Second Law Research Papers - Academia.edu (original) (raw)

The release kinetics of nisin from poly(butylene adipate-co-terephthalate) (PBAT) to distilled water was studied at of 5.6, 22 and 40°C. The release kinetics of nisin from PBAT film was described using Fick's second law of diffusion, partition coefficient, and Weibull model. The diffusion coefficients (D) determined were 0.93, 2.29, and 5.78 Â 10 À10 cm 2 /s at 5.6, 22, and 40°C, respectively. The partition coefficients (K) calculated were 0.84, 3.89, and 5.2 Â 10 3 at 5.6, 22, and 40°C, respectively. The nisin release data at selected temperatures were fitted with the Weibull model (R 2 > 0.97) with b and n values ranging from 0.02 to 0.98 and from 0.28 to 0.45, respectively. The temperature dependence of D, K, and Weibull model parameter b was modeled using the Arrhenius equation giving values of activation energy (E a ) of 38.3 kJ mol À1 (for D), 38.5 kJ mol À1 (for K), and 79.5 kJ mol À1 (for b).

- by and +1
- •
- Food Engineering, Kinetics, Food, Activation Energy

The management of municipal solid waste (MSW) and the current status of world energy resources crisis are important problems. Gasification is a kind of waste-to-energy conversion scheme that offers the most attractive solution to both waste disposal and energy problems. In this study, the thermodynamic equilibrium model based on equilibrium constant for predicting the composition of producer gas in a downdraft waste gasifier was developed. To enhance the performance of the model, further modification was made by multiplying the equilibrium constants with coefficients. The modified model was validated with the data reported by different researchers. MSW in Thailand was then used to simulate and to study the effects of moisture content (MC) of the waste on the gasifier's performance. The results showed that the mole fraction of H 2 gradually increases; CO decreases; CH 4 , which has a very low percentage in the producer gas increases; N 2 slightly decreases; and CO 2 increases with increasing MC. The reaction temperature, the calorific value, and the second law efficiency, decrease when MC increases.

- by sajid iqbal
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- Mechanical Engineering, Thermodynamics, Renewable Energy, Energy

Most hypotheses of the evolutionary origin of genome imprinting assume that the biochemical character on which natural selection has operated is the expression of the allele from only one parent at an affected locus. We propose an alternative - that natural selection has operated on differences in the chromatin structure of maternal and paternal chromosomes to facilitate pairing during meiosis and to maintain the distinction between homologues during DNA repair and recombination in both meiotic and mitotic cells. Maintenance of differences in chromatin structure in somatic cells can sometimes result in the transcription of only one allele at a locus. This pattern of transcription might be selected, in some instances, for reasons that are unrelated to the original establishment of the imprint. Differences in the chromatin structure of homologous chromosomes might facilitate pairing and recombination during meiosis, but some such differences could also result in non-random segregation of chromosomes, leading to parental-origin-dependent transmission ratio distortion. This hypothesis unites two broad classes of parental origin effects under a single selective force and identifies a single substrate through which Mendel's first and second laws might be violated.

The design and performance of the Ghazlan power plant (Kingdom of Saudi Arabia) are described. The study is based on first-and second-law analyses. A full exergy analysis is carried out to identify the potential for improving the plant... more

- by Mohamed Habib
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- Engineering, Mechanical Engineering, Thermodynamics, Energy

In this study solar-assisted heat pump (SAHP) system with flat plate collectors was investigated experimentally and tested for domestic space heating. SAHP system was located in a test room with 60 m 2 floor area in Firat University, Elazig (38,411N, 39,141E) Turkey. The experiments were performed in heating season of January 2003. The coefficient of performance of the SAHP system was calculated. The system COP of the SAHP was obtained as 3.08 while the exergy loss of the solar collector was found to be 1.92 kW. The second law efficiency of the compressor, condenser, evaporator and solar heat exchanger in SAHP system were evaluated 42.1%, 83.7%, 43.2% and 9.4%, respectively. The first law efficiency and exergetic efficiency of the whole system are found to be 65.6%, 30.8%, respectively. Consequently the energy and exergy loss analysis results show that the COP increase when the exergy loss of evaporator decrease.

- by Abdullah Akbulut
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- Architecture, Heat Exchanger, Seasonality, Building

Helium reversed cycles Advanced turbomachines for liquefiers a b s t r a c t An innovative, efficient and large hydrogen liquefier is described. Innovations lie in the fact that (i) the feed, 10 kg s À1 , is refrigerated in heat exchangers catalytically promoting the ortho-para conversion (ii) down to the low temperature of 20.5 K and at the high pressure of 60 bar at which it is available and (iii) lastly expanded to the storage conditions of 1.5 bar and 20 K through a liquid-phase turbomachine; (iv) refrigeration is via four helium recuperative Joule-Brayton cycles arranged so that the refrigerant follows the cooling curve of hydrogen and the volume flow rates in compression and expansion processes are typical of axial-flow high-efficiency turbomachines; (v) compression is accomplished in 15 intercooled 8-stage devices derived from gas turbine technology. Heat exchangers require specific surfaces comparable to current state-of-the-art liquefiers. Nevertheless, the predicted work of approximately 18 MJ kg À1 is half as much as the requirement of those liquefiers and corresponds to a second-law efficiency of almost 48%. (E. Macchi). 1 Tel.: +39 02 2399 3907. 2 Quack gives two estimates of the second-law efficiency: 60.7% that reduces to 53.8% if pressure drops are included in the calculations. Moreover, Quack adopts a dead-state temperature of 300 K, whereas the present work assumes one of 288.15 K.

