Thermodynamic analysis of car air cooler is presented in this paper. Typical refrigerator cycles are studied. The first: with uncontrolled orifice and non controlled compressor and the second one with the thermostatic controlled expansion valve and externally controlled compressor. The influence of the refrigerant decrease and the change of the air temperature which gets to exchangers on the refrigeration efficiency of the system; was analysed. Also, its effectiveness and the power required to drive the compressor were investigated. The impact of improper refrigerant charge on the performance of air conditioning systems was also checked.

Waste disposal is imposed by the European Union under Treaty of Accession concerning waste management order. One of the waste disposal methods is thermal utilisation. The paper presents an investigation of sewage sludge briquettes used as a fuel in combustion process. The research study was carried out on samples taken from the Municipal Wastewater Treatment Plant in Bochnia. Briquettes with lime were formed. The analysis of the elementary chemical composition of municipal sewage sludge, the composition of the ash and thermogravimetric analysis were carried out. The results indicate that the prepared briquettes had sufficient fuel properties.

There has been a growing interest in the peritectic due to increasing productivity, quality, and alloy development. Differential scanning calorimetry (DSC) has traditionally been used to study steel solidification but suffers significant limitations when measuring the solidus and peritectic. This work covers a new thermal analysis system that can characterize the peritectic reaction. Heats of AISI/SAE 1030 and 4130 steel were poured to provide some benchmarking of this new technique. The peritectic was detected and the reaction temperature measured. Measurements agree reasonably well with reference information. A review of the literature and thermodynamic calculations did find some disagreement on the exact temperatures for the peritectic and solidus. Some of this difference appears to be related to the experimental techniques employed. It was determined that the system developed accurately indicates these reaction temperatures. The system provides a unique method for examining steel solidification that can be employed on the melt deck.

The problem of harmful casting resins has been present in foundries for many years. Manufacturers are introducing new products that contain in their composition environmentally and eco-friendly ingredients. Unfortunately, not all types of technology can be used, sometimes environmental benefits are disproportionate to the quality of castings and their price. In the foundry industry, the most popular binders are based on organic compounds (often carcinogenic) and other harmful substances. Due to strict legal regulations regarding environmental protection, as well as care for the foundry's workers' comfort - their occurrence should be reduce to a minimum. These compounds often behave also depending on the conditions of use (temperature, atmosphere). The application of various methods of thermal analysis and spectroscopic methods allows to verify the mechanism of resin decomposition process in relation to conditions in the form in both inert and oxidizing atmosphere. For analysis the resins from cold-box technology, were used TG–DTG–DSC, Py-GC/MS methods and specified the course of changes occurring in combination of different atmosphere.

This work presents an influence of cooling rate on crystallization process, structure and mechanical properties of MCMgAl12Zn1 cast magnesium alloy. The experiments were performed using the novel Universal Metallurgical Simulator and Analyzer Platform. The apparatus enabled recording the temperature during refrigerate magnesium alloy with three different cooling rates, i.e. 0.6, 1.2 and 2.4°C/s and calculate a first derivative. Based on first derivative results, nucleation temperature, beginning of nucleation of eutectic and solidus temperature were described. It was fund that the formation temperatures of various thermal parameters, mechanical properties (hardness and ultimate compressive strength) and grain size are shifting with an increasing cooling rate.

The results of investigations of spent moulding sands taken from the mould in which the metal core cooling system - to increase the

cooling rate of the ladle casting - was applied, are presented in the hereby paper. The changes of the spent moulding sand at the casting

external side being the result of degradation and destruction processes of organic binder, were analysed in this publication. Since the

reclaimed material, obtained as a result of the mechanical reclamation of spent sands of the same type, is used as a grain matrix of the

moulding sand, the amount of a binder left from the previous technological cycle is essential for the sound castings production. On the

bases of investigations of the thermal analysis, ignition losses, dusts contents and pH values of the samples taken from the spent sand the

conditions under which the process of gases displacing in the casting mould was realised as well as factors limiting the efficient mould

degassing - were considered in this study. The possible reason of a periodical occurrence of an increased number of casting defects due to

changing gas volume emission, being the reason of the realised technological process, was indicated.

