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Chapter: 3 -Problem: 102 >> A rigid tank holds 0.75 kg ammonia at 70?C as saturated vapor. The tank is now cooled to 20?C by heat transfer to the ambient temperature. Which two properties determine the final state? Determine the amount of work and heat transfer during the process.
Answer Preview: Step 1 Step 2 We are given following data for Ammonia …

, Chapter: 13 -Problem: 171 >> A rigid vessel initially contains 2 lbm of carbon and 2 lbm of oxygen at 77 F, 30 lbf/in.2. Combustion occurs, and the resulting products consist of 1 lbm ofCO2, 1 lbm of CO, and excess O2 at a temperature of 1800 R. Determine the final pressure in the vessel and the heat transfer from the vessel during the process.
Answer Preview: The final pressure in the vessel can be determined using the ideal gas law PV nRT where P is the pre…

, Chapter: 4 -Problem: 117 >> The intercooler in the previous problem uses cold liquid water to cool the nitrogen. The nitrogen flow is 0.1 kg/s, and the liquid water inlet is 20?C and is set up to flow in the opposite direction from the nitrogen, so the water leaves at 35?C. Find the flow rate of the water.
Answer Preview: To find the flow rate of the water we need to first determine the heat transfer rate between the wat…

, Chapter: 7 -Problem: 12 >> A tank contains air at 400 kPa, 300 K, and a valve opens up for flow out to the outside, which is at 100 kPa, 300 K. How does the state of the air that flows out change?
Answer Preview: Since the pressure and temperature of the air in the tank and the pressure and tempe…

, Chapter: 6 -Problem: 74 >> Find the total work the heat engine can give out as it receives energy from the rock bed as, described in Problem 5.60 (see Fig. P6.74). Write the entropy balance equation for the control volume that is the combination of the rock bed and the heat engine. Transcribed Image Text: W ?? Rockbed ?? FIGU
Answer Preview: Problem 5 60 refers to a heat engine that receives energy from a hot rock bed at a temperature of T1 …

, Chapter: 3 -Problem: 116 >> In a sink, 5 L of water at 70?C is combined with 1 kg of aluminum pots, 1 kg of silverware (steel), and 1 kg of glass, all put in at 20?C. What is the final uniform temperature, neglecting any heat loss and work?
Answer Preview: w for water a for aluminium s for silver g for glass mw rho V 1 5 5 …

, Chapter: 14 -Problem: 55 >> A piston/cylinder contains 0.1 kmol H2 and 0.1 kmol Ar gas at 25?C, 200 kPa. It is heated in a Constant-pressure process, so the mole fraction of atomic hydrogen, H, is 10%. Find the final temperature and the heat transfer needed.
Answer Preview: This problem can be solved using the ideal gas law To find the final tempe…

, Chapter: 3 -Problem: 238 >> A piston/cylinder setup, shown in Fig. P3.238, contains R-410a at ?20?C, x = 20%. The volume is 0.2 m3. It is known that Vstop = 0.4 m3, and if the piston sits at the bottom, the spring force balances the other loads on the piston. The system is now heated to 20?C. Find the mass of the fluid and show the P–v diagram. Find the work and heat transfer.
Answer Preview: To find the mass of R 410a in the piston cylinder setup you can use the Ideal Gas Law PV nRT where P …

, Chapter: 6 -Problem: 239 >> A room at 72 F is heated electrically with 1500W to keep a steady temperature. The outside ambient air is at 40 F. Find the flux of S (= ?Q /T ) into the room air, into the ambient, and the rate of entropy generation.
Answer Preview: To calculate the flux of entropy into the room into the ambient and the rate of entropy generation w…

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, Chapter: 3 -Problem: 191 >> As fresh-poured concrete hardens, the chemical transformation releases energy at a rate of 2 W/kg. Assume that the center of a poured layer does not have any heat loss and that it has an average heat capacity of 0.9 kJ/kg K. Find the temperature rise during 1 h of the hardening (curing) process.
Answer Preview: increase in final heat capacity of the conc…

, Chapter: 13 -Problem: 85 >> Extend the solution to the previous problem by using Table A.9 for the ?HP terms.
Answer Preview: The extended solution to the problem is to use Table A 9 to calculate the HP terms This ta…

, Chapter: 3 -Problem: 282 >> Oxygen at 50 lbf/in.2, 200 F is in a piston/cylinder arrangement with a volume of 4 ft3. It is now compressed in a polytropic process with exponent, n = 1.2, to a final temperature of 400 F. Calculate the heat transfer for the process.
Answer Preview: Heat Transfer nRT Vf Vi n 1 2 R 10 73 ft l…

, Chapter: 6 -Problem: 177 >> Water in a piston/cylinder, shown in Fig. P6.177, is at 1 MPa, 500?C. There are two stops, a lower one at which Vmin = 1 m3 and an upper one at Vmax = 3 m3. The piston is loaded with a mass and outside atmosphere such that it floats when the pressure is 500 kPa. This setup is now cooled to 100?C by rejecting heat to the surrounding at 20?C. Find the total entropy generated in the process.
Answer Preview: The total entropy generated in the process can be calculated by using the equation Sgen S2 S1 where …

, Chapter: 6 -Problem: 20 >> Use the inequality of Clausius to show that heat transfer from a cold space toward a warmer space without work is an impossible process, i.e., a heat pump with no work input.
Answer Preview: As the speed of a pump impeller increases the size of the impeller and pump can be reduced for …

, Chapter: 3 -Problem: 184 >> Air in a rigid tank is at 100 kPa, 300 K with a volume of 0.75m3. The tank is heated to 400 K, state 2. Now one side of the tank acts as a piston, letting the air expand slowly at constant temperature to state 3 with a volume of 1.5 m3. Find the pressure at states 2 and 3. Find the total work and total heat transfer.
Answer Preview: At constant temperature the pressure volume relationship for an ideal gas is given by the ideal gas …

, Chapter: 13 -Problem: 208 >> When a power plant burns coal or some blends of oil, the combustion process can generate pollutants as SOx and NOx Investigate the use of scrubbers to remove these products. Explain the processes that take place and the effect on the power plant operation (energy, exhaust pressures, etc.).
Answer Preview: Scrubbers are devices that are used to remove pollutants such as SOx and NOx from the exhaust gases …

, Chapter: 4 -Problem: 119 >> For the steam power plant shown in Problem 4.118, assume that the cooling water comes from a lake at 15?C and is returned at 25?C. Determine the rate of heat transfer in the condenser and the mass flow rate of cooling water from the lake. Data from Problem 4.118,The following data are for a simple steam power plant as shown in Fig. P4.118. State 6 has x6 =0.92 and velocity of 200 m/s. The rate of
Answer Preview: Velocity of State 5 75 m s Power Output of Turbine 257 …

, Chapter: 7 -Problem: 47 >> A certain industrial process requires a steady 0.75 kg/s supply of compressed air at 500 kPa at a maximum temperature of 30?C, as shown in Fig. P7.47. This air is to be supplied by installing a compressor and an aftercooler. Local ambient conditions are 100 kPa, 20?C. Using a reversible compressor, determine the power required to drive the compressor and the rate of heat rejection in the aftercool
Answer Preview: The power required to drive the compressor can be calculated as the change in enthalpy between the i…