- by Gianluca Valenti and +1
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- Engineering, High Pressure, GAS TURBINE, Heat Exchanger

A computer model is developed for studying the first-and second-law (availability) balances of a turbocharged diesel engine, operating under transient load conditions. Special attention is paid to the direct comparison between the results from the two laws, for various operating parameters of the engine. The model simulates the transient operation on a degree crank angle basis, using a detailed analysis of mechanical friction, a separate consideration for the processes of each cylinder during a cycle (''multi-cylinder'' model) and a mathematical model of the fuel pump. Experimental data taken from a marine duty, turbocharged diesel engine, located at the authors' laboratory, are used for the evaluation of the model's predictive capabilities. The first-law (e.g., engine speed, fuel pump rack position, engine load, etc.) and second-law (e.g., irreversibilities, heat loss and exhaust gases) terms for the diesel engine cylinder are both computed and depicted in comparison, using detailed diagrams, for various engine operating parameters. It is revealed that, at least for the specific engine type and operation, a thermodynamic, dynamic or design parameter can have a conflicting impact on the engine transient response as regards energy and availability properties, implying that both a first-and second-law optimization is needed for best performance evaluation. r

- by veena chaudhary
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- Thermodynamics, Renewable Energy, Transient analysis, Second Law
- by Afshin Shafiee
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- Thermodynamics, Second Law, Second Law of Thermodynamics

Bioerodible polymers used in controlled drug delivery systems, such as poly(lactic-co-glycolic acid) (PLGA) undergo radiolytic degradation during γ-irradiation. In spite of the considerable practical importance, yet only little knowledge is available on the consequences of this sterilization method on the resulting drug release patterns in a quantitative way. The major objectives of the present study were: (i) to monitor the

- by Joel Richard
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- Monte Carlo Simulation, Kinetics, Scanning Electron Microscopy, Drug Delivery System

Heat pump Thermodynamics R410A Renewable energy Ground source a b s t r a c t This paper presents data, analyses, measures of performance, and conclusions for a ground-source heat pump (GSHP) providing space conditioning to a 345 m 2 house whose envelope is made of structural insulated panels. The entire house thermal load with R SI -3.7 (R US -21) walls, triple-pane windows (U-factor of 1.64 W m À2 K (0.29 Btu h À1 ft À2 F À1 )) and solar heat gain coefficient of 0.25, a roof assembly with overall thermal resistance of about R SI -8.8 (R US -50), and low leakage rates of 0.74 ACH at 50 Pa, was satisfied with a 2.16 ton (7.56 kW) GSHP unit. Coefficient of performance is calculated on the basis of the total power input (including duct, ground loop, and control power losses). Exergy analysis provides a true measure of how closely actual performance approaches the ideal, and it unequivocally identifies, better than energy analysis does, the sources and causes of lost work d the root cause of system inefficiencies and wasted energy.

- by Moonis Ally and +2
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- Engineering, Thermodynamics, Renewable Energy, Refrigeration

A conductivity relaxation experiment has been conducted on an SrFeCo0.5Ox sample by abruptly changing the oxygen partial pressure in the atmosphere and monitoring the change of conductivity as a function of time. The re-equilibrium process obeys Fick's second law. By fitting the relaxation data to the solution of the diffusion equation with appropriate boundary conditions, we could determine the oxygen chemical diffusion coefficient and the activation energy. The oxygen diffusion coefficient is 8.9 × 10−7 cm2/s at 900 °C and it increases with increase in temperature. Measured activation energy is 0.92 eV, which is slightly lower than that of other oxides in the system SrFe1 − xCoxOy.

- by Carlo U Segre
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- Engineering, Materials Engineering, Condensed Matter Physics, Cyclic Voltammetry

This paper presents the performance analysis of an air-to-water vapor compression heat pump system using pure refrigerants and zeotropic refrigerant mixtures. The heat pump system is composed of a compressor, condenser, air cooled evaporator, expansion valve, a receiver tank, a superheater/subcooler, refrigerant mixture unit and some auxiliary and measurement devices. The study focuses on the second law efficiency characteristics of the heat pump system. Comparisons are made between the pure refrigerants and refrigerant mixtures on the basis of the COP and second law efficiency. Also, the effect of the evaporator source inlet temperature on the COP and second law efficiency is presented. It was found that the mixture ratio affects the COP and second law efficiency significantly, and the COP and second law efficiency for the pure refrigerants could be improved by using an appropriate mixture of the refrigerants.

