Unit 31 Thermodynamic Principles and Practice - BTEC Level 3 National Extended Diploma in Engineering

Investigate thermodynamic principles related to the expansion and compression of gases that are applied in mechanical systems

Assignment - Investigate thermodynamic principles and polytropic processes

You are a final year apprentice within an engineering organisation which specialises in thermal engineering systems. Your supervisor has been observing your progress and is impressed by your knowledge and understanding of the theory which underpins thermodynamic systems. He has asked you to produce a written report which could be used to introduce the subject to future first year apprentices to provide them with a background into the subject.

You are to produce a written report about thermodynamic systems, which:
a) explains the fundamental parameters of thermodynamics and thermodynamic process parameters,
b) explains the need for different types of temperature scale, and
c) evaluates the polytropic processes, explaining the relationships between parameters and what the results from relevant and accurate calculations.

To do this.
Your tutor will provide you with a range of thermodynamic parameters to research and investigate, along with gases to consider when carrying out calculations to an appropriate degree of accuracy and using appropriate units throughout. Your report should contain:

• Explanations of the differences between sensible heat, latent heat, including latent heat of fusion and latent heat of vaporisation and relationship between temperature at constant pressure or volume during expansion and/or compression.
• Calculations of the values and explanations of the significance of the answers:
- Thermal energy of Gas A
- Thermal power of Gas A.
• Explanations for why different temperature scales are needed, and why conversions are carried out between the scales.

You then need to:
• Complete the following calculations, using the data provided for Gases B and C, where Parts 1, 2, 3 and 4 relate to different polytropic processes:

Part 1 - A cylinder of air occupies a volume of 30 litres. The temperature of the gas is T1 and the pressure is P1 (seedata table).
Assume the gas constant of air is 287 Jkg-1K-1.
Calculate the mass of the air.

Part 2 - A piston contains air at temperature T1 and pressure P1 (seedata table). The air is heated to 1200K while being kept at a constant volume of 5 litres.
Assume the gas constant for air is 287 Jkg-1K-1.
Calculate the pressure and the mass of the air following heating.

