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3 pages, A 2019 comment by Hochet and Tailleux and the corresponding reply by Holmes et al. discuss the volume and mass balance on a control volume bounded by a given isotherm and the ocean free surface. This note partly reconciles the terms of discrepancy on volume or mass transport appearing in these publications by proving that the integral expressions in the comment of Hochet and Tailleux, using a particular parameterization of the moving surfaces in Cartesian coordinates, correspond to the mass transport across the moving surfaces, as long as the mass density is included, as given in direct vector notation by Holmes et al. in their reply, Partial support for this study was obtained through project RTI2018-100844-B-C33 (Spanish Ministry of Science, Innovation and Universities), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Unsteady natural convection in a fluid saturated porous enclosure with a pair of vertical diathermal partition separated at equal distance from centre of enclosure is studied in this paper. The purpose is to curtail the convection heat transfer rate across a differentially heated enclosure. The governing equations are based on Darcy's model and solved using Successive Accelerated Replacement and explicit scheme. Streamlines and isotherms are observed for various values of partition ratio, where partition ratio is the ratio of distance of from enclosure centre to either of the partition to the total length of the enclosure; while Nusselt number is evaluated to manifest the heat transfer rate of each configuration. It is found that, employing partition in the porous enclosure substantially attenuates the value of Nusselt number. It has been also found that lower the value of partition ratio, higher will be the reduction in Nusselt number.

The rate at which the ocean moves heat from the tropics toward the poles, and from the surface into the interior, depends on diabatic surface forcing and diffusive mixing. These diabatic processes can be isolated by analyzing heat transport in a temperature coordinate (the diathermal heat transport). This framework is applied to a global ocean sea ice model at two horizontal resolutions (1/4° and 1/10°) to evaluate the partioning of the diathermal heat transport between different mixing processes and their spatial and seasonal structure. The diathermal heat transport peaks around 22°C at 1.6 PW, similar to the peak meridional heat transport. Diffusive mixing transfers this heat from waters above 22°C, where surface forcing warms the tropical ocean, to temperatures below 22°C where midlatitude waters are cooled. In the control 1/4° simulation, half of the parameterized vertical mixing is achieved by background diffusion, to which sensitivity is explored. The remainder is associated with parameterizations for surface boundary layer, shear instability, and tidal mixing. Nearly half of the seasonal cycle in the peak vertical mixing heat flux is associated with shear instability in the tropical Pacific cold tongue, highlighting this region’s global importance. The framework presented also allows for quantification of numerical mixing associated with the model’s advection scheme. Numerical mixing has a substantial seasonal cycle and increases to compensate for reduced explicit vertical mixing. Finally, applied to Argo observations the diathermal framework reveals a heat content seasonal cycle consistent with the simulations. These results highlight the utility of the diathermal framework for understanding the role of diabatic processes in ocean circulation and climate.

Italy is celebrated in the world for its agri-food industries while the process of production of pasta is highly energy demanding and requires both electrical and thermal energy simultaneously. Because most of the Italian factories producing pasta are located in the Southern part of the country, the direct use of thermal energy generated from the sun would be particularly profitable. In this study, the authors examine the possibility of generating by a Solar Industrial Process Heating plant the thermal energy required annually by an existing factory that produces durum wheat pasta located in Sicily (Italy). The hypothesized plant scheme consists of an array of Fresnel linear solar collectors and a concrete thermal energy storage system in which a heat transfer diathermal fluid circulates. This particular combination, although not the most efficient from the thermodynamic point of view, determines a lower visual impact and easier maintenance during the life span of the system. The use of food graded thermal oil ensures a high level of safety. A TRNSYS model has been developed in order to simulate the energy performance of the above described plant with the aim of optimizing the design of the solar heat for industrial process systems in terms of solar collectors and thermal energy storage dimensions taking into account the available space in the specific location. The obtained results show that the direct use of the thermal energy generated with the Fresnel solar collectors can significantly contribute to increase the sustainability of the most thermal energy-demanding factories working in the food industry, a strategic sector in the Mediterranean Area. The average annual solar contribution can reach about 40% of the total thermal energy requirement, maximizing the solar energy production during the summer season. Moreover, the proposed study allowed the determination of the maximum investment cost of the plant linked to a simple payback time, without external incentives, of 8 years.

