Thermal Energy Storage Systems and Applications. Ibrahim Dincer

      1 1.24 What is the compressibility factor?

      2 1.25 When can we invoke the ideal gas assumption for real gases?

      3 1.26 Define isothermal, isobaric, and isochoric processes.

      4 1.27 What is an isentropic process? Is a constant‐entropy process necessarily reversible and adiabatic?

      5 1.28 What is the difference between heat and work?

      6 1.29 An elastic tank contains 0.8 kmol of air at 23°C and 600 kPa. Determine the volume of the tank. If the volume is doubled at the same pressure, what is the temperature at the new state?

      7 1.30 A 50 l piston–cylinder device contains oxygen at 52°C and 170 kPa. If the oxygen is heated until its temperature reaches 77°C, what is the amount of heat transfer during the process?

      8 1.31 A 50 l rigid tank contains oxygen at 52°C and 170 kPa. If the oxygen is heated until its temperature reaches 77°C, what is the amount of heat transfer during the process?

      9 1.32 A 50 l rigid tank contains oxygen at 52°C and 170 kPa. If the oxygen is heated until the temperature reaches 77°C, what is the entropy change during the process?

      10 1.33 A rigid tank contains 2.5 kg of oxygen at 52°C and 170 kPa. If the oxygen is heated in an isentropic process until it reaches 77°C, what is the pressure at the final state? What is the work interaction during this process?

      11 1.34 A piston–cylinder device contains 2.5 kg oxygen at 52°C and 170 kPa. If the oxygen is heated until it reaches 77°C, what is the work done and the amount of heat transfer during the process?

      1 1.35 What is the Kelvin–Planck statement of the second law of thermodynamics?

      2 1.36 What is the Clausius statement of the second law of thermodynamics?

      3 1.37 Define the terms energy, exergy, entropy, and enthalpy.

      4 1.38 What is the second‐law efficiency? How does it differ from the first‐law efficiency?

      5 1.39 What is the relationship between entropy generation and irreversibility?

      6 1.40 What are the two common causes of irreversibility?

      7 1.41 During an irreversible process, do the parameters mass, energy, entropy, and exergy decrease or increase or remain conserved?

      8 1.42 How does an exergy analysis help the goal of more efficient energy‐resource use? What are the advantages of using exergy analysis?

      1 1.43 What is the physical meaning of the Reynolds number? What makes the flow laminar and what makes it turbulent?

      2 1.44 What is viscosity? How does viscosity change with temperature for gases and for liquids?

      1 1.45 What is the difference between heat conduction and heat convection?

      2 1.46 Define the terms forced convection and natural convection, and explain the difference between them.

      3 1.47 Define the term heat generation. Give some examples.

      4 1.48 What are the modes of heat transfer? Explain the physical mechanism of each mode.

      5 1.49 How much energy does it take to convert 10.0 kg of ice at 0°C to water at 25°C?

      6 1.50 A 20 cm thick wall of a house made of brick (k = 0.72 W/m°C) is subjected to inside air at 22°C with a convection heat transfer coefficient of 15 W/m2 °C. The temperature of the inner surface of the wall is 18°C and the outside air temperature is −1°C. Determine the temperature of the outer surface of the wall and the heat transfer coefficient at the outer surface.

      7 1.51 A satellite is subjected to solar energy at a rate of 300 W/m2. The absorptivity of the satellite surface is 0.75 and its emissivity is 0.60. Determine the equilibrium temperature of the satellite.

      8 1.52 An 80‐cm‐diameter spherical tank made of steel contains liquefied natural gas (LNG) at −160°C. The tank is insulated with a 4 cm thickness of insulation (k = 0.015 W/m°C). The tank is subjected to ambient air at 18°C with a convection heat transfer coefficient of 20 W/m2 °C. How long will it take for the temperature of the LNG to decrease to −150°C. Neglect the thermal resistance of the steel tank. The density and the specific heat of LNG are 425 kg/m3 and 3.475 kJ/kg°C, respectively.