, Chapter: 6 -Problem: 86 >> Consider a small air pistol (Fig. P6.86) with a cylinder volume of 1 cm3 at 250 kPa, 27?C. The bullet acts as a piston initially held by a trigger. The bullet is released, so the air expands in an adiabatic process. If the pressure should be 120 kPa as the bullet leaves the cylinder, find the final volume and the work done by the air.
Answer Preview: Final volume 2 19 cm 3 Work done by the air 0 046 J The work done by a gas in an adiabatic process …

, Chapter: 3 -Problem: 152 >> Air in a piston/cylinder is at 1800 K, 7 MPa and expands in a polytropic process with n = 1.5 to a volume eight times larger. Find the specific work and specific heat transfer in the process and draw the P–v diagram. Use constant specific heats to solve the problem.
Answer Preview: A work P1 v1 P2 V2 n 1 here n 1 5 now for air P1 v1 Rair T1 fo…

, Chapter: 14 -Problem: 46 >> A mixture flows with 2 kmol/s CO2, 1 kmol/s Ar, and 1 kmol/s CO at 298 K and it is heated to 3000 K at constant 100 kPa. Assume the dissociation of CO2 is the only equilibrium process to be considered. Find the exit equilibrium composition and the heat transfer rate.
Answer Preview: The composition of the chemical equilibrium mixture at 3000 K can be calculated using the equilibriu…

, Chapter: 4 -Problem: 13 >> A pool is to be filled with 60 m3 water from a garden hose of 2.5 cm diameter flowing water at 2 m/s. Find the mass flowrate of water and the time it takes to fill the pool.
Answer Preview: It can take 12 hours to fill a swimming pool using two pipes If the pipe of larger diamete…

, Chapter: 7 -Problem: 93 >> A factory generates compressed air from ambient 100 kPa, 17?C by compression to 1000 kPa, 600 K, after which it cools in a constant-pressure cooler to 300 K by heat transfer to the ambient. Find the specific entropy generation in the compressor and in the cooler.
Answer Preview: Given p 1 100 KPa T 1 17 c 290 K P 2 1000 KPa T 2 600 K T 3 300 K P …

, Chapter: 5 -Problem: 107 >> Give an estimate for the COP in the previous problem and the power needed to drive the heat pump when the outside temperature drops to ?15?C.Data from previous problemA house should be heated by a heat pump, ?' = 2.2, and maintained at 20?C at all times. It is estimated that it loses 0.8 kW for each degree that the ambient is lower than the inside. Assume an outside temperature of ?10?C and find t
Answer Preview: The COP of the heat pump would be the ratio of the heat output of the heat pump to the power input r…

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, Chapter: 3 -Problem: 310 >> Use the supplied software to track the process in Problem 3.96 in steps of 10?C until the two-phase region is reached, after that step with jumps of 5% in the quality. At each step write out T, x, and the heat transfer to reach that state from the initial state. Data from Problem 3.96A cylinder fitted with a frictionless piston contains 2 kg of superheated refrigerant R-134a vapor at 350 kPa, 100?
Answer Preview: To track the process in Problem 3 96 you can use thermodynamic software such as Aspen MATLAB or Cool…

, Chapter: 10 -Problem: 28 >> A Brayton cycle produces 14 MW with an inlet state of 17?C, 100 kPa, and a compression ratio of 16:1. The heat added in the combustion is 1160 kJ/kg. What are the highest temperature and the mass flow rate of air, assuming cold air properties?
Answer Preview: The highest temperature 2 963 K The mass flow rate of air 0 67 kg s The inlet …

, Chapter: 6 -Problem: 198 >> Do Problem 6.197E using refrigerant R-134a instead of R-410a. Data from Problem 6.197EConsider a Carnot-cycle heat pump with R-410a as the working fluid. Heat is rejected from the R-410a at 110 F, during which process the R-410a changes from saturated vapor to saturated liquid. The heat is transferred to the R-410a at 30 F.a. Show the cycle on a T–s diagram.b. Find the quality of the R-410a at the
Answer Preview: To solve Problem 6 197E using refrigerant R 134a instead of R 410a we will need to use the thermodyn…

, Chapter: 6 -Problem: 4 >> Consider the previous setup with the mass mA and the piston/cylinder of mass mp starting out at two different temperatures (Fig. P6.3). After a while, the temperature becomes uniform without any external heat transfer. Write the entropy equation storage term (S2 ? S1) for the total mass.In figure P6.3 Transcribed Image Tex
Answer Preview: The entropy equation for the storage term S2 S1 f…

, Chapter: 3 -Problem: 82 >> Take the whole room as a C.V. and write both conservation of mass and conservation of energy equations. Write equations for the process (two are needed) and use them in the conservation equations. Now specify the four properties that determine the initial state (two) and the final state (two); do you have them all? Count unknowns and match them with the equations to determine those.
Answer Preview: Conservation of Mass Equation m1 m2 m3 Process m1 is the mass of the ro…

, Chapter: 13 -Problem: 166 >> Liquid methanol is burned with stoichiometric air, both supplied at P0, T0 in a constant-pressure process, and the product exits a heat exchanger at 1600 R. Find the heat transfer per lbmol fuel.
Answer Preview: To find the heat transfer per lbmol of fuel when liquid methanol is burned with stoichiometric air i…

, Chapter: 3 -Problem: 311 >> Examine the sensitivity of the final pressure to the containment room volume in Problem 3.101. Solve for the volume for a range of final pressures, 100–250 kPa, and sketch the pressure versus volume curve. Data from Problem 3.101A water-filled reactor with a volume of 1 m3 is at 20 MPa and 360?C and is placed inside a containment room, as shown in Fig. P3.101. The room is well insulated and initia
Answer Preview: Answer The sensitivity of the final pressure to the contai…

, Chapter: 10 -Problem: 47 >> Consider an ideal air-standard cycle for a gas turbine, jet propulsion unit, such as that shown in Fig. 10.11. The pressure and temperature entering the compressor are 90 kPa, 290 K. The pressure ratio across the compressor is 14:1, and the turbine inlet temperature is 1500 K. When the air leaves the turbine, it enters the nozzle and expands to 90 kPa. Determine the velocity of the air leaving the
Answer Preview: To determine the velocity of the air leaving the nozzle we need to use the energy equation for an id…

, Chapter: 7 -Problem: 33 >> A highly cooled compressor brings a hydrogen gas flow at 300 K, 100 kPa up to a pressure of 800 kPa in an isothermal process. Find the specific work assuming a reversible process.
Answer Preview: Solution Given data initial temperature T 1 300 K initial pressure …

, Chapter: 5 -Problem: 158 >> A window air conditioner cools a room at TL = 68 F with a maximum of 1.2 kW power input. The room gains 0.33 Btu/s per degree temperature difference from the ambient, and the refrigeration COP is ? = 0.6 ?Carnot. Find the maximum outside temperature, TH, for which the air conditioner provides sufficient cooling.
Answer Preview: To find the maximum outside temperature TH for which the air conditioner provides sufficient cooling …