Hochet and Tailleux (2019), in a comment on Holmes et al. (2019), argue that under the incompressible Boussinesq approximation the “sum of the volume fluxes through any kind of control volume must integrate to zero at all times.” They hence argue that the expression in Holmes et al. (2019) for the change in the volume of seawater warmer than a given temperature is inaccurate. Here we clarify what is meant by the term “volume flux” as used in Holmes et al. (2019) and also more generally in the water-mass transformation literature. Specifically, a volume flux across a surface can occur either due to fluid moving through a fixed surface, or due to the surface moving through the fluid. Interpreted in this way, we show using several examples that the statement from Hochet and Tailleux (2019) quoted above does not apply to the control volume considered in Holmes et al. (2019). Hochet and Tailleux (2019) then derive a series of expressions for the water-mass transformation or volume flux across an isotherm in the general, compressible case. In the incompressible Boussinesq limit these expressions reduce to a form (similar to that provided in Holmes et al. 2019) that involves the temperature derivative of the diabatic heat fluxes. Due to this derivative, can be difficult to robustly estimate from ocean model output. This emphasizes one of the advantages of the approach of Holmes et al. (2019), namely, does not appear in the internal heat content budget and is not needed to describe the flow of internal heat content into and around the ocean.

Much like other scientific disciplines, thermodynamics also has its own vocabulary. For instance, while dealing with objects composed of very large numbers of particles, one might use terms like thermodynamic system; adiabatically isolating, and adiabatically enclosing, walls; adiabatic and nonadiabatic enclosures; conducting and/or diathermal walls; isothermal, isobaric, isochoric, quasistatic, reversible, and irreversible processes; state functions and state variables; thermodynamic equilibrium and, of course, temperature in its various representations.

The material presented in this lecture is adapted from Chapter 15 in T&M. First, we will discuss the infinite-dilution reference state typically used to describe solutions where the solvent dominates (that is, the solvent mole fraction approaches unity), and the solutes are present at mole fractions which approach zero. In this context, we will discuss colligative properties, including freezing-point depression, boiling-point elevation, vapor-pressure lowering, and osmotic pressure. Second, we will discuss the thermodynamic criteria of phase equilibria for a system consisting of π phases, each containing n components, and separated by boundaries that are open, diathermal, and movable. Accordingly, the entire composite system is simple. Third, we will show that, at thermodynamic equilibrium, the system is in thermal, mechanical, and diffusional equilibrium for each of the component present in each phase. Fourth, we will present a derivation of the celebrated Gibbs Phase Rule, which specifies the number of independent intensive variables that we need to select in order to unambiguously characterize the intensive equilibrium thermodynamic state of the system. Note that the Gibbs Phase Rule does not specify which intensive variables we need to select, but only their number. Finally, we will show how the Gibbs Phase Rule needs to be generalized when the multiphase, multicomponent system is not simple, including discussing the number of independent extensive variables that we need to select to fully characterize the extensive equilibrium thermodynamic state of the system.

Holmes et al. (2019) have proposed a new theoretical framework for studying ocean heat uptake in potential temperature coordinates. One important step in their derivations requires understanding the temporal changes of the volume of water V with temperature greater than some value, which they write as the sum of two terms. The first one is due to the surface freshwater fluxes and is well defined, but the second one—attributed to the volume fluxes through the lower boundary of the domain—is given no explicit expression. What the authors mean exactly is unclear, however, because in the incompressible Boussinesq approximation, the use of a divergenceless velocity field implies that the sum of the volume fluxes through any kind of control volume must integrate to zero at all times. In this comment, we provide two alternative explicit mathematical expressions linking the volume change of Holmes et al. (2019) to the diabatic sources and sinks of heat that clarify their result. By contrasting Holmes et al.’s (2019) approach with that for a fully compressible ocean, it is concluded that the volume considered by Holmes et al. (2019) is best interpreted as a proxy for the Boussinesq mass M0 = ρ0V, where ρ0 is the reference Boussinesq density. If V were truly meant to represent volume rather than a proxy for the Boussinesq mass, the Boussinesq expression for dV/dt would have to be regarded as inaccurate because of its neglect of the volume changes resulting from mean density changes.

