Questions and Answers of Fundamentals Of Thermodynamics

Figure P3.11 shows three physical situations. Show the possible process in a P–v diagram. R-410a (a) (b) (c) FIGURE P3.11
Two hydraulic piston/cylinders are connected through a hydraulic line, so they have roughly the same pressure. If they have diameters of D1 and D2 = 2D1, respectively, what can you say about the
Two engines provide the same amount of work to lift a hoist. One engine provides a force of 3 F in a cable and the other provided 1 F. What can you say about the motion of the point where the force
A500-W electric space heater with a small fan inside heats air by blowing it over a hot electrical wire. For each control volume—(a) Wire only, (b) All the room air, (c) Total room air
In Fig. P3.5, CV A is the mass inside a piston/ cylinder, and CV B is the mass plus the piston outside, which is the standard atmosphere. Write the energy equation and work term for the two CVs,
If a process in a control mass increases energy E2 − E1 > 0, can you say anything about the sign for 1Q2 and 1W2?
A car engine is rated at 110 kW. What is the power in hp?
The specific volume of saturated liquid can be approximated by the Rackett equation aswith the reduced temperature, Tr = T/Tc, and the compressibility factor, Zc = Pcvc/RTc. Using values from Table
The refrigerant fluid in a household refrigerator changes phase from liquid to vapor at the low temperature in the refrigerator. It changes phase from vapor to liquid at the higher temperature in the
As the atmospheric temperature and pressure vary with elevation, the air density varies and the pressure is therefore not linear in elevation, as it is in a liquid. Develop an expression for the
Make a spreadsheet that will tabulate and plot values of P and T along a constant specific volume line for water. The starting state is 100 kPa, the quality is 50%, and the ending state is 800 kPa.
Make a spreadsheet that will tabulate and plot saturated pressure versus temperature for ammonia starting at T = −40◦C and ending at the critical point in steps of 10◦C.
Determine the pressure of R-410a at 100 F, v = 0.2 ft3/lbm using ideal gas and the Redlich- Kwong EOS.
Determine the pressure of R-410a at 100 F, v = 0.2 ft3/lbm using ideal gas and the van der Waal EOS.
Refrigerant-410a in a piston/cylinder arrangement is initially at 60 F, x = 1. It is then expanded in a process so that P = Cv−1 to a pressure of 30 lbf/in.2. Find the final temperature and
A pressure cooker (closed tank) contains water at 200 F, with the liquid volume being 1/10th of the vapor volume. It is heated until the pressure reaches 300 lbf/in.2. Find the final temperature. Has
Give the phase and the missing properties of P, T, v, and x. These may be a little more difficult to determine if the appendix tables are used instead of the software.a. R-410a, T = 50 F, v = 0.4
A 35-ft3 rigid tank has air at 225 psia and ambient 600 R connected by a valve to a piston/cylinder. The piston of area 1 ft2 requires 40 psia below it to float (see Fig. P2.166E). The valve is
Air in an internal-combustion engine has 440 F, 150 psia, with a volume of 2 ft3. Combustion heats it to 3000 R in a constant-volume process. What is the mass of air, and how high does the pressure
Give the phase and the specific volume for the following:a. CO2, T = 510 F, P = 75 lbf/in.2b. Air, T = 68 F, P = 2 atmc. Air, T = 300 F, P = 30 lbf/in.2
Ammonia at 70 F with a quality of 50% and a total mass of 4.5 lbm is in a rigid tank with an outlet valve at the bottom. How much liquid mass can be removed through the valve, assuming the
A glass jar is filled with saturated water at 300 F and quality 25%, and a tight lid is put on. Now it is cooled to 10 F. What is the mass fraction of solid at this temperature?
Saturated water vapor at 240 F has its pressure decreased to increase the volume by 10%, keeping the temperature constant. To what pressure should it be expanded?
You want a pot of water to boil at 220 F. How heavy a lid should you put on the 6-in.-diameter pot when Patm = 14.7 psia?