, Chapter: 3 -Problem: 143 >> A closed rigid container is filled with 1.5 kg water at 100 kPa, 55?C; 1 kg of stainless steel, and 0.5 kg of polyvinyl chloride, both at 20?C, and 0.1 kg air at 400 K, 100 kPa. It is now left alone, with no external heat transfer, and no water vaporizes. Find the final temperature and air pressure.
Answer Preview: To find the final temperature and air pressure of the system you will need to know the initial tempe…

, Chapter: 14 -Problem: 125 >> Assume we have air at 4 atm, 3600 R (as 21% O2 and 79% N2), and we can neglect dissociations ofO2 andN2. What is the equilibrium mole fraction of NO? Find the enthalpy difference in the gases due to the formation of the NO.
Answer Preview: The equilibrium mole fraction of NO can be found using the equilibrium constant for the reaction tha…

, Chapter: 4 -Problem: 4 >> Air at 500 kPa is expanded to 100 kPa in two steady flow cases. Case one is a nozzle and case two is a turbine; the exit state is the same for both cases. What can you say about the specific turbine work relative to the specific kinetic energy in the exit flow of the nozzle?
Answer Preview: We are given following data for Air P 500kPa P2 100kPa Let us assume that nozzle and …

, Chapter: 9 -Problem: 113 >> Give an estimate for the overall COP' of an ammonia absorption cycle used as a chiller to cool water to 5?Cina25?Cambientwhen the small pump work is neglected. A heat source is available at 100?C. Also find the efficiency of the heat engine part and the COP of the refrigeration cycle part.
Answer Preview: The overall COP of an ammonia absorption cycle used as a chiller can be estimated by considering the …

, Chapter: 6 -Problem: 222 >> Consider a heat transfer of 100 Btu from 2400 R hot gases to a steel container at 1200 R that has a heat transfer of the 100 Btu out to some air at 600 R. Determine the entropy generation in each of the control volumes indicated in Fig. P6.115. Transcribed Image Text: CV1 CV2 Hot Steel Air gas FIGUR
Answer Preview: The entropy generation can be calculated using the formula Sgen Q T where Q is the heat transfer and …

, Chapter: 6 -Problem: 88 >> Air in a rigid tank is at 100 kPa, 300 K with a volume of 0.75m3. The tank is heated to 400 K, state 2. Now one side of the tank acts as a piston, letting the air expand slowly at constant temperature to state 3 with a volume of 1.5 m3. Find the entropy at states 1, 2, and 3.
Answer Preview: Following is the given data T 300 K T T 400 K V 1 5 …

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, Chapter: 13 -Problem: 84 >> A gas turbine burns methane with 200% theoretical air. The air and fuel come in through two separate compressors bringing them from 100 kPa, 298 K, to 1400 kPa, and after mixing they enter the combustion chamber at 600 K. Find the adiabatic flame temperature using constant specific heat for the ?HP terms.
Answer Preview: To find the adiabatic flame temperature we need to use the equation for adiabatic flame temperature …

, Chapter: 3 -Problem: 245 >> Look at the R-410a value for uf at ?60 F. Can the energy really be negative? Explain.
Answer Preview: Reason Potential energy is always negative and if it is greater than kinetic energy total mechani…

, Chapter: 9 -Problem: 129 >> A new air conditioner using R-410a is used in heat pump mode. The high pressure is 2000 kPa and the low pressure is 400 kPa. It warms a house at 20?C driven by an electric power input of 2 kW in an ambient at ?5?C. Find the destruction of exergy in four places: (1) Inside the heat pump, (2) In the high-T heat exchanger, (3) In the low-T heat exchanger, and (4) In the house walls/windows, and so on
Answer Preview: 1 Inside the heat pump Not applicable no exergy destruction occurs in the heat p…

, Chapter: 7 -Problem: 107 >> In a heat-driven refrigerator with ammonia as the working fluid, a turbine with inlet conditions of 2.0 MPa, 70?C is used to drive a compressor with inlet saturated vapor at ?20?C. The exhausts, both at 1.2 MPa, are then mixed together, as shown in Fig. P7.107. The ratio of the mass flow rate to the turbine to the total exit flow was measured to be 0.62. Can this be true?
Answer Preview: It is not possible for the ratio of the mass flow rate to …

, Chapter: 11 -Problem: 150 >> A new refrigerant, R-410a, is a mixture of R-32 and R-125 in a 1:1 mass ratio. What is the overall molecular weight, the gas constant, and the ratio of specific heats for such a mixture?
Answer Preview: The molecular weight of a mixture is the sum of the molecular weights of the individual components o…

, Chapter: 6 -Problem: 26 >> Find the missing properties of P, v, s, and x for ammonia (NH3) ata. T = 65?C, P = 600 kPa b. T = 20?C, u = 800 kJ/kg c. T = 50?C, v = 0.1185 m3/kg
Answer Preview: a T 65C P 600 kPa v 0 002869 m3 kg s 1 5398 kJ kgK x 0 957 …

, Chapter: 3 -Problem: 99 >> Ammonia (0.5 kg) in a piston/cylinder at 200 kPa, ?10?C is heated by a process in which pressure varies linearly with volume to a state of 120?C, 300 kPa. Find the work and heat transfer for the ammonia in the process.
Answer Preview: A potential enabler of a low is the energy vector hydrogen However issues associated with an…

, Chapter: 13 -Problem: 192 >> Propene, C3H6, is burned with air in a steady flow burner with reactants at P0, T0. The mixture is lean, so the adiabatic flame temperature is 3200 R. Find the entropy generation per lbmol fuel, neglecting all the partial pressure corrections.
Answer Preview: To find the entropy generation per lbmol of fuel we first need to determine the change …

, Chapter: 3 -Problem: 262 >> Saturated vapor R-410a at 60 F in a rigid tank is cooled to 0 F. Find the specific heat transfer.
Answer Preview: An electric heater is an electrical device that converts an …

, Chapter: 10 -Problem: 95 >> A supercharger is used for a two-stroke, 10-L diesel engine, so intake is 200 kPa, 320 K, and the cycle has a compression ratio of 18:1 and a mean effective pressure of 830 kPa. The engine is 10 L running at 200 RPM. Find the power output.
Answer Preview: The power output of the engine can be calculated using the formula …

, Chapter: 6 -Problem: 235 >> Do Problem 6.234E using Table F.5. Data from Problem 6.234EA constant-pressure piston/cylinder is 2 lbm steel and it contains 1 lbm air at 540 R, 60 psia. The system is now heated to 2600 R by a 2800 R source, and the steel has the same temperature as the air. Find the entropy generation using constant specific heats.
Answer Preview: Using Table F 5 the specific heats of the steel and air are 0 …

, Chapter: 11 -Problem: 120 >> A flow out of a clothes dryer of 0.1 kg/s dry air is at 60?C and relative humidity 60%. It flows through a heat exchanger, where it exits at 20?C. After exiting the heat exchanger, the flow combines with another flow of 0.03 kg/s dry air at 30?C and relative humidity 40%. Find the dew point of state 1 (see Fig. P11.120), the heat transfer per kg dry air, and the final exit state humidity ratio and
Answer Preview: To find the final exit state we need to find the dew point heat transfer and relative humidity Here …