The influence of the initial tank temperature on the evolution of the internal gas temperature during the refuelling of on-board hydrogen tanks is investigated in this paper. Two different types of tanks, four different fuel delivery temperatures (from ambient temperature refuelling to a pre-cooled hydrogen at −40 °C), several filling rates and initial pressures are considered. It has been found that the final gas temperature increases linearly with the increase of the initial tank temperature while the temperature increase (ΔT) and the final state of charge (SOC) decrease linearly with increasing the initial temperature. This dependency has been found to be larger on type III than on type IV tank and larger the larger the initial pressure. Additionally CFD simulations are performed to better understand the role of the relevant phenomena on the gas temperature histories e.g. gas compression, gas mixing, and heat transfer. By comparing the results of calculations with adiabatic and diathermal tank walls, the effect of the initial gas temperature has been separated from the effect of the initial wall temperature on the process.

We consider a model for thermal contact through a diathermal interface between two macroscopic bodies at different temperatures: an Ising spin chain with nearest neighbor interactions is endowed with a Glauber dynamics with different temperatures and kinetic parameters on alternating sites. The inhomogeneity of the kinetic parameter is a novelty with respect to the model of Ref.[1] and we exhibit its influence upon the stationary non equilibrium values of the two-spin correlations at any distance. By mapping to the dynamics of spin domain walls and using free fermion techniques, we determine the scaled generating function for the cumulants of the exchanged heat amounts per unit of time in the long time limit., 20 pages

The thermohaline inverse method (THIM) is presented that provides estimates of the diathermohaline streamfunction , the downgradient along-isopycnal diffusion coefficient K, and the isotropic downgradient turbulent diffusion coefficient D of small-scale mixing processes. This is accomplished by using the water mass transformation framework in two tracer dimensions: here in Absolute Salinity SA and Conservative Temperature Θ coordinates. The authors show that a diathermal volume transport down a Conservative Temperature gradient is related to surface heating and cooling and mixing, and a diahaline volume transport down an Absolute Salinity gradient is related to surface freshwater fluxes and mixing. Both the diahaline and diathermal flows can be calculated using readily observed parameters that are used to produce climatologies, surface flux products, and mixing parameterizations for K and D. Conservation statements for volume, salt, and heat in (SA, Θ) coordinates, using the diahaline and diathermal volume transport expressed as surface freshwater and heat fluxes and mixing, allow for the formulation of a system of equations that is solved by an inverse method that can estimate the unknown diathermohaline streamfunction and the diffusion coefficients K and D. The inverse solution provides an accurate estimate of , K, and D when tested against a numerical climate model for which all these parameters are known.

Much attention has been paid to study the state of charge (SOC) during fast filling process. However, investigation on identifying the foremost factors and contribution of them to the filling mass is still an open issue. In essence, the contributing factors are multiple, of which, the most important factors can be found out by thermodynamical analysis. Based on the thermodynamical analysis and mass flow rate balance, some equations calculating filling mass and heat transfer are outstanding. The mass filling rate, the initial pressure in the cylinder and the inlet temperature of hydrogen are confirmed to be the utmost important factors influencing the filling mass. A computational fluid dynamics (CFD) model is established. The simulation results show the liner or inverse proportional relationship between filling mass and the three factors, hence, a formula for the final mass with diverse filling conditions is figured out. By means of studying the state of charge obtained by adiabatic and diathermal filling processes, a formula to investigate the heat transfer is proposed. Both the filling mass and heat transfer are coupled with the three factors. Therefore, the effect of heat transfer on filling mass has been investigated. It seems that the filling mass is dependent on the total heat transfer during fast filling.

