Journal articles on the topic 'Heat – Transmission Refrigerants Thermodynamics'

The decarbonisation of building heating in urban areas can be achieved by heat pumps connected to district heating networks. These could be ‘third-generation’ (85/75 °C), ‘fourth-generation’ (50/40 or 50/25 °C) or ‘fifth-generation’ (near ambient) water loops. Networks using thermochemical reactions should require smaller pipe diameters than water systems and be more economic. This work investigates thermochemical transmission systems based on liquid–gas absorption intended for application in urban district heating networks where the main heat source might be a MW scale heat pump. Previous studies of absorption for heat transmission have concentrated on long distance (e.g., 50 km) transmission of heat or cold utilizing waste heat from power stations or similar but these are not directly applicable to our application which has not been investigated before. Absorbent-refrigerant pairs are modelled using water, methanol and acetone as absorbates. Thermodynamic properties are obtained from the literature and modelling carried out using thermodynamic analysis very similar to that employed for absorption heat pumps or chillers. The pairs with the best performance (efficiency and power density) both for ambient loop (fifth-generation) and high temperature (fourth-generation) networks use water pairs. The next best pairs use methanol as a refrigerant. Methanol has the advantage of being usable at ambient temperatures below 0 °C. Of the water-based pairs, water–NaOH is good for ambient temperature loops, reducing pipe size by 75%. Specifically, in an ambient loop, heat losses are typically less than 5% and the heat transferred per volume of pumped fluid can be 30 times that of a pumped water network with 10 K temperature change. For high temperature networks the heat losses can reach 30% and the power density is 4 times that of water. The limitation with water–NaOH is the low evaporating temperature when ambient air is the heat source. Other water pairs perform better but use lithium compounds which are prohibitively expensive. For high temperature networks, a few water- and methanol-based pairs may be used, but their performance is lower and may be unattractive.

In this review, the condensation HTCs (heat transfer coefficients) and pressure drop characteristics of some major low-global-warming-potential (GWP) refrigerants alternative to R-134a such as R-1234ze(E), R-1234ze(Z), R-1234yf, R-513A, and R-450A are reviewed. The thermofluids’ characteristics inside/outside a tube, minichannel, microfin tube, and plate heat exchanger are examined. In addition, several other refrigerants attributed to low GWP are also included in the present review. The experimental/numerical/simulation results’ analysis reveals that condensation HTCs and pressure drop characteristics depend on several parameters such as thermodynamics and transport properties of the working fluid, mass flux of the refrigerants, heat flux, saturation temperature, vapor quality, flow patterns, flow conditions, orientation of the condensing geometry, and condensation geometry (shape, size, and smooth/enhanced).

The theoretical limit on Coefficient of performance (COP), which is maximum and ideal one, is investigated with a sequential Carnot heat pump where multiple Carnot heat pumps are interconnected in parallel. Using fundamental relations from thermodynamics and heat transfer, the performance of a sequential Carnot heat pump is obtained analytically. The effect of major parameters of the system, such as the number of individual heat pumps in a sequential system, the number of transfer unit of heat exchangers, and temperatures of heat sources, on the performance is researched. Also, expressions for ideal COP derived by limit calculation when the system has an infinite number of Carnot heat pumps or infinite number of transfer unit are suggested. For example, the most ideal COP is the ratio of the final heat source temperature to the difference between the initial and final heat source temperature. To support the result of theoretical analysis, a simple simulation of sequential Carnot heat pumps is carried out with thermodynamic properties of real refrigerants. The result of a simulation quite accords with that of theoretical analysis.

Abstract The requirements for environmentally friendly refrigerants promote application of CO2 and water as working fluids. However there are two problems related to that, namely high temperature limit for CO2 in condenser due to the low critical temperature, and low temperature limit for water being the result of high triple point temperature. This can be avoided by application of the hybrid adsorption-compression system, where water is the working fluid in the adsorption high temperature cycle used to cool down the CO2 compression cycle condenser. The adsorption process is powered with a low temperature renewable heat source as solar collectors or other waste heat source. The refrigeration system integrating adsorption and compression system has been designed and constructed in the Laboratory of Thermodynamics and Thermal Machine Measurements of Cracow University of Technology. The heat source for adsorption system consists of 16 tube tulbular collectors. The CO2 compression low temperature cycle is based on two parallel compressors with frequency inverter. Energy efficiency and TEWI of this hybrid system is quite promising in comparison with the compression only systems.

In order to restrain the hydrate formation in the gas transmission pipeline, according to the heat transfer theory of fluid in the circular tube of multilayer cylindrical wall, comprehensively considering many factors such as earth temperature variation, natural gas physical property and so on, we theorized numerical method and computational formula of thermodynamic calculation of buried electric heat tracing gas transmission pipeline, which are used to the field calculation. The results show that the outlet temperature of pipelines with electric tracing ribbon has a sensible rise, and the minimum is 3.8°C, under the conditions given in this paper, the maximum ups to 19.8°C, the relative percentage error between calculation results and actual measurement values is less than 5%, so we can concluded that the derived temperature drop formulas and the calculation software can totally meet the requirement in oilfield production.

Results of the comprehensive experimental and computational phase studies of the systems ZrO2-REO1.5 (RE = La, Nd, Sm, Gd, Dy, Yb) are summarized. Various experimental techniques, X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), transmission electron microscopy (TEM), differential thermal analysis (DTA), and high-temperature calorimetry are employed to study the phase transformation, phase equilibria between 1400 and 1700 °C, heat content and heat capacity of the materials. A lot of contradictions in the literature are resolved, and the phase diagrams are reconstructed. Based on the experimental data obtained in this work and literature, the systems ZrO2-REO1.5 are thermodynamically optimized using the CALPHAD (CALculation of PHase Diagram) approach. Most of the experimental data are well reproduced. Based on the present experiments and calculations, some clear characteristic evolutions with the change of the ionic radius of doping element RE+3 can be concluded.

