Lecture 1 - Introduction

Question 1

Formula for energy required to change temperature Q=

Answer 1

Mcp(T1-T2)

Question 2

What is thermodynamics?

Answer 2

Thermodynamics focuses on transferring work into heat and heat into work

Question 3

What is heat transfer?

Answer 3

Heat transfer looks at the movement of heat, no work is done

Question 4

What is fluid dynamics?

Answer 4

The movement of fluid

Question 5

What are the three types of system?

Answer 5

Closed system
Open system
Isolated system

Question 6

What happens in an open system?

Answer 6

Heat and mass can be transferred

Question 7

What happens in a closed system?

Answer 7

Heat can be transferred but mass cannot

Question 8

What happens in an isolated system?

Answer 8

No heat or mass can be transferred to a system

Question 9

What is the first law of thermodynamics?

Answer 9

When any closed system is taken through a cycle the net work delivered to the surroundings is proportional to the net heat taken from the surroundings

Question 10

What is the simplified version of the first law of thermodynamics?

Answer 10

Energy in = energy out

Question 11

What is the equation deduced from the first law of thermodynamics?

Answer 11

The non flow energy equation

Question 12

What is internal energy a property of?

Answer 12

The fluid

Question 13

What is the non flow energy equation?

Answer 13

Q - W = deltU

Heat - Work done = Change in internal energy

Question 14

In an adiabatic process how can the non flow energy equation be simplified?

Answer 14

No heat transferred to or from the system; therefore Q = 0

-W = deltaU

Question 15

What happens in an adiabatic expansion?

Answer 15

Work is done at the expense of the internal energy of the system

Question 16

What happens in an adiabatic compression?

Answer 16

Work is done on the system by the surroundings, causing a rise in internal energy

Question 17

How is the non flow energy equation simplified in a constant volume process?

Answer 17

Work done by the system is zero
W = 0
Q = deltaU

Question 18

What happens to heat in a constant volume system?

Answer 18

Heat supplied across the system boundary for a closed system is equal to the change in internal energy of the system

Question 19

If a constant pressure process is reversible how can the non flow energy equation be written?

Answer 19

deltaW = pdv
dQ - pdv = du
Since P is constant after integrating
Q - p(v2 -v1) = u2 - u1

Question 20

What is enthalpy?

Answer 20

Enthalpy is the amount of heat content used or released in a system at constant pressure

Question 21

Mathematical definition of enthalpy

Answer 21

u + pv = h

Question 22

What is the difference between enthalpy and internal energy?

Answer 22

Reversible constant-volume processes: heat added is equal to the increase in internal energy
Constant pressure processes: heat added is equal to the enthalpy increase

Question 23

Where did the majority of worlds power come from?

Answer 23

Oil

Question 24

What has happened to the UK’s energy supply in recent years and why is this?

Answer 24

Big decrease in supply from coal, increase in gas supply as well as nuclear and renewables

Question 25

What is the largest consumer of energy in the UK?

Answer 25

Industry and domestic which use approximately 34% of each

Question 26

What is the advantage of gas turbine powerstations over coal stations?

Answer 26

Smaller
More compact
Much faster response
Much higher energy output (3MW vs 500MW)

Question 27

1kWh is equal to how many joules?

Answer 27

1000W * 60s * 60s = 3.6MJ

Question 28

What is a system?

Answer 28

Loosely defined as a region in space containing a quantity of fluid