Suitability of the given binding agent for the moulding sands preparation depends on the one hand on the estimation of technological properties of the sand and the mould made of it and the obtained casting quality and on the other hand on the assessment of this sand influence on the natural and working environment. Out of moulding sands used in the foundry industry, sands with organic binders deserve a special attention. These binders are based on synthetic resins, which ensure obtaining the proper technological properties and sound castings, however, they negatively influence the environment. If in the initial state these resins are not very dangerous for people and for the environment, thus under an influence of high temperatures they generate very harmful products, being the result of their thermal decomposition. Depending on the kind of the applied resin (phenol-formaldehyde, urea, furfuryl, urea–furfuryl, alkyd) under an influence of a temperature such compounds as: furfuryl alcohol, formaldehyde, phenol, BTEX group (benzene, toluene, ethylbenzene, xylene), and also polycyclic aromatic hydrocarbons (PAH) can be formed and released. The aim of the study was the development of the method, selection of analytical methods and the determination of optimal conditions of formation compounds from the BTEX group. An emission of these components constitutes one of the basic criteria of the harmfulness assessment of binders applied for moulding and core sands. Investigations were carried out in the specially designed set up for the thermal decomposition of organic substances in a temperature range: 5000 C – 13000 C at the laboratory scale. The object for testing was alkyd resin applied as a binding material for moulding sands. Within investigations the minimal amount of adsorbent necessary for the adsorption of compounds released during the decomposition of the resin sample of a mass app. 15 mg was selected. Also the minimal amount of solvent needed for the desorption of compounds adsorbed in the column with adsorbent was found. The temperature range, in which the maximal amounts of benzene, toluene, ethylobenzene and xylenes are released from the resin, was defined. The qualitative and quantitative analyses of compounds from the BTEX group were performed by means of the gas chromatography combined with the mass spectrometry (GC/MS).

The paper presents the results of thermoanalytical studies by TG/DTG/DTA, FTIR and GC/MS for the oil sand used in art and precision foundry. On the basis of course of DTG and DTA curves the characteristic temperature points for thermal effects accompanying the thermal decomposition reactions were determined. This results were linked with structural changes occurred in sample. It has been shown that the highest weight loss of the sample at temperatures of about 320°C is associated with destruction of C-H bonds (FTIR). In addition, a large volume of gases and high amounts of compounds from the BTEX group are generated when liquid metal interacts with oil sand. The results show, that compared to other molding sands used in foundry, this material is characterized by the highest gaseous emissions and the highest harmfulness, because benzene emissions per kilogram of oil sand are more than 7 times higher than molding sand with furan and phenolic binders and green sand with bentonite and lustrous carbon carrier.

In the dissertation it has been shown, that so called “time-thermal treatment” (TTT) of the alloy in liquid state as overheating the metal

with around 250o

C above Tliq. and detailing it in temperature for 30 to 40 minutes has the influence on changing the crystallization

parameters (Tliq., TEmin.

, TEmax., TE(Me), TSol.). It was ascertained, that overheating the AlSi17Cu5Mg alloy substantially above Tliq. results

with microcrystalline structure. Evenly distributed in the eutectic warp primeval silicon crystals and supersaturated with alloying additives

of base content (Cu, Mg, Fe) of α(Al) solution, ensures not only increase durability in ambient temperature, but also at elevated

temperature (250o

C), what due to it’s use in car industry is an advantage.