Nowadays, the development of electric vehicle equipped with a two-speed automatic transmission has become a hotspot. As well known, the automatic transmission operates with power loss including gear meshing loss, bearing loss, and oil churning loss. This paper focuses on the bulk temperature prediction of a two-speed automatic transmission using thermal network method. An integrated model, including an efficiency model and a heat balance model, is proposed, which makes it possible to predict power loss, bulk temperature, and temperature distributions under different conditions. In the efficiency model, each part of power losses from gear meshes is studied to calculate the summation of mechanical power losses in the transmission, including losses of gear meshing, bearing and oil churning. In the heat balance model, the entire gearbox is divided into elements with a uniform temperature connected by thermal resistances which account for conduction, convection, and radiation, based upon the first law of thermodynamics for transient conditions. The effectiveness of bulk temperature prediction using thermal network method is validated by the comparison between simulation results and the experimental data. Consequently, this study on heat transfer characteristics, thermal characteristics, and bulk temperature prediction of the two-speed automatic transmission has significant academic and application values.

A significant amount of energy in the form of heat is lost in industrial processes once it is used in specific processes. Among different technologies, high-temperature heat pumps (HTHP) are a valuable method of recovering low-temperature waste heat in the industry in a very efficient way that can be activated using clean electricity. As a recently investigated technology, they are not yet spread in industrial processes, where traditional technologies are preferred. Therefore, this work shows an HTHP computer program (named HeatPack) to be used as a simulator by the university or technical students of courses included in the area of applied thermodynamics engineering. This interactive and user-friendly platform allows the modification of different operating and design parameters and the working fluid. As outputs, the program provides the rest of the operating parameters and the energy performance of the cycle (quantified by the coefficient of performance, COP). A comparison between the proposed HTHP and a gas boiler is also performed by the program and the energetic, environmental, and economic savings are displayed. Students, as the main target of users of the program, can observe how this technology can provide very relevant emission reductions in comparison with fossil fuel-based boilers, under which situation the energy performance of the HTHP is higher, and which alternative low global warming potential (GWP) refrigerants can provide more advantages. In addition to the educational use, this software can be used to design and study the integration of HTHPs in existing industrial needs to evaluate the feasibility.

The dependency on fossil fuels for power generation can be reduced by enhancing the energy efficiency of power generating systems. The refrigeration systems that typically use electricity consume a significant portion of the electricity supplied to cities. The STAND-ALONE refrigeration system which consists of a combined Organic Rankine Cycle and Vapor Compression (ORC-VCR) system is analyzed using the first law of thermodynamics. Dry natural hydrocarbons such as n-Dodecane is used as the working fluid in Organic Rankine Cycle (ORC) and natural Working fluid such as isobutane (R600a) is utilized in Vapor Compression Refrigeration (VCR) Cycle. The study shows that the system can be driven efficiently with Low-grade waste heat from industries or thermal energy from renewable energy sources typically in the range from 1000C to 3500C thus reducing reliance on fossil fuel sources. The results also show that the overall Coefficient of performance COP overall of the system and the energy efficiency of the ORC was greatly affected by the evaporation temperature of ORC, Teva_ORC followed by, the evaporation temperature of VCR, Teva_VCR. The maximum COP overall of the system was found to be 0.558 and the energy efficiency of ORC was found to be 20.69% for Teva_ORC of 3150C and Teva_VCR of -300C.

In the present investigation, an aluminum powder of 99.7% purity with particle size of ~45 µm was cryomilled for 7 hours. The produced powder as characterized by scanning, transmission electron microscopy, and X-ray diffraction gave a particle size of ~1 µm and grain (crystallite) size of23±6 nm. This powder, after degassing process, was consolidated using high-frequency induction heat sintering (HFIHS) at various temperatures for short periods of time of 1 to 3 minutes. The present sintering conditions resulted in solid compact with nanoscale grain size (<100 nm) and high compact density. The mechanical properties of a sample sintered at 773 K for 3 minutes gave a compressive yield and ultimate strength of 270 and 390 MPa, respectively. The thermal stability of grain size nanostructured compacts is in agreement with the kinetics models based on the thermodynamics effects.

Based on the theory of thermal transmission, this article provides a new method to acquire the friction coefficient in ball screw mechanism. While the screw is in thermal equilibrium, the heat absorption is equal to the heat dissipation. The heat absorption is able to be achieved by calculating the heat energy due to the friction at the contact area and the heat dissipation can be calculated by the law of thermodynamics. When the temperature rise is determined, the heat dissipation can be obtained and the friction coefficient in ball screw mechanism can be calculated further. In order to confirm the validity of this method, a measuring system is constructed to obtain the temperature rise of ball screws. The experimental results show that the temperature rise has the same tendency with the theoretical values depending on this model. Therefore, it can be exploited to predict the temperature rise of ball screws in the rated life cycle when the ball screw is under the condition of thermal equilibrium. Furthermore, this model can be used to evaluate the mechanical efficiency, which is an important parameter for the performance of the ball screw.

Nanoscale thermodynamics and kinetics were explored via the manipulation of Pb/PbO core-shell nanoparticles with a focused electron beam which served as a nanometer heating probe. In the electron transmission microscope (TEM), when an electron beam of moderate intensity was used to irradiate the nanoparticles, the amorphous particles gradually crystallized and showed distinct boundaries between lead cores and oxide shells. In such a way, the oxide shell could be easily measured to be 0.5-2 nanometers. With a high intensity electron beam, melting of the lead cores could be observed, indicating a sufficient local temperature increasing induced by the concentrated heat generated by inelastic electron collisions. The fluidic metal core erupted out through the cracked shells accompanied with the vanish of the boundaries between the cores and shells. Manipulations on nanoparticle decorated carbon wires proved that the lead oxide shells could sustain the irradiation of intense electron beam.

