THERMODYNAMICS

50問 • 1年前

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50 grams of ice at 0-C is added to 200 gm of water at 40-C contained in a 100-gm calorimeter of specific heat of 0.093 Cal/g-C. If the final temperature of the mixture is 16-C. find the heat of fusion of ice.

84.5 cal/g

A 2 Ibm of 200°F iron (Cp = 0.1 BTU/lbm-°F) are dropped into a gallon of 40°F water. What is the final temperature of the mixture? Exclusively Distributed by Powerline Review Center.

43.74 °F

How much heat is required to change 30 kg of 20°C water into 100°C steam at one atmosphere?

77,757 kJ

A 500 kcal of heat is added to 2 kg of water at 80°C. How much steam is produced? Take latent heat of evaporation as 540 kcal/kg.

0.85 kg

Heat is supplied to 20 lbm of ice (Cp = 0.5 BTU/lbm-°F) at 0°F at the rate 160 BTU/sec. How long will it take to convert the ice to steam (Cp = 0.5 BTU/lbm-°F) at 213°F?

163.78 sec

A 287,5 cm³ of vapor at 100°C and 100kPa has a mass of 725 gr. What is the molecular weight of the vapor? Exclusively Distributed by Powerline Review Center.

77.94 g/mole

7. A tank whose capacity is 0.1~m^{3} contains helium at an absolute pressure of 10 atm and a temperature of 20°C. A rubber balloon is inflated with this helium. The gas cools as it expands and when the pressure of the helium in the balloon is 1 atm its temperature is - 40°C. Find the volume of the balloon.

0.7 m^3

An automobile tire is inflated to 220.6 kPa gage pressure at 16°C. After the car has been driven the temperature rises to 24°C. If the volume remains constant. What is the final gage pressure?

230 kPa gage

Air is an ideal gas with a value of R=0.287 kJ/kg-°K. If there are 2 kg of air in a piston-cylinder at a temperature of 280°K, a volume of 0.2~m^{3}. find the pressure.

803.6 kPa

* A sealed tank contains 27°C at a pressure of 2 alm. If the temperature increases to 100°C the pressure inside the tank will be.....

2.49 atm

A motorist equips his automobile tires with a relief type valve so that the pressure inside the tire will never exceed 240 kPa (gauge). He started his trip with the tire pressure of 200 kPa (gauge) and a temperature of 23°C. During the long drive the air temperature of the tire reaches 83°C. Each tires contains 0.11 kg of air. Determine the mass of the air escaping each tire.

6.37×10 to the negative 3 kg

Find the change in internal energy of 5 to 100°F to 120°F, C_{v}=0.157~BTU/lbm-^{0}R oxygen gas when the temperature changes from

15.7 BTU

A 12 V battery receives 20 min charging during which time it receives a steady current of 50 amp. In this period it experiences a heat loss of 127 kJ. Find the change in internal energy in the battery during this period.

593 kJ

When the temperature of an idea gas is doubled, while the absolute pressure is halved, the volume is

quadrupled

The specific heat capacity is an S.I. derived unit described as

J/kg-K

How much energy is required to just vaporized 0.5 kg of water which is originally at 24°C and one atmosphere?

1287.57 kJ

Heat is supplied to 20 lbm of ice (Cp=0.5 BTU/lbm-°F) at 0°F at the rate 160 BTU/sec. How long will it take to convert the ice to steam (Cp=0.5 BTU/lbm-°F) at 213°F?

163.78 sec

A 0.71 m^3 tank contains 4.5 kg of an ideal gas. The gas has a molecular weight of 44 and is at 21°C. What is the pressure of the gas?

352.2 kPa

A closed constant volume system receives 10.5 kJ of paddle work. The system contains oxygen at 344 kPa, 278°K and occupies 0.06m^{3}. Find the heat loss if final temp. is 400°K.

Q = 12.39 kJ

Three (3) designs are proposed for an engine which is to operate between 500 K and 30K. Designed A is claimed to produce 3000 J. Which design would you choose?

C alone

What is the maximum amount of work that a Carnot engine can perform per kilocalories of heat input if it absorbs heat at 427^{\circ}C and exhausts heat at 177°C?

