MI-106 Tut Thermo
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MI-106 Tut Thermo...
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MI-106 : Engineering Thermodynamics (Tutorial I) Department of Mechanical and Industrial Engineering, IIT Roorkee Tropic: Introduction and Basic concepts 1. Explain by giving suitable examples: (a) System, surroundings, boundary, (b) Closed system, control volume, isolated system 2. Differentiate between microscopic and macroscopic approaches for the study of thermodynamic systems. Give the problems or areas to which they have successfully been applied. 3. What is a quasi-static or quasi-equilibrium process? Can you represent a non equilibrium process on thermodynamic-coordinate diagrams (like PV diagram). 4. For analyzing each of the listed events, specify the kind of system you would use and sketch the system boundary, showing energy or mass interaction: (a) (b) (c) (d) (e) (f) (g) (h)
Inflating a bicycle tire with a hand pump. Cooling the power supply of a desktop computer. The change in size of a balloon left in the sun The change in air pressure within a sealed package as temperature changes. Pumping water from a lake to an overhead storage tank A gas in a cylinder expanding against a piston to compress a coil spring Mixing of foods by an electric mixer. Heating water in a household gas- fired water heater.
5. Three thermodynamic quantities X, Y, Z are defined as
X ( Pdv vdP); Y P(dv vdP); and
Z ( RdT Pdv )
where R Pv / T constant. Which of these quantities X, Y, and Z are properties? 6. The water in a tank pressurized by air and the pressure is measured by a multi-fluid manometer as shown in Fig. 1. Determine the gage pressure of air in the tank if h1 = 0.2 m, h2 = 0.3 m, and h3 = 0.46 m. Take the densities of mercury, water, and oil are 13,600, 1000, and 850 kg/m3, respectively. Ans: 56.9 kPa 7. A gas is contained in a vertical frictionless piston-cylinder device as shown in Fig 2. The piston has a mass of 4 kg and a cross sectional area of 35 cm2. A compressed spring above the piston exerts a force of 60 N on the piston. If the atmospheric pressure is 95 kPa, determine the pressure inside the cylinder. Ans: 123.4 kPa 8.
Both a gauge and a manometer is attached to a gas tank to measure its pressure as shown in Fig 3. If the reading on the pressure gauge is 80 kPa, determine the distance between the fluid levels of the manometer if the fluid is (a) mercury (ρ = 13,600 kg/m3) and (b) water (ρ = 1000 kg/m3). Ans: 0.6 m, and 8.16 m P.T.O.
9. Fresh and seawater flowing in parallel horizontal pipelines are connected to each other by a double U-tube manometer as shown in Fig. 4. Determined the pressure difference between the two pipelines. The densities of seawater and mercury are given to be ρsea = 1035 kg/m3 and ρHG = 13,600 kg/m3. We take the density of water to be ρw =1000 kg/m3. Can the air column be ignored in the analysis? Ans: 3.39 kPa. 10. Water pipe is connected to a double-U manometer whose free arm is open to the atmosphere as shown in Fig. 5. The local atmospheric pressure is 98 kPa. Determined the absolute pressure at the center of the pipe. The specific gravities of mercury and oil are given to be 13.6 and 0.80, respectively. Take the density of water to be ρw = 1000 kg/m3. Ans: 156 kPa
Fig.1
Fig.2
Fig. 3
Fig. 4 Fig. 5
2014‐15
I
II III
MI 106 ENGINEERING THERMODYNAMICS Tutorial Sheet 2 Properties of Pure Substances ‐I (a) A propane tank is filled with a mixture of liquid and vapor propane. Can the contents of this tank be considered a pure substance? Explain. (b) What is the difference between: i saturated liquid and compressed liquid? ii saturated vapor and superheated vapor? iii critical point ant triple point? (c) Is there any difference between the intensive properties of saturated vapor at a given temperature and the vapor of a saturated mixture at the same temperature? Determine the phase or phases in a system consisting of H2O at the following conditions and sketch the P‐v and T‐v diagrams showing the location of each state: i P = 5 bars, T = 151.9o C ii P = 5 bars, T = 200o C iii P = 2.5 MPa, T = 200o C iv P = 4.8 bars, T = 160o C v P = 1 bar, T = ‐12o C Complete the following table for H2 O:
IV
V
T, °C
P, kPa
h, kJ / kg
x
Phase description
200
0.7
140
1800
950
0.0
80
500
800
3162.2
A two–phase liquid ‐ vapor mixture of H2O has a pressure of 150 bar and occupies a volume of 0.2 m3. The masses of saturated liquid and vapor present are 3.8 kg and 4.2 kg respectively. Determine the mixture specific volume, internal energy and enthalpy. (0.025 m3/kg, ) A sealed rigid vessel has volume of 1 m3 and contains 2 kg of water at 100°C. The vessel is now heated. If a safety pressure valve is installed, at what pressure should the valve be set so that maximum temperature in the vessel does not exceed 200°C? (431.3 kPa)
VI
VII
VIII
IX
X
A 0.3 m3 rigid vessel initially contains saturated liquid‐vapor mixture of water at 150°C. The water is now heated until it reaches the critical state. Determine the mass of the liquid water and the volume occupied by the liquid at the initial state. (96.10kg, 0.105m3) Water is being heated in a vertical piston cylinder device. The piston has a mass of 20 kg and a cross sectional area of 100 cm2. If the local atmospheric pressure is 100 kPa determine the temperature at which the water starts vaporizing. (104.7o C) o A piston cylinder device contains 0.8 kg of steam at 300 C and 1 MPa. Steam is cooled at constant pressure until one half of the mass condenses. (a) Show the process on T‐v diagram (b) Find the final temperature (c) Determine the volume change. A piston cylinder arrangement is loaded with a linear spring and the outside atmosphere. It contains water at 5 MPa, 400o C with the volume being 0.1 m3. If the piston is at the bottom, the spring exerts a force such that Plift =200 kPa. The system now cools until the pressure reaches 1200 kPa. Find the mass of water and v1. Find the final state (T2, v2 ) and plot the P‐v diagram for the process. (1.73kg, 0.05781 m3/ kg; 188o C; 0.01204 m3/ kg) The spring loaded piston‐cylinder device shown in the figure is filled with 0.5 kg of water vapor that is initially at 4 MPa and 400oC. Initially the spring exerts no force against the piston. The spring constant (in the spring force relation F=kx) k=0.9 kN/cm and the piston diameter is D=20 cm. The water now undergoes a process until its volume is one half of original volume. Calculate the final temperature and the specific enthalpy of the water. (220 o C, 1721kJ/kg)
SOLUTION Prob II
Prob. III
Prob. IV
At 150 bar uf = 1585.5 kJ/kg
ug = 2455.7 kJ/kg
hf = 1610.3 kJ/kg
hg = 2610.8 kJ/kg
x = 4.2/(4.2+3.8)
= 0.525
u = uf + x(ug‐ uf)
=2042.41 kJ/kg
h = hf + x (hg ‐ hf)
= 2135.5 kJ/kg
Prob. V
Prob. VI
Prob. VII
Prob. VIII
Prob. IX
Prob. X
Tutorial – III (2014-15) MI 106: Engineering Thermodynamics Department of Mechanical and Industrial Engineering, IIT Roorkee Topic: Heat and work 1.
A steam radiator in a room at 25°C has saturated water vapor at 110 kPa flowing through it, when the inlet and exit valves are closed. What is the pressure and the quality of the water, when it has cooled to 25oC? How much work is done?
2.
(3.169 kPa, 0.0361, 0)
A piston/cylinder contains 1 kg of liquid water at 20°Cand 300 kPa. Initially the piston floats, similar to the setup in figure, with a maximum enclosed volume of 0.002 m3 if the piston touches the stops. Now heat is added so a final pressure of 600 kPa is reached. Find the final volume and the work in the process.
3.
H2O
(0.30 kJ)
A cylinder having an initial volume of 3m3 contains 0.1 kg of water at 40oC. The water is then compressed in an isothermal quasi-equilibrium process until it has a quality of 50%. Calculate the work done in the process. Assume the water vapor is an ideal gas. (-13.4 kJ)
4.
A piston cylinder contains 1 kg of liquid water at 20oC and 300 kPa. There is a linear spring mounted on the piston such that when the water is heated the pressure reaches 3 MPa with a volume of 0.1 m3. a) Find the final temperature
(404oC)
b) Plot the process in a P-v diagram. c) Find the work in the process 5.
(163.35 kJ )
Air goes through a polytropic process from 125 kPa, 325 K to 300 kPa and 500 K. Find the polytropic exponent n and the specific work in the process.
6.