A comparison between the standard adiabatic piston dynamics and that of a perfectly conducting (diathermal) piston helps to clarify their different behaviors and, in particular, the anomalously large random displacement of the adiabatic piston as compared to the diathermal one. It is shown to be associated with a situation where the presence of a single massive “particle” (the piston), acting as an internal constraint in a many-particle system, plays a somewhat unexpected relevant role. A significant physical insight accounting for the above difference is gained by means of a simple analysis of the phase space available to our system.

Annual mean net heat fluxes from ocean general circulation models (OGCMs) are systematically too low in the tropical Indian Ocean, compared to observations. In the models, only some of the geostrophic inflow replacing southward Ekman outflow is colder than the minimum sea surface temperature (MINSST). Observed heat fluxes imply that much more inflow is colder than MINSST. Since inflow below MINSST can only join the surface Ekman transport after diathermal warming, the OGCMs must underestimate diathermal effects. A crude analog of the annual mean Indian Ocean heat budget was generated, using a rectangular box model with a deep “Indo–Pacific” gap at 7°–10°S in its eastern side. Wind stress was zonal and proportional to the Coriolis parameter, so Ekman transport was spatially constant and equaled Sverdrup transport. For three experiments, zonally integrated Ekman transport was steady and southward at 10 Sv (Sv ≡ 106 m3 s−1). In steady state, a 10 Sv “Indonesian Throughflow” fed a northward western boundary current of 10 Sv, which turned eastward along the northern boundary at 10°N to feed the southward Ekman transport. Most diathermal mixing occurred within an intense eddy in the northwest corner. Some of the geostrophic inflow was at temperatures colder than MINSST (found at the northeast corner of the eddy); it must warm to MINSST via diathermal mixing. Northern boundary upwelling exceeded the 10-Sv Ekman transport. The excess warms as it recirculates around the eddy, apparently supplying the heat to warm inflow below MINSST. In an experiment using the “flux-corrected transport” (FCT) scheme, diathermal mixing occurred in the strongly sheared currents around the eddy. However the Richardson number never became low enough to drive strong diathermal mixing, perhaps because (like that of other published models) the present model’s vertical resolution was too coarse. In three experiments, the dominant mixing was caused by horizontal diffusion, spurious convective overturn, and numerical mixing invoked by the FCT scheme, respectively. All three mixing mechanisms are physically suspect; such model problems (if widespread) must be resolved before the mismatch between observed and modeled heat fluxes can be addressed. However, the fact that the density profile at the western boundary must be hydrostatically stable places a lower limit on the area-integrated heat fluxes. Results from the three main experiments—and from many published OGCMs—are quite close to this lower limit.

Closure is a key concept in the physical sciences that has infrequently been used in ecology. The paper reviews closure to the flow of matter and energy (adiabatic walls) and closure to the flow of matter (diathermal walls). A system with rigid adiabatic walls will degrade eventually to chemical equilibrium, a state of maximum entropy. A third type of closure involves semi-permeable walls permitting the flow of one or more types of chemicals. These closure concepts were important to the development of classical thermodynamics and statistical mechanics in the 19th and 20th centuries. ‘‘Equilibrium’’ is often used to describe a time independent steady state. This usage leads to confusion, because equilibrium has such a precise meaning in thermal physics. All living systems are farfrom-equilibrium and life cannot persist without the flow of energy. The Earth is an almost materially closed system. Only a small amount of cosmic matter is captured by the Earths gravitational field and only a small fraction of lighter elements escape that field. The Earth receives photon flux from the sun and generates thermal energy from the planetary decay of radioisotopes. A hypothesis can be advanced that the planetary biosphere exists in part because of material closure due to gravitation. In the science of ecology partial material closure has been introduced in limnology and island ecology. This has advanced biogeographical theory and systems ecology. The development in the past half century of first balanced aquaria and terrariums, and then partially materially closed microcosms and mesocosms has also greatly aided the development of ecology as an experimental rather than merely descriptive science. All the above systems are open atmospherically, and often have some water and nutrient inputs. The development of truly materially closed man-made systems offers further scope for the development of experimental ecology. The paper reviews and defines the various types of closed ecological systems: Class 1: natural planetary biospheres (like the Earths); and Class 2: man-made systems which range from laboratory microbial ecospheres to ones capable of human life support: Controlled Environmental Life Support Systems (CELSS such as are being developed by NASA and the European Space Agency), Closed Ecological Systems (such as Bios-3 at the Institute of Biophysics in Krasnoyarsk, Russia and the Biosphere 2 Test Module) to mini-biospheric systems with a complexity of internal ecosystems (e.g., Biosphere 2 and the Closed Ecology Experimental Facility, CEEF, in Japan). 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.