Superalloys show a good combination of mechanical strength and resistance to surface degradation under the influence of chemically

active environments at high temperature. They are characterized by very high heat and creep resistance. Their main application is in gas

turbines, chemical industry, and in all those cases where resistance to creep and the aggressive corrosion environment is required. Modern

jet engines could never come into use if not for progress in the development of superalloys. Superalloys are based on iron, nickel and

cobalt. The most common and the most interesting group includes superalloys based on nickel. They carry loads at temperatures well in

excess of the eighty percent of the melting point. This group includes the H282 alloy, whose nominal chemical composition is as follows

(wt%): Ni - base, Fe - max. 1.5%, Al - 1.5% Ti - 2.1%, C - 0.06% Co - 10% Cr - 20% Mo - 8.5%. This study shows the results of thermal

analysis of the H282 alloy performed on a cast step block with different wall thickness. Using the results of measurements, changes in the

temperature of H282 alloy during its solidification were determined, and the relationship dT / dt = f (t) was derived. The results of the

measurements taken at different points in the cast step block allowed identifying a number of thermal characteristics of the investigated

alloy and linking the size of the dendrites formed in a metal matrix (DAS) with the thermal effect of solidification. It was found that the

time of solidification prolonged from less than ome minute at 10 mm wall thickness to over seven minutes at the wall thickness of 44 mm

doubled the value of DAS.

The conducted work shows and confirms how thermal analysis of grey and ductile iron is an important source for calculating metallurgical data to be used as input to increase the precision in simulation of cooling and solidification of cast iron. The aim with the methodology is to achieve a higher quality in the prediction of macro– and micro porosity in castings. As comparison objects standard type of sampling cups for thermal analysis (solidification module M ≈ 0.6 cm) is used. The results from thermal analysis elaborated with the ATAS MetStar system are evaluated parallel with the material quality (including tendency to external and internal defects) of the tested specimen. Significant temperatures and calculated quality parameters are evaluated in the ATAS MetStar system and used as input to calibrate the density curve as temperature function in NovaFlow&Solid simulation system. The modified data are imported to the NovaFlow&Solid simulation system and compared with real results.

The aim of any industrial plant, which is dealing in the energy sector, is to maximise the revenue generation at the lowest production cost. It can be carried out either by optimizing the manpower or by improving the performance index of the overall unit. This paper focuses on the optimisation of a biomass power plant which is powered by G50 hardwood chips (Austrian standard for biomass chips). The experiments are conducted at different operating conditions. The overall effect of the enhanced abilities of a reactor on the power generation is examined. The output enthalpy of a generated gas, the gas yield of a reactor and the driving mechanism of the pyrolysis are examined in this analysis. The thermal efficiency of the plant is found to vary from 44 to 47% at 400◦C, whereas it is 44 to 48% for running the same unit at 600 ◦C. The transient thermal condition is solved with the help of the lumped capacitance method. The thermal efficiency of the same design, within the constraint limit, is enhanced by 5.5%, whereas the enthalpy of the produced gas is magnified by 49.49% through nonlinear optimisation. The temperature of biomass should be homogenous, and the ramping rate must be very high. The 16% rise in temperature of the reactor is required to reduce the mass yield by 20.17%. The gas yield of the reactor is increased by up to 85%. The thermal assessment indicates that the bed is thermally thin, thus the exterior heat transfer rate is a deciding factor of the pyrolysis in the reactor.

This paper presents the results of a thermal computational analysis of a two-dimensional laser array emitting from a surface. The array consisted of eight equispaced ridge-waveguide edge-emitting nitride diode lasers. Surface emission of light was obtained using mirrors inclined at 45°. The authors investigate how the geometrical dimensions of the array emitters and their pitch in the array affect the increase and distribution of temperature in the device. They also examine the influence on the temperature increase and distribution of the thickness of the insulating SiO2, the thickness of the gold layer forming the top contact of the laser, and the thickness of the GaN substrate, as well as the influence of the ridge-waveguide width.

