Chapter 6, Problem 6.51CU

2. Please consider a universe that consisted of two very, very large bodies that exchanged 1,000 Btu. The first body was at 1,000 R. Please determine the change in entropy of (1) each body and (2) of the universe (in Btul R) if the second body was at a. 200 •R. b. 500 R c. 1,000 R.

answer 99 and 100

A 60-lb aluminum bar, initially at T₂ = 150°F, is placed in a tank together with 190 lb of liquid water, initially at Tw= 70°F, and allowed to achieve thermal equilibrium. The aluminum bar and water can be modeled as incompressible with specific heats c₂ = 0.216 Btu/lb.ºR and cw = 0.998 Btu/lb.°R, respectively. Consider the aluminum bar and water as the system and ignore heat transfer between the system and its surroundings. Determine the final temperature Tf, in °F, and the amount of entropy produced within the tank, in Btu/°R.

answer 96,97,98

The system shown is at steady state, steady flow. At inlet 1, the rates of kinetic energy, potential energy and enthalpy entering the system are: KE1 = 0.10 kW, PE1 %3D 0.22 kW, and H1 = 27.0 kW. At inlet 2, the rates are: KE2 = 0.23 kW, PE2 = 0.18 kW, and H2 = 18.0 kVW. At exit 3, the rates are: KE3 = 0.52 kW, PE3 = 0.28 kW, and H3 = 7.0 kW. If the system gives up 5.0 kW of heat to the surroundings, what is the rate of work transfer of the system? Express the answer in kw. %3D KE3 PE3 1 KE. РЕ H. KE2 PE2 На Control volume boundary

answer the following true or false. (a) A process that violates the second law of thermodynamics violates the first law of thermodynamics. (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) A closed system can experience an increase in entropy only when a net amount of entropy is transferred into the system. (d) The change in entropy of a closed system is the same for every process between two specified end states.

A divider separates 1 lb mass of carbon monoxide (CO) from a thermal reservoir at 150o F. the carbon monoxide, initially at 60o F  and 150 lbf/in2, expands isothermally to a final pressure of 10 lbf/in2 while receiving heat transfer through the divider from the reservoir. The carbon monoxide can be modeled as an ideal gas. (a) For the carbon monoxide as the system, evaluate the work and heat transfer, each in Btu and the amount of entropy produced, in Btu/oR. (b) Evaluate the entropy production, in Btu/oR, for an enlarged system that includesthe carbon monoxide and the divider, assuming the state of the divider remains unchanged. Compare with the entropy production of part (a) and comment on the difference.

One kg of an ideal gas (gas constant R = 287 J/kg.K) undergoes an irreversible process from state-1 (1 bar, 300 K) to state -2 (2 bar, 300 K). The change in specific entropy (52 - s1) of the gas (in J/kg. K) in the process is

A 300-lb iron casting, initially at 1500°F, is quenched in a tank filled with 2121 lb of oil, initially at 80°F. The iron casting and oil can be modeled as incompressible with specific heats 0.10 Btu/lb · °R, and 0.45 Btu/lb · °R, respectively. (a) For the iron casting and oil as the system,determine the final equilibrium temperature, in °F. Ignore heat transfer between the system and its surroundings. Tf = i °F (b) For the iron casting and oil as the system,determine the amount of entropy produced within the tank, in Btu/°R. Ignore heat transfer between the system and its surroundings. O = i Btu/°R