- by Mehmet YILMAZ
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- Performance Analysis, Second Law, Heat pump, CoP

Grapes of Corvina, Corvinone and Rondinella cultivars used for the production of ''Amarone" and ''Recioto" wines were withered under fixed conditions of temperature (10, 15, 20 and 25°C) and relative humidity (53%, 75% and 95%) in order to evaluate their withering kinetics in an 80 days time-frame. Withering kinetics were described by means of linear and exponential regression equations. In agreement with basic dehydration theory, withering kinetic rates were found to increase with increasing temperature and with decreasing relative humidity (both above and below the value of the critical moisture). Moisture diffusion coefficients, calculated for each trial condition by solving a simplified equation based on Fick's second law, varied from 1.63 Â 10 À13 to 6.34 Â 10 À12 . Withering kinetic rates showed an opposite dependence on temperature and relative humidity as shown by multiple linear regression analysis results. Grape surface/volume ratio affected the withering kinetic rates for values above 3.8 cm À1 and at low relative humidity (53%).

- by Michela Cipriani
- •
- Production, Food Engineering, Kinetics, Food

The second law of thermodynamics has played an important role in ecological economics as providing a justification for the view that economies have limits to growth. Yet beyond basic textbooks statements of this law, we seldom find informed philosophical examinations of the meaning and metaphysical justification for the second law. In this paper we shall examine some challenges which have

- by Claire Smith
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- Economics, Ecological Economics, Environmental Sciences, Population environment

The tecond law of thermodynamics is used as a basis for evaluating the irreversibility (entropy generation) associated with simple heat transfer processes. In the first part of this paper, the irreversibility production is analyzed from the local level, at one point in a convective heat transfer arrangement. The second part of the paper is devoted to a limited review of second law analysis applied to classic engineering components for heat exchange. In this categ&y, the paper includes such topics as: heat transfer augmentation techniques, heat exchanger design, and thermal insulation systems. Analytical methods for evaluating and minimizing the irreversibility associated with textbook-type components of heat transfer equipment are presented. NOTATION Row cross sectional area: duty parameter in Eq. (14) duty parameter in Eq. (I I) hydraulic diameter. D = 4r, Eckert number. o'(r,AT) friction factor " dimensionless mass velocity in Eq. (23) flow path length mass flow rate number of heat transfer units entropy generation number Nusselt number Prandtl number heat transfer rate, W Reynolds number entropy generation rate, W/K Stanton number absolute temperature insulation thickness heat exchanger effectiveness irreversibility distribution ratio, S,JS,, temperature difference number AT/T reference heat exchanger passage heat transfer-augmented passage

- by Adrian Bejan
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- Engineering, Mechanical Engineering, Physics, Thermodynamics

This paper presents a second law analysis for the optimal geometry of fin array by forced convection. The analytical analysis involves the achievement of a balance between the entropy generation due to heat transfer and entropy generation due to fluid friction. In the design of a thermal system, it is important to minimize thermal irreversibilities because the optimal geometry will be found when the entropy generation rate is minimized. In this paper, the entropy generation rate is discussed and optimum thickness for fin array is determined on the basis of entropy generation minimization subjected to the global constraint. In addition, the influence of cost parameters on the optimum thickness of fin array is also considered and presented in graphical form. It has been found that the increase in cross flow fluid velocity will enhance the heat transfer rate that will reduce the heat transfer irreversibility.

The constructal law accounts for the universal phenomenon of generation and evolution of design (configuration, shape, structure, pattern, rhythm). This phenomenon is observed across the board, in animate, inanimate and human systems. The constructal law states the time direction of the evolutionary design phenomenon. It defines the concept of design evolution in physics. Along with the first and second law, the constructal law elevates thermodynamics to a science of systems with configuration. In this article we review the more recent work of our group, with emphasis on the advances made with the constructal law in the natural sciences. Highlighted are the oneness of animate and inanimate designs, the origin of finite-size organs on animals and vehicles, the flow of stresses as the generator of design in solid structures (skeletons, vegetation), the universality and rigidity of hierarchy in all flow systems, and the global design of human flows. Noteworthy is the tapestry of distributed energy systems, which balances nodes of production with networks of distribution on the landscape, and serves as key to energy sustainability and empowerment. At the global level, the constructal law accounts for the geography and design of human movement, wealth and communications.

- by Sylvie Lorente
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- Evolutionary Biology, Thermodynamics, Design, Organizational Change

Design Experiment a b s t r a c t Air-source heat pumps for residential heating are more widely used than geothermal heat pumps mainly due to their lower installation costs. Major disadvantages of air-source heat pumps are the decrease of heat output and coefficient of performance (COP), and increase in discharge temperature, towards low outdoor temperatures. In this paper an air-source two-stage heat pump using R410A as the refrigerant was simulated, designed, constructed, and tested at ambient temperatures as low as À30 C and supply temperatures of up to 50 C in air and water heating mode. In addition, the system is able to provide sufficient air conditioning in cooling mode (approximately 50-60% of the design heat transfer rate in heating mode). A short summary of an extended literature review is shown as well as a theoretical screening study of the three most promising cycles. Furthermore, the design and test results of a breadboard system and a comparison with commercially available heat pumps are presented. Second law efficiencies of up to 45% could be achieved, resulting in a coefficient of performance (COP) of 2.1 at À30 C ambient temperature. ª 2008 Elsevier Ltd and IIR. All rights reserved. Pompe à chaleur bié tagé e air-eau dans les applications ré sidentielles de chauffage et de refroidissement dans les climats septentrionaux aux Etats-Unis Mots clés : Pompe à chaleur ; Air-eau ; Systè me à compression ; Systè me bié tagé ; R410A ; Conception ; Expé rimentation 1. (E.A. Groll).

