# TD 2

15.Centrifugal compressor
1. Head developed by centrifugal compressor

2.Power developed by centrifugal compressor

3.Energy balance for compressor

4.Work done in compression per kg and power
Work done due to compression in per kg and power developed by compressor

5.Change in temperature with intercooling

6.Gas horse power of a compressor

16.Turbine

1.Maximum work output from turbine
For turbine to have maximum power output, process should be isentropic

17.Maxwell relation

18.Compressibility factor

19.Isothermal Compressibility

20.Change in enthalpy due to mixing

21.Real fluid
differential change in volume for real fluid is given by

22.Combustion engines (otto cycle and diesel cycle)

Relation between compression ratio and expansion ratio
Cut off ratio is defined as ratio of volume of cylinder after combustion to volume of cylinder before combustion

2.Efficiency of diesel engine

3.Efficiency of otto engine

23.Specific heat capacity for a mixture of reactants and products
Specific heat capacity for a mixture of reactant and products (Cp, mix)

24.Phase equilibrium
A system with unit mass at equilibrium consists of two phases, ∝ and β of extent x and (1-x). The conditions for phase equilibrium are

25.Energy of mixture

2. Thermodynamics

1.Enthalpy

• Enthalpy of mixing (not reacting species) may be positive (endothermic) or negative (exothermic) depending upon composition of mixing solutions.
• Entropy increases with increase in occupied space.
• For an irreversible system, Δs >= 0. But even for reversible and adiabatic process for which Δs = 0, if heat is added to system the overall change in entropy (Δs = ΔQ/T) will be positive.
• Total entropy change is change in entropy in system plus change in entropy in surrounding.
• The change in entropy of a system undergoing a cyclic irreversible process is equal to zero.

3.Gibbs energy

• ΔG = ΔH – TΔS. Isothermal mixing of pure gases leads to decrease in Gibbs energy. Hence, work has to be done on system for separating a mixture of gases into its components.

4.Process and cycles

• The steady state approximation of radical chain mechanism involves the assumption that the concentration of the intermediate species is not changing rapidly with time (quasi-static state). This is known as bode stein steady state approximation theory.
• When an insoluble gas is passed through a volatile liquid, some amount of liquid is volatized and escapes with the insoluble gas (the quantity of liquid volatized depends upon the vapour pressure of the liquid and the total pressure). The liquid contained in the perfectly insulated container supplies the latent heat of vaporization and as a result the temperature of the liquid drops.
• A solid is transformed into vapour without going through liquid phase at temperature below triple point. At triple point all three phases coexist, but do not transform from one phase to the other.
• When dilute solution of two salts are mixed, the process is associated with change in temperature which is a function of composition.
• Work performed by ideal gas during adiabatic expansion and adiabatic compression in Carnot cycle will be equal and opposite.
• Expansion against vacuum in perfectly insulated cylinder has zero work done and there is no change in temperature.
• For any cyclic process ΔU = 0.

6.Joule thompson

• At room temperature all gases except hydrogen, helium and neon cool down upon expansion by Joule-Thompson process. These three gases experience the same effect but only at lower temperatures.
• At inversion temperature Joule-Thompson coefficient is zero. For ideal gases Joule-Thompson coefficient is zero. Ideal gases neither warm nor cool upon being expanded.

7.Kinetic energy of a gas

• The average kinetic energy of a gas molecule is Kt, where k is Boltzmann constant = 1.38 x 10^-23J/K.

8.For estimation of heat capacity of solid compound, one can use kopp’s law.

9.For organic compound group contribution method can be used for estimation of critical properties.