A 50-L electrical radiator containing heating oil is placed in a well-sealed 75-m3 room. Both the air in the room and the oil in the radiator are initially at the environment temperature of 6°C. Electricity with a rating of 2.4 kW is now turned on. Heat is also lost from the room at an average rate of 0.75 kW. The heater is turned off after some time when the temperatures of the room air and oil are measured to be 20°C and 60°C, respectively. Taking the density and the specific heat of oil to be 950 kg/m3 and 2.2 kJ/kg⋅°C, determine the second-law efficiency for this process.

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: Is the boundary work associated with constant-volume systems always zero?

A: The expression for boundary work is given by, Here, W is net work done by the system; P is the net…

Q: 2 kg of air at 298 K and 120 kPa inside a piston cylinder device is heated to 860 K in an isochoric…

A: Given, m = 2 kg T1 = 298 K P1 = 120 kPa T2 = 860 K T3 = 1200 K Taking cP of air as 1.00 KJ/kg.K

Q: What is the second-law efficiency? How does it differ from the first-law efficiency?

A: Before understanding the first and second law efficiency and the difference we have to understand…

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: Determine the work interaction when a gas absorbs 12 kJ of heat which cause the internal energy to…

A: Givenq=12 kJE=30 kJAskedWork done=?SolutionE=q+W

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: a piston cylinder containing air receives heat at a constant temperature of 500k and an initial…

A:

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

A:

Q: Q1/ A frictionless piston–cylinder device initially contains 200 L of saturated liquid…

A: Given: Initial volume (V)=200L or 200×10-3m3Pressure P=900kPaFinal Temperature T2=70°C

Q: Steam at 75 kPa and 8 percent quality is contained in a spring-loaded piston–cylinder device, with…

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: Is the energy required to heat air from 295 to 305 K the same as the energy required to heat it from…

A:

Q: The work required to compress 5 kg of air in an insulated cylinder from 200°C and 300 kPa to 800 kPa…

A: Write the given data. m=5 kgT=200 °C=473 KP1=300 kPaP2=800 kPa

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: Consider two bodies of identical mass m and specific heat c used as thermal reservoirs (source and…

A: Consider the diagram shown below for the thermodynamic system.

Q: Water is heated in an insulated, constant-diameter tube by a 7-kW electric resistance heater. If the…

A: Given: The water enters the heater is T1 = 20 °C. The water leaves the heater is T2 = 75 °C. The…

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

A:

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

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: 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: Why do we use enthalpy in place of Internal Energy In the energy Balance for open systems?

A: Given data: Enthalpy is used in place of internal energy because its gives more precise value of…

Q: A 5-ft3 rigid tank initially contains refrigerant-134a at 60 psia and 100 percent quality. The tank…

A: The properties of refrigerant 134a at 60 psia and 100 percent quality are: The enthalpy of…

Q: The radiator of a steam heating system has a volume of 20 L and is filled with superheated water…

A: Given: The volume of the system is V=20 L. The initial temperature and pressure are T1=200 ⁰C and…

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

A:

Q: The volume of 1 kg of helium in a piston-cylinder device is initially 5 m³. Now helium is compressed…

A:

Q: A piston-cylinder device contains 6 kg of air at 440 kPa and 32°C. During an isothermal expansion…

A:

Q: Consider a 300-liter water heater that is initially filled with water at 290 K. Determine how much…

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: Determine the work done in KJ in a piston which has a constant pressure of 25 psi. Its initial…

A:

Q: A 2 kW electric resistance heater in a room is turned on and kept on for 30 min. The amount of…

A: Power, P = 2 kW = 2000 W Time, t = 30 minutes = 1800 seconds Work Done, W = ?

Q: ) Stainless steel ball bearings (ρ = 8085 kg/m3 and cp = 0.480 kJ/kgC) having a diameter of 1.22 cm…

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: 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: A piston–cylinder device contains 15 kg of air at 599 kPa and 38oC. During a quasi-equilibium…

A: Given conditions , Mass of piston cylinder device = 15 kg Temperature = 38oC Pressure = 599 kPa…

Q: A gas enclosed in a container that has a piston with a cross-sectional area of 0.15 m2 has a vacuum…

A: Calculated work done in KJ.

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: An ordinary egg with a mass of 0.1 kg and a specific heat of 3.32 kJ/kg·°C is dropped into boiling…

A:

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: 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: In a piston cylinder device, by means of a polytropic process, nitrogen is expanded with an n of…

A:

Q: A piston–cylinder device contains 4 kg of argon at 250 kPa and 35°C. During a quasi-equilibrium,…

A: From the first law of thermodynamics,                                   Qin+Win-Wout=∆U For…

Q: The volume of 1 kg of helium in a piston–cylinder device is initially 5 m3 . Now helium is…

A: Ideal Gas Equation is given by PV=mRT P is pressure V is Volume M is mass of the Gas R is Universal…

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.