Computational fluid dynamics (CFD) has become effective and crucial to several applications in science and engineering. The dynamic behavior of buoyancy induced flow of water in partially heated tall open-ended vertical annulus is analyzed based on a CFD technique. For a vertical annulus, the natural convective heat transfer has a broad application in engineering. The annulus is the most common structure used in various heat transmission systems, from the basic heat transfer device to the most sophisticated atomic reactors. The annular test sections of such a large aspect ratio are of practical importance in the design of equipment’s associated with the reactor systems. However, depending on the geometrical structure and heating conditions, it exhibits different flow behavior. The annulus may either be closed or open-ended. In this study, we carry out CFD analysis to examine the thermodynamics properties and the detailed thermal induced flow behavior of the water in Tall open-ended vertical concentric annuli. The purpose of this study is to evaluate the impact of a partially heating on mechanical properties and design parameters like Nusselt number, mass flow rate and pressure defect. For Rayleigh number ranging from 4.4 × 103 to 6.6 × 104, while the Prandtl number is 6.43, the numerical solution was obtained. The modelling result showing the measurement and transient behavior of different parameters is presented. The numerical results would be both qualitatively and quantitatively validated. The presentation of unstable state profiles and heat variables along the annulus are also discussed.

AbstractIn numerical control machines, the thermal elongation of the ball screw influences the position accuracy. Different rotational speeds lead to different temperature changes at different positions in a ball screw system. In this paper, a new method is proposed to calculate the temperature rise of different positions when the ball screw is in the thermal equilibrium state. The thermal transmission of ball screws is analyzed, and the heat generation and transfer coefficient are calculated based on the laws of thermodynamics. The function between the temperature rise and position is built by solving the thermal equilibrium differential equations. The thermal elongation is obtained after the temperature rise is calculated. In order to prove the validity of this model, a series of detection tests are conducted to obtain the temperature rise of a ball screw and the thermal elongation under different rotational speeds. The experimental results show that the realistic temperature rise and the thermal elongation agree well with the theoretical values.

Abstract In this paper, a new model of the three-electron reservoir energy selective electronic cooling device applying double-resonance energy filters is proposed by using finite time thermodynamics. The analytical formulas of the main performance parameters for the double-resonance three-electron reservoir cooling device are derived. The optimal cooling load and coefficient of performance of the cooling device varying with major structure design parameters are explored and the optimal operation regions are further determined. Moreover, detailed analyses are conducted to reveal the influences of center energy level difference, chemical potential difference, energy level width, energy spacing and the phonon transmission induced heat leakage on the optimal performance characteristics of the cooling device. Finally, a performance comparison is made between the double-resonance and single-resonance three-electron reservoir electronic cooling devices. It is shown that through reasonable structure design, the optimal performance characteristics of the double-resonance device can be controlled to be much higher than those of the single-resonance cooling device.

The effect of different regimes of combustion of glycine–nitrate precursors on the formation of perovskite phases (LaMnO3 and LaCrO3) without additional heat treatment was studied. The following three combustion regimes were compared: the traditional solution combustion synthesis (SCS), volume combustion synthesis (VCS) using a powdered precursor, and self-propagating high-temperature synthesis (SHS) using a precursor pellet. The products of combustion were studied using a series of physicochemical methods (attenuated total reflection infrared spectroscopy (ATR FTIR), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and thermal analysis). SHS was found to be the most productive regime for the formation of perovskite because of its ability to develop high temperatures in the reaction zone, which led to a reduced content of the thermally stable lanthanum carbonate impurities and to an increased yield and crystallite size of the perovskite phase. The reasons for the better crystallinity and purity of LaCrO3 as compared with LaMnO3 is also discussed, namely the low temperatures of the onset of the thermolysis, the fast rate of combustion, and the favorable thermodynamics for the achievement of high temperatures in the reaction zone.

Abstract Basing on the first and second law of thermodynamics the fundamental trends in the Polish energy policy are analysed, including the aspects of environmental protection. The thermodynamical improvement of real processes (reduction of exergy losses) is the main way leading to an improvement of the effectivity of energy consumption. If the exergy loss is economically not justified, we have to do with an error from the viewpoint of the second law analysis. The paper contains a thermodynamical analysis of the ratio of final and primary energy, as well as the analysis of the thermo-ecological cost and index of sustainable development concerning primary energy. Analyses of thermo-ecological costs concerning electricity and centralized heat production have been also carried out. The effect of increasing the share of high-efficiency cogeneration has been analyzed, too. Attention has been paid to an improved efficiency of the transmission and distribution of electricity, which is of special importance from the viewpoint of the second law analysis. The improvement of the energy effectivity in industry was analyzed on the example of physical recuperation, being of special importance from the point of view of exergy analysis.

Heat transfer is a vital fact of daily life, engineering, and industrial mechanisms such as cryogenic systems, spaceborne thermal radiometers, electronic cooling, aircraft engine cooling, aircraft environmental control systems, etc. The addition of nanoparticles helps to stabilize the flowing of a nanofluid and keeps the symmetry of the flowing structure. Purpose: In this attempt, the effect of endothermic/exothermic chemical reactions accompanied by activation energy on a ternary hybrid nanofluid with the geometry of a wedge is taken into consideration. The mathematical form of PDEs is obtained by Navier–Stokes equations, the second law of thermodynamics, and Fick’s second law of diffusion. The geometric model is therefore described using a symmetry technique. Formulation: The MATLAB built-in Lobatto III A structure is utilized to find the computational solution of the dimensionless ODEs. All computational outcomes are presented by graphs and statistical graphs in order to check the performance of various dimensionless quantities against drag force factor and Nusselt quantity. Finding: the addition of tri-hybridizing nanomolecules in the standard liquid improves the thermic performance of the liquid much better in comparison to simple hybrid nanofluids. Wedge angle parameter α brings about a decrement in fluid velocity and augmentation in thermal conductivity ϵ, thermal radiation Rd, thermophoresis parameter Nt and endothermic/exothermic reaction Ω, and fitted rate constant n accelerates the heat transmission rate. Novelty: The effect of tri-hybridizing nanomolecules along with endothermic/exothermic reactions on the fluid past a wedge have not been investigated before in the available literature.