Saturated liquid water at 150 F is put under pressure to decrease the volume by 1% while keeping the temperature constant. To what pressure should it be compressed?
Give the missing property of P, T, v, and x fora. R-410a at 80 F, v = 0.2 ft3/lbmb. R-410a at 60 psia, v = 1.1 ft3/lbmc. Ammonia at 60 F, v = 3.2 ft3/lbm
Determine the specific volume for R-410a at these states:a. 20 F, 70 psiab. 70 F, 150 psiac. 70 F, quality 25%
Fill out the following table for substance ammonia:Place the two states a–b as labeled dots in a sketch of the P–v and T–v diagrams. Plpsial T|F| v[ft*/bm| a. 120 1.876 b. 120 0.5
Give the phase and the missing property of P, T, v, and x for R-134a at a. T =−10 F, P = 18 psiab. P = 40 psia, v = 1.3 ft3/lbm
Determine the phase of the substance at the given state using Appendix F tables.a. Water: 200 F, 70 psiab. Ammonia: 10 F, 20 psiac. R-410a: 30 F, 50 psia
Determine the missing property (of P, T, v, and x if applicable) for water ata. 680 psia, 0.03 ft3/lbmb. 150 psia, 320 Fc. 400 F, 3 ft3/lbm
Find the specific volume for carbon dioxide at 0◦C and 625 kPa.
A piston/cylinder arrangement, shown in Fig. P2.125, contains air at 250 kPa and 300◦C. The 50-kg piston has a diameter of 0.1 m and initially pushes against the stops. The atmosphere is at 100 kPa
What is the percent error in pressure if the ideal gas model is used to represent the behavior of superheated vapor R-410a at 60◦C, 0.03470m3/kg? What if the generalized compressibility chart, Fig.
A cylinder/piston arrangement contains water at 105◦C, 85% quality, with a volume of 1 L. The system is heated, causing the piston to rise and encounter a linear spring, as shown in Fig. P2.119. At
A container with liquid nitrogen at 100 K has a cross-sectional area of 0.5 m2, as shown in Fig. P2.117. Due to heat transfer, some of the liquid evaporates, and in 1 h the liquid level drops 30 mm.
A spring-loaded piston/cylinder assembly contains water at 500◦C and 3 MPa. The setup is such that pressure is proportional to volume, P = CV. It is now cooled until the water becomes
Consider two tanks, A and B, connected by a valve, as shown in Fig. P2.113. Each has a volume of 200 L, and tank A has R-410a at 25◦C, 10% liquid and 90% vapor by volume, while tank B is evacuated.
Refrigerant-410a in a piston/cylinder arrangement is initially at 15◦C with x=1. It is then expanded in a process so that P=Cv−1 to a pressure of 200 kPa. Find the final temperature and specific
Give the phase and the missing properties of P, T, v, and x. These may be a little more difficult to determine if the appendix tables are used instead of the software.a. R-410a, T = 10◦C, v = 0.02
Find the phase, quality x, if applicable, and the missing property P or T.a. NH3 at P = 800 kPa with v = 0.2 m3/kgb. NH3 at T = 20◦C with v = 0.1 m3/kg
Find the phase, the quality x if applicable, and the missing property P or T.a. H2O at T = 120◦C with v = 0.5 m3/kgb. H2O at P = 100 kPa with v = 1.8 m3/kgc. H2O at T = 263 K with v = 200 m3/kg
Give the phase and the missing properties of P, T, v, and x fora. R-410a at 10◦C with v = 0.01 m3/kgb. Water at T = 350◦C with v = 0.2 m3/kgc. R-410a at −5◦C and P = 600 kPad. R-134a at 294
Determine the quality (if saturated) or temperature (if superheated) of the following substances at the given two states:a. Water at 1: 120◦C, 1 m3/kg; 2: 10 MPa, 0.01 m3/kgb. Nitrogen at 1: 1 MPa,
Do the previous problem using the Redlich-K wong EOS.