This paper focuses on the thermal behavior of the starch-based binder (Albertine F/1 by Hüttenes-Albertus) used in foundry technology of molding sand. The analysis of the course of decomposition of the starch material under controlled heating in the temperature range of 25-1100°C was conducted. Thermal analysis methods (TG-DTG-DSC), pyrolysis gas chromatography coupled with mass spectrometry (Py-GC/MS) and diffuse reflectance spectroscopy (DRIFT) were used. The application of various methods of thermal analysis and spectroscopic methods allows to verify the binder decomposition process in relation to conditions in the form in both inert and oxidizing atmosphere. It was confirmed that the binder decomposition is a complex multistage process. The identification of CO2 formation at set temperature range indicated the progressive process of decomposition. A qualitative evaluation of pyrolysis products was carried out and the course of structural changes occurring in the presence of oxygen was determined based on thermo-analytical investigations the temperature of the beginning of binder degradation in set condition was determined. It was noticed that, significant intensification of Albertine F/1 sample decomposition with formation of more degradation products took place at temperatures above 550ºC. Aromatic hydrocarbons were identified at 1100ºC.

Monitoring the solidification process is of great importance for understanding the quality of the melt, for controlling it, and for predicting the true properties of the alloy. Solidification is accompanied by the development of heat, the magnitude of which depends on the different phases occurring during solidification. Thermal analysis is now an important part of and tool for quality control, especially when using secondary aluminium alloys in the automotive industry. The effect of remelting on the change of crystallization of individual structural components of experimental AlSi9Cu3 alloy was determined by evaluation of cooling curves and their first derivatives. Structural analysis was evaluated using a scanning electron microscope. The effect of remelting was manifested especially in nucleation of phases rich in iron and copper. An increasing number of remelts had a negative effect after the fourth remelting, when harmful iron phases appeared in the structure in much larger dimensions.

With the aid of eutectic modification treatment, the precipitation of coarse lamellar eutectic silicon can be suspended during the solidification of aluminum-silicon alloys, thereby the formation of fine-grained, fibrous eutectic Si can be promoted by the addition of small amounts of modifying elements, such as Sr, to the liquid alloy. The effectiveness of this technique is, however, highly dependent on many technological factors, and the degree of modification can be lowered during the various stages of melt preparation due to the oxidation of the Sr-content of the melt. During our research, we investigated the effect of rotary degassing melt treatments coupled with the addition of three different fluxes on the degree of modification of an Al-Si-Mg-Cu casting alloy. It was also studied, that whether additional Sr alloying made before and during the melt treatments can compensate the Sr fading with time. The degree of eutectic modification was characterized by thermal analysis (TA) and the microscopic investigation of TA specimens. It was found, that by using one of the three fluxes, and by adding Sr master alloy rods before the melt treatments, better modification levels could be achieved. It was also found that the measurement of Sr-concentration by optical emission spectroscopy alone cannot be used for controlling the level of eutectic modification.

The aim of the study was to determine the influence of the amount of a commonly used binder in foundry work, furfuryl resin – on the course of the thermal regeneration of used moulding sand. The thermal regeneration procedure was carried out at a temperature of 525°C, the required temperature determined according to a specific procedure, and a lower and less effective temperature of 400°C. On the basis of the ignition losses, the influence of the regeneration temperature on the effects of the procedures carried out was compared. It was found that 400°C was too low to effectively clean the binder matrix, but that the more resin in the spent sand, the more intense the cleaning effect. When the required regeneration temperature for furfuryl resin of 523°C was used, higher binder degradation kinetics were observed due to the additional energy supplied to the process from the combustion of a large amount of organic material in the moulding sand.

The paper presents the results of the analysis of physical phenomena associated with the degradation processes of the surface layer of polymeric materials. During the interaction disturbance of ultraviolet radiation, atoms are knocked out of the polymer chains, thus breaking the macromolecules, which leads to the disturbance in the structural stability of the materials. The standardised test samples obtained using the injection moulding method were subjected to the degradation process in natural and accelerated conditions in the UV Test device. The degradation process in laboratory conditions was carried out during 750 hours with the use of lamps with a wavelength of 313 nanometers and an irradiation level of 0.76 W/m ², which corresponds to a period of 2 years in natural conditions. Using of thermogravimetric TGA and differential scanning calorimetry DSC analysis, the influence of energy applied from lamps and the energy reaching the earth’s surface on the change of melting enthalpy ∆ H_m, quantitative index of the crystalline phase and the temperature of phase changes were determined.

