Specific properties of water and steam Keywords: enthalpy- dryness fraction- specific volume-entropy- internal energy Definition: Specific properties are per kg. Examples are specific volume, specific enthalpy, specific entropy, specific internal energy, specific latent heat. Symbol These specific properties are represented by the small alphabet like v, h,s,u,cP etc. Reference temperature for the enthalpy and entropy […]
Highlights of general thermodynamic relations If f(x,y,z) =0 then (i) (∂x/∂y)z (∂y/∂z)x(∂z/∂x)y = –1 (∂y/∂x)z(∂x/∂y)z=(∂y/∂z)x(∂z/∂y)x =(∂z/∂x)y(∂x/∂z)y=1 Z=z(x,y), y =y(z,x) and x=x(y,z) If z = z(x,y) then dz = (∂z/∂x)y dx + (∂z/∂y)x dy For a continuous function ∂2z/∂x∂y =∂2z/∂y∂x Internal energy(U), Helmholtz energy (A), enthalpy (H) and Gibb’s free energy(G) are characteristic functions in thermodynamics.These […]
HIGHLIGHTS OF AVAILABILITY Availability is the maximum theoretical work which can be obtained by a heat engine. Since some heat is rejected in a heat engine, therefore recovery of maximum work is not possible. The work which cannot be recovered because of heat rejection to the surroundings is the unavailability. When heat is added to […]
THERMODYNAMIC: AVAILABILITY, UNAVAILABILITY AND IR-REVERSIBILITY 10. AVAILABILITY, UNAVAILABILITY AND IR-REVERSIBILITY (a) Available Energy Available energy is related to the energy grade.There are two grades of energy available from the various sources. HIGH GRADE ENERGY—Can be fully converted useful work (Shaft Work) and is not governed by the Second Law of Thermodynamics (no ir-reversibility).Examples of high […]
THERMODYNAMIC —TRANSPORT PROPERTIES 5. TRANSPORT PROPERTIES–three These include the specific heat, viscosity and thermal conductivity. SPECIFIC HEATS There can be three values of Cp and three values of Cv depending upon whether the gas is monoatomic, diatomic or polyatomic. As per Equi-partition theorem, energy is equally distributed for each degree of freedom by […]
THERMODYNAMIC: TEMPERATURE ENTROPY CHART AND PRESSURE ENTHALPY CHART TEMPERATURE ENTROPY CHART As entropy is a thermodynamic parameter (property) like other thermodynamic parameters namely internal energy/enthalpy, it is used as abscissa (x –co-ordinate) and ABSOLUTE temperature as the ordinate. This chart is very useful in comparing the performance of various heat engine and refrigeration cycles. Although […]
DERIVED THERMODYNAMIC PROPERTIES 6. THERMODYNAMIC PROPERTIES (a) Fundamental Thermodynamic Properties–three Measurable properties like temperature, pressure and volume are the three fundamental thermodynamic properties. (b) Derived Thermodynamic Properties–three Non measureable properties like internal energy, enthalpy and entropy are called derived thermodynamic properties. Definition of internal energy comes from the First Law of Thermodynamics Definition of entropy comes […]
THERMODYNAMIC TEMPERATURE AND THERMODYNAMIC SCALE THERMODYNAMIC TEMPERATURE Development of Thermodynamic Temperature Scale and its Practical Utility Temperature is due to the random translation, rotational motions and vibrations of the submicroscopic particle constituents of matter. These motions constitute the internal energy of a substance. Thermodynamic temperature is the measure of the average kinetic energy per degree […]
THERMODYNAMIC POTENTIALS AND THERMODYNAMIC PARAMETERS—-SHEET 3—Natural variables, Maxwell relations and Exact differentials dU, dW and dQ NATURAL VARIABLES The variables which are kept constant in a process are called the natural variables of that potential. Thermodynamic potential can be found as a function of its natural variables only. Then only the thermodynamic properties of the […]
THERMODYNAMIC POTENTIALS AND THERMODYNAMIC PARAMETERS—SHEET 2—–Euler’s Law of Reciprocity Thermodynamic potentials are useful in the thermodynamics of chemical reactions. These potentials also describe the non-cyclic processes. They are four thermodynamic potentials. These are internal energy, the enthalpy, the Helmholtz free energy and the Gibbs free energy. All the thermodynamic potentials are energy terms. These potentials cannot be […]