(1.969, -51.8 kJ/kg )
Two kilograms of water is contained in a piston/cylinder with a mass less piston loaded with a linear spring and the outside atmosphere. Initially the spring force is zero and P1 = Po = 100 kPa with a volume of 0.2 m3. If the piston just hits the upper stops the volume is 0.8 m3 and
T = 600°C. Heat is now added until the pressure reaches 1.2 MPa. Find the final temperature, show the P–V diagram and find the work done during the process. 7.
(770°C, 330 kJ)
A piston/cylinder contains 1 kg of water at 20°C with a volume of 0.1 m3. Initially the piston rests on some stops with the top surface open to the atmosphere, Po and a mass so a water pressure of 400 kPa will lift it. To what temperature should the water be heated to lift the piston? If it is heated to saturated vapor find the final temperature, volume and the work, 1W2.
8.
(143.6°C, 145 kJ)
A piston cylinder setup similar to Problem 7 contains 0.1 kg saturated liquid and vapor water at 100 kPa with quality 25%. The mass of the piston is such that a pressure of 500 kPa will float it. The water is heated to 300°C. Find the final pressure, volume and the work, 1W2.
(500 kPa, 0.05226 m3, 4.91 kJ)
Tutorial – III(2011-12) MI 101: Thermodynamics Department of Mechanical and Industrial Engineering, IIT Roorkee Topic: Heat and work 1.
A steam radiator in a room at 25°C has saturated water vapor at 110 kPa flowing through it, when the inlet and exit valves are closed. What is the pressure and the quality of the water, when it has cooled to 25oC? How much work is done? (3.169 kPa, 0.0361, 0)
2.
A piston/cylinder contains 1 kg of liquid water at 20°Cand 300 kPa. Initially the piston floats, similar to the setup in figure, with a maximum enclosed volume of 0.002 m3 if the piston touches the stops. Now heat is added so a final pressure of 600 kPa is reached. Find the final volume and the work in the process.
(0.30 kJ)
H2O
3.
A cylinder having an initial volume of 3m3 contains 0.1 kg of water at 40oC. The water is then compressed in an isothermal quasi-equilibrium process until it has a quality of 50%. Calculate the work done in the process. Assume the water vapor is an ideal gas. (-13.4 kJ)
4.
A piston cylinder contains 1 kg of liquid water at 20oC and 300 kPa. There is a linear spring mounted on the piston such that when the water is heated the pressure reaches 3 MPa with a volume of 0.1 m3. a) Find the final temperature (404oC) b) Plot the process in a P-v diagram. c) Find the work in the process (163.35 kJ )
5.
Air goes through a polytropic process from 125 kPa, 325 K to 300 kPa and 500 K. Find the polytropic exponent n and the specific work in the process. (1.969, -51.8 kJ/kg )
6.
Two kilograms of water is contained in a piston/cylinder with a mass less piston loaded with a linear spring and the outside atmosphere. Initially the spring force is zero and P1 = Po = 100 kPa with a volume of 0.2 m3. If the piston just hits the upper stops the volume is 0.8 m3 and T = 600°C. Heat is now added until the pressure reaches 1.2 MPa. Find the final temperature, show the P–V diagram and find the work done during the process.
7.
(770°C, 330 kJ)
A piston/cylinder contains 1 kg of water at 20°C with a volume of 0.1 m3. Initially the piston rests on some stops with the top surface open to the atmosphere, Po and a mass so a water pressure of 400 kPa will lift it. To what temperature should the water be heated to lift the piston? If it is heated to saturated vapor find the final temperature, volume and the work, 1W2.
(143.6°C, 145 kJ)
8.
A piston cylinder setup similar to Problem 7 contains 0.1 kg saturated liquid and vapor water at 100 kPa with quality 25%. The mass of the piston is such that a pressure of 500 kPa will float it. The water is heated to 300°C. Find the final pressure, volume and the work, 1W2.
(500 kPa, 0.05226 m3, 4.91 kJ)
Tutorial – IV(2014-15) MI 106: Engineering Thermodynamics Department of Mechanical and Industrial Engineering, IIT Roorkee Topic: First law of Thermodynamics (closed system) 1.
A piston/cylinder contains 50 kg of water at 200 kPa with a volume of 0.1 m3. Stops in the cylinder are placed to restrict the enclosed volume to 0.5 m3. The water is now heated until the piston reaches the stops. Find the necessary heat transfer. (Ans: 995 kJ)
2.