, Chapter: 6 -Problem: 82 >> A closed rigid container is filled with 1.5 kg water at 100 kPa, 55?C, 1 kg of stainless steel and 0.5 kg of polyvinyl chloride, both at 20?Cand 0.1 kg of hot air at 400 K, 100 kPa. It is now left alone, with no external heat transfer and no water vaporizes. Find the final temperature and the change in entropy of the masses.
Answer Preview: The final temperature of the system is 55C The change in entropy of the …

, Chapter: 3 -Problem: 35 >> Solve Problem 3.34, but assume that the steam pressure in the cylinder starts at 1000 kPa, dropping linearly with volume to reach 100 kPa at the end of the process.Data from Problem 3.34,Airplane takeoff from an aircraft carrier is assisted by a steam-driven piston/cylinder with an average pressure of 1250 kPa. A 17 500-kg airplane should accelerate from zero to 30 m/s, with 30% of the energy comi
Answer Preview: For the airplane No change in internal or potential energ…

, Chapter: 14 -Problem: 69 >> Consider the previous reaction in equilibrium at 150?C, 5 MPa. For an initial composition of 25% nitrogen, 75% hydrogen, on a mole basis, calculate the equilibrium composition.
Answer Preview: At 150C and 5 MPa the equilibrium constant for the reaction 2NO N2 O2 can be calculated using the Ar…

, Chapter: 4 -Problem: 109 >> A de-super heater has a flow of ammonia of 1.5 kg/s at 1000 kPa, 100?C that is mixed with another flow of ammonia at 25?C and quality 50% in an adiabatic mixing chamber. Find the flow rate of the second flow so that the outgoing ammonia is saturated vapor at 1000 kPa.
Answer Preview: To determine the flow rate of the second flow of ammonia in a de super heater that is mixed with ano…

, Chapter: 10 -Problem: 8 >> For a given compression ratio, does an Otto cycle have a higher or lower efficiency than a diesel cycle?
Answer Preview: TRUE A projectile has a vertical acceleration of 9 8 m s s throughout the entire trajectory T…

, Chapter: 6 -Problem: 197 >> Consider a Carnot-cycle heat pump with R-410a as the working fluid. Heat is rejected from the R-410a at 110 F, during which process the R-410a changes from saturated vapor to saturated liquid. The heat is transferred to the R-410a at 30 F.a. Show the cycle on a T–s diagram.b. Find the quality of the R-410a at the beginning and end of the isothermal heat addition process at 30 F.c. Determine the CO
Answer Preview: a The cycle on a T s diagram is shown in Figure 1 below b The quality of the R 410a at the beginning …

, Chapter: 11 -Problem: 138 >> An insulated rigid 2-m3 tank A contains carbon dioxide gas at 200?C, 1MPa. An uninsulated rigid 1-m3 tank B contains ethane, (C2H6), gas at 200 kPa, room temperature 20?C. The two tanks are connected by a one-way check valve that will allow gas to flow from A to B but not from B to A. The valve is opened, and gas flows from tank A to B until the pressure in B reaches 500 kPa and the valve is close
Answer Preview: To find the total number of moles and the ethane mole fraction in the final state in tank B we can u…

, Chapter: 5 -Problem: 96 >> In the previous problem, it was assumed that the COP will be the same when the outside temperature drops. Given the temperatures and the actual COP at the ?10°C winter day, give an estimate for a more realistic COP for the outside ?15°C case.Data from previous problemOn a cold (?10?C) winter day, a heat pump provides 20 kW to heat a house maintained at 20?C, and it has a COPHP of 4. How much power
Answer Preview: It is difficult to give an exact estimate for a more realistic COP for the outs…

, Chapter: 3 -Problem: 21 >> Liquid water is heated, so it becomes superheated vapor. Can specific heat be used to find the heat transfer? Explain.
Answer Preview: The specific heat is numerically equal to the amount of heat necessary to change the temperature …

, Chapter: 13 -Problem: 93 >> A special coal burner uses a stoichiometric mixture of coal and an oxygen–argon mixture (1:1 mole ratio), with the reactants supplied at the reference conditions P0, T0. Find the adiabatic flame temperature, assuming complete combustion.
Answer Preview: The adiabatic flame temperature will depend on the composition of the coal the oxygenargon …

, Chapter: 4 -Problem: 115 >> A flow of 5 kg/s water at 100 kPa, 20?C should be delivered as steam at 1000 kPa, 350?C to some application. Consider compressing it to 1000 kPa, 20?C and then heat it at a constant rate of 1000 kPa to 350?C. Determine which devices are needed and find the specific energy transfers in those devices.
Answer Preview: To deliver a flow of 5 kg s of water at 100 kPa 20C as steam at 1000 kPa 350C to some applications t…

, Chapter: 9 -Problem: 191 >> The condenser in Problem 4.118 uses cooling water from a lake at 20?C and it should not be heated more than 5?C, as it goes back to the lake. Assume the heat transfer rate inside the condenser is ?Q = 350 (W/m2 K) × A ?T . Estimate the flow rate of the cooling water and the needed interface area. Discuss your estimates and the size of the pump for the cooling water. Data from Problem 4.118A conden
Answer Preview: Estimate The flow rate of the cooling water needed to maintain the condenser at 60C and not all…

, Chapter: 7 -Problem: 26 >> Atmospheric air at ?45?C, 60 kPa enters the front diffuser of a jet engine, shown in Fig. P7.26, with a velocity of 900 km/h and a frontal area of 1 m2. After adiabatic diffuser process, the velocity is 20 m/s. Find the diffuser exit temperature and the maximum pressure possible. Transcribed Image Text:
Answer Preview: The first step to solve this problem is to determine the specific volume velocity and temperatur…

, Chapter: 11 -Problem: 123 >> Consider several flow processes with ideal gases: (1) Compression of a gas mixture from 100 kPa to 200 kPa; (2) Cooling a gas mixture from 50?C to ambient 20?C using ambient air; (3) Mixing two different gases at 100 kPa; (4) Throttling a gas mixture from 125 kPa to 100 kPa. For each case, explain what happens to the exergy, whether there is any exergy destruction, and whether the composition is n
Answer Preview: Exergy is a measure of the maximum work that can be answeed from a system as it returns to equilibrium with its environment It is defined as the dif…

, Chapter: 6 -Problem: 46 >> A piston/cylinder contains 0.5 kg of water at 200 kPa, 300?C, and it now cools to 150?C in an isobaric process. The heat goes into a heat engine that rejects heat to the ambient at 25?C (shown in Fig. P6.46), and the whole process is assumed to be reversible. Find the heat transfer out of the water and the work given out by the heat engine.
Answer Preview: Q m C T3 T2 W m p C T3 T1 The heat lost by the water is calculated as follows Q …

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, Chapter: 14 -Problem: 10 >> If a reaction is insensitive to pressure, prove that it is also insensitive to dilution effects at a given T.
Answer Preview: To improve the safety of HMX a two dimensional 2D graphene oxide GO …