A first principle analysis of an open system thermodynamical Carnot cycle is provided and the results are compared to those proposed by Gibbs for open systems. The Kelvin–Clausius statement concerning heat transfer for reversible cycles is taken as an axiom, from which several rigorous theorems are proven. An equation is derived that resembles a Gibbs–Duhem relation equating convected entropies, from which two distinguishable forms of entropy are proven to exist for such systems; this questions prevailing developments which presume a singular or characteristic entropic form that couple all work and heat flows, such as in Onsager first-order thermodynamics. In particular, a closed path undergone by the system does not return the environment to the initial state for one of these entropic forms. The Biot assertion that the entropy contribution due to diathermal heat transfer does not form a state function is therefore contradicted and a local entropy is shown to exist. Several other new composite state functions for work and heat flow are shown to exist for open systems. From Gibbs’ results, it is suggested that the ensuing chemical potentials used routinely may possibly ignore heat effects. The functions developed here are suitable for application since the functions are proven to exist, rather than presumed to exist.

Numerical analysis of 3D regimes of convection-radiation heat transfer in cubic enclosure with two isothermal faces and adiabatic walls is performed. The mathematical model is constructed in dimensionless variables “vector potential-vorticity vector-temperature” in the Boussinesq approximation and with regard to diathermal medium filling the enclosure. 3D temperature and velocity fields, medium motion trajectories in a wide range of key parameters are obtained. Correlations for the integral heat exchange coefficient as a function of the key process characteristics are found.

This article presents a theoretical model for the nonlinear description of vibrations occurring in the rotor-bearings-supports system. A new approach to the determination of viscous-elastic properties of the oil film that does not draw on the commonly used principle of superposition of pressure or hydrodynamic forces in the bearing is put forward. The dynamic features of the oil film are determined by means of nonlinear coefficients of stiffness and damping calculated by using a fast and modified perturbation method. The method applied to describe the oil filin properties enables us to take advantage of the equations of motion of the entire system derived on the basis of the finite element method. The theoretical model takes also into account the effect of heat transfer within the bearing. With regard to kinetostatic problems, the temperature distribution in the film is calculated on the basis of a sophisticated so-called diathermal model of the bearing that permits the determination of a mean dynamic viscosity of the oil, further applied to the problems of the system dynamics. A general calculation algorithm and a computer program consisting of two clearly separated parts, kinetostatic and dynamic, is described. This article also gives examples of experimental verification of the model at a special large-size test rig and presents the analysis of nonlinear vibrations of a real large turbo-set carried out with the help of the developed theoretical method and computer program.

