# Thermodynamics Questions And Solutions

Thermodynamics is a branch of science that studies the concepts of heat and temperature and the inter-conversion of heat and other forms of energy. The term thermodynamics was coined in 1749 by William Thomson.

Thermodynamics is a macroscopic science that is divided into .

chemical thermodynamics, statistical thermodynamics, equilibrium thermodynamics, and classical thermodynamics.

The types of thermodynamic systems are: .

Closed System . Isolated System .

When changes in volume, pressure and internal energy occur, a system experiences a thermodynamic process.

Thermodynamic processes are the movement of heat energy within or between systems. Factors that take place out of the system and those that impact the system’s behaviour are referred to as a surrounding. Adiabatic Process – no heat transfer occurs in or out of the system. Isochoric Process – no volume change occurs, and this system does not work. Isobaric Process – no pressure change takes place. Isothermal Process – no temperature change takes place. Enthalpy is the measurement of energy in a thermodynamic system. Calculation of energy in a thermodynamic system gives enthalpy and its formula is: . The thermodynamic value is dependent on the physical state of a system known as the entropy. The measure of the stored energy in a system is given by the thermodynamic potential. Internal Energy of the thermodynamics system is given by . U=∫TdS−PdV + ∑iμidNi . Helmholtz free energy: F = U – TS . Enthalpy: H = U + PV . Gibbs Free Energy: G = U + PV – TS .

Helmholtz free energy is given by the formula ______. Answer: d) F = U – TS . Explanation: Helmholtz free energy is given by the formula F = U – TS . Entropy is defined in which law of thermodynamics? Answer: c) Second . Explanation: Entropy is defined in the second law of thermodynamics. Match the following:. Adiabatic Process i) no volume change takes place . Isochoric Process ii) no pressure change takes place. Isobaric Process iii) no temperature change takes place. Isothermal Process iv) no heat transfer takes place. a)-iv b) iii c) ii d) i . a)-i b) iv c) ii d) iii . a)-iv b) i c) ii d) iii . a)-i b) ii c) iii d) iv . Answer: 3) a)-iv b) i c) ii d) iii .

Fill in the blanks: _____ coined the term thermodynamics. Answer: William Thomson . Explanation: The term thermodynamics was coined by William Thomson in 1749.

State true or false: Thermodynamic potentials are quantitative measures of the external energies associated with the system. Answer: b) FALSE . Explanation: Thermodynamic potentials are quantitative measures of the stored energy in a system. The entropy of a system approaches a constant value as the temperature ______.

Approaches absolute zero. None of the options.

Answer: c) Approaches absolute zero. Explanation: According to the third law of thermodynamics, the constant value is approached by the system when the temperature approaches absolute zero. What are the branches of thermodynamics? Branches of thermodynamics are: . Classical Thermodynamics . Statistical Thermodynamics . Chemical Thermodynamics . Equilibrium Thermodynamics . A thermodynamic system undergoes ______. Changes in pressure . Changes in volume . Changes in internal energy . All the above options .

Answer: d) All the above options. Explanation: A thermodynamic system undergoes changes in pressure, volume, and internal energy. The measurement of energy in a thermodynamic system is referred to as ______. None of the options. Answer: a) Enthalpy . Explanation: Enthalpy is the measurement of energy in a thermodynamic system.

10.Internal Energy of the thermodynamics system is given by the formula ______. Answer: c) U=∫TdS−PdV+∑iμidNi . Define thermodynamics. What are the types of thermodynamic systems? Give the formula to find Gibbs free energy.

Which law of thermodynamics states that “the entropy of a system approaches a constant value as the temperature approaches absolute zero”? The process where no heat transfer in or out of the system occurs is known as ______ . Adiabatic Process . Isochoric Process .

Isobaric Process . Isothermal Process .

Watch the video below to understand thermodynamic devices in detail.

For an internal combustion engine, the transfer function with injected fuel flow rate as input and fuel flow rate into the cylinder as output, is given by 1. TS 1 where ? is a time constant and ? is fuel split parameter (constant). Obtain the transfer function Gzas() in terms of the system parameters.

Example Problem: 2nd Law of Thermodynamics Which of the following is not allowed by the 2nd law of thermodynamics? A. An engine that converts 150 J of heat into 20 J of work and exhausts 130 J of B. A refrigerator with a coefficient of C. A refrigerator that does 50 J of work D. An engine with an efficiency (e) heat into its surroundings. performance (K) greater than 1. for every 100 J of heat it removes. greater than 1.

Thermodynamics II Assignment. Water is the working fluid in an ideal Rankine cycle. Superheated vapor enters the turbine at 10 MPa, 480°C, and the condenser pressure is 6 kPa. Show the cycle on a T-s diagram with respect to saturation lines and determine for the cycle (a) the rate of heat transfer to the working fluid passing through the steam generator, in kJ per kg of steam flowing. (b) the thermal efficiency (c) the rate of heat transfer from the g fluid passing through the condenser to the cooling water, in kJ per kg of steam flowing. Assumptions/Engineering Model:

1. Each component of the cycle is analyzed as a control volume at steady state.

2. All processes

3. The turbine and pump operate adiabatically

4. Kinetic and potential energy effects are negligible.

5. Saturated vapor enters the turbine. Condensate exits the condenser as saturated liquid. of the working fluid are internally reversible. 2. The below figure provides steady-state operating data for a vapor power plant using water as the working fluid. The mass flow rate of water is 12 kgs. The turbine and pump operate adiabatically but not reversibly (pump and turbine efficiencies are 88%; other assumptions: problem

1). Determine

(a) the thermal efficiency

(b) the rates of heat transfer Qin and Qout each in kw Steam generator m-12 kg's F Condenser T(C) 500 h(KJ/Kg) 3422.2 1633.3 191.83 199.4 167.57 3545.3 State 6 MPa 10 kPa 10 kPa 7.5 MPa 7 MPa 6 MPa Sat. 40 550