Chapter 7, Problem 7.13CU

1. The first law of thermodynamics discussesa. Thermal equilibriumb. Energy conservationc. Direction of heat flowd. Entropy is zero at absolute zero temperature 2. A tank contains 1 kg mass gas whose density is 700 kg/m3. The pressure is increased from 1 bar to 3 bar. The approximate specific boundary work of the system isa. Cannot be find since some data is missingb. 285 kJ/kgc. 0 kJ/kgd. 0.285 kJ/kg 3. The nozzle is a device in whicha. Area decreases b. Area increasesc. Velocity decreases d. Velocity increases 4. Choose the correct statement/s with respect to entropy change during a processa. Entropy increases with increase in pressure at constant temperatureb. Entropy increases with increase in temperature at constant pressurec. Entropy can be kept constant by systematically increase both pressure and temperatured. Entropy can not be changed 5. The isentropic process is also called asa. Adiabatic processb. Irreversible adiabatic processc. Reversible adiabatic processd. Reversible…

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A domestic water heater holds 189 L of water at 60°C, 1 atm. Determine the exergy of the hot water, in kJ. To what elevation, in m, would a 1000-kg mass have to be raised from zero elevation relative to the reference environment for its exergy to equal that of the hot water? Let To = 298 K, po = 1 atm, g = 9.81 m/s².

A domestic water heater holds 189 L of water at 60°C, 1 atm. Determine the exergy of the hot water, in kJ. To what elevation, in m, would a 1000-kg mass have to be raised from zero elevation for its exergy to equal that of the hot water? Let T0 = 298 K, p0 = 1 atm, g = 9.81 m/s2 .

A heat engine operates between two temperature limits of 1300 K and 400 K. It receives 1.2 MJ of heat while producing 500 kJ of useful work. Determine: a. The exergy of the heat received by the heat engine, in kJ. b. The energy that is not available for work production, in kJ. c. The irreversibility of the process, in kJ. а. 370 kJ b. 830 kJ с. 330 kJ a. 830 kJ b. 330 kJ c. 370 kJ a. 330 kJ b. 370 kJ c. 830 kJ а. 830 kJ b. 370 kJ с. 330 kJ

TRUE OR FALSE 1. Heat flows from hot object to cold object and vice versa, as exhibited by heat pumps.2. It's impossible to have 100% efficient engines, however, it's possible to convert 100% of heat into useful work.3. Natural processes tend to be more ordered than disordered due to entropy.4. The efficiency e of a heat engine is defined as the ratio of the work W done by the engine to the high temperature heat input Qh.5. All heat engines give rise to thermal pollution.

A granite rock of mass 900 kg is situated on a hill at an elevation of 1000 m. On a sunny day its temperature rises to 95"C Use the SL system state Part A Determine the maximum useful work that can be extracted from the rock if the atmospheric temperature is 30"C Express your answer to three significant figures. * O a ? vec kJ Submit Request Answer Part B Compare the potential energy (PE) of the rock with its stored exergy () 16"C Günesli Express your answer to three significant figures.

Exergy flow associated with a fluid stream when the fluid properties are variable can be determined by.

7.27 Figure P7.27 provides steady-state data for the outer wall of a dwelling on a day when the indoor temperature is maintained at 25°C and the outdoor temperature is 35°C. The heat transfer rate through the wall is 1000 W. Determine, in W, the rate of exergy destruction (a) within the wall, and (b) within the enlarged system shown on the figure by the dashed line. Comment. Let T₂ = 35°C. 20.13, 33-56 Indoor Boundary of enlarged- temperature=25°C T=27C T-3C FIGURE PLAT Outdoor temperature=35°C