, Chapter: 3 -Problem: 312 >> Using states with given (P, v) and properties from the supplied software, track the process in Problem 3.105. Select five pressures away from the initial toward the final pressure so that you can plot the temperature, the heat added, and the work given out as a function of the volume. Data from Problem 3.105.A cylinder having a piston restrained by a linear spring (of spring constant 15 kN/m) cont
Answer Preview: To track the process in Problem 3 105 you need to calculate five pressures away from the initial 120…

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, Chapter: 7 -Problem: 129 >> A steam turbine inlet is at 1200 kPa, 400?C. The exit is at 200 kPa. What is the highest possible exit temperature? Which efficiency does that correspond to?
Answer Preview: The highest possible exit temperature for the steam turbine is the temperature at which the steam is saturated Saturated steam is a mixture of water v…

, Chapter: 11 -Problem: 158 >> A piston/cylinder device contains 0.3 lbm of mixture of 40% methane and 60% propane by mass at 540 R, 15 psia. The gas is now slowly compressed in an isothermal (T =constant) process to a final pressure of 40 psia. Show the process in a P–V diagram, and find both the work and the heat transfer in the process.
Answer Preview: The work done in this process is given by the formula W P V2 V…

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, Chapter: 3 -Problem: 162 >> A piston/cylinder contains pure oxygen at ambient conditions 20?C, 100 kPa. The piston is moved to a volume that is seven times smaller than the initial volume in a polytropic process with exponent n = 1.25. Use the constant heat capacity to find the final pressure and temperature, the specific work, and the specific heat transfer.
Answer Preview: Initial pressure is Initial temperature is For 100 kP…

, Chapter: 14 -Problem: 47 >> A mixture of 1 kmol CO2, 2 kmol CO, and 2 kmol O2, at 25? C, 150 kPa, is heated in a constant pressure, steady-state process to 3000 K. Assuming that only these substances are present in the exiting chemical equilibrium mixture, determine the composition of that mixture.
Answer Preview: The composition of the chemical equilibrium mixture at 3000 K can be calculated using the equilibriu…

, Chapter: 4 -Problem: 53 >> A refrigerator uses the natural refrigerant carbon dioxide where the compressor brings 0.02 kg/s from 1MPa,?20?C to 6 MPa using 2 kW of power. Find the compressor exit temperature.
Answer Preview: Typically air exiting a compressor is between 180F 82 2C to 350F 176 6C To sele…

, Chapter: 10 -Problem: 142 >> A Brayton cycle has a compression ratio of 15:1 with a high temperature of 2900 R and the inlet at 520 R, 14 psia. Use cold air properties and find the specific heat transfer and specific net work output.
Answer Preview: The Brayton cycle is an ideal gas cycle used to describe the operation of a gas turbine engine In a …

, Chapter: 7 -Problem: 99 >> Two flows of air are both at 200 kPa; one has 2 kg/s at 400 K, and the other has 1 kg/s at 290 K. The two flows are mixed together in an insulated box to produce a single exit flow at 200 kPa. Find the exit temperature and the total rate of entropy generation.
Answer Preview: The temperature of the mixture of the two flows of air can be calculated using the first law of ther…

, Chapter: 11 -Problem: 95 >> An air flow of 2 kg/s at 30?C, relative humidity 80%, is conditioned by taking half of the air flow, cooling it, and mixing it with the other half. Assume the outlet flow should have a water content that is 75% of the original flow. Find the temperature to cool to, the rate of cooling, and the final exit flow temperature.
Answer Preview: CV Total Continuity water ma1mliqma3 mliq ma 13 Pg1 4 246 Pv1 0 84 246 3 3968 kPa 1 …

, Chapter: 5 -Problem: 136 >> Consider the combination of a heat engine and a heat pump, as given in Problem 5.41, with a low temperature of 720 R. What should the high temperature be so that the heat engine is reversible? For that temperature, what is the COP for a reversible heat pump?Data from problem 5.41Consider a heat engine and heat pump connected as shown in Fig. P5.41. Assume that TH1 = TH2 > Tamb and determine for ea
Answer Preview: The high temperature must be greater than 720 R for the h…

, Chapter: 3 -Problem: 83 >> Consider a steel bottle as a CV. It contains carbon dioxide at?20?C, quality 20%. It has a safety valve that opens at 6 MPa. The bottle is now accidentally heated until the safety valve opens. Write the process equation that is valid until the valve opens and plot the P–v diagram for the process.
Answer Preview: The process equation that is valid until the safety valve opens can be determined using the principl…

, Chapter: 14 -Problem: 58 >> A tank contains 0.1 kmol H2 and 0.1 kmol Ar gas at 25? C, 200 kPa, and the tank maintains constant volume. To what T should it be heated to have a mole fraction of atomic hydrogen, H, of 10%?
Answer Preview: The mole fraction of a gas is defined as the number of moles of a particular gas divided by the tota…

, Chapter: 4 -Problem: 94 >> A dual-fluid heat exchanger has 5 kg/s water entering at 40?C, 150 kPa and leaving at 10?C, 150 kPa. The other fluid is glycol, entering at ?10?C, 160 kPa and leaving at 10?C, 160 kPa. Find the required mass flow rate of glycol and the rate of internal heat transfer.
Answer Preview: To determine the required mass flow rate of glycol and the rate of internal heat …

, Chapter: 10 -Problem: 1 >> Is a Brayton cycle the same as a Carnot cycle? Name the four processes.
Answer Preview: The output work is always less than the input work …

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, Chapter: 11 -Problem: 17 >> A mixture of 60% N2, 30% Ar, and 10% O2 on a mass basis is in a cylinder at 250 kPa, 310 K with a volume of 0.5 m3. Find the mole and the mass fractions and the mass of argon.
Answer Preview: The mole fractions of the gas mixture can be calculated by dividing the number of moles of each gas …

, Chapter: 5 -Problem: 125 >> An industrial machine is being cooled by 0.8 lbm/s water at 60 F that is chilled from 95 F by a refrigeration unit with a COP of 3. Find the rate of cooling required and the power input to the unit.
Answer Preview: To find the rate of cooling required we need to first find the heat transfer rate of the water as it …

, Chapter: 3 -Problem: 199 >> Consider the pot in Problem 3.119. Assume the stove supplies 1 kW of heat. How much time does the process take? Data from Problem 3.119.A 1-kg steel pot contains 1 kg liquid water, both at 15?C. The pot is now put on the stove, where it is heated to the boiling point of the water. Neglect any air being heated and find the total amount of energy needed.
Answer Preview: The process described is a heating process where the pot of water is he…

, Chapter: 14 -Problem: 44 >> Assume the equilibrium mole fractions of oxygen and nitrogen are close to those in air. Find the equilibrium mole fraction for NO at 3000 K, 500 kPa, disregarding dissociations.
Answer Preview: To find the equilibrium mole fraction for NO at 3000 K and 500 kPa we can use the equilibrium consta…

, Chapter: 3 -Problem: 304 >> Ammonia is contained in a sealed, rigid tank at 30 F, x = 50% and is then heated to 200 F. Find the final state P2, u2 and the specific work and heat transfer.
Answer Preview: The final state P2 u2 is 10 31 psia 11 14 Btu lbm The specific work and heat …