- by Eckhard Groll
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- Engineering, Design, Water, Refrigeration

The objective of this study was to introduce and evaluate UV imaging technology for real-time characterization of drug diffusion in and release from hydrogels. Piroxicam and human serum albumin diffusion in Pluronic F127 hydrogel was monitored by measuring the absorbance of light passing through the diffusion cell at 26°C, thus providing real-time concentration maps (7 Â 3 mm imaging area) within the gel as a function of time. Apparent diffusion coefficients were obtained on the basis of Fick's second law. Piroxicam and human serum albumin diffusivities in 20% (w/w) F127 gel were 8 and 24 times lower than those determined in the phosphate buffer (pH 7.4). The effect of increasing polymer concentration (20%, 25% and 30% (w/w)) on piroxicam diffusion was further investigated. The decreasing diffusion rate with increasing F127 concentration agreed well with small-angle X-ray scattering (SAXS) measurements. UV imaging was also successfully applied to monitor piroxicam release from 30% (w/w) F127 gel into a stirred aqueous buffer solution, providing simultaneous information on gel dissolution rate, change in thickness of gel-aqueous boundary layer as well as the release of piroxicam into bulk aqueous phase. The current study indicates that UV imaging has great potential for measuring drug diffusion in and release from gel matrices. Compared to the currently used conventional techniques, this technology has several advantages including high information content, non-intrusive measurements without the need for labeling, flexibility with respect to experimental design and simplicity of operation.

The translation from Latin of Newton's First Law (NFL) was considered in a historical perspective. The study showed that Newton's original yields two versions of complementary meanings, one temporal and the other quantitative. The latter is especially important in presenting the idea of inertia of massive bodies, and a new paradigm of understanding motion. The presentation of NFL in physics textbooks was reviewed and a decline in the status of NFL in the physics curriculum was noted. As a rule, if quoted at all, NFL is presented in its temporal form, while the quantitative form does not appear. Normally, NFL is interpreted as a special case: a trivial deduction from Newton's Second Law. Some advanced textbooks replace NFL by a modernized claim, which abandons its original meaning. We advocate the importance and nontrivial meaning of NFL, and call for its `rehabilitation' in physics instruction within the discourse mode of education.

- by Igal Galili
- •
- Science Education, Physics Education, Second Law, Curriculum and Pedagogy

The objective of this investigation was to study the kinetics of NaCl (sodium chloride) diffusion in chicken breast during curing process. By means of experimental planning, tests were carried out to optimise the process variables: concentrations of NaCl, phosphate and dextrose in the curing brine and the process temperature. Based on the improvement of brine gain during curing and reducement of losses during cooking, four conditions were determined to assess the kinetics of curing. The analytical solution of Fick's Second Law was used to calculate the effective diffusion coefficients of sodium chloride and to estimate the amount of NaCl absorbed. Good agreement was obtained between the analytical model and the experimental data. The diffusivities of sodium chloride in chicken breast were in the range of 8.99 · 10 À10 -9.55 · 10 À10 m 2 /s.

- by José Carlos Cunha Petrus
- •
- Food Engineering, Kinetics, Food, Second Law

This paper surveys the publications available in the literature concerning the application of the second-law of thermodynamics to internal combustion engines. The availability (exergy) balance equations of the engine cylinder and subsystems are reviewed in detail providing also relations concerning the definition of state properties, chemical availability, flow and fuel availability, and dead state. Special attention is given to identification

The laws of physics, especially the first and second laws of thermodynamics, have significant implications for economic theory. The major implications of the First Law (conservation of mass/energy) are straightforward and have been discussed at length elsewhere. In brief, raw material inputs to economic processes are not 'consumed'. Having been extracted from the environment in the first place, they eventually return to the environment as wastes. The economic implications of the Second Law (entropy law) are far more subtle. There is considerable literature, initiated by the work of Georgescu-Roegen, on the supposed constraints on economic growth imposed by the fact that economic processes utilize 'low-entropy' raw materials (fossil fuels and high grade metal ores) and discard 'high entropy' wastes. However, as a practical matter the flux of available low-entropy energy (exergy) from the sun is extremely large and certainly adequate to sustain economic activity in the solar system indefinitely, even though fossil fuel and metal ore stocks may eventually be exhausted. It is argued in this paper that the real economic significance of the Second Law lies in the fact that exergy is: (i) not conserved; and (ii) is a useful common measure of resource quality, as well as quantity, applicable to both materials and energy. Thus, exergy can be used to measure and compare resource inputs and outputs, including wastes and losses. This is potentially important in itself. Moreover, since exergy is not conserved it is truly consumed (i.e. used up) in economic processes. Hence, exergy is no less a 'factor of production' than labor or capital. This fact has strong implications for economic growth theory, especially with regard to assessing the role of technical progress.