The historical development of the Carnot cycle necessitated the construction of isothermal and adiabatic pathways within the cycle that were also mechanically "reversible" which lead eventually to the Kelvin-Clausius development of the entropy function where the heat absorption is for the diathermal (isothermal) paths of the cycle only. It is deduced from traditional arguments that Fourier heat conduction involves mechanically "reversible" heat transfer with irreversible entropy increase. Here we model heat conduction as a thermodynamically reversible but mechanically irreversible process. The MD simulations conducted shows excellent agreement with the theory. Such views and results as these, if developed to a successful conclusion could imply that the Carnot cycle be viewed as describing a local process of energy-work conversion and that irreversible local processes might be brought within the scope of this cycle, implying a unified treatment of thermodynamically (i) irreversible, (ii) reversible, (iii) isothermal and (iv) adiabatic processes., 10 pages, 2 figures. Material for talk at conference and ICNPAA 2014 (Narvik, Norway) Conference Proceedings

Nonadiabatic one-dimensional flow of steam in elementary modules of pipe networks, i.e. straight pipes and fittings, has been considered. A simple method of determining the amount of condensed water, distributions of pressure and temperature along these modules has been developed. The problem of critical flow regime has been discussed and a general formula of checking for the presence of sonic velocities at arbitrary cross section of the pipeline has been given. When embedded into a supervising procedure, the described routines can be used to build a mathematical model of a steam pipe network of arbitrary topology. Numerical examples are included. A set of equations describing all the steam properties used in the calculations is given in the Appendix.

The compact thermodynamic approach to the systems containing calcium, magnesium, and carbonate species is referred to dissolution of dolomite, as an example of nonequilibrium ternary salt when introduced into aqueous media. The study of dolomite is based on all attainable physicochemical knowledge, involved in expressions for equilibrium constants, where the species of the system are interrelated. The species are also involved in charge and concentration balances, considered as constraints put on a closed system, separated from the environment by diathermal walls. The inferences are gained from calculations performed with use of an iterative computer program. The simulated quasistatic processes occurred under isothermal conditions, started at a preassumed pH0 value of the solution where dolomite was introduced, and are usually involved with formation of other solid phases. None simplifying assumptions in the calculations were made.

Much like other scientific disciplines, thermodynamics also has its own vocabulary. For instance, while dealing with objects composed of very large numbers of particles, one might use terms like: thermodynamic system; adiabatically isolating and adiabatically enclosing walls; adiabatic and non-adiabatic enclosures; conducting and/or diathermal walls; isothermal, isobaric, isochoric, quasi-static, reversible, and irreversible processes; state functions and state variables; thermodynamic equilibrium; and, of course, temperature in its various representations.

Laminar natural convection heat transfer in inclined porous layers with multiple diathermal partitions is studied analytically and numerically. On the basis of the Darcy-Oberbeck-Boussinesq equations, the problem is solved analytically in the limit of a thin layer with constant flux boundary conditions. The relationship between overall heat transfer and the number of partitions N, their relative positions Nu and the angle of inclination φ of the system is determined The critical Darcy-Rayleigh number R c for the onset of convection in a bottom-heated horizontal system is predicted. The results are compared with limiting cases of the problem and are found to be in agreement. The influence of a thermal barrier which is sandwiched between two porous layers is also discussed. A numerical study of the same phenomenon, obtained by solving the complete system of governing equations, is conducted. A good agreement is found between the analytical predictions and the numerical simulation.

In nature water presents itself in solid, liquid and gaseous phases. Energy transfers during transformations among these phases have important consequences in weather and climate. The system of redistribution of water on the planet constitutes the hydrological cycle which is central to weather and climate research and operations. Water is also an important solvent in the oceans, soils and in cloud droplets. The presence of tiny particles in the air can influence the formation of cloud drops and thereby change the Earth's radiation balance between absorbed and emitted and/or reflected radiation. These and other effects lead us into the fascinating role of water in the environment. Of course, thermodynamics is an indispensable tool in unraveling this very challenging puzzle. Vapor pressure We start with a discussion of the equilibrium gas pressure in a chamber in diathermal contact with a reservoir at a fixed temperature, T 0 . The chamber is to have a volume that is adjustable, as shown in Figure 5.1. In the following let the chamber have no air present – only the gas from evaporation of the liquid. We are to choose a volume V such that there is some liquid present at the bottom of the chamber (we say here the bottom of the chamber, but otherwise we ignore gravity). There are gas molecules constantly striking the liquid from above and sticking. […]

The passage of powerful laser radiation in a flat layer of diathermal medium with specularly reflecting and diffusely emitting boundaries is studied. The conditions under which “optical turbulence” arises are examined. It is shown that the optical characteristics of the boundaries of the flat layer are bifurcational parameters.