10-kg of water is in a piston-cylinder device at 4500C, 0.633 m3. It is now cooled to 20C at constant pressure. Show the P–v diagram and find the work and heat transfer for the process. (Ans:-3115 kJ, -32276 kJ)
3.
A piston-cylinder device contains 0.15 kg of air initially at 2MPa and 350°C. The air first expands isothermally to 500 kPa, then compressed polytropically with a polytropic exponent of 1.2 to the initial pressure, and finally compressed at constant pressure to the initial state. Determine the boundary work for each process and the net work of the cycle. Ans: 37.18 kJ, -34.86 kJ, -6.97 kJ, -4.65 kJ
4.
1-kg of water that is initially at 90°C with a quality of 10% occupies a linear spring-loaded piston-cylinder device. This device is heated until the pressure and temperature rises to 800 kPa and 250°C. Determine the work done during this process. Ans: 24.5 kJ
5.
Saturated water vapor at 200°C is isothermally condensed to a saturated liquid in a pistoncylinder device. Determine the specific work and the heat transfer in the process. Ans: 196.0 kJ/kg, 1940 kJ/kg
6.
An insulated rigid tank contains 5 kg of saturated liquid-vapor mixture of water at 100 kPa. Initially ¾ of the mass is in liquid phase. An electric heater (220V, 4A current) in the tank is turned on, and the entire liquid in the tank is vaporized. Determine the length of time the heater was kept on, and show the process is to be shown on a P-v diagram. Ans: 153.1 min
7.
A piston-cylinder contains 0.2 kg of water initially at 800 KPa, 0.06 m3. Now 200 kJ of heat is supplied while the pressure kept constant. Determined the final temperature of the water and show the process on a T-v diagram. Ans: 721.1°C.
8.
Two tanks initially separated by a partition contain steam at different states as shown in Fig. Now the partition is removed and they are allowed to mix until equilibrium is established. If the pressure at the final state is 300 kPa, determine the temperature and quality of the steam (if mixture) at the final state and the amount of heat lost from the tanks. Ans: 133.5 C, 0.3641, and 3959 kJ
9.
A 0.2 m3 adiabatic rigid container is divided into two equal parts. One part contains air at 700 kPa and 37°C while the other side is evacuated as shown in the figure. Determine the internal energy change of the air and the final air pressure when the partition is removed. Ans: 0, 350 kPa
10.
A closed system containing 2 kg of air undergoes an isothermal process from 600 kPa and 200°C to 80 kPa. Determine the initial volume, the work done, and the heat transfer for the process. Ans: 0.4525 m3, 547.1 kJ, 547.1 kJ.
11.
A piston-cylinder device, whose piston is resting on top of a set of stops, initially contains 3 kg of air at 200 kPa and 27°C. The mass of piston is such that a pressure of 400kPa is required to move it. Heat is now transferred to the air until the volume doubled. Determine the work done by the air and the amount of heat transfer, and show the process on a P-v diagram. Ans: 258 kJ, 2416 kJ. The gas constant of air (R) is 0.287 kJ/kg.K
Tutorial – IV(2014-15) MI 106: Engineering Thermodynamics Department of Mechanical and Industrial Engineering, IIT Roorkee Topic: First law of Thermodynamics (closed system) 1.
A piston/cylinder contains 50 kg of water at 200 kPa with a volume of 0.1 m3. Stops in the cylinder are placed to restrict the enclosed volume to 0.5 m3. The water is now heated until the piston reaches the stops. Find the necessary heat transfer. (Ans: 995 kJ)
2.
10-kg of water is in a piston-cylinder device at 4500C, 0.633 m3. It is now cooled to 20°C at constant pressure. Show the P–v diagram and find the work and heat transfer for the process. (Ans:-3115 kJ, -32276 kJ)
3.
A piston-cylinder device contains 0.15 kg of air initially at 2MPa and 350°C. The air first expands isothermally to 500 kPa, then compressed polytropically with a polytropic exponent of 1.2 to the initial pressure, and finally compressed at constant pressure to the initial state. Determine the boundary work for each process and the net work of the cycle. Ans: 37.18 kJ, -34.86 kJ, -6.97 kJ, -4.65 kJ
4.
1-kg of water that is initially at 90°C with a quality of 10% occupies a linear spring-loaded pistoncylinder device. This device is heated until the pressure and temperature rises to 800 kPa and 250°C. Determine the work done during this process. Ans: 24.5 kJ
5.