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, Chapter: 7 -Problem: 1 >> If we follow a mass element going through a reversible adiabatic flow process, what can we say about the change of state?
Answer Preview: Then by eq 1 de 0 du dw if form process A to B work …

, Chapter: 6 -Problem: 9 >> Air at 290 K, 100 kPa in a rigid box is heated to 325 K. How do the properties (P, v, u, and s) change (increase, stay about the same, or decrease)?
Answer Preview: Air is heated in a rigid box from 290K 100 kPa to 325K As the box is rigid then the following con…

, Chapter: 3 -Problem: 90 >> A constant-pressure piston/cylinder assembly contains 0.2 kg of water as saturated vapor at 400 kPa. It is now cooled so that the water occupies half of the original volume. Find the work and heat transfer done in the process.
Answer Preview: The work done in the process is equal to the change in internal energy which is the difference betwe…

, Chapter: 13 -Problem: 154 >> Phenol, C6H5OH (M = 94.11 kg/kmol, CP = 1.7 kJ/kg-K), is used in a combustion process being burned with stoichiometric air. The reactants are supplied at 1.21 MPa, the air at T0 and the phenol as liquid at 100?C. Enough heat transfer, Q1, takes place after the combustion so that the products reach 1500 K. After the heat transfer the products are send through a turbine, where they expand to 120 kPa
Answer Preview: a To find the heat transfer Q1 we need to find the change in enthalpy of the reactants and products …

, Chapter: 3 -Problem: 219 >> A piston/cylinder setup (Fig. P3.171) 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, P0, and a mass such that 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 work, 1W2
Answer Preview: First calculate the initial pressure of the water P 0 400 kP…

, Chapter: 9 -Problem: 136 >> For a cryogenic experiment, heat should be removed from a space at 75 K to a reservoir at180 K. A heat pump is designed to use nitrogen and methane in a cascade arrangement (see Fig. 9.28), where the high temperature of the nitrogen condensation is 10 K higher than the low-temperature evaporation of the methane. The two other phase changes take place at the listed reservoir temperatures. Find the
Answer Preview: The saturation temperature in the heat exchanger between the two c…

, Chapter: 7 -Problem: 37 >> A reversible adiabatic compression of an air flow from 20?C, 100 kPa to 200 kPa is followed by an expansion down to 100 kPa in an ideal nozzle. What are the two processes? How hot does the air get? What is the exit velocity?
Answer Preview: The two processes are adiabatic compression and adiabatic expansion The air temperature will incr…

, Chapter: 5 -Problem: 83 >> A house is cooled by a heat pump driven by an electric motor using the inside as the low temperature reservoir. The house gains energy in direct proportion to the temperature difference as ?Q gain = K(TH ? TL ). Determine the minimum electric power to drive the heat pump as a function of the two temperatures. Transcribed I
Answer Preview: It s related to heat pump efficiency and power minimum by output A house is …

, Chapter: 3 -Problem: 77 >> Determine the phase of the following substances and find the values of the unknown quantities.a. R-410a: T =?20?C, u=220 kJ/kg, P=?, x=?b. Ammonia: T =?20?C, v = 0.35 m3/kg, P = ?, u = ?c. Water: P=400 kPa, h=2800 kJ/kg, T =?, v=?
Answer Preview: a R 410a The phase of R 410a at 20C is a superheated vapor To find the values of the unknown quantit…

, Chapter: 14 -Problem: 135 >> An important step in the manufacture of chemical fertilizer is the production of ammonia, according to the reaction N2 + 3H2 ? 2NH3. Show that the equilibrium constant is K =6.826 at 300 F.
Answer Preview: K NH3 2 N2 H2 3 Given that K 6 826 and T 300 F NH3 2 6 826 …

, Chapter: 4 -Problem: 116 >> A two-stage compressor takes nitrogen in at 20?C, 150 kPa and compresses it to 600 kPa, 450 K. Then it flows through an inter cooler, where it cools to 320 K, and the second stage compresses it to 3000 kPa, 530 K. Find the specific work in each of the two compressor stages and the specific heat transfer in the intercooler.
Answer Preview: To determine the specific work done by each stage of a two stage compressor and the specific heat tr…

, Chapter: 9 -Problem: 118 >> A condenser is maintained at 60?C by cooling it with atmospheric air coming in at 20?C and leaving at 35?C. The condenser must reject 25 MW from the water to the air. Find the flow rate of air and the second-law efficiency of the heat exchanger.
Answer Preview: Flow rate of air 585 7 kg s Second law efficiency 0 57 The heat transfer …

, Chapter: 6 -Problem: 199 >> R-410a at 150 psia and 140 F is expanded in a piston/cylinder to 75 psia, 80 F in a reversible process. Find the sign for both the work and the heat transfer for this process.
Answer Preview: Question R 410a at 150 psia and 140 F is expanded in a piston cylinder to 7…

, Chapter: 6 -Problem: 37 >> Do Problem 6.36 using refrigerant R-134a instead of R-410a. Data from Problem 6.36Consider a Carnot-cycle heat pump with R-410a as the working fluid. Heat is rejected from the R-410a at 35?C, during which process the R-410a changes from saturated vapor to saturated liquid. The heat is transferred to the R-410a at 0?C.a. Show the cycle on a T–s diagram.b. Find the quality of the R-410a at the begin
Answer Preview: a The T s diagram for a Carnot cycle heat pump with R 134a as the working fluid would be similar to …

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, Chapter: 13 -Problem: 139 >> An oven heated by natural gas burners has the combustion take place inside a U-shaped steel pipe, so the heating is done from the outside surface of the pipe by radiation. Each burner delivers 15 kW of radiation, burning 110% theoretical air with methane. The products leave the pipe at 800 K. Find the flow(kg/s) of methane. The burner is now switched to oxygen-enriched air (30% O2 and 70% N2), so
Answer Preview: To find the flow of methane in kg s we can use the ideal gas law PV nRT Given P 1 atm approximately …

, Chapter: 4 -Problem: 43 >> A wind turbine with a rotor diameter of 20 m takes 40% of the kinetic energy out as shaft work on a day with a temperature of 20?C and a wind speed of 35 km/h. What power is produced?
Answer Preview: To determine the power produced by the wind turbine we need to first calculate the kinetic energy of …

, Chapter: 10 -Problem: 63 >> The mean effective pressure scales with the net work and thus with the efficiency. Assume the heat transfer per unit mass is a given (it depends on the fuel–air mixture). How does the total power output then vary with the inlet conditions (P1, T1)?
Answer Preview: The mean effective pressure MEP is defined as the average pressure acting on the piston during the p…

, Chapter: 7 -Problem: 45 >> A two-stage compressor having an intercooler takes in air at 300 K, 100 kPa, and compresses it to 2MPa, as shown in Fig. P7.45. The cooler then cools the air to 340 K, after which it enters the second stage, which has an exit pressure of 15 MPa. Both stages are adiabatic and reversible. Find q in the cooler, total specific work, and compare this to the work required with no intercooler.
Answer Preview: q in the cooler 7 352 kJ kg Total specific work 79 895 kJ kg The work required with no intercoo…