0.357

How many kilograms of water at 0°C can freezer with a coefficient of performance 5 make Into ice cubes at 0°C with a working input of 3.6 MJ (one kilowatt-hour)? Use Table 17-1 for data,

53.699 kg

Work of a polytrophic (n=1.21) compression of air (Cp/Cv=1.4) in a system with moving boundary from P1=15 psia, V1=1.0 ft^3 to P₂= 150 psia, V2=0.15 ft^3 is

5150ft-lb

In an adiabatic, isentropic process, P1=200 psia, P2=300 psia, and T1=700°R Find T2 Using g=1.4

786°R

Pure water is boiling in an open pan at atmospheric pressure. Salt at a temperature equal to that of the boiling water is added. Immediately after the salt dissolves, which of the following will most likely to occur?

The boiling ceases

It is planned to lift and move logs from almost inaccessible forest areas by means of balloons. Helium at atmospheric pressure (101,325 N/m²) and temperature 21.1°C is to be used in the balloons. What minimum balloon diameter (assume spherical shape) will be required for a gross lifting force of 30,000 kg? Gas constant for air and Helium are 287.08 and 2077.67 J/kg-°K respectively.

38.121 m

The heat transfer during adiabatic process is

zero

A pump is used to increase the pressure of the water entering the boiler of a steam power cycle. Which statement is true concerning the pump?

The enthaply of the water leaving the pump is higher than the enthaply of water

Enthalpy of an ideal gas is a function only of:

temperature

Entropy is the measure of

rabdomness or disorder

An isentropic process is one which

is adiabatic and reversible

Name the process that has no heat transfer.

Isentropic

Which of the following thermodynamic cycles is the most efficient?

Carnot cycle

A compression ignition cycle is modelled by which ideal cycle?

Diesel Cycle

When cooled to a temperature approaching absolute zero, many materials have a sudden drop in their electrical resistivity to a value of almost zero. This phenomenon is known as

superconductivity

An inventor proposes to propel a ship by withdrawing heat from seawater and converting it all into work. Since the thermal energy of the sea is essentially unlimited, the ship could almost run forever without any fuel. This scheme fails because

it violates the second law of thermodynamics

Equilibrium conditions exists in all except which of the following

in a steady flow system process

A 3000 cfm of 65°F air is required to maintain a house at 76°F. 25% wt of air entering the air conditioner is from the outside at 90°F, and the remainder is recycled from the inside at 76°F. Required: Determine the rating in tons of the air conditioner. (Assume sensible heat changes only, ignore any dehumidification).

3.95 tons

Isentropic compression of 0.0283 m^3 of air. k = Cp/Cv = 1.40, at 137.86 kPaa to a pressure of 689.29 kPaa gives a final volume of

0.009m^3

Second Law of Limitation or tre maximandrepowerloutput from any unit buming 1,000,000 BTU/hr of fuel with high and low temperature extremes of 1540°F and 40°F is:

295

An economizer is used to...

heat the feedwater before it enters the boiler

Two liquids enter a mixing chamber and are discharged at 80°F at the rate of 50 gal/min. Liquid A enters at 140°F with specific heat of 10 BTU/gal-°F. Liquid B enters at 86°F with specific heat of 8.33 BTU/gal-°F. What is the volume flow for liquid A?

6.62 gal/min

What is the color code of steam pipe lines?

Silver gray

The presence of oil or scale on boiler tubes causes.

Overheating

All of the following statements about the Carnot cycle are true EXCEPT

it is irreversible

Cooling air in intercoolers between compression stages in a multi-stage air compressor

requires less horsepower for compressor than without intercoolers.

Determine the changes in enthalpy per Ib of nitrogen gas as its temperature changes from 600°F, Cp = 0.2483 BTU/lbm-°R.

-74.49 BTU/lbm

Which of the following is a safety device on compressor

Relief valve

In the deep well installation or operation, the difference between static water level and operating water level is called

drawdown

Energy changes are represented by all EXCEPT which one of the following

dG=VdP+SdT

DC CIRCUITS POWERLINE

premopremo remo · 75問 · 2年前

DC CIRCUITS POWERLINE