Thermodynamics: First Law Applied to Flow Processes

Questions and Answers

What is the fundamental principle that all processes in the universe comply with?

Both first and second laws of thermodynamics

What is the maximum amount of heat that an electric heater can produce if it consumes 1 kW of electricity?

Exactly 1 kW

What is the type of flow where the rate of fluid flow through a machine or apparatus is constant?

Steady flow

What is the purpose of the Steady Flow Energy Equation (SFEE)?

To relate the energy changes between the inlet and outlet of a control volume Signup and view all the answers

What is the term for the energy transferred due to the movement of a fluid in and out of a control volume?

Flow work Signup and view all the answers

What is the equation that represents the Steady Flow Energy Equation (SFEE)?

All of the above Signup and view all the answers

What is the assumption made in the analysis of the Steady Flow Energy Equation (SFEE)?

All of the above Signup and view all the answers

What is the term for the energy per unit mass of a fluid?

Specific enthalpy Signup and view all the answers

What is the formula for the specific kinetic energy of a fluid?

V²/2 Signup and view all the answers

What is the force that moves the mass in and out of a control volume?

Piston force Signup and view all the answers

What does the First Law of Thermodynamics state about energy?

Energy can be converted from one form to another. Signup and view all the answers

What is the mathematical statement of the First Law of Thermodynamics?

dU = dQ - dW Signup and view all the answers

What is the corollary to the First Law of Thermodynamics?

There exists a property of closed system. Signup and view all the answers

What is the total energy of a system?

Internal energy, kinetic energy, potential energy, and others. Signup and view all the answers

What is a Perpetual Motion Machine of First Kind (PMM1)?

A machine that produces useful work without any source. Signup and view all the answers

Why is a Perpetual Motion Machine of First Kind (PMM1) impossible?

It violates the First Law of Thermodynamics. Signup and view all the answers

What is the cyclic integral of heat added equal to?

Integral of work done. Signup and view all the answers

What is the equation that represents the First Law of Thermodynamics?

()dQ - dW) = 0 Signup and view all the answers

What is the SFEE equation for the throttle valve?

h1 + KE1 + PE1 = h2 + KE2 + PE2 + E Signup and view all the answers

What happens to energy in an isolated system?

Energy is constant. Signup and view all the answers

What is the purpose of a boiler?

To generate steam by heating water Signup and view all the answers

What is the SFEE equation for the condenser?

m (h1 - h2) = Q Signup and view all the answers

What is the property of a closed system that is changed by the difference between heat supplied and work done?

Internal energy. Signup and view all the answers

What is the purpose of a pump?

To increase the pressure of the fluid Signup and view all the answers

What is the term for the work done by the fluid as it enters or leaves a system?

Flow work Signup and view all the answers

What is the equation for the total work done during a steady flow process?

W_total = W_flow + W_shaft + W_internal Signup and view all the answers

What is the term for the heat transfer between the system and the surroundings?

External heat transfer Signup and view all the answers

What is the equation for the external heat transfer?

Q_external = m × cp × (T2 - T1) Signup and view all the answers

What is the term for the heat transfer due to frictional losses or other internal energy changes within the system?

Internal heat transfer Signup and view all the answers

What is the equation for the total heat transfer during a steady flow process?

Q_total = Q_external + Q_internal Signup and view all the answers

What is the unit of pressure in the equation W = F × L = pA × L?

Pa Signup and view all the answers

What is the primary function of a nozzle?

To increase the velocity of a fluid at the expense of pressure Signup and view all the answers

What is the equation for the work output of a turbine?

W = (m × (h1 - h2)) + (V1² - V2²) / 2 + (Z1 - Z2) Signup and view all the answers

What is the purpose of the SFEE in compressor design?

To design and optimize compressor performance, ensuring efficient compression and minimal energy losses Signup and view all the answers

What is the equation for the work input required to compress a fluid in a compressor?

W = (m × (h2 - h1)) + (V2² - V1²) / 2 + (Z2 - Z1) Signup and view all the answers

What is the primary function of a heat exchanger?

To transfer heat energy from one fluid to another Signup and view all the answers

What is the purpose of the SFEE in turbine design?

To determine the work output of a turbine Signup and view all the answers

What is the function of a throttle valve?

To restrict fluid flow, reducing pressure and temperature Signup and view all the answers

What is the equation for the work output of a turbine in terms of turbine efficiency?

?_t = (W / (m × (h1 - h2))) × 100 Signup and view all the answers

What is the equation for the compressor efficiency?

?_c = (W / (m × (h2 - h1))) × 100 Signup and view all the answers

Study Notes

First Law of Thermodynamics

The first law states that energy is neither created nor destroyed, but can be converted from one form to another.
The total energy of the universe is a constant.

Corollaries to the First Law

There exists a property of a closed system called internal energy (U), which changes by the difference between heat supplied and work done.
For an isolated system, energy is constant, and neither heat nor work interactions occur.
It is impossible to create a perpetual motion machine of the first kind, which would produce useful work without any energy input.

Steady Flow Energy Equation (SFEE)

The SFEE is a fundamental equation that relates the energy changes between the inlet and outlet of a control volume.
The SFEE accounts for energy losses due to heat transfer, friction, and other interactions.
The SFEE is written as: m (h1 + KE1 + PE1) = m (h2 + KE2 + PE2) + E

Applications of SFEE

Nozzles

SFEE helps understand the relationship between inlet and outlet conditions.
The equation reduces to: h1 + KE1 = h2 + KE2, showing a conversion of thermal energy to kinetic energy.

Diffusers

SFEE helps understand the relationship between inlet and outlet conditions.
The equation reduces to: h1 + KE1 = h2 + KE2, showing a conversion of kinetic energy to thermal energy.

Turbines

SFEE helps design and optimize turbine performance.
The equation is used to determine the work output (W) of a turbine.

Compressors

SFEE is essential for designing and optimizing compressor performance.
The equation is used to determine the work input (W) required to compress a fluid.

Heat Exchangers

SFEE helps analyze the heat transfer process.
The equation is: m1 (h1 - h2) = m2 (h3 - h4)

Throttle Valve

SFEE applies to the throttle valve, showing a conversion of thermal energy to kinetic energy.

Boiler

SFEE helps analyze the energy transfer in a boiler.
The equation is: m (h2 - h1) = Q

Condenser

SFEE applies to the condenser, showing a conversion of thermal energy to kinetic energy.

Pump

SFEE helps analyze the energy transfer in a pump.
The equation is: h1 + p1/ρg + V1²/2g + z1 = h2 + p2/ρg + V2²/2g + z2

Work Done During Steady Flow Processes

Work done during steady flow processes can be categorized into three types: flow work, shaft work, and internal work.
The total work done is the sum of these three types of work.

Heat Transfer During Steady Flow Processes

Heat transfer can be categorized into two types: external heat transfer and internal heat transfer.
The total heat transfer is the sum of external and internal heat transfer.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the application of the First Law of Thermodynamics to flow processes, including the concept of internal energy and the equation dU = dQ - dW. Test your understanding of the first law equation and its corollaries.