- by Robert U. Ayres
- •
- Thermodynamics, Ecological Economics, Economic Growth, Energy

In this study, energy and conservation analyses are applied to the production of steel process in the electric arc furnace. The scrap pre-heating system, stack gas and cooling water leaving the furnace are investigated, and the obtained... more

- by Valérie Guillard
- •
- Nutrition and Dietetics, Water, Polysaccharides, Transport phenomena

Since about a decade various fluctuation relations for the entropy production have been derived and analyzed. These relations deal with symmetries of the entropy production under time-reversal and have been proposed as a non-perturbative generalization of fluctuation-dissipation relations. I describe a unifying framework for understanding these relations and I present an algorithm to derive them. The fluctuation relations all follow from the main observation that in great generality the pathdependent entropy production is the source-term of time-reversal breaking in the Lagrangian over space-time histories. That is illustrated via a number of examples as well as via a general theoretical argument. I move these relations away from the strict dynamical background in which they originated and take them back to the context of statistical mechanics where entropy is understood in the sense of Boltzmann, as measuring the typicality of a manifest condition. I discuss how a relation between work and free energy is naturally put in that framework and how the transient and steady state fluctuation theorems are simple consequences. The fact that fluctuation symmetries for the entropy production are in general only valid asymptotically for large times, makes them mostly inaccessible for experimental verification, in contrast with a recent claim that they would usefully quantify second law violations. Part of the interest in the resulting fluctuation symmetries is that they are so universally valid, a rare occasion in nonequilibrium statistical mechanics. However they do not provide a systematic perturbation expansion for response functions. For that one needs to go back to the full Lagrangian and also consider the nonequilibrium modifications to its time-symmetric part. * http://itf.fys.kuleuven.ac.be/∼christ/ under time-reversal, the antisymmetric term in the Lagrangian L gives S(ω) = L(Θω) − L(ω) = R(ω) + log ρ t (ω t ) − log ρ 0 (ω 0 ) (2.3)

In this study, the first and the second law of thermodynamics are used to analyze the performance of a single-stage water-lithium bromide absorption refrigeration system (ARS) when some working parameters are varied. A mathematical model based on the exergy method is introduced to evaluate the system performance, exergy loss of each component and total exergy loss of all the system

- by Muhsin Kiliç
- •
- Mechanical Engineering, Thermodynamics, Energy, Heat Exchanger

Recent advances in nonequilibrium thermodynamics leads to the conclusion that similar processes, constrained by the second law of thermodynamics, give rise to the emergence of structure and process in a broad class of dissipative systems. The second law suggests that, in systems moved away from equilibrium, processes can emerge so that the system organizes in a way that reduces the effect of the applied gradient. If dynamic and or kinetic conditions permit, self organization processes can be expected. As biosystems grow and develop, they should increase their total dissipation, and develop more complex structures with more energy flow, increase their cycling activity, develop greater diversity and generate more hierarchical levels. As a corollary to this general statement, biosystems which do not increase their total dissipation, are organisms dedicated to death, like observed during the aging of any biosystem. Species which survive in ecosystems are those that funnel energy into their own production and reproduction and contribute to autocatalytic processes which increase the total dissipation of the ecosystem while at same time surviving within the constraints of their changing environment. In a broad class of biosystems, stress and aging have similar thermodynamic properties and suggests common underlying principles.

- by Olivier Toussaint
- •
- Physiology, Zoology, Thermodynamics, Kinetics

Despite counter examples in nature, it has been argued that total recycling is impossible for an industrial society as a consequence of the second law of thermodynamics. In this paper it is shown that there is no such limitation. However, it is also shown that ther must be a large stockpile of inactive materials as well as an exogenous source of exergy (e.g. from the sun) for a stable steady-state recycling system to function.

- by Robert U. Ayres
- •
- Ecological Economics, Economic Growth, Recycling, Applied Economics

Berberis is known as a medicinal and ornamental plant in the world. Berberis fruit is used in medicine to cure liver, neck and stomach cancer, blood purification and mouth scent. Dried berberis fruit using new technology was preserved for relatively long time. Thin-layer drying simulation was used to obtain experiment data, using laboratory scale hot-air dryer of the static tray. Fick’s second law was used as a major equation to calculate the moisture diffusivity with some simplification. The calculated value of moisture diffusivity varied from a minimum of 3.320 × 10−10 to a maximum of 9 × 10−9 m2/s and the value of energy activation from a minimum of 110.837 to a maximum of 130.61 kJ/mol of from 50 °C to 70 °C with drying air velocities of 0.5–2 m/s. The high value of the energy of activation for berberis fruit probably related to the tissue of berberis fruit and high moisture content (about 74.28%w.b), and intensive changes in Deff values for a different air temperature at constant air velocity. The input energy values and specific energy requirement for thin-drying of berberis fruit were found to be in the range of 0.643348–35.20032 (kWh) and 20.9355–1110.0700 (kWh/kg) from 50 °C to 70 °C with drying air velocities of 0.5–2 m/s, respectively.

- by Mortaza Aghbashlo
- •
- Energy Consumption, Energy Conversion, New Technology, Activation Energy

A miniature-scale refrigeration system suitable for electronics cooling applications was developed and experimentally investigated. A detailed review of the literature on refrigeration systems and system simulation models for application to electronics cooling is also provided. Experimental results obtained with the prototype system demonstrate its feasibility for use in cooling compact electronic devices. The cooling capacity of the system investigated varied

- by Eckhard Groll
- •
- Heat Transfer, Manufacturing Engineering, Second Law, System Simulation

The paper describes a model of entropy production in a diesel engine turbocharging system, discussing the processes occurring in the compressor, turbine, piping system, charge-air cooler and valves with the exclusion of combustion. The charging efficiency of the system is studied in two distinct engine operating states, conforming to maximum torque and nominal power conditions. Unlike in the standard approach, where the irreversibilities are derived from the balance equation for exergy and thus are addressed inexactly, the criterion function based on the notion of entropy generation, introduced in this paper, improves second law analysis of turbocharged engines by accounting for a direct description of the system internal irreversibilities. This function is used for the examination of an impact of the system design parameters on its efficiency. Computations based on the unsteady one-dimensional flow model show that, under the variations of the inlet pipe length, the timings of inlet valve opening and exhaust valve closure, and the valve overlap period, a favourable correlation can be found between the decrease of entropy production and the increase in amount of air charged into the engine cylinders. The other variables under study, including the turbine equivalent area, temperature decrease in intercooler and wastegate effective area ratio, show an opposite correlation, and thus, can be viewed as constraints in the system optimisation. 

- by K. Nakonieczny
- •
- Mechanical Engineering, Energy, System Design, Entropy generation

Hydrogen-enriched methane flame Second law analysis Propagating triple flame a b s t r a c t A theoretical-numerical analysis based on the second law of thermodynamics is used to examine the propagation of laminar H 2 -enriched CH 4 -air flames. The analysis is based on computing the various entropy generation terms in a transient reacting flow field. A comprehensive, time-dependent computational model, which employs a detailed description of chemistry and transport, is used to simulate the transient ignition and flame propagation in this reacting flow field. Flames are ignited in a jet-mixing layer far downstream of the burner. Following ignition, a well-defined triple flame is formed that propagates upstream with nearly constant flame displacement speed along the stoichiometric mixture fraction line. As the flame approaches the burner, it transitions to a double flame, and subsequently to a burner-stabilized nonpremixed flame. The triple point exhibits the maximum entropy generation, indicating that this point is characterized by high chemical reactivity, as well as large temperature and mass fraction gradients. The volumetric

- by suresh aggarwal
- •
- Engineering, Thermodynamics, Numerical Analysis, Entropy

The aim of this research was to study the behaviour of the drying kinetics of pepino fruit (Solanum muricatum Ait.) at five temperatures (50, 60, 70, 80 and 90°C). In addition, desorption isotherms were determined at 20, 40 and 60°C over a water activity range from 0.10 to 0.90. The Guggenheim, Anderson and de Boer model was suitable to depict the desorption data. A monolayer moisture content from 0.10 to 0.14 g water g −1 d.m. was reported. The equations of Newton, Henderson-Pabis, Modified Page, Wang-Singh, Modified Henderson-Pabis, Logarithmic as well as standardised Weibull were tested for modelling drying kinetics. Besides, Fick's second law model was used to calculate the water diffusion coefficient which increased with temperature from 2.55 to 7.29× 10 −10 m 2 s −1 , with estimated activation energy of 27.11 kJ mol −1 . The goodness of fit of the models was evaluated using sum squared error and chi-square statistical tests. The comparison of the experimental moisture values with respect to the calculated values showed that the standardised Weibull model presented the best goodness of fit, showing that this equation is very accurate for simulating drying kinetics for further optimisation of drying times.

- by Jorge Saavedra Torrico
- •
- Goodness of Fit, Standardisation, Activation Energy, Water Activity

Molecular dynamics (MD) simulation is a powerful tool to investigate the nanoscale fluid flow. In this article, we review the methods and the applications of MD simulation in liquid flows in nanochannels. For pressuredriven flows, we focus on the fundamental research and the rationality of the model hypotheses. For electrokineticdriven flows and the thermal-driven flows, we concentrate on the principle of generating liquid motion. The slip boundary condition is one of the marked differences between the macro-and micro-scale flows and the nanoscale flows. In this article, we review the parameters controlling the degree of boundary slip and the new findings. MD simulation is based on the Newton's second law to simulate the particles' interactions and consists of several important processing methods, such as the thermal wall model, the cut-off radius, and the initial condition. Therefore, we also reviewed the recent improvement in these key methods to make the MD simulation more rational and efficient. Finally, we summarized the important discoveries in this research field and proposed some worthwhile future research directions.

- by Yuxiu Li
- •
- Molecular Dynamics Simulation, Nanofluidics, Nanotechnology, Nanostructures

The inertia property of matter is discussed in terms of a type of induction law related to the extended charged particle's own vector potential. Our approach is based on the Lagrangian formalism of canonical momentum writing Newton's second law in terms of the vector potential and a development in terms of obtaining retarded potentials, that allow an intuitive physical interpretation of its main terms. This framework provides a clear physical insight on the physics of inertia. It is shown that the electron mass has a complete electromagnetic origin and the covariant equation obtained solves the "4/3 mass paradox". This provides a deeper insight into the significance of the main terms of the equation of motion. In particular a force term is obtained from the approach based on the continuity equation for momentum that represents a drag force the charged particle feels when in motion relatively to its own vector potential field lines. Thus, the time derivative of the particle's vector potential leads to the acceleration inertia reaction force and is equivalent to the Schott term responsible for the source of the radiation field. We also show that the velocity dependent term of the particle's vector potential is connected with the relativistic increase of mass with velocity and generates a stress force that is the source of electric field lines deformation. This understanding broadens the possibility to manipulate inertial mass and potentially suggests some mechanisms for possible applications to electromagnetic propulsion and the development of advanced space propulsion physics.

- by Mario Pinheiro
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- Second Law, Drag Force, Equation of Motion, Potential Field

The chemical diffusion coefficients of lithium ion (D Li +) in intercalation-type Li 3 V 2 (PO 4 ) 3 (LVP) anode material as a function of cell voltage between 3.0 and 0.0 V are systematically determined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT). The true chemical diffusion coefficients (D Li + true ) obtained from EIS and GITT for the singlephase region (1.6-0.0 V vs. Li + /Li) are in the range of 10 −10 to 10 −9 cm 2 s −1 and 10 −11 to 10 −10 cm 2 s −1 , respectively, and exhibit a decreasing trend of the change of D Li + true vs. voltage as the discharge and charge proceeded. The apparent chemical diffusion coefficients (D Li + app ) measured from CV and GITT for the two-phase regions (around 2.5-1.6 V) are in the range of 10 −10 cm 2 s −1 and 10 −12 to 10 −10 cm 2 s −1 , respectively. For GITT, D Li + app vs. voltage plots display a characteristic of "W" shape due to the strong interactions of Li + with surrounding ions. Finally, the D Li + values of LVP anode are compared with other anode materials, illustrating that LVP can also be used as a potential anode material to achieve high rate capability.

- by Beihai Ma
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- Engineering, Materials Engineering, Condensed Matter Physics, Cyclic Voltammetry

The paper argues against the claim made by Emergy Analysts that emergy is an exergy-based procedure. Both Emergy-and Exergy Analysis employ space-and time integrated energy input/output models to quantitatively assess the resource consumption of physical systems: the issue at stake is whether Emergy is embodied energy or embodied exergy. Although the compatibility of Exergy-and Emergy accounting procedures, the significance of the peculiar Emergy Algebra, and some cost-allocation issues have been studied in detail, a final agreement could not be reached, so that some doubt exists about the degree of compatibility of the two methods. The present paper shows that the definitions and the procedures employed in Emergy Analysis are in fact First Law-based, and that they neglect or misrepresent Second Law issues. This conclusion is reached by carefully reviewing and critically analyzing a series of general and specific procedures contained in the original Odum books and in some of the most representative publications by Emergy analysts.

- by enrico sciubba
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- Mechanical Engineering, Civil Engineering, Energy, Systems Analysis

Even when the Higgs particle is finally detected, it will continue to be a legitimate question to ask whether the inertia of matter as a reaction force opposing acceleration is an intrinsic or extrinsic property of matter. General relativity specifies which geodesic path a free particle will follow, but geometrodynamics has no mechanism for generating a reaction force for deviation from geodesic motion. We discuss a different approach involving the electromagnetic zero-point field (ZPF) of the quantum vacuum. It has been found that certain asymmetries arise in the ZPF as perceived from an accelerating reference frame. In such a frame the Poynting vector and momentum flux of the ZPF become non-zero. Scattering of this quantum radiation by the quarks and electrons in matter can result in an acceleration-dependent reaction force. Both the ordinary and the relativistic forms of Newton's second law, the equation of motion, can be derived from the electrodynamics of such ZPF-particle interactions. Conjectural arguments are given why this interaction should take place in a resonance at the Compton frequency, and how this could simultaneously provide a physical basis for the de Broglie wavelength of a moving particle. This affords a suggestive perspective on a deep connection between electrodynamics, the origin of inertia and the quantum wave nature of matter.

- by Alfonso Diaz Rueda
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- General Relativity, Quantum Vacuum, Mathematical Sciences, Physical sciences

A genetic algorithm based optimisation technique has been developed for crossflow plate-fin heat exchangers using offset strip fins. The algorithm takes care of large number of continuous as well as discrete variables in the presence of given constraints. The optimisation program aims at minimising the number of entropy generation units for a specified heat duty under given space restrictions. The results have also been obtained and validated through graphical contours of the objective function in the feasible design space. The effect of variation of heat exchanger dimensions on the optimum solution has also been presented.