, Chapter: 6 -Problem: 65 >> In a sink, 5 L of water at 70?C is combined with 1 kg of aluminum pots, 1 kg of flatware (steel), and 1 kg of glass, all put in at 20?C. What is the final uniform temperature and change in stored entropy, neglecting any heat loss and work?
Answer Preview: Energy U U mi U U Q W 0 Entropy S S fdQ T Sz For wa…

, Chapter: 3 -Problem: 117 >> A computer CPU chip consists of 50 g silicon, 20 g copper, and 50 g polyvinyl chloride (plastic). It now heats from 15?C to 70?C as the computer is turned on. How much energy did the heating require?
Answer Preview: The formula for specific heat capacity C of a substance …

, Chapter: 14 -Problem: 114 >> Combustion of stoichiometric benzene,C6H6, and air at 80 kPa with a slight heat loss gives a flame temperature of 2400 K. Consider the dissociation of CO2 to CO and O2 as the only equilibrium process possible. Find the fraction of the CO2 that is dissociated.
Answer Preview: The fraction of CO2 that is dissociated can be calculated using the equilibriu…

, Chapter: 3 -Problem: 231 >> A piston/cylinder arrangement has a linear spring and the outside atmosphere acting on the piston shown in Fig. P3.231. It contains water at 3 MPa and 400?C with a volume of 0.1 m3. If the piston is at the bottom, the spring exerts a force such that a pressure of 200 kPa inside is required to balance the forces. The system now cools until the pressure reaches 1 MPa. Find the heat transfer for the
Answer Preview: To find the heat transfer for the process we need to use the first law of thermodynamics which state…

, Chapter: 10 -Problem: 115 >> A Miller cycle has state 1 as 150 kPa, 300 K, a compression ratio of 9, and a heat release of 1000 kJ/kg. Find the needed expansion ratio so that P4 is 250 kPa.
Answer Preview: The expansion ratio needed to achieve a pressure of 2…

, Chapter: 7 -Problem: 126 >> An insulated piston/cylinder contains 0.1 m3 air at 250 kPa, 300 K and it maintains constant pressure. More air flows in through a valve from a line at 300 kPa, 400 K, so the volume increases 60%. Use constant specific heats to solve for the final temperature and the total entropy generation.
Answer Preview: The final temperature of the air in the piston cylinder can be calculated using the first law of thermodynamics which states that the change in intern…

, Chapter: 6 -Problem: 45 >> A piston/cylinder contains 0.25 kg of R-134a at 100 kPa. It will be compressed in an adiabatic reversible process to 400 kPa and should be at 70?C. What should the initial temperature be?
Answer Preview: In an adiabatic reversible process the internal energy of the gas does not change because no heat is …

, Chapter: 3 -Problem: 150 >> A constant-pressure piston/cylinder contains 0.5 kg air at 300 K, 400 kPa. Assume the piston/ cylinder has a total mass of 1 kg steel and is at the same temperature as the air at any time. The system is now heated to 1600 K by heat transfer.a. Find the heat transfer using constant specific heats for air.b. Find the heat transfer not using constant specific heats for air.
Answer Preview: To find the heat transfer in part a you can use the first law of thermodynamics which states that the change in internal energy of a closed system is …

, Chapter: 14 -Problem: 14 >> Does a dissociation process require energy or does it give out energy?
Answer Preview: Dissociation in chemistry the ending of a compound into less complicated constituents that area unit …

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, Chapter: 6 -Problem: 5 >> Water at 100?C, quality 50% in a rigid box is heated to 110?C. How do the properties (P, v, x, u, and s) change (increase, stay about the same, or decrease)?
Answer Preview: Water at 100C quality 50 in a rigid box is heated to 110C …

, Chapter: 3 -Problem: 85 >> The final state was given, but you were not told that the piston hits the stops, only that Vstop = 2 V1. Sketch the possible P–v diagram for the process and determine which number(s) you need to uniquely place state 2 in the diagram. There is a kink in the process curve; what are the coordinates for that state? Write an expression for the work term.
Answer Preview: The kink in the process curve occurs when the piston hits the stops At this point the pressure in th…

, Chapter: 14 -Problem: 13 >> In equilibrium, the Gibbs function of the reactants and the products is the same; how about the energy?
Answer Preview: S is the change in entropy disorder from reactants …

, Chapter: 3 -Problem: 309 >> Ammonia vapor is compressed inside a cylinder by an external force acting on the piston. The ammonia is initially at 30?C, 500 kPa, and the final pressure is 1400 kPa. The following data have been measured for the process: Determine the work done by the ammonia by summing the area below the P–V process curve. As you plot it, P is the height and the change in volume is the base of a number of recta
Answer Preview: To calculate the work done by the ammonia during the compression process we need to sum the area bel…

, Chapter: 7 -Problem: 98 >> A dual fluid heat exchanger has 5 kg/s water enter at 40?C, 150 kPa and leave at 10?C, 150 kPa. The other fluid is glycol coming in at ?10?C, 160 kPa and leaving at 10?C, 160 kPa. Find the mass flow rate of glycol and the rate of entropy generation.
Answer Preview: The heat transfer between the two fluids in the heat exchanger can be calculated using the heat transfer coefficient the surface area of the heat exch…

, Chapter: 5 -Problem: 157 >> The air conditioner in the previous problem is turned off. How quickly does the house heat up in degrees per second (F/s)?Data from previous problem An air conditioner on a hot summer day removes 8 kW of energy from a house at 21?C and pushes energy to the outside, which is at 31?C. The house has a mass of 15 000 kg with an average specific heat of 0.95 kJ/kgK. In order to do this, the cold side o
Answer Preview: To find the rate at which the house heats up we need to determine the rate of heat transfer into the …

, Chapter: 3 -Problem: 169 >> A piston/cylinder shown in Fig. P3.169 contains 0.5 m3 of R-410a at 2 MPa, 150?C. The piston mass and atmosphere give a pressure of 450 kPa that will float the piston. The whole setup cools in a freezer maintained at ?20?C. Find the heat transfer and show the P–v diagram for the process when T2 =?20?C.A Transcribed Image T
Answer Preview: The heat transfer for the process can be calculated using the first l…

, Chapter: 14 -Problem: 148 >> Examine the chemical equilibrium that takes place in an engine where CO and various nitrogen– oxygen compounds summarized as NOx may be formed. Study the processes for a range of air– fuel ratios and temperatures for typical fuels. Are there important reactions not listed in the book?
Answer Preview: In fluid dynamics a stagnation point is a point in a flow …

, Chapter: 3 -Problem: 267 >> Ammonia (1 lbm) in a piston/cylinder at 30 psia, 20 F is heated in a process in which the pressure varies linearly with the volume to a state of 240 F, 40 psia. Find the work and the heat transfer in the process.
Answer Preview: To calculate the amount of heat released in a chemica…

, Chapter: 7 -Problem: 21 >> A reversible isothermal expander (a turbine with heat transfer) has an inlet flow of carbon dioxide at 3MPa, 80?C and an exit flow at 1 MPa, 80?C. Find the specific heat transfer from the entropy equation and the specific work from the energy equation assuming ideal gas.
Answer Preview: The specific heat transfer heat transfer per unit mass can be calculated using the formula Q m T s2 …