Saturated water vapor at 200°C is isothermally condensed to a saturated liquid in a piston-cylinder device. Determine the specific work and the heat transfer in the process. Ans: 196.0 kJ/kg, 1940 kJ/kg
6.
An insulated rigid tank contains 5 kg of saturated liquid-vapor mixture of water at 100 kPa. Initially ¾ of the mass is in liquid phase. An electric heater (220V, 4A current) in the tank is turned on, and the entire liquid in the tank is vaporized. Determine the length of time the heater was kept on, and show the process is to be shown on a P-v diagram. Ans: 153.1 min
7.
A piston-cylinder contains 0.2 kg of water initially at 800 KPa, 0.06 m3. Now 200 kJ of heat is supplied while the pressure kept constant. Determined the final temperature of the water and show the process on a T-v diagram. Ans: 721.1°C.
8.
Two tanks initially separated by a partition contain steam at different states as shown in Fig. Now the partition is removed and they are allowed to mix until equilibrium is established. If the pressure at the final state is 300 kPa, determine the temperature and quality of the steam (if mixture) at the final state and the amount of heat lost from the tanks. Ans: 133.5 C, 0.3641, and 3959 kJ
9.
A 0.2 m3 adiabatic rigid container is divided into two equal parts. One part contains air at 700 kPa and 37°C while the other side is evacuated as shown in the figure. Determine the internal energy change of the air and the final air pressure when the partition is removed. Ans: 0, 350 kPa
10.
A closed system containing 2 kg of air undergoes an isothermal process from 600 kPa and 200°C to 80 kPa. Determine the initial volume, the work done, and the heat transfer for the process. Ans: 0.4525 m3, 547.1 kJ, 547.1 kJ.
11.
A piston-cylinder device, whose piston is resting on top of a set of stops, initially contains 3 kg of air at 200 kPa and 27°C. The mass of piston is such that a pressure of 400kPa is required to move it. Heat is now transferred to the air until the volume doubled. Determine the work done by the air and the amount of heat transfer, and show the process on a P-v diagram. Ans: 258 kJ, 2416 kJ. The gas constant of air (R) is 0.287 kJ/kg.K
MI-106 : Thermodynamics Department of Mechanical and Industrial Engineering, IIT Roorkee
Tutorial - V
Topic: First law of Thermodynamics for open systems 1. Steam at 500 kPa, 300oC is used to heat cold water at 15oC to 75oC for domestic hot
water supply. How much steam per kg liquid water is needed if the steam should not condense? (0.795 ) 2. A nozzle receives 0.1 kg/s steam at 1 MPa, 400 C with negligible kinetic energy. The o
exit is at 500 kPa, 350oC and the flow is adiabatic. Find the nozzle exit velocity and the exit area. (438.7 m/s, 1.3 cm2 ) 3. Water at 1.5 MPa, 150°C, is throttled adiabatically through a valve to 200 kPa. The inlet
velocity is 5 m/s, and the inlet and exit pipe diameters are the same. Determine the state (neglecting kinetic energy in the energy equation) and the velocity of the water at the exit. (xe = 0.0579, 240 m/s) 4. A liquid water turbine receives 2 kg/s water at 2000 kPa, 20 C and velocity of 15 m/s. o
The exit is at 100 kPa, 20oC and very low velocity. Find the specific work and the power produced. (1.99 kJ/kg, 3.985 kW) 5. Consider a water pump that receives liquid water at 15 C, 100 kPa and delivers it to a o
same diameter short pipe having a nozzle with exit diameter of 1 cm to the atmosphere at 100 kPa. Neglect the kinetic energy in the pipes and assume constant u for the water. Find the exit velocity and the mass flow rate if the pump draws a power of 1 kW. (29.43 m/s, 2.31 kg/s) 6. A large expansion engine has two low velocity flows of
water entering. High pressure steam enters at point 1 with 2.0 kg/s at 2 MPa, 500°C and 0.5 kg/s cooling water at 120 kPa, 30°C enters at point 2. A single flow exits at point 3 with 150 kPa, 80% quality, through a 0.15 m diameter exhaust pipe. There is a heat loss of 300 kW. Find the exhaust velocity and the power output of the engine.