- by Manish Mishra
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- Mechanical Engineering, Heat Exchanger, Genetic Algorithm, Entropy
- by Luqman Chuah Abdullah
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- Chemical Engineering, Drying Technology, Drying, Second Law

A moving boundary diusion model has been used to predict drying curves for dehydrating prunes (Prunus Domestica). The model is a numerical solution based on Fick's Second Law and takes into account shrinkage of the fruit during the process. The model was validated against experimental drying data as a function of temperature using a laboratory scale dehydrator. A least square ®t of the model results with the experimental data yielded the eective moisture diusion coecient, D(H 2 O), through the fruit and was assumed to be constant during the drying process. Over a temperature range of 70±80°C (commonly used commercially) D(H 2 O) values of 4X3 À 7X6 Â 10 À10 m 2 s À1 were obtained. This yielded an activation energy for the process of 57 kJ mol À1 . It was found that the model gave a much better ®t at the higher temperature end. This was interpreted in terms of the length of any constant-rate (evaporation driven) period. Both air-¯ow velocity and particularly the skin resistance were found to aect the results of the model. For example, removing the skin from the fruit increased D(H 2 O) by 2.5 times. The model is also compared with a previous two-regime model

- by Henry Sabarez
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- Food Engineering, Food Technology, Air flow, Drying

The first and second laws of thermodynamics were used to analyze a novel thermodynamic cycle proposed by Goswami in 1995 that uses an ammonia-water binary mixture as the working fluid, while producing both power and refrigeration simultaneously. The thermodynamic performance of the cycle was optimized for maximum second law efficiency using a commercially available optimization program. A maximum second law efficiency of 65.8% was obtained at a heat source temperature of 420 K. An exergy analysis was performed to study losses in different components of the cycle. It is seen that the largest contribution to cycle irreversibility comes from the absorber, with the rectifier and solution heat exchanger also contributing significantly. Irreversibility generation in the boiler is high at very low heat source temperatures, but drops at higher temperatures.

- by D. Yogi Y Goswami
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- Engineering, Thermodynamics, Water, Performance

- by Mehmet Ali Yilmaz
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- Performance Analysis, Second Law, Heat pump, CoP

In this study, analysis of the second law of thermodynamics is applied to the ladle furnace in an important alloyed and special steel production company in Turkey. Taking liquid steel and stack gas temperatures and production time of liquid steel in the ladle furnace into consideration, actual work, irreversibility and exergy eciency have been calculated. In general, exergy eciency is found to be 50%. Irreversibilities which cause the signi®cant production costs are investigated in detail. Ó

- by murat tunc
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- Mechanical Engineering, Thermodynamics, Second Law, Interdisciplinary Engineering

The purpose of this paper is to collect and interrelate the fundamental concepts about second law analysis of thermal radiation. This heat transfer mode plays a leading role in solar energy utilization and in high-temperature devices, representing a significant contribution to irreversibility that is frequently omitted in engineering analysis. Entropy and exergy of thermal radiation are reviewed first. Radiative transfer processes are reviewed next, including exchange between surfaces, the presence of a participative medium, and the analysis of combined heat transfer modes. Emphasis is put on grey body radiation when treating with non-black body radiation, due to its relevance in engineering applications. The mathematical formulation of second law analysis of thermal radiation is complex, which limits its use in conventional heat transfer analysis. For this reason, numerical approaches reported to date deal with quite simple cases, leaving an open promising field of research.

- by Andres Agudelo
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- Mechanical Engineering, Energy, Heat Transfer, Solar Energy

... The second law analysis can be used to calculate the system performance based on exergy. Exergy analysis is the combination of the first and second laws of thermodynamics and is defined as the maximum amount of work potential of a... more

- by Umit Unver
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- Mechanical Engineering, Renewable Energy, Exergy Analysis, Second Law

Various solutions (Crank's) of Fick's law of diffusion have been used to predict moisture loss (ML) in osmotic dehydration, by correlating experimental data. Selection of a particular solution should depend on the sample geometry and the fulfillment of a number of assumptions made to obtain that solution. Crank developed solutions for long-time, short-time, and a solution for diffusion into a sample from a well-stirred tank for sheets, cylinders and spheres. This work was carried out to find the most suitable Crank's solution to predict ML for a wide range of published data. The long-time solution and the solution for a well-agitated tank, for plane sheets, satisfactorily predicted ML of semi-infinite sheets and semi-infinite cylinders. PRACTICAL APPLICATIONS Crank's solutions of Fick's law for various geometric shapes are used in practice to determine the diffusivity from experimental data for unit operations governed by mass transfer. Once the diffusivity is known, those solutions can be used to predict the kinetics of mass transfer. One of the specific cases where this information is useful is in determining the loss of water for the process of osmotic dehydration. Crank developed solutions for several sets of initial and

- by Hosahalli Ramaswamy
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- Food Process Engineering, Second Law, Osmotic Dehydration, Food Sciences