A passive solar house that is losing heat to the outdoors at an average rate of 50,000 kJ/h is maintained at 22°C at all times during a winter night for 10 h. The house is to be heated by 50 glass containers each containing 20 L of water that is heated to 80°C during the day by absorbing solar energy. A thermostat-controlled 15-kW back-up electric resistance heater turns on whenever necessary to keep the house at 22°C. (a) How long did the electric heating system run that night? (b) How long would the electric heater run that night if the house incorporated no solar heating?

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 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: An isentropic steam turbine processes 2 kg/s of steam at 3 MPa, which is exhausted at 100 kPa and…

A:

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

A:

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

A:

Q: A 1200-W electric resistance heating element whose diameter is 0.5 cm is immersed in 40 kg of water…

A: The data given is, Total power of the electric heater, P = 1200 W The diameter of element, d = 0.5…

Q: Argon is heated at 350 K with a mass flow of 4 kg/s as it passes through a pipe. Given that the heat…

A:

Q: During some actual expansion and compression processes in piston–cylinder devices, the gases have…

A: Given: The initial pressure of the gas is P1=350 kPa. The initial volume of the gas is V1=0.03 m3.…

Q: An inventor claims to have invented an adiabatic steady-flow device with a single inlet-outlet that…

A:

Q: The compressor in a refrigerator compresses saturated R-134a vapor at 0°F to 200 psia. Calculate the…

A: Given: The initial temperature of the refrigerant is T1=0 °F The final pressure of the refrigerant…

Q: Steam enters a nozzle at 400°C and 800 kPa with a velocity of 10 m/s, and leaves at 3008C and 200…

A:

Q: Steam is condensed in a closed system at a constant pressure of 75 kPa from a saturated vapor to a…

A: Given data as per question Pressure of the condensed steam = 75 kpa thermal energy reservoir…

Q: Two rigid tanks are connected by a valve. Tank A is insulated and contains 0.3 m of steam at 400 kPa…

A:

Q: Wet steam at 2000C and 20% moisture is compressed in an irreversible adiabatic process to a pressure…

A:

Q: Saturated liquid water is heated in a steady-flow steam boiler at a constant pressure of 2 MPa at a…

A: Given data: Inlet pressure ,P1 = 2 MPa Outlet temperature, T2 = 2500C Mass flow rate, m = 4 kg/s Now…

Q: Electric heating systems used in many homes consist of a simple duct with resistance heaters. As it…

A: From the 1st law of Thermodynamics & energy balancing, we can write…

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: 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: Show that the law of the adiabatic process is given by PV ˠ = constant Where: (ˠ) is the ratio of…

A:

Q: In a production facility, 1.6-in-thick 2-ft × 2-ft square brass plates (ρ = 532.5 lbm/ft3 and cp =…

A: Given Data: The thickness of plate is t = 1.6 in. The area of plate is A = 2-ft × 2-ft. The density…

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

A:

Q: Steam enters a turbine at 6 MPa and 450°C at a rate of 33 kg/s and exits at 50 kPa as saturated…

A:

Q: An inventor claims that a new fridge can operate between -15 degree Celsius and 150 degree C while…

A: Given:T2=-15°C =258 KT1=150°C =423 KHeat taken from sink,Q2=2200 WWork input,W=2000 W

Q: A piston–cylinder device contains 5 kg of air at 400 kPa and 30°C. During a quasi-equilibium…

A: Given: The mass of the air is m=5 kg. The pressure of the air P=400 kPa. The temperature of air is…

Q: What is the minimum internal energy that steam can achieve as it is expanded adiabatically in a…

A: Given: The initial pressure of the steam, P1 = 1500 kPa The final pressure of the steam, P2 = 100…

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

A: Given, Before Heater is on, P1 = 100 kPa T1 = 250 K V1 = 0.8 m3 After Heater is on, P2 = 175 kPa…

Q: One kg of air at 200 kPa and 127°C is contained in a piston–cylinder device. Air is now allowed to…

A: Given: The mass of the air is m=1 kg. The temperature of the air is T=127°C. The initial pressure of…

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: 5. During some actual expansion and compression processes in piston-cylinder devices, the gases have…

A:

Q: Two rigid tanks are connected by a valve. Tank A is insulated and contains 0.3 m3 of steam at 400…

A: Given data Pressure in rigid tank A is: PA=400 kPa. The quality of steam in tank A is: x=60%. The…

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

A: The value of specific volume at an initial point having P1=100 kPa, T1=20°C and at the final point…

Q: An adiabatic open feedwater heater in an electric power plant mixes 0.2 kg/s of steam at 100 kPa and…

A: Given data: The mass flow rate of steam, ms = 0.2 kg/s. The mass flow rate of feed water, mw = 10…

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

A:

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

A:

Q: Steam at 3 MPa and 400°C is expanded to 30 kPa in an adiabatic turbine with an isentropic efficiency…

A: Work done can be determined by using Steady flow energy equation Values from steam table at given…

Q: A long roll of 2-m-wide and 0.5-cm-thick 1-Mn manganese steel plate (ρ = 7854 kg/m3 and cp = 0.434…

A:

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: 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: Determine the work required (in kJ/kg) for a pump that is used to increase the pressure of a liquid…

A: Given: P1 = 100 kPa   P2 = 1500 kPa ,    v = 0.001031 m3/kg Work required for pump to increase the…

Q: Carbon dioxide is compressed in a reversible, isothermal process from 100 kPa and 20°C to 400 kPa…

A: Given data: The initial pressure is Pi = 100 kPa. The final pressure is  Pf = 400 kPa. The…

Q: The kitchen, bath, and other ventilation fans in a house should be used sparingly since these fans…

A: Calculate the density of air in the room, Calculate the volume of the room as,

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: A rigid tank contains air at 500 kPa and 150°C. AS a result of heat transfer to the surroundings,…

A: Pressure P1 = 500 kpa Pressure P2 = 400 kpa Temperature T1 = 150 C Temperature T2 = 65 C

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

A:

Q: Two rigid tanks are connected by a valve. Tank A is insulated and contains 0.2 m3 of steam at 400…

A: Specific volume of a substance is defined as the volume of the substance per unit mass. Quality of…

Q: Refrigerant-134a is compressed steadily from the saturated vapor state at 120 kPa to 1.6 MPa and 60…

A:

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.