicted flow geometries and details. The colored Schlieren method has been developed in the late 1890s and has always had the intent to provide quantitative data rather than qualitative pictures of the studied phenomena. This paper centers on applying a quantitative color Schlieren method to help determine the gasodynamic parameters of an H2–O2 exhaust jet, developing in air. A comparison between the parameters obtained through calibrating the color filter for the Schlieren method and the results from a CFD simulation is performed to assess the range of the CS (color Schlieren) measurement. This paper's findings address the issues of calibrated color filter Schlieren encounter during its implementation and discusses possible errors appearing when the method is applied to a 3D flow. While the qualitative Schlieren images are still impressive to observe, the quantitative Schlieren presents challenges and a low measurement accuracy (75%) when applied to 3D flows and compared to 2D cases found in the literature (97–98%). [ABSTRACT FROM AUTHOR]

The paper presents and discusses medical waste issues (including the hazardous ones 15%) and their proper management in Iraq. Hence, improper handling of infectious medical waste endangers human health and the environment. Incineration is considered one of the effective ways to dispose of medical waste, especially in the time of Coronavirus (COVID-19) can eliminate all pathogens, reduce waste weight by more than 60-75% by weight and reduce volume accordingly. But that goes with ◌ِ a large quantities of heavy metals and reactive, toxic materials produced, which are throws in municipal in the landfill area. That causes pollution of the soil, groundwater and air as a result of its light flying ash. The only disposal method available in Iraq is incineration in purpose-built incinerators. This paper examined three incineration processes for three hospitals in Bagdad; Medical City Complex, Al-Amal National Hospital and Al Shifa coronavirus Hospital, and we worked on burning waste and analyzing ash. The results were that most of the waste after incineration had high heavy mineral concentrations and a small amount of other materials.

Medical waste production has increased with many government and private hospitals and health centres due to the increase in the population, especially in the spread of Coronavirus Covid-19. This increase in medical waste is treating in medical incinerators. One of the advantages of incineration is the reduction of volume, weight and energy recovery. This paper examines the medical waste incinerator of one of the Medical City hospitals in Baghdad, as this incinerator internally divided into primary and secondary chambers. The medical waste for yellow bags placed in the primary chamber is burned with the help of air and a burner of 178-356 kW, resulting in waste burned. Then the combustion products pass through the secondary chamber, wherewith air and another burner of 178-356 kW, the combustion of gases and volatile materials from the waste completed. Air is then supplied to the flue gases to dilute the emission concentrations and reduce the flue gas temperature. This paper presents a study on the inputs and outputs of waste, air, fuel and the advantage of the heat quantity generated from the combustion of biomedical waste. As a result of this theoretical work, this incinerator provides an acceptable and durable solution to waste disposal problems and the risks of spreading viruses today.

Research was carried out at the experimental installation defined by the 2 MW furnace pilot from the Politehnica University of Bucharest and ICEMENRG institute who was involved for measurements. The purpose of the experimental study is to confirm that the use of a coal with low sulphur content S

This paper presents the energetic and exergetic analysis of a widely used flat plate collector based on the collector testing equations. The evaluation of the performances of the collector is done under the climatic conditions corresponding to a typical meteorological year in Constanta, Romania. Using a dimensionless-geometric optimization criterion, the climatic conditions for which the energy efficiency and exergetic efficiency have the maximum values are determined. The optimal weather conditions for the collector's operation are: the solar irradiation of 916 W/m2 and the air temperature of 15.4 °C; under these conditions, the energy and exergy efficiencies of the collector are 57% and 4.8%, respectively.

Visualization methods have always been used to inspect flows that are invisible to the naked eye. Seedless velocimetry has been regarded as an alternative to other intrusive quantitative methods and adapted to fit many applications in the industrial or scientific field. Schlieren image velocimetry (SIV) uses the general working principle of a schlieren system to acquire flow images, while relying on a particle image velocimetry (PIV)-like algorithm to obtain quantitative data related to the studied flow. The test case of this study consists of a turbulent round exhaust jet generated by a micro-thruster that uses H 2 − O 2 as a propellent. Mapping the local velocities of the flow is achieved by initially performing a lagrangian tracking method which makes use of a direct image correlation algorithm. These results are then compared to the velocity map obtained from a kymograph applied to a series of images. The velocity profiles obtained through SIV will be compared to the velocity profile of the jet provided by the CFD simulation. The schlieren investigation of the jet's local velocity map is set to determine the thruster's capabilities, and conclude if the thruster reaches the desired Mach for which it has been designed. [ABSTRACT FROM AUTHOR]

This paper describes the development of a small-scale solar simulator for research and educational purposes. The main goal is to provide a uniform and stable distribution of irradiation from a set of four floodlight halogen lamps, over a targeted area of 40x40 cm2. The floodlights are placed perpendicularly to each other, on the top end of a light tube. Two types of halogen lamps were characterised and the total irradiation of the solar simulator was measured over a 5x5 grid. The results showed that the two arrangements of lamps are able to achieve a level of 1000 W/m2 on the 40x40 cm2 targeted area, but the non-uniformity is unsatisfactory. In order to reach a non-uniformity level of 10% using the proposed lamps arrangements, the targeted area should be reduced to 31x31 cm2.

Distributed power generation may become an important segment in the energy sector in Iraq. The main objective of this paper is to estimate the potential of heat recovery from the Internal Combustion Engines (ICE) driving electric generators in Iraq. The heat recovery solution considered here is based on Organic Rankine Cycles (ORCs). A model has been developed for an ORC-based system recovering heat from a small/medium size ICE (37.7 kW), which is appropriate for large-scale implementation in Iraq. The model has been validated against results reported in the literature. The main steps of the procedure used to design an ORC-based system are presented, with proper illustrations. They include working fluid selection, performance analysis for each component of the system (evaporator, condenser, and expander) and sizing the main components of the system (evaporator and condenser). The heat recovery efficiency is higher in the North of Iraq and ranges between 8% and 11% in January and between 4% and 7% in July, depending on working fluid and geographical location. R134a provides the highest efficiency, while the second-best working fluid is R1234ze. We adopted the hypothesis that 20% of the power capacity to be installed in Iraq until 2020 is provided by electric generators driven by ICEs of medium power (37 kW). 125000 units should be installed and the investment is about 1.5 billion Euro while heat recovery units may cost about 500 million euro, if manufactured in dedicated factories. Heat recovery may save about 7.5% of the installed power. The government should prepare appropriate policies to stimulate distributed power generation and heat recovery. [ABSTRACT FROM AUTHOR]

This paper analyzes the heat transfer characteristics of an ORC evaporator applied on a diesel engine using measured data from experimental work such as flue gas mass flow rate and flue gas temperature. A mathematical model was developed with regard to the preheater, boiler and the superheater zones of a counter flow evaporator. Each of these zones has been subdivided into a number of cells. The hot source of the ORC cycle was modeled. The study involves the variable heat input's dependence on the ORC system's heat transfer characteristics, with especial emphasis on the evaporator. The results show that the refrigerant's heat transfer coefficient has a higher value for a 100% load from the diesel engine, and decreases with the load decrease. Also, on the exhaust gas side, the heat transfer coefficient decreases with the decrease of the load. The refrigerant's heat transfer coefficient increased normally with the evaporator's tube length in the preheater zone, and then increases rapidly in the boiler zone, followed by a decrease in the superheater zone. The exhaust gases’ heat transfer coefficient increased with the evaporator’ tube length in all zones. The results were compared with result by other authors and were found to be in agreement.