The thermochemical sulfur-iodine cycle is a potential method for hydrogen production, and the hydrogen iodide (HI) decomposition is the key step to determine the efficiency of hydrogen production in the cycle. To further reduce the irreversibility of various transmission processes in the HI decomposition reaction, a one-dimensional plug flow model of HI decomposition tubular reactor is established, and performance optimization with entropy generate rate minimization (EGRM) in the decomposition reaction system as an optimization goal based on finite-time thermodynamics is carried out. The reference reactor is heated counter-currently by high-temperature helium gas, the optimal reactor and the modified reactor are designed based on the reference reactor design parameters. With the EGRM as the optimization goal, the optimal control method is used to solve the optimal configuration of the reactor under the condition that both the reactant inlet state and hydrogen production rate are fixed, and the optimal value of total EGR in the reactor is reduced by 13.3% compared with the reference value. The reference reactor is improved on the basis of the total EGR in the optimal reactor, two modified reactors with increased length are designed under the condition of changing the helium inlet state. The total EGR of the two modified reactors are the same as that of the optimal reactor, which are realized by decreasing the helium inlet temperature and helium inlet flow rate, respectively. The results show that the EGR of heat transfer accounts for a large proportion, and the decrease of total EGR is mainly caused by reducing heat transfer irreversibility. The local total EGR of the optimal reactor distribution is more uniform, which approximately confirms the principle of equipartition of entropy production. The EGR distributions of the modified reactors are similar to that of the reference reactor, but the reactor length increases significantly, bringing a relatively large pressure drop. The research results have certain guiding significance to the optimum design of HI decomposition reactors.

The thermochemical sulfur-iodine cycle is a potential method for hydrogen production, and the hydrogen iodide (HI) decomposition is the key step to determine the efficiency of hydrogen production in the cycle. To further reduce the irreversibility of various transmission processes in the HI decomposition reaction, a one-dimensional plug flow model of HI decomposition tubular reactor is established, and performance optimization with entropy generate rate minimization (EGRM) in the decomposition reaction system as an optimization goal based on finite-time thermodynamics is carried out. The reference reactor is heated counter-currently by high-temperature helium gas, the optimal reactor and the modified reactor are designed based on the reference reactor design parameters. With the EGRM as the optimization goal, the optimal control method is used to solve the optimal configuration of the reactor under the condition that both the reactant inlet state and hydrogen production rate are fixed, and the optimal value of total EGR in the reactor is reduced by 13.3% compared with the reference value. The reference reactor is improved on the basis of the total EGR in the optimal reactor, two modified reactors with increased length are designed under the condition of changing the helium inlet state. The total EGR of the two modified reactors are the same as that of the optimal reactor, which are realized by decreasing the helium inlet temperature and helium inlet flow rate, respectively. The results show that the EGR of heat transfer accounts for a large proportion, and the decrease of total EGR is mainly caused by reducing heat transfer irreversibility. The local total EGR of the optimal reactor distribution is more uniform, which approximately confirms the principle of equipartition of entropy production. The EGR distributions of the modified reactors are similar to that of the reference reactor, but the reactor length increases significantly, bringing a relatively large pressure drop. The research results have certain guiding significance to the optimum design of HI decomposition reactors.

Optimizing efficiency studies were carried out to comply with environmental norms by using MCDM techniques to pick low GWP refrigerants for automotive air conditioning. Multi-criteria optimization for time consumption based on ratio analysis plus full multiplicative form (MULTIMOORA), is being employed in this work to compare 10 distinct alternatives with 10 criteria. Thermal conductivity, vapor pressure, saturation fluid density, latent specific heat, fluid viscosity, GWP, ozone-depleting potential, and cost per pound are among the many response qualities suited for data acquisition in terms of thermodynamics, environmental stewardship, and economics. It is possible to standardize decision-makers' grading and weighting systems using MCDM methodologies. RAA3 had the greatest rank among the 10 refrigerants tested in the MULTIMOORA methodology. The EDAS and TOPSIS techniques identified R-744 to be the worst refrigerant, whereas the MOORA approach showed RAA5 to be the worst refrigerant.

Abstract This research is about “controversial analysis of a refrigeration vapor-compression cycle,” using R22, and environmentally friendly hydrofluorocarbon (HFC) refrigerants such as R134a, R407c, and R410a in various climatic conditions. For initiation, a complete database was provided for thermophysical properties of the refrigerants’ performances. Then, P–h, s–T, s–h equations are derived in matlab and Excel with the maximum R2. Meanwhile, five climatic conditions (from hot to cold state) are assumed. Consequently, temperature, pressure, enthalpy, and entropy of the cycle states are illustrated for aforesaid conditions as per working fluids properties in the form of quadripartite diagrams. Subsequently, the cycle was analyzed thermodynamically. The coeffcient of performance (COP) was performed for refrigeration (cooling procedure), heat pump (heating procedure), and both heating and cooling for both standard and actual conditions. Afterward, the calculation was performed for parameters like energy efficiency ratio (EER), heat rejected ratio (HRR), capacity, energy, exergy, irreversibility, and exergy destruction ratio (EDR) of each system component according to the first and second laws of thermodynamics, individually. Derived and calculated values in each session illustrated in 3D diagrams on which TEvap s, TCond s and working fluids for each assumed climatic condition can be distinguished easily. A concise analytic study was performed for the increasing and decreasing in values. Forecast for two steps upper and lower than all values derived for trending. Making a trend for indicating either positive or negative inclines of the values and proposing a development for all similar cycles can be considered as the novelty of this research.

In this paper, the different forms of the Clausius statement of second law of thermodynamics presented by various authors have been critically reviewed and compared with the original statement of Clausius to identify the variations. The notable deviations from the original Clausius statement have been found regarding the conditions and constraints for applicability of this law, which can be of great concern for engineers. It has been found that the original statement has no ambiguity and it addresses all the issues relating to heat transfer between cold and hot bodies and hence it has been concluded that the original Clausius statement of the law must be always stated verbatim. Since the engineers regard two-way radiation heat transmission for net heat transfer calculation, i.e., from hot to the cold as well as from cold to the hot body, the law has been reviewed from a heat transfer engineer's point of view for the radiation heat transfer and modification in the original Clausius statement or inclusion of an explanation has been suggested for the sake of clarity or to avoid any ambiguity.

