A window air conditioner uses 1307 W of electricity and has a coefficient of performance of...
A window air conditioner uses 1307 W of electricity and has a coefficient of performance of 2.75. For simplicity, let's assume that all of that electrical energy is transformed into work done by the air conditioner to cool a room with dimensions of 7 m x 7 m x 3 m. The air inside this room will initially have the same temperature as the air outside (319 K) and the air conditioner will attempt to cool the room to 295 K. For the purposes of estimation, assume that the air in this room will be cooled at constant volume, that the specific heat of the air at constant volume is 720 J/kg-K, and that the density of the air is 1.2 kg/m3.
1)
How much energy must be transferred out of this room in order to decrease the temperature of the air from 319 K to 295 K?
How much work will be done by the air conditioner during the process of cooling the room?
)
How much time in minutes will it take for the room to cool using this air conditioner?
How much time in minutes would the cooling process take if instead we used an air conditioner that uses a Carnot cycle that operates between 319 K and 295 K?
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A window air conditioner uses 1307 W of electricity and has a
coefficient of performance of...
2. The temperature of the air in a room needs to be adjusted (from room temperature...
2. The temperature of the air in a room needs to be adjusted (from room temperature and pressure, 298 K and latm). The room is 10.0 m wide, 22.0 m deep, and 3.0 m high. The approximate constant pressure heat capacity of air is Cp 1.0 kJ/(K*kg)1. Assume the air in the room is an ideal gas. 2.1 What is the approximate mass of the air in the room? (Use molar volume and molar weight of air) 2.2 How much...
This is for static air don't just copy from others', this is a different problem. 1. A very long horizontal cylinder of Unobtainium, of diameter 100 mm, is initially at a uniform temperature...
This is for static air don't just copy from others', this is a
different problem.
1. A very long horizontal cylinder of Unobtainium, of diameter 100 mm, is initially at a uniform temperature of 500 K. The cylinder is left to cool in a large room of static air at 300 K. Calculate a) the average convective heat transfer coefficient at the beginning of the cooling process when the initial temperature of the cylinder is 500 K, and 10] 15]...
5. Air expands isothermally constant temperature) in a closed, piston-cylinder device. The original state is given...
5. Air expands isothermally constant temperature) in a closed, piston-cylinder device. The original state is given by pı = 20 MPa, T = 1000 K. the process continues until the pressure drops to 2 MPa. The original volume of the air is V1 = 1 m². Determine the following: a. the mass of the air in the system, in kg. b. the final density of the air, in kg/m". Remember, Rair = 0.287 kJ/kg-K c. the final volume of the...
USE THE AIR TABLES 0.5 kg of air is initially at 280 K, 100 kPa in...
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2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The wall is 20 cm thick and has a surface area of 10 m2. One side of the wall is exposed to outside air blowing against the wall resulting in a heat transfer coefficient of 20 W/(m2-K). The other side is exposed to an air-conditioned room with a convective heat transfer coefficient of 5 W/(m2-K). a. What are the thermal resistances corresponding to conduction through...
An aluminum alloy (2024) plate, heated to a uniform temperature of 227°C, is allowed to cool while vertically suspended in a room where the ambient air and surroundings are at 27°C. The plate is 0.3...
An aluminum alloy (2024) plate, heated to a uniform temperature of 227°C, is allowed to cool while vertically suspended in a room where the ambient air and surroundings are at 27°C. The plate is 0.3 m square with a thickness of 15 mm. a) calculate the rate of heat transfer from the plate to the surrounding air. b) Develop an expression for the time rate of change of the plate temperature, assuming the temperature to be uni form at any...
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Over a period of time, a hot object cools to the temperature of the surrounding air. This is described mathematically by Newton's Law of Cooling T = C+ (To-C) e-kt, where t is the time it takes for an object to cool from temperature Toto temperature T, C is the surrounding air temperature, and k is a positive constant that is associated with the cooling object. A cake removed from the oven has a temperature of 207°F and is left...
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Steel Beam A beam used in construction is made of steel, which has a coefficient of...
Steel Beam A beam used in construction is made of steel, which has a coefficient of linear expansion of 1.3 x 105 K1. The beam is 30 m long at a temperature of 1635 K when it is made. As it cools, the temperature of the beam decreases to 300 K 1) What is the change in the length of the beam due to cooling? m Submit 2) If the mass of the steel beam is 390 kg and the...
2. The temperature of the air in a room needs to be adjusted (from room temperature and pressure, 298 K and latm). The room is 10.0 m wide, 22.0 m deep, and 3.0 m high. The approximate constant pressure heat capacity of air is Cp 1.0 kJ/(K*kg)1. Assume the air in the room is an ideal gas. 2.1 What is the approximate mass of the air in the room? (Use molar volume and molar weight of air) 2.2 How much...
This is for static air don't just copy from others', this is a
different problem.
1. A very long horizontal cylinder of Unobtainium, of diameter 100 mm, is initially at a uniform temperature of 500 K. The cylinder is left to cool in a large room of static air at 300 K. Calculate a) the average convective heat transfer coefficient at the beginning of the cooling process when the initial temperature of the cylinder is 500 K, and 10] 15]...
5. Air expands isothermally constant temperature) in a closed, piston-cylinder device. The original state is given by pı = 20 MPa, T = 1000 K. the process continues until the pressure drops to 2 MPa. The original volume of the air is V1 = 1 m². Determine the following: a. the mass of the air in the system, in kg. b. the final density of the air, in kg/m". Remember, Rair = 0.287 kJ/kg-K c. the final volume of the...
USE THE AIR TABLES 0.5 kg of air is initially at 280 K, 100 kPa in a frictionless adiabatic piston-cylinder. Find the volume of the cylinder (m). Find the initial internal energy (kj/kg) using the air tables. A. B. The air is compressed po ytropically according to P * (V)1.4 = constant to a volume which is 32.3% of the initial volume (V.-0323 V). Find the new volume (m), pressure (kPa), temperature (K) and internal energy (kJ/kg). Find the work...
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The wall is 20 cm thick and has a surface area of 10 m2. One side of the wall is exposed to outside air blowing against the wall resulting in a heat transfer coefficient of 20 W/(m2-K). The other side is exposed to an air-conditioned room with a convective heat transfer coefficient of 5 W/(m2-K). a. What are the thermal resistances corresponding to conduction through...
An aluminum alloy (2024) plate, heated to a uniform temperature of 227°C, is allowed to cool while vertically suspended in a room where the ambient air and surroundings are at 27°C. The plate is 0.3 m square with a thickness of 15 mm. a) calculate the rate of heat transfer from the plate to the surrounding air. b) Develop an expression for the time rate of change of the plate temperature, assuming the temperature to be uni form at any...
Over a period of time, a hot object cools to the temperature of the surrounding air. This is described mathematically by Newton's Law of Cooling T = C+ (To-C) e-kt, where t is the time it takes for an object to cool from temperature Toto temperature T, C is the surrounding air temperature, and k is a positive constant that is associated with the cooling object. A cake removed from the oven has a temperature of 207°F and is left...
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Steel Beam A beam used in construction is made of steel, which has a coefficient of linear expansion of 1.3 x 105 K1. The beam is 30 m long at a temperature of 1635 K when it is made. As it cools, the temperature of the beam decreases to 300 K 1) What is the change in the length of the beam due to cooling? m Submit 2) If the mass of the steel beam is 390 kg and the...
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