Proper design of power installations with the participation of power cables buried in homogeneous and thermally well-conductive ground does not constitute a major problem. The situation changes when the ground is non-homogeneous and thermally low-conductive. In such a situation, a thermal backfill near the cables is commonly used. The optimization of thermal backfill parameters to achieve the highest possible current-carrying capacity is insufficiently described in the standards. Therefore, numerical calculations based on computational fluid dynamics could prove helpful for designers of power cable lines. This paper studies the influence of dimensions and thermal resistivity of the thermal backfill and thermal resistivity of the native soil on the current-carrying capacity of power cables buried in the ground. Numerical calculations were performed with ANSYS Fluent. As a result of the research, proposals were made on how to determine the current-carrying capacity depending on the dimensions and thermal properties of the backfill. A proprietary mathematical function is presented which makes it possible to calculate the cable current-carrying capacity correction factor when the backfill is used. The research is expected to fill the gap in the current state of knowledge included in the provisions of standards.

The main purpose of the present paper is to distinguish water located in various types of pores contained within cement paste. The water sorption isotherm is the starting point of the experimental analysis. The investigation was conducted employing the conventional gravimetric method on cement paste composed with w/c=0.5. The investigation was conducted for the following relative humidity values: 11%, 54%, 75%, 84%, 93%, 97% and 100%. Once samples reached the equilibrium water content they were investigated by means of differential scanning calorimetry (DSC), which enabled us to record exothermic peaks corresponding to the crystallization of different water portions. Moreover, we intended to investigate the thermodynamic characteristics of the liquid phase confined within cementitious materials. Hence, the artificial pore solution was prepared. In order to determine the phase transition temperature and the amount of formed ice, the solution was used to saturate silica gel, which is a chemically passive material. Then the thermal analysis was conducted.

The work presents results of solution combustion method utilization for yttria (Y2O3) nanopowder fabrication. Experiments were carried out with four different reducing agents: urea, glycine, citric acid and malonic acid added in stoichiometric ratio. The reactions were investigated using simultaneous DSC/DTA thermal analysis. After synthesis the reaction products were calcined at temperature range of 800-1100°C and analyzed in terms of particle size, specific surface area and morphology. Best results were obtained for nanoyttria powder produced from glycine. After calcination at temperature of 1100°C the powder exhibits in a form of nanometric, globular particles of diameter <100 nm, according to SEM analysis. The dBET for thus obtained powder is 104 nm, however the powder is agglomerated as the particle size measured by dynamic light scattering analysis is 1190 nm (dV50).

The paper presents the results of studies on the development of correlation of solidification parameters and chemical composition of nickel

superalloy IN-713C, which is used i.a. on aircraft engine turbine blades. Previous test results indicate significant differences in

solidification parameters of the alloy, especially the temperatures Tliq and Tsol for each batch of ingots supplied by the manufacturer.

Knowledge of such a relationship has important practical significance, because of the ability to asses and correct the temperatures

of casting and heat treatment of casts on the basis of chemical composition. Using the statistical analysis it was found that the temperature

of the solidification beginning Tliq is mostly influenced by the addition of carbon (similar to iron alloys). The additions of Al and Nb have

smaller but still significant impact. Other alloying components do not have significant effect on Tliq. The temperature Teut is mostly

affected by Ni, Ti and Nb. The temperature Tsol is not in any direct correlation with the chemical composition, which is consistent with

previous research. The temperature Tsol depends primarily on the presence of non-metallic inclusions present in feed materials and

introduced during the melting and casting processes.