ABSTRACTPulsed laser mixing has been used as surface modification technique for the improvement in the mechanical properties of ceramics. Thin metallic layers of nickel were deposited on structural silicon nitride and were irradiated with Xenon Chloride (XeCl) laser pulses. The laser parameters were optimized to lead to the formation of mixed layers. The mixed interfacial layers were analyzed using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Rutherford Backscattering (RBS) techniques. Detailed heat flow calculations were performed to simulate the effects of intense laser irradiation on metal coated ceramic structures. The melt lifetimes and the interfacial temperatures obtained using these calculations, were applied to understand the laser mixing phenomena occuring in these layered structures. Thermodynamics of chemical reactions between the metal overlayers and the substrate were done to predict the formation of mixed interfacial layers during laser irradiation.

This research interprets the features of triple diffusion in naturally convected viscous material flow through a horizontal plate embedded in a porous regime. The heat and mass transmission process is evaluated by the implication of Cattaneo and Christov (CC) models of energy and mass diffusions. Entropy analysis is executed with the help of the second law of thermodynamics. The homogeneous and local thermal equilibrium is assumed for porous medium. The physically modeled expressions are reframed into an ordinary differential system. This re-structured system of expressions is computed numerically by the implication of the Runge–Kutta Fehlberg method. The computed solutions are visualized graphically and in numeric forms. The validation of present solutions is reported by the comparative benchmark with already available results in a limiting sense. It is evident that the opposing and assisting flows show higher entropy generation at the convective wall. An increment in surface entropy generation rate is achieved for higher thermal and solutal relaxation times.

Electro-hydrostatic actuators (EHAs) are emerging transmission techniques originated from aerospace industry and being introduced to various application fields, such as ships, robots, construction machines, and machine tools. Despite the advantages of high efficiency, easy maintenance, electrified power, etc., EHAs are usually self-contained integrated devices, resulting in low heat dissipation ability. Therefore, thermal coupling models are necessary for the evaluation of each design option during the EHA development. In this paper, a thermal coupling model was established for EHA thermal characteristic analysis during the detail design stage. The disciplines of electrics, mechanics, system level hydraulics, losses, and control are implemented by lumped parameter modeling while the disciplines of thermodynamics and fluid dynamics are simulated by computational fluid dynamics (CFD). Subsequently, a simulation analysis focusing on the critical temperature conditions was conducted, and the dynamic thermal and power responses were achieved. The simulation results are applicable to gain confidence for EHA detail design work as well as proved the functions of the proposed model as a practical development tool.

This volume presents up-to-date contributions in the field of mechanical engineering. The following topics are covered: Machine Design; Tribology, Materials and Surface Engineering; Mechatronics; Computer Aided Design; Mechanical Vibrations; Theory of Mechanisms and Machinery; Robotics; Mechanics of Deformable Bodies; Automotives; Engine and Transmission; Road Safety; Applied Thermodynamics, Heat Transfer, and Renewable Energy; Thermal Systems; Technologies in Agriculture and Food Processing. The results reported in this volume should interest researchers, scientists, industrial experts, teachers and students in the field of mechanical engineering related to design, control and applications. The authors discussed their results at The 10th International Conference on Advanced Concepts in mechanical Engineering (ACME 2022), held in Iasi, Romania, on June 09-10, 2022. The contributions had rigorously reviewed and selected by independent reviewers, members of the International Scientific Committee of this conference. ACME 2022 was organized by Mechanical Engineering Faculty, at “Gheorghe Asachi” Technical University of Iasi, Romania, under the aegis of Romanian Ministry of National Education and Scientific Research, Romanian Academy of Technical Sciences, Academy of Romanian Scientists, in the partnership with American University of Madaba, Jordan, SIAR - Society of Automotive Engineers of Romania, ARoTMM - Romanian Association for Mechanisms and Machine Science, SROMECA – Romanian Association of Mechatronics, ART – Romanian Tribology Association, SRT – Romanian Society of Thermodynamics, AFCR – Romanian Association for Refrigeration and Cryogenics Engineers. We are grateful to the authors for their valuable contributions and to the reviewers for their timely reviews and recommendations as improvement guidance for the selected papers. We thank also the members of Organizing Committee for the enthusiastic work of organizing this conference and the publisher, IOP Publishing, who paved the way to the timely publication of this volume with their excellent technical and editorial support. List of CONFERENCE CHAIRMEN, HONORARY COMMITTEE, SCIENTIFIC COMMITTEE, ORGANIZING COMMITTEE are available in this pdf.

Background: Compared with other types of compressors, although the scroll compressor has a simple structure and low noise, due to the limitation of the structure, it has defects such as excessively high discharge temperature, and has extremely high requirements on the machining accuracy of parts. The oil-free scroll compressor is a new type of scroll machine, which does not contain oil during the working process; it can be applied to cases with low displacement requirements and a high-pressure ratio. Objective: Taking a scroll compressor with a rated displacement of 0.6 as the research object, the analysis and research of the working performance parameters of the scroll compressor in actual work provide a certain theoretical basis for the improvement and optimization of the test prototype. Methods: The thermodynamic model of the scroll compressor in the actual working process is established by the variable-mass system thermodynamics and the control volume method. Based on the CFD method, a three-dimensional unsteady-state numerical simulation of the flow characteristics of the working fluid in the scroll compressor's working chamber is carried out in order to verify the thermodynamic model. Considering the accuracy of numerical simulation, a test platform with air as the working fluid is set up. Results: Through the thermodynamic model and numerical simulation, the changes of temperature, pressure and velocity in the working chamber of the scroll compressor with the orbiting angle of the main shaft as well as the gas force and torque acting on the orbiting scroll tooth are obtained. Through experiments, the law of volume flow and shaft power of the scroll compressor with the speed of change, and the law of the change of discharge temperature with pressure at different speeds are obtained. Conclusion: At the same time, the thermodynamic model established by considering heat transfer and leakage is more in line with the actual working process of the compressor; the mass exchange between adjacent working chambers of the scroll compressor has a greater impact on the temperature and pressure in the working chamber. Due to internal leakage and irreversible loss, such as heat transmission, there is a deviation between the theoretical volume flow and the actual volume flow.