This chapter introduces a set of idealized auxiliary thermodynamic systems with special properties that they possess by definition. These systems are the reversible work, heat, and matter sources and reservoirs. They are called “auxiliary systems” because they serve as components in composite systems whose main component is to be investigated. Their primary purpose is to assure constancy of one or the other intensive parameter such as temperature, pressure, or chemical potential in the main component. A very large reversible work source is called a “work reservoir.” If the work is pressure–volume work, the pressure of a volume reservoir is constant. Such a work reservoir acts as a “manostat.” Similarly in case of heat reservoir, temperature is constant. A heat reservoir coupled to another system through a diathermal wall acts as a “thermostat.” In a matter reservoir, the chemical potential of the species of which it consists is constant and it thus acts as a “chemostat.” In the interaction of a given thermodynamic system with a reversible heat, work, or matter source the total change in entropy is zero because the processes are reversible.

A diathermal wall between two heat baths at different temperatures can be mimicked by a layer of independent spin pairs with some internal energy and where each spin ?a is flipped by thermostat a (a?=?1,2). The transition rates are determined from the modified detailed balance. Generalized heat capacities, excess heats, the housekeeping entropy flow and the thermal conductivity in the steady state are calculated. The joint probability distribution of the heat cumulated exchanges at any time is computed explicitly. We obtain the large deviation function of heat transfer via a variety of approaches. In particular, by a saddle-point method performed accurately, we obtain the explicit expressions not only of the large deviation function, but also of the amplitude prefactor, in the long-time probability density for the heat current. The following physical properties are discussed: the effects of typical time scales of the mesoscopic dynamics which do not appear in equilibrium statistical averages and the limit of strict energy dissipation towards a thermostat when its temperature goes to zero.

Experiments using an isoperibolic (diathermal) adsorption calorimeter show that in some adsorption systems there is an exothermic or endothermic consecutive process following the primary adsorption step. For the simple case of a consecutive process of first order it is possible to derive as well the kinetic as the energetic parameters describing the formation of the intermediate and final adsorption state.

The calculations for the three diathermal calorimeter designs are given and their merits and dismerits are compared. The recommendations for the embodiment of the respective design versions are proposed.

A numerical study has been made of natural convection in an inclinded porous enclosure with an off-center diathermal partition. A temperature difference is imposed between the two isothermal end walls and the other two walls are assumed to be adiabatic. Numerical results are obtained for Rayleigh numbers (Ra) in the range of 10 to 500, the dimensionless partition location (\(\bar S\)) ranging from 0.125 to 0.875, the aspect ratios (A) of the enclosure ranging from 0.5 to 5, and the inclination angles (φ) of −60, −30, 0, 30, 60 degrees. It is found that the partition location has strong influence at lowRa and relatively weaker influence at highRa. The average Nusselt number reaches the minimum value when the partition is in the middle of the vertical enclosure, and the maximum Nusselt number occurs around φ = 30 degrees.

The spatial distribution of radiation is examined in calculating radiation heat transfer between surfaces in a diathermal medium.

When adsorption calorimeters of the Beebe type are used with particulate adsorbents having low thermal conductivity, the assumption of thermal equilibrium in the calorimeter system is not valid. A differential equation is developed relating calorimeter wall temperature to the balance between cooling losses and heat transferred by the several internal conduction paths. Unique calorimeter parameters are obtained from cooling curve analysis for both calibration and adsorption processes. Techniques for resolving accurate heats of adsorption are discussed.