(131.2 m/s, 1056 kW)
7. An initially empty bottle is filled with water from a line at 0.8 MPa, 350 C. Assume no o
heat transfer and that the bottle is closed when the pressure reaches the line pressure. If the final mass is 0.75 kg find the final temperature and the volume of the bottle. (520oC, 0.342 m3 ) 8. A rigid 100-L tank contains air at 1 MPa, 200°C. A valve on the tank is now opened and
air flows out until the pressure drops to 100 kPa. During this process, heat is transferred from a heat source at 200°C, such that when the valve is closed, the temperature inside the tank is 50°C. What is the heat transfer? (+25.7 kJ) 9. A 1-m , 40-kg rigid steel tank contains air at 500 kPa, and both tank and air are at 20°C. 3
The tank is connected to a line flowing air at 2 MPa, 20°C. The valve is opened, allowing air to flow into the tank until the pressure reaches 1.5 MPa and is then closed. Assume the air and tank are always at the same temperature and the final temperature is 35°C. Find the final air mass and the heat transfer. (16.96 kg, – 468.9 kJ) 10. A 200 liter tank initially contains water at 100 kPa and a quality of 1%. Heat is
transferred to the water thereby raising its pressure and temperature. At a pressure of 2 MPa a safety valve opens and saturated vapor at 2 MPa flows out. The process continues, maintaining 2 MPa inside until the quality in the tank is 90%, then stops. Determine the total mass of water that flowed out and the total heat transfer. (8.90 kg, 25.46 MJ)
Pb 1
Pb 2
Pb 3
Pb 4
Pb 5
Pb 6
Pb 7
Pb 8
Pb 9
Pb 10
Tutorial – V -A(2014-15) MI-106 : Engineering Thermodynamics Department of Mechanical and Industrial Engineering, IIT Roorkee Topic: First law of Thermodynamics for open systems 1. A desuperheater mixes superheated water vapor with liquid water in a ratio that produces saturated water vapor as output without any external heat transfer. A flow of 0.5 kg/s superheated vapor at 5 MPa, 400C and a flow of liquid water at 5 MPa, 40C enters a desuperheater. If saturated water vapor at 4.5 MPa is produced, determine the flow rate of the liquid water. (0.0757 kg/s) 2. An open feedwater heater (Fig. 5.1) in a powerplant heats 4 kg/s water at 45oC, 100 kPa by mixing it with steam from the turbine at 100 kPa, 250oC. Assume the exit flow is saturated liquid at the given pressure and find the mass flow rate from the turbine. (0.358 kg/s) 3. A condenser (heat exchanger) brings 1 kg/s water flow at 10 kPa from 300C to saturated liquid at 10 kPa (Fig. T5.2). The cooling is done by lake water at 20C that returns to the lake at 30C. For an insulated condenser, find the flow rate of cooling water. (69 kg/s) 4. A steam turbine receives steam from two boilers. One flow is 5 kg/s at 3 MPa, 700C and the other flow is 15 kg/s at 800 kPa, 500C. The exit state is 10 kPa, with a quality of 96%. Find the total power out of the adiabatic turbine. (21.99 MW) 5. A steam turbine receives water at 15 MPa, 600C at a rate of 100 kg/s, shown in Fig. T5.3. In the middle section 20 kg/s is withdrawn at 2 MPa, 350C, and the rest exits the turbine at 75 kPa, and 95% quality. Assuming no heat transfer and no changes in kinetic energy, find the total turbine power output. (91.57 MW) 6.
A 2-m3 insulated vessel contains saturated vapor steam at 4 MPa. A valve on the top of the tank is opened, and steam is allowed to escape. During the process any liquid formed collects at the bottom of the vessel, so that only saturated vapor exits. Calculate the total mass that has escaped when the pressure inside reaches 1 MPa. (27.24 kg)
7.
A 1-m3, 40-kg rigid steel tank contains air at 500 kPa, and both tank and air are at 20°C. The tank is connected to a line flowing air at 2 MPa, 20°C. The valve is opened, allowing air to flow into the tank until the pressure reaches 1.5 MPa and is then closed. Assume the air and tank are always at the same temperature and the final temperature is 35°C. Find the final air mass and the heat transfer. (16.96 kg, – 468.9 kJ)
8.
A 200 liter tank initially contains water at 100 kPa and a quality of 1%. Heat is transferred to the water thereby raising its pressure and temperature. At a pressure of 2 MPa a safety valve opens and saturated vapor at 2 MPa flows out. The process continues, maintaining 2 MPa inside until the quality in the tank is 90%, then stops. Determine the total mass of water that flowed out and the total heat transfer. (8.90 kg, 25.46 MJ)
Fig T5.1 Fig T5.2
Fig T5.3
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