Our culture abhors the world.Yet Quicksand is swallowing the duellists; the river is threatening the fighter: earth, waters and climate, the mute world, the voiceless things once placed as a decor surrounding the usual spectacles, all those things that never interested anyone, from now on thrust themselves brutally and without warning into our schemes and manoeuvres (Michel Serres, The Natural Contract, p 3). When Michel Serres describes culture's abhorrence of the world in the opening pages of The Natural Contract he draws our attention to the sidelining of nature in histories and theories that have sought to describe Western culture. As Serres argues, cultural histories are quite often built on the debates and struggles of humanity, which are largely held apart from their natural surroundings, as if on a stage, "purified of things" (3). But, as he is at pains to point out, human activity and conflict always take place within a natural milieu, a space of quicksand, swelling rivers, shifting earth, and atmospheric turbulence. Recently, via the potential for vast environmental change, what was once thought of as a staid “nature” has reasserted itself within culture. In this paper I explore how Serres’s positioning of nature can be understood amid new communication systems, which, via the apparent dematerialization of messages, seems to have further removed culture from nature. From here, I focus on a set of artworks that work against this division, reformulating the connection between information, a topic usually considered in relation to media and anthropic communication (and something about which Serres too has a great deal to say), and nature, an entity commonly considered beyond human contrivance. In particular, I explore how information visualisation and sonification has been used to give a new sense of materiality to the atmosphere, repotentialising the air as a natural and informational entity. The Natural Contract argues for the legal legitimacy of nature, a natural contract similar in standing to Rousseau’s social contract. Serres’ss book explores the history and notion of a “legal person”, arguing for a linking of the scientific view of the world and the legal visions of social life, where inert objects and living beings are considered within the same legal framework. As such The Natural Contract does not deal with ecology per-se, but instead focuses on an argument for the inclusion of nature within law (Serres, “A Return” 131). In a drastic reconfiguring of the subject/object relationship, Serres explains how the space that once existed as a backdrop for human endeavour now seems to thrust itself directly into history. "They (natural events) burst in on our culture, which had never formed anything but a local, vague, and cosmetic idea of them: nature" (Serres, The Natural Contract 3). In this movement, nature does not simply take on the role of a new object to be included within a world still dominated by human subjects. Instead, human beings are understood as intertwined with a global system of turbulence that is both manipulated by them and manipulates them. Taking my lead from Serres’s book, in this paper I begin to explore the disconnections and reconnections that have been established between information and the natural environment. While I acknowledge that there is nothing natural about the term “nature” (Harman 251), I use the term to designate an environment constituted by the systematic processes of the collection of entities that are neither human beings nor human crafted artefacts. As the formation of cultural systems becomes demarcated from these natural objects, the scene is set for the development of culturally mediated concepts such as “nature” and “wilderness,” as entities untouched and unspoilt by cultural process (Morton). On one side of the divide the complex of communication systems is situated, on the other is situated “nature”. The restructuring of information flows due to developments in electronic communication has ostensibly removed messages from the medium of nature. Media is now considered within its own ecology (see Fuller; Strate) quite separate from nature, except when it is developed as media content (see Cubitt; Murray; Heumann). A separation between the structures of media ecologies and the structures of natural ecologies has emerged over the history of electronic communication. For instance, since the synoptic media theory of McLuhan it has been generally acknowledged that the shift from script to print, from stone to parchment, and from the printing press to more recent developments such as the radio, telephone, television, and Web2.0, have fundamentally altered the structure and effects of human relationships. However, these developments – “the extensions of man” (McLuhan)— also changed the relationship between society and nature. Changes in communications technology have allowed people to remain dispersed, as ideas, in the form of electric currents or pulses of light travel vast distances and in diverse directions, with communication no longer requiring human movement across geographic space. Technologies such as the telegraph and the radio, with their ability to seemingly dematerialize the media of messages, reformulated the concept of communication into a “quasi-physical connection” across the obstacles of time and space (Clarke, “Communication” 132). Prior to this, the natural world itself was the medium through which information was passed. Rather than messages transmitted via wires, communication was associated with the transport of messages through the world via human movement, with the materiality of the medium measured in the time it took to cover geographic space. The flow of messages followed trade flows (Briggs and Burke 20). Messages moved along trails, on rail, over bridges, down canals, and along shipping channels, arriving at their destination as information. More recently however, information, due to its instantaneous distribution and multiplication across space, seems to have no need for nature as a medium. Nature has become merely a topic for information, as media content, rather than as something that takes part within the information system itself. The above example illustrates a separation between information exchange and the natural environment brought about by a set of technological developments. As Serres points out, the word “media” is etymologically related to the word “milieu”. Hence, a theory of media should be always related to an understanding of the environment (Crocker). But humans no longer need to physically move through the natural world to communicate, ideas can move freely from region to region, from air-conditioned room to air-conditioned room, relatively unimpeded by natural forces or geographic distance. For a long time now, information exchange has not necessitated human movement through the natural environment and this has consequences for how the formation of culture and its location in (or dislocation from) the natural world is viewed. A number of artists have begun questioning the separation between media and nature, particularly concerning the materiality of air, and using information to provide new points of contact between media and the atmosphere (for a discussion of the history of ecoart see Wallen). In Eclipse (2009) (fig. 1) for instance, an internet based work undertaken by the collective EcoArtTech, environmental sensing technology and online media is used experimentally to visualize air pollution. EcoArtTech is made up of the artist duo Cary Peppermint and Leila Nadir and since 2005 they have been inquiring into the relationship between digital technology and the natural environment, particularly regarding concepts such as “wilderness”. In Eclipse, EcoArtTech