, Chapter: 6 -Problem: 29 >> Determine the missing properties among (T, P, v, s)a. H2O 20? C, v = 0.001000 m3/kgb. R-410a 400 kPa, s = 1.17 kJ/kg-Kc. NH3 10?C, v = 0.1 m3/kgd. N2 101.3 kPa, s = 3.5 kJ/kg-K
Answer Preview: a For H2O 20 C the missing property is the pre…

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, Chapter: 15 -Problem: 17 >> An object from space enters the earth’s upper atmosphere at 5 kPa, 100 K, with a relative velocity of 2500 m/s or more. Estimate the object’s surface temperature.
Answer Preview: To estimate the temperature of an object entering the Earths upper atmosphere at 5 kPa a…

, Chapter: 3 -Problem: 263 >> Saturated vapor R-410a at 200 psia in a constant pressure piston/cylinder is heated to 140 F. Find the specific heat transfer.
Answer Preview: Subtract the final and initial temperature to get the change in temperature …

, Chapter: 6 -Problem: 251 >> Write a program to solve the general case of Problem 6.111, in which the initial state and the expansion ratio are input variables. Data from Problem 6.111The power stroke in an internal combustion engine can be approximated with a poly tropic expansion. Consider air in a cylinder volume of 0.2 L at 7MPa, 1800 K, shown in Fig. P6.111. It now expands in a reversible poly tropic process with exponen
Answer Preview: Here is a Python code to solve the general case of the Problem 6 111 import numpy as np def polytrop…

, Chapter: 5 -Problem: 126 >> A water cooler for drinking water should cool 10 gal/h water from 65 F to 50 F using a small refrigeration unit with a COP of 2.5. Find the rate of cooling required and the power input to the unit.
Answer Preview: To find the rate of cooling required we need to first find the heat transfer rate of the water as it …

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, Chapter: 14 -Problem: 147 >> Study the chemical reactions that take place when CFC-type refrigerants are released into the atmosphere. The chlorine may create compounds such as HCl and ClONO2 that react with the ozone, O3.
Answer Preview: 1 The reaction between chlorine and the ozone is as follows Cl O3 ClO O2 2 The reacti…

, Chapter: 3 -Problem: 221 >> Two springs with the same spring constant are installed in a massless piston/cylinder arrangement with the outside air at 100 kPa. If the piston is at the bottom, both springs are relaxed, and the second spring comes in contact with the piston at V = 2 m3. The cylinder (Fig. P3.221) contains ammonia initially at ?2?C, x = 0.13, V = 1 m3, which is then heated until the pressure reaches 1200 kPa. At
Answer Preview: The pressure at which the piston will touch the second spring is equal to the sp…

, Chapter: 7 -Problem: 14 >> A condenser receives R-410a at ?20?C and quality 80%, with the exit flow being saturated liquid at ?20?C. Consider the cooling to be a reversible process and find the specific heat transfer from the entropy equation.
Answer Preview: Specific heat transfer q T ds T s2 s1 From R 410a tables at 20 …

, Chapter: 5 -Problem: 113 >> A Carnot heat engine, shown in Fig. P5.113, receives energy from a reservoir at Tres through a heat exchanger where the heat transferred is proportional to the temperature difference as ?Q H = K(Tres ? TH). It rejects heat at a given low temperature TL. To design the heat engine for maximum work output, show that the high temperature, TH, in the cycle should be selected as TH =?TresTL
Answer Preview: TH TresTL The maximum work output of the Carnot heat engine occurs when the heat exchange is maximiz…

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, Chapter: 13 -Problem: 102 >> Consider the combustion of hydrogen with pure O2 in a stoichiometric ratio under steady-flow adiabatic conditions. The reactants enter separately at 298 K, 100 kPa, and the product(s) exit at a pressure of 100 kPa. What is the exit temperature, and what is the irreversibility?
Answer Preview: H2 0 5 O2 H20 Thus we are making 9 gram of water for every gra…

, Chapter: 4 -Problem: 69 >> Carbon dioxide used as a natural refrigerant flows through a cooler at 10 MPa, which is supercritical, so no condensation occurs. The inlet is at 220?Cand the exit is at 50?C. Find the specific heat transfer.
Answer Preview: The specific heat transfer of carbon dioxide can be calculated using the follow…

, Chapter: 7 -Problem: 41 >> A turbocharger boosts the inlet air pressure to an automobile engine. It consists of an exhaust gas driven turbine directly connected to an air compressor, as shown in Fig. P7.41. For a certain engine loadthe conditions are given in the figure. Assume that both the turbine and the compressor are reversible and adiabatic, having also the same mass flow rate. Calculate the turbine exit temperature a
Answer Preview: We can use the energy equation to calculate the turbine exit temperature and power output The energy …

, Chapter: 6 -Problem: 81 >> Prove that the two relations for changes in s, Eqs. 6.16 and 6.17, are equivalent once we assume constant specific heat.  Transcribed Image Text: P2 R In P1 T2 $2 - S1 = Cpo I (6.16) T2 V2 + R In T S2 - S1 = Cyo In (6.17) V1
Answer Preview: To prove that Eqs 6 16 and 6 17 are equivalent when we assume constant specific heat we start with E…

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, Chapter: 13 -Problem: 173 >> Acetylene gas, C2H2, is burned with stoichiometric air in a torch. The reactants are supplied at the reference conditions P0, T0. The products come out from the flame at 4500 R after some heat loss by radiation. Find the heat loss per kmol of fuel.
Answer Preview: The heat loss per kmol of fuel can be calculated using the ideal gas law and the ent…

, Chapter: 4 -Problem: 107 >> An open feedwater heater in a power plant heats 4 kg/s water at 45?C, 100 kPa by mixing it with steam from the turbine at 100 kPa, 250?C, as in Fig. P4.107. Assume the exit flow is saturated liquid at the given pressure and find the mass flow rate from the turbine. Transcribed Image Text: 1 3 Mixing
Answer Preview: The mass flow rate from the turbine can be calculate…

, Chapter: 7 -Problem: 63 >> An irrigation pump takes water from a river at 10?C, 100 kPa and pumps it up to an open canal at a 50-m higher elevation. The pipe diameter into and out of the pump is 0.1 m, and the motor driving the pump is 5 hp. Neglect kinetic energies and friction and find the maximum possible mass flow rate.
Answer Preview: The maximum mass flow rate through the pump can be calculated using the Bernoulli equation which sta…

, Chapter: 6 -Problem: 6 >> Liquid water at 20?C, 100 kPa is compressed in a piston/cylinder without any heat transfer to a pressure of 200 kPa. How do the properties (T, v, u, and s) change (increase, stay about the same, or decrease)?
Answer Preview: An adiabatic process is carried out in a piston cylinder arrangement when liquid water is …

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, Chapter: 14 -Problem: 6 >> In a steady-flow burner, T is not controlled; which properties are?
Answer Preview: Forms Control These include properties such as Font …

, Chapter: 3 -Problem: 314 >> Write a program to solve Problem 3.123 for a range of initial velocities. Let the car mass and final velocity be input variables. Data from Problem 3.123A car with mass 1275 kg is driven at 6

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