(c) Enthalpy constant process -ISEN-THALPIC (h=constant)
(d) Entropy constant process -ISEN-TROPIC (s=constant)
(e) Volume constant process -ISO-CHORIC (V=constant)
(f) No heat exchange -ADIABATIC PROCESS
A thermodynamic cycle will have four processes.
Carnot cycle consists of two iso-thermal and two isentropic processes.
Thermodynamic and Transport Properties
Fundamental Properties- these are measurable properties.
i. Specific volume of saturated liquid
ii. Saturated vapor specific volume
iii. Specific volume of super heated vapor
Derived Properties- These are non-measurable properties.
Specific enthalpy of saturated liquid
Enthalpy(specific) of saturated vapor
Specific enthalpy of super heated vapor
Specific entropy of saturated liquid
Entropy(specific) of saturated vapor
Entropy(specific) of super heated vapor
Internal Energy is the sum of kinetic and potential energy. These energies are of random translation, rotational and vibratory motion of the atoms of the system. Its symbol for 1 kg is ‘u’ for 1 kg mass. U is symbol for m kg mass. Its units are kJ. From the First Law of Thermodynamics, the internal energy of a system increases with rise of temperature.
dU = Q – W= heat supplied into the system—work done by the system.
Entropy is measure of disorder. More is the disorder, more will be entropy. Mathematically δV/V is a measure of disorder. It will increase in an expansion process and vice versa. Take entropy zero with respect to a datum. Various processes use difference of entropies. Take entropy of water zero at 0 0 C. Based on this, calculate the values of entropy. Similar is the case of refrigerants. Take entropy of each refrigerant zero at –40 0 C. Calculate entropy values at other temperatures and tabulate. Temperature-entropy charts are mad from the tabulated data. Units of specific entropy are k J / kg K. The symbols for specific entropy is ‘s’. S is total entropy for m kg. Read Specific entropy (k J/ kg K) values from tables and charts.
It is sum of internal energy and flow work.
h = u+ p v
Transport properties are
Specific heat of liquid
Vapor specific heat
Thermal conductivity of liquid
Conductivity(thermal) of vapor
Viscosity of liquid
Origin of transport properties
Internal energy comes from the First Law of Thermodynamics
Entropy comes from the Second Law of Thermodynamics. Measurement of entropy comes from the Third Law of Thermodynamics.
Definition of enthalpy comes from the total heat content which the sum of internal energy and the flow work.
SPECIFIC AND TOTAL PROPERTIES
(a) Specific property
Properties for 1 kg mass are specific properties. Refrigerant charts and tables have specific properties.
(i) specific entropy (s),
(ii) Enthalpy (specific) (h),
(iii) specific volume (v),
(iv) Humidity(specific) (w).
Specific properties are for
(i) Subcooled liquid
(ii) Saturated liquid
(iii) Wet vapor
(iv) Dry saturated vapor
(v) Superheated vapor
The symbol of specific property is small alphabet.
2(b). Total properties
Total property is equal to specific property multiplied by mass (m). This represented by the corresponding capital alphabet symbol like H=m h, S=m s, V=m v.
Thermodynamic relations used in the derivation of derived properties
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