garner photographs of American national parks from social media and photo sharing sites. Air quality data gathered from the nearest capital city is then inputted into an algorithm that visibly distorts the image based on the levels of particle pollution detected in the atmosphere. The photographs that circulate on photo sharing sites such as Flickr—photographs that are usually rather banal in their adherence to a history of wilderness photography—are augmented by the environmental pollution circulating in nearby capital cities. Figure 1: EcoArtTech, Eclipse (detail of screenshot), 2009 (Internet-based work available at:http://turbulence.org/Works/eclipse/) The digital is often associated with the clean transmission of information, as packets of data move from a server, over fibre optic cables, to be unpacked and re-presented on a computer's screen. Likewise, the photographs displayed in Eclipse are quite often of an unspoilt nature, containing no errors in their exposure or focus (most probably because these wilderness photographs were taken with digital cameras). As the photographs are overlaid with information garnered from air quality levels, the “unspoilt” photograph is directly related to pollution in the natural environment. In Eclipse the background noise of “wilderness,” the pollution in the air, is reframed as foreground. “We breathe background noise…Background noise is the ground of our perception, absolutely uninterrupted, it is our perennial sustenance, the element of the software of all our logic” (Serres, Genesis 7). Noise is activated in Eclipse in a similar way to Serres’s description, as an indication of the wider milieu in which communication takes place (Crocker). Noise links the photograph and its transmission not only to the medium of the internet and the glitches that arise as information is circulated, but also to the air in the originally photographed location. In addition to noise, there are parallels between the original photographs of nature gleaned from photo sharing sites and Serres’s concept of a history that somehow stands itself apart from the effects of ongoing environmental processes. By compartmentalising the natural and cultural worlds, both the historiography that Serres argues against and the wilderness photograph produces a concept of nature that is somehow outside, behind, or above human activities and the associated matter of noise. Eclipse, by altering photographs using real-time data, puts the still image into contact with the processes and informational outputs of nature. Air quality sensors detect pollution in the atmosphere and code these atmospheric processes into computer readable information. The photograph is no longer static but is now open to continual recreation and degeneration, dependent on the coded value of the atmosphere in a given location. A similar materiality is given to air in a public work undertaken by Preemptive Media, titled Areas Immediate Reading (AIR) (fig. 2). In this project, Preemptive Media, made up of Beatriz da Costa, Jamie Schulte and Brooke Singer, equip participants with instruments for measuring air quality as they walked around New York City. The devices monitor the carbon monoxide (CO), nitrogen oxides (NOx) or ground level ozone (O3) levels that are being breathed in by the carrier. As Michael Dieter has pointed out in his reading of the work, the application of sensing technology by Preemptive Media is in distinct contrast to the conventional application of air quality monitoring, which usually takes the form of extremely high resolution located devices spread over great distances. These larger air monitoring networks tend to present the value garnered from a large expanse of the atmosphere that covers individual cities or states. The AIR project, in contrast, by using small mobile sensors, attempts to put people in informational contact with the air that they are breathing in their local and immediate time and place, and allows them to monitor the small parcels of atmosphere that surround other users in other locations (Dieter). It thus presents many small and mobile spheres of atmosphere, inhabited by individuals as they move through the city. In AIR we see the experimental application of an already developed technology in order to put people on the street in contact with the atmospheres that they are moving through. It gives a new informational form to the “vast but invisible ocean of air that surrounds us and permeates us” (Ihde 3), which in this case is given voice by a technological apparatus that converts the air into information. The atmosphere as information becomes less of a vague background and more of a measurable entity that ingresses into the lives and movements of human users. The air is conditioned by information; the turbulent and noisy atmosphere has been converted via technology into readable information (Connor 186-88). Figure 2: Preemptive Media, Areas Immediate Reading (AIR) (close up of device), 2011 Throughout his career Serres has developed a philosophy of information and communication that may help us to reframe the relationship between the natural and cultural worlds (see Brown). Conventionally, the natural world is understood as made up of energy and matter, with exchanges of energy and the flows of biomass through food webs binding ecosystems together (DeLanda 120-1). However, the tendencies and structures of natural systems, like cultural systems, are also dependent on the communication of information. It is here that Serres provides us with a way to view natural and cultural systems as connected by a flow of energy and information. He points out that in the wake of Claude Shannon’s famous Mathematical Theory of Communication it has been possible to consider the relationship between information and thermodynamics, at least in Shannon’s explanation of noise as entropy (Serres, Hermes74). For Serres, an ecosystem can be conceptualised as an informational and energetic system: “it receives, stores, exchanges, and gives off both energy and information in all forms, from the light of the sun to the flow of matter which passes through it (food, oxygen, heat, signals)” (Serres, Hermes 74). Just as we are related to the natural world based on flows of energy— as sunlight is converted into energy by plants, which we in turn convert into food— we are also bound together by flows of information. The task is to find new ways to sense this information, to actualise the information, and imagine nature as more than a welter of data and the air as more than background. If we think of information in broad ranging terms as “coded values of the output of a process” (Losee 254), then we see that information and the environment—as a setting that is produced by continual and energetic processes—are in constant contact. After all, humans sense information from the environment all the time; we constantly decode the coded values of environmental processes transmitted via the atmosphere. I smell a flower, I hear bird songs, and I see the red glow of a sunset. The process of the singing bird is coded as vibrations of air particles that knock against my ear drum. The flower is coded as molecules in the atmosphere enter my nose and bind to cilia. The red glow is coded as wavelengths from the sun are dispersed in the Earth’s atmosphere and arrive at my eye. Information, of course, does not actually exist as information until some observing system constructs it (Clarke, “Information” 157-159). This observing system as we see the sunset, hear the birds, or smell the flower involves the atmosphere as a medium, along with our sense organs and cognitive and non-cognitive processes. The molecules in the atmosphere exist independently of our sense of them, but they