A tank contains 8.35 kg of methane in 0.1 m3 at 250 K. Find the pressure using ideal gas, the van der Waals EOS, and the methane table.
Solve Problem 2.101 using the Soave EOS. Notice that this becomes a trial-and-error process.Data from Problem 2.101Carbon dioxide at 60◦C is pumped at a very high pressure, 10 MPa, into an oil well
Solve the previous problem using the Redlich- K wong EOS. Notice that this becomes a trial-and error process.
Carbon dioxide at 60◦C is pumped at a very high pressure, 10 MPa, into an oil well to reduce the viscosity of oil for better flow. Find its specific volume from the carbon dioxide table, ideal gas,
Determine the pressure of nitrogen at 160 K, v = 0.00291 m3/kg using the Soave EOS and the nitrogen table.
Determine the pressure of nitrogen at 160 K, v = 0.00291 m3/kg using the Redlich-Kwong EOS and the nitrogen table.
Determine the pressure of nitrogen at 160 K, v = 0.00291 m3/kg using ideal gas, the van der Waals EOS, and the nitrogen table.
Estimate the saturation pressure of chlorine at 300 K.
Find the compressibility for carbon dioxide at 60◦C and 10 MPa using Fig. D.1.
Find the compressibility factor for nitrogen ata. 2000 kPa, 120 Kb. 2000 kPa, 300 Kc. 120 K, v = 0.005 m3/kg
Find the compressibility factor (Z) for saturated vapor ammonia at 100 kPa and at 2000 kPa.
Ammoniain a piston/cylinder arrangement is at 700 kPa and 80◦C. It is now cooled at constant pressure to saturated vapor (state 2), at which point the piston is locked with a pin. The cooling
A 1-m3 rigid tank has propane at 100 kPa, 300 K and connected by a valve to another tank of 0.5 m3 with propane at 250 kPa, 400 K. The valve is opened, and the two tanks come to a uniform state at
Air in an internal-combustion engine has 227◦C, 1000 kPa, with a volume of 0.1 m3. Combustion heats it to 1800 K in a constant-volume process. What is the mass of air, and how high does the
A glass is cleaned in hot water at 45◦Cand placed on the table bottom up. The room air at 20◦C that was trapped in the glass is heated up to 40◦C and some of it leaks out, so the net resulting
Is it reasonable to assume that at the given states the substance behaves as an ideal gas?a. Oxygen at 30◦C, 3 MPab. Methane at 30◦C, 3 MPac. Water at 30◦C, 3 MPad. R-134a at 30◦C, 3 MPae.
A pneumatic cylinder (a piston/cylinder with air) must close a door with a force of 500 N. The cylinder’s cross-sectional area is 5 cm2. With V = 50 cm3, T = 20◦C, what is the air pressure and
A pressure cooker has the lid screwed on tight. A small opening with A = 5 mm2 is covered with a petcock that can be lifted to let steam escape. How much mass should the petcock have to allowboiling
Repeat the previous problem with the substancesa. R-134ab. R-410a
Water at 400 kPa with a quality of 25% has its temperature raised 20◦Cin a constant-pressure process. What is the new quality and specific volume?
Two tanks are connected as shown in Fig. P2.52, both containing water. Tank A is at 200 kPa, v = 0.5 m3/kg, VA = 1 m3, and tank B contains 3.5 kg at 0.5 MPa and 400◦C. The valve is now opened and
Water at 400 kPa with a quality of 25% has its pressure raised 50 kPa in a constant-volume process. What is the new quality and temperature?
Give the missing property of P, T, v, and x fora. R-410a at 25◦C, v = 0.01 m3/kgb. R-410a at 400 kPa, v = 0.075 m3/kgc. Ammonia at 10◦C, v = 0.1 m3/kg
Calculate the following specific volumes:a. Carbon dioxide: 10◦C, 80% qualityb. Water: 4 MPa, 90% qualityc. Nitrogen: 120 K, 60% quality
Give the specific volume of carbon dioxide at −20◦C for 2000 kPa and for 1400 kPa.
