For the cases below, a closed system undergoes a process in which work is done on the system and the heat transfer Q occurs only at a location on the boundary where the temperature is Tb. For each case, determine whether the entropy change of the system is positive, negative, zero, or indeterminat. a. internally reversible process, Q > 0.b. internally reversible process, Q = 0.c. internally reversible process, Q < 0.d. internal irreversibilities present, Q > 0.e. internal irreversibilities present, Q = 0.f. internal irreversibilities present, Q < 0.

Water at 70°f and streams enter the mixing chamber at the same mass flow rate, determine the temperature and the quality of the exiting stream. 0 psia is heated in a chamber by mixing it with saturated water vapor at 20 psia. if both streams enters the mixing chamber at the same mass flow rate, determine the temperature and the quality of the existing system.

What is the heat treatment of metals? what is the benefit of it? why and how it's useful? answer in details, do not write by hand.

To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.