do not actualise as information until they are operationalised by the observational system. Prior to this, information can be thought of as noise circulating within the atmosphere. Heinz Von Foester, one of the key figures of cybernetics, states “The environment contains no information. The environment is as it is” (Von Foester in Clarke, “Information” 157). Information, in this model, actualises only when something in the world causes a change to the observational system, as a difference that makes a difference (Bateson 448-466). Air expelled from a bird’s lungs and out its beak causes air molecules to vibrate, introducing difference into the atmosphere, which is then picked up by my ear and registered as sound, informing me that a bird is nearby. One bird song is picked up as information amid the swirling noise of nature and a difference in the air makes a difference to the observational system. It may be useful to think of the purpose of information as to control action and that this is necessary “whenever the people concerned, controllers as well as controlled, belong to an organised social group whose collective purpose is to survive and prosper” (Scarrott 262). Information in this sense operates the organisation of groups. Using this definition rooted in cybernetics, we see that information allows groups, which are dependent on certain control structures based on the sending and receiving of messages through media, to thrive and defines the boundaries of these groups. We see this in a flock of birds, for instance, which forms based on the information that one bird garners from the movements of the other birds in proximity. Extrapolating from this, if we are to live included in an ecological system capable of survival, the transmission of information is vital. But the form of the information is also important. To communicate, for example, one entity first needs to recognise that the other is speaking and differentiate this information from the noise in the air. Following Clarke and Von Foester, an observing system needs to be operational. An art project that gives aesthetic form to environmental processes in this vein—and one that is particularly concerned with the co-agentive relation between humans and nature—is Reiko Goto and Tim Collin’s Plein Air (2010) (fig. 3), an element in their ongoing Eden 3 project. In this work a technological apparatus is wired to a tree. This apparatus, which references the box easels most famously used by the Impressionists to paint ‘en plein air’, uses sensing technology to detect the tree’s responses to the varying CO2 levels in the atmosphere. An algorithm then translates this into real time piano compositions. The tree’s biological processes are coded into the voice of a piano and sensed by listeners as aesthetic information. What is at stake in this work is a new understanding of atmospheres as a site for the exchange of information, and an attempt to resituate the interdependence of human and non-human entities within an experimental aesthetic system. As we breathe out carbon dioxide—both through our physiological process of breathing and our cultural processes of polluting—trees breath it in. By translating these biological processes into a musical form, Collins and Gotto’s work signals a movement from a process of atmospheric exchange to a digital process of sensing and coding, the output of which is then transmitted through the atmosphere as sound. It must be mentioned that within this movement from atmospheric gas to atmospheric music we are not listening to the tree alone. We are listening to a much more complex polyphony involving the components of the digital sensing technology, the tree, the gases in the atmosphere, and the biological (breathing) and cultural processes (cars, factories and coal fired power stations) that produce these gases. Figure 3: Reiko Goto and Tim Collins, Plein Air, 2010 As both Don Ihde and Steven Connor have pointed out, the air that we breathe is not neutral. It is, on the contrary, given its significance in technology, sound, and voice. Taking this further, we might understand sensing technology as conditioning the air with information. This type of air conditioning—as information alters the condition of air—occurs as technology picks up, detects, and makes sensible phenomena in the atmosphere. While communication media such as the telegraph and other electronic information distribution systems may have distanced information from nature, the sensing technology experimentally applied by EcoArtTech, Preeemptive Media, and Goto and Collins, may remind us of the materiality of air. These technologies allow us to connect to the atmosphere; they reformulate it, converting it to information, giving new form to the coded processes in nature.AcknowledgmentAll images reproduced with the kind permission of the artists. References Bateson, Gregory. Steps to an Ecology of Mind. Chicago: University of Chicago Press, 1972. Briggs, Asa, and Peter Burke. A Social History of the Media: From Gutenberg to the Internet. Maden: Polity Press, 2009. Brown, Steve. “Michel Serres: Science, Translation and the Logic of the Parasite.” Theory, Culture and Society 19.1 (2002): 1-27. Clarke, Bruce. “Communication.” Critical Terms for Media Studies. Eds. Mark B. N. Hansen and W. J. T. Mitchell. Chicago: University of Chicago Press, 2010. 131-45 -----. “Information.” Critical Terms for Media Studies. Eds. Mark B. N. Hansen and W. J. T. Mitchell. Chicago: University of Chicago Press, 2010. 157-71 Crocker, Stephen. “Noise and Exceptions: Pure Mediality in Serres and Agamben.” CTheory: 1000 Days of Theory. (2007). 7 June 2012 ‹http://www.ctheory.net/articles.aspx?id=574› Connor, Stephen. The Matter of Air: Science and the Art of the Etheral. London: Reaktion, 2010. Cubitt, Sean. EcoMedia. Amsterdam and New York: Rodopi, 2005 Deiter, Michael. “Processes, Issues, AIR: Toward Reticular Politics.” Australian Humanities Review 46 (2009). 9 June 2012 ‹http://www.australianhumanitiesreview.org/archive/Issue-May-2009/dieter.htm› DeLanda, Manuel. Intensive Science and Virtual Philosophy. London and New York: Continuum, 2002. Fuller, Matthew. Media Ecologies: Materialist Energies in Art and Technoculture. Cambridge, MA: MIT Press, 2005 Harman, Graham. Guerilla Metaphysics. Illinois: Open Court, 2005. Ihde, Don. Listening and Voice: Phenomenologies of Sound. Albany: State University of New York, 2007. Innis, Harold. Empire and Communication. Toronto: Voyageur Classics, 1950/2007. Losee, Robert M. “A Discipline Independent Definition of Information.” Journal of the American Society for Information Science 48.3 (1997): 254–69. McLuhan, Marshall. Understanding Media: The Extensions of Man. London: Sphere Books, 1964/1967. Morton, Timothy. Ecology Without Nature: Rethinking Environmental Aesthetics. Cambridge: Harvard University Press, 2007. Murray, Robin, and Heumann, Joseph. Ecology and Popular Film: Cinema on the Edge. Albany: State University of New York, 2009 Scarrott, G.C. “The Nature of Information.” The Computer Journal 32.3 (1989): 261-66 Serres, Michel. Hermes: Literature, Science Philosophy. Baltimore: The John Hopkins Press, 1982. -----. The Natural Contract. Trans. Elizabeth MacArthur and William Paulson. Ann Arbor: The University of Michigan Press, 1992/1995. -----. Genesis. Trans. Genevieve James and James Nielson. Ann Arbor: The University of Michigan Press, 1982/1995. -----. “A Return to the Natural Contract.” Making Peace with the Earth. Ed. Jerome Binde. Oxford: UNESCO and Berghahn Books, 2007. Strate, Lance. Echoes and Reflections: On Media Ecology as a Field of Study. New York: Hampton Press, 2006 Wallen, Ruth. “Ecological Art: A Call for Intervention in a Time of Crisis.” Leonardo 45.3 (2012): 234-42.