Chapter 7, Problem 7.4E

Could you help solve the thermodynamics question? Answers are given.

Can closed-system exergy be negative? How about flow exergy? Explain using an incompressible substance as an example.

Consider a heat transfer process of the steady form that occurs along a plain wall. While the inner room temperature was kept at 25 °C, the outdoor environment temperature was measured to be 2 °C. If the heat transfer at this plain wall in an hour is 3,528 kJ, determine the.total exergy destruction per unit time (the rate), which occurs during this heat transfer process, a) use the total entropy generation to find the rate of the total exergy destruction in the room (i.e.., use the entropy balance), b) use the exergy balance to find the rate of the total exergy destruction in the room

Answer the following true or false. Explain. (a) A process that violates the second law of thermodynamics violates the first law of thermidynamics. (b) When a net amount of work is done on a closed system undergoing an internally reversible process, a net heat transfer of energy from the system also occurs. (c) One corollary of the second law of thermodynamics states that the change in entropy of a closed system must be greater than zero or equal to zero. (d) A closed system can experience an increase in entropy only when irreversibilities are present within the system during the process. (e) Entropy is produced in every internally reversible process of a closed system. (f) In an adiabatic and internally reversible process of  a closed system, the entropy remains constant. (g) The energy of an isolated system must remain constant, but the entropy can only decrease.

Identify the major sources of entropy generation in your house and propose ways of reducing them.

0.05 kg of carbon dioxide (molecular weight 44), occupying a volume of 0.03 m3 at 1.025 bar, is compressed reversibly until the pressure is 6.15 bar. Calculate final temperature, the work done on the CO2, the heat flow to or from the cylinder walls, (i) When the process is according to law pv1.4 = constant, (ii) When the process is isothermal, (iii) When the process takes place in a perfectly thermally insulated cylinder. Assume CO2 to be a perfect gas, and take n = 1.3.

Describe the isentropic process involves no irreversibilities and serves as the ideal process for adiabatic devices.

Water enter a pump at environmental conditions, 100 kPa and 20°C at a rate of 1.5 kg/s and leave at 5 MPa. The pump has an isentropic effficiency of 80 percent, determine (a) Show the system sketch(b) the actual power input(c) the exergy destruction

A system consists of 2 kg of water at 100°C and 1 bar. Determine the exergy, in kJ, if the system is at rest and zero elevation relative to an exergy reference environment for which To = 20°C, po =1 bar.