A building with an internal volume of 400 m3 is to be heated by a 30-kW electric resistance heater placed in the duct inside the building. Initially, the air in the building is at 14°C, and the local atmospheric pressure is 95 kPa. The building is losing heat to the surroundings at a steady rate of 450 kJ/min. Air is forced to flow through the duct and the heater steadily by a 250-W fan, and it experiences a temperature rise of 5°C each time it passes through the duct, which may be assumed to be adiabatic. How long will it take for the air inside the building to reach an average temperature of 24°C?

Q: A piston cylinder device containing 3 lbm of water is allowed to expand while being heated with 250…

A:

Q: A piston–cylinder device initially contains 1.4 kg of refrigerant-134a at 100 kPa and 20°C. Heat is…

A: Given data

Q: A 5-cm-external-diameter, 10-m-long hot water pipe at 80°C is losing heat to the surrounding air at…

A:

Q: An adiabatic air compressor is to be powered by a direct-coupled adiabatic steam turbine that is…

A: Given Data:

Q: A frictionless piston-cylinder device contains 4 kg of nitrogen at 100 kPa and 300 K. Nitrogen is…

A: Data given-  m = 4 kg  P1 = 100 kPa  T1 = 300 K  T2 = 340 K

Q: Water is being heated in a closed pan on top of a range while being stirred by a paddle wheel.…

A: Given data: The heat transferred to the water is Q1=30 kJ. The heat lost by the surroundings is…

Q: In a closed system, steam at 120 psia and 700 Fis expanded adiabatically to 10 psia. Determine the…

A:

Q: A building with an internal volume of 400 m3 is to be heated by a 30-kW electric resistance heater…

A: Given data: *The power of the fan used to heat the air is Pf= 250 W. *The power of the electric…

Q: Two constant-volume tanks, each filled with 30 kg of air, have temperatures of 900 K and 300 K. A…

A: Given data: Mass of air, m = 30 kg Initial temperature of source, T1 = 900 K Initial temperature of…

Q: Consider a rigid vessel that is initially empty, connected by a valve to a feed line of water at 1…

A:

Q: A heat engine receives heat from a source at 1100 K at a rate of 400 kJ/s, and it rejects the waste…

A:

Q: Air enters the duct of an air-conditioning system at 15 psia and 50°F at a volume flow rate of 450…

A: Given: The inlet pressure of the air in the duct is P1=15 psia. The inlet temperature of the air in…

Q: How does the efficiency of an idealized automobile engine depend on the operating temperature of the…

A: Draw the PV diagram of the heat engine.

Q: 20 kg of steam contained in a high-pressure tank. Tank is isolated, but heat loss to the surrounding…

A:

Q: A heat engine receives heat from a source at 1100 K at a rate of 400 kJ/s, and it rejects the waste…

A: Given: The temperature of the source is T1=1100 K. The temperature of the medium is T2=320 K. The…

Q: A 4-m × 5-m × 6-m room is to be heated by an electric resistance heater placed in a short duct in…

A: Given, T1 = 15°C+273 = 288 K P1 = 98 kPa Qrejected = 150 kJ/ min=  Wfan = 200 W = 200 x 10-3 KW mf…

Q: What are adiabatic and isothermal processes? Calculate the work done in adiabatic…

A:

Q: A rigid container with 6 m × 9 m × 3 m can be considered a closed system in which the container's…

A: Given: Volume of the container= 6×9×3=162m2 Initial pressure P1=110kPa Inital temperature=32°C or…

Q: 5-83 Refrigerant-134a at 700 kPa, 70°C, and 8 kg/min is cooled by water in a condenser until it…

A: Given Data The pressure of the refrigerant is: P=700 kPa The temperature of refrigerant is: T=70°C…

Q: A hair dryer is basically a duct in which a few layers of electric resistors are placed. A small fan…

A: P1 = 100 kPa T1 = 295 K Q ˙= 1200 J/s T2 = 320 K A2 = 60 cm2 Control volume of a given problem is…

Q: Does a heat engine that has a thermal efficiency of 100 percent necessarily violate the first law.

A: The 1st law of thermodynamics states the conversion of one form of energy to another completely.…

Q: A hair dryer is basically a duct in which a few layers of electric resistors are placed. A small fan…

A: Given Data:-                P =1200w                P1=100kPa                   T1 =22°C…

Q: The temperature at the inner and outer surfaces of a boiler wall made of 25 mm thick steel and…

A: solutiongiven dataTi=350°CT∘=600°Cb1=25 mmb2=15 mmks=68 w/m°CKins=0.126 w/m°C

Q: A 4-m × 5-m × 6-m room is to be heated by an electric resistance heater placed in a short duct in…

A: Given: The length of the room, l = 4 m The width of the room, b = 5 m The height of the room, h = 6…

Q: Does a heat engine that has a thermal efficiency of 100 percent necessarily violate the second law…