Give the missing property of P, T, v, and x for CH4 ata. T = 155 K, v = 0.04 m3/kgb. T = 350 K, v = 0.25 m3/kg
Determine the specific volume for R-410a at these states:a. −15◦C, 400 kPab. 20◦C, 1500 kPac. 20◦C, quality 25%
Give the missing property of P, T, v, and x for R-410a ata. T =−20◦C, P = 450 kPab. P = 300 kPa, v = 0.092 m3/kg
Determine whether refrigerant R-410a in each of the following states is a compressed liquid, a superheated vapor, or a mixture of saturated liquid and vapor.a. 50◦C, 0.05 m3/kgb. 1.0 MPa, 20◦Cc.
For water at 200 kPa with a quality of 10%, find the volume fraction of vapor.
Give the missing property of P–v–T and x for water ata. 10 MPa, 0.003 m3/kgb. 1 MPa, 190◦Cc. 200◦C, 0.1 m3/kgd. 10 kPa, 10◦C
Determine the phase of the substance at the given state using Appendix B tables.a. Water: 100◦C, 500 kPab. Ammonia: −10◦C, 150 kPac. R-410a: 0◦C, 350 kPa
Determine the phase of water ata. T = 260◦C, P = 5 MPab. T =−2◦C, P = 100 kPa
Give the phase for the following states:a. CO2 at T = 40◦C and P = 0.5 MPab. Air at T = 20◦C and P = 200 kPac. NH3 at T = 170◦C and P = 600 kPa
Find the lowest temperature in Kelvin for which metal can exist as a liquid if the metal is (a) Mercury or (b) Zinc.
The ice cap at the North Pole may be 1000 m thick, with a density of 920 kg/m3. Find the pressure at the bottom and the corresponding melting temperature.
Carbon dioxide at 280 K can be in three different phases: vapor, liquid, and solid. Indicate the pressure range for each phase.
As the pressure of a gas becomes larger, Z becomes larger than 1. What does that imply?
If v = RT/P for an ideal gas, what is the similar equation for a liquid?
How does a constant-v process for an ideal gas appear in a P–T diagram?
If I have 1 L of R-410a at 1 MPa, 20◦C what is the mass?
Can a vapor exist below the triple point temperature?
At higher elevations, as in mountains, air pressure is lower; how does that affect the cooking of food?
What is the minimum pressure for liquid carbon dioxide?
A micromanometer uses a fluid with density 1000 kg/m3, and it is able to measure height difference with an accuracy of ±0.5 mm. Its range is a maximum height difference of 0.5 m. Investigate to
Blood pressure is measured with a sphygmomanometer while the sound from the pulse is checked. Investigate how this works, list the range of pressures normally recorded as the systolic (high) and
Investigate possible transducers for the measurement of temperature in a flame with temperatures near 1000 K. Are any transducers available for a temperature of 2000 K?
Athermistor is used as a temperature transducer. Its resistance changes with temperature approximately as R = R0 exp[α(1/T − 1/T0)] where it has resistance R0 at temperature T0. Select the
Collect information for a resistance- and thermocouple-based thermometer suitable for the range of temperatures from 0◦C to 200◦C. For each of the two types, list the accuracy and response of the
Thermometers are based on several principles. Expansion of a liquid with a rise in temperature is used in many applications. Electrical resistance, thermistors, and thermocouples are common in
Make a list of different weights and scales that are used to measure mass directly or indirectly. Investigate the ranges of mass and the accuracy that can be obtained.
Write a program that will input pressure in kPa, atm, or lbf/in.2 and write the pressure in kPa, atm, bar, and lbf/in.2
Write a program to list corresponding temperatures in ◦C, K, F, and R from −50◦C to 100◦C in increments of 10 degrees.
The human comfort zone is between 18 and 24◦C. What is the range in Fahrenheit?
A tornado rips off a 1000-ft2 roof with a mass of 2000 lbm. What is the minimum vacuum pressure needed to do that if we neglect the anchoring forces?

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