This numerical study documents the effect of internal flow obstructions on heat transfer through a 2-dim. porous layer heated from the side. Three types of flow obstructions have been considered. Horizontal diathermal partitions were found to decrease the heat transfer rate in cases where the overall heat transfer was dominated by convection. In the conduction-dominated regime, horizontal diathermal partitions were found to increase the heat transfer rate slightly. Horizontal adiabatic partitions, on the other hand, were found to increase the heat transfer rate when the dominating mechanism is convection. Finally, vertical diathermal partitions were shown to reduce the heat transfer rate by roughly 50% in the convection-dominated regime. Numerical heat transfer results are reported in the domain 0.1

A new method is proposed, for the determination of thermal radiation properties, which allows prompt and exact determination of optical characteristics of the surfaces of bodies taking part in radiative heat exchange, as well as of angular coefficients of radiation, surface density of the resultant radiant flow and surface intensity of heat accumulation. The method is based on an analytical treatment of the curve obtained from a heated sample. When optical characteristics of materials are determined, the geometry of the radiative system is taken from the values of angular coefficients of radiation known exactly beforehand. This provides a reliable criterion for estimating the correctness of an experimental installation and the accuracy of results obtained in experiments carried out in accordance with developed methods.

The PMI, recrystallized from dry benzene, had m.p. 89-90 °. For the calorimetric investigation we used the diathermal calorimeter described in reference [3]. Some minor changes in design (increase of the power of the heater, improvement in the thermal insulation etc.) enabled the working temperature range to be extended to 370°K. The PMI samples were irradiated in the calorimeter cells by 6°Co y-radiation at a dose rate of 4.5 Mrad]hr, at 77°K. The irradiated cell containing the monomer was transferred to the calorimeter at 77°K and the calorimetric melting curve was recorded at a uniform rate of warming up. After melting of the contents the cell was opened and the yield of polymer was determined gravimetrieally.

PUBLISHED LITERATURE STRESSES THE PHYSIOCOCHEMICAL APPROACH TO CLAY SWELLING. IN THIS PAPER, EQUILIBRIUM THERMODYNAMICS IS EXPLORED AS ANOTHER APPROACH WORTHY OF CONSIDERATION, HOWEVER, THE MECHANISM OF SWELLING IS NOT INCLUDED. A MACROSCOPIC, HOMOGENEOUS MASS IS USED TO DESCRIBE THE COMPOSITION OF A CLAY-WATER SYSTEM WHICH IS FREE OF EXTERNAL FIELDS, INCLUDING GRAVITATIONAL FIELDS. AN EXAMPLE IS GIVEN OF A CLAY-WATER SYSTEM WHICH IS ENCLOSED BY MOVABLE, DIATHERMAL WALLS THAT ARE PERMEABLE ONLY TO LIQUID AND GAS PHASES. EQUATIONS ARE PRESENTED TO SHOW THE PHASES THAT A CLAY-WATER SYSTEM UNDERGOES IN REACHING A STATE OF THERMODYNAMIC EQUILIBRIUM. FOR A GIVEN QUASISTATIC PROCESS THE TEMPERATURE AND THE CLAY MASS ARE HELD CONSTANT WHILE CHANGES IN THE VOLUME OF THE CLAY-WATER SYSTEM AND CHANGES IN THE PRESSURE, BOTH FOR INTERNAL PRESSURE AND THE FINAL PRESSURE, OF THE WATER CONTENT HAD AFTER COMPRESSION AS NOTED. AS AN ALTERNATIVE METHOD OF PRESENTING THE VOLUME CHANGES, THE TRANSFER OF WATER FROM A SERIES OF RESERVOIRS IS DISCUSSED WITH APPROPRIATE EQUATIONS. IN ADDITION, THE GEOMETRY FACTOR, ALTHOUGH MENTIONED, IS NOT DISCUSSED BECAUSE OF ITS RELATIONSHIP TO THE MICROSCOPIC CONCEPTS OF THERMODYNAMICS. THE CLAY-WATER SYSTEMS WITH THE SAME TEMPERATURE, PRESSURE, AND WATER CONTENT ARE CONSIDERED WITH DIFFERENT BULK DENSITIES.