A: Yes, a heat engine having 100% thermal efficiency will violate the Kelvin Planck statement of the…

Q: A piston-cylinder device initially contains 1.4 kg of refrigerant-134a at 100 kPa and 20oC. Heat is…

A:

Q: . A 4-m x 5-m x 7-m room is heated by the radiator of a steam-heating system. The steam radiator…

A:

Q: Steam enters the condenser of a steam power plant at 50 kPa and a quality of 85 percent with a mass…

A: Given Data: The pressure of steam entering the condenser is, P1=50 kPa. The quality of steam at the…

Q: Consider an insulated system with piston and cylinder arrangement in which Nitrogen gas is present.…

A: It is given that the system is insulated. thus, dQ=0

Q: In a steady flow apparatus 135kJ of work is done on each kg of fluid. The specific volume of the…

A:

Q: An exercise room has 6 weight-lifting machines that have no motors and 7 treadmills each equipped…

A: Given data: The number of treadmills (n) = 7 The efficiency of the treadmill = 0.77 Average load…

Q: Air enters the duct of an air-conditioning system at 15 psia and 50°F at a volume flow rate of 450…

A: Air inlet temperature T1 = 50 F Air inlet pressure P1 = 15 psia Duct diameter D = 10 in The volume…

Q: What is an adiabatic process? What is an adiabatic system?

A:

Q: Determine the maximum possible thermal efficiency of the power plant, and the maximum power output

A: Given : TH=80°C=80+273=353°K            TL=30°C=30+273=303°K           Qs=1 KJ/s

Q: Steam enters a nozzle steadily 400°C and 800 kPa with a velocity of 10 m/s, and leaves at 300°C and…

A: Calculated exit velocity of nozzle in (m/s).

Q: A 0.05-m3 rigid tank initially contains refrigerant134a at 0.8 MPa and 100 percent quality. The tank…

A: Given Volume of tank = 0.05 m3 Pressure in tank = 0.8 MPa Quality = 100% Valve pressure = 1.2 MPa…

Q: A piston–cylinder device initially contains 1.4 kg of refrigerant-134a at 100 kPa and 20°C. Heat is…

A: Given data m=1.4 kgP1=100 kPaT1=20°cP2=120 KPa

Q: 0.018 m gas at a pressure of 3.070 Kpa expands to a pressure of 0.00207 bar according to the law…

A:

Q: A student living in a 4m x 6m x 6m dormitory room turns on her 150 W fan before she leaves the room…

A: GivenV = 4 x 6 x 6 = 144 m3              1 or i - initial  ; F - FinalP = 150 w , SQ = 0t = 10 h , R…

Q: Air enters a compressor at ambient conditions of 15 psia and 60°F with a low velocity and exits at…

A: Given Data Work inlet is: win=400 hp=282.72 Btu/s Heat output is: Q˙=1500 Btu/min=25 btu/s

Q: Consider two identical rooms, one with a 2-kW electric resistance heater and the other with three…

A: Given data as per the question Power of heater =2KW

Q: A student living in a 4 - m 5 - m 3 - m dormitory room turns on her 100 - W fan before she leaves…

A: Given, V = 4 m × 5 m × 3 m = 60 m3W˙= 100 Wt = 8 h = ( 8 × 3600) sP1 = 100 kPaT1 = 20 °C = 293 K…

Q: Nitrogen at 100 psia and 300°F in a rigid container is cooled until its pressure is 50 psia.…

A: Find out the final temperature T2=T1P2P1=76050100R=380R

Q: On a hot summer day, the air in a well-sealed room is circulated by a 0.50-hp fan driven by a 65…

A: This question is based on the concept of thermodynamics.

Q: Consider an insulated system with piston and cylinder arrangement in which Nitrogen gas is present.…

A: Given Data ∆U=1000 kJ Q=0 (insulated system)

Q: A hair dryer basically a duct in which a few layers of electric resistors are placed. A small fan…

A: Given Data The power of the hair drier is: P=1200 W=1.2 kW The Pressure of the air at inlet and…

Q: A room contains 60 kg of air at 100 kPa and 15°C. The room has a 250-W refrigerator (the…

A:

Q: 1-122 A4-m-long section of an air heating system of a house passes through an unheated space in the…

A:

Q: A 0.8-m3 rigid tank contains carbon dioxide (CO2) gas at 250 K and 100 kPa. A 500-W electric…

A: Given Data⇒P1=100 KPaV=0.8 m3For CO2COnsider gas constant  R=0.189JkgT1=250 KP2=175 KPaProblem…

Work and Heat Transfer

It is generally related to thermal engineering which tells about the use, creation, conversion and transfer of heat energy between the systems. It is also considered that to transfer heat from one source to another, transfer of masses is also required. There are various mechanisms by which, transfer of heat takes place i.e. thermal conduction, convection, radiation or by change of phase. All these mechanisms have their own specific features which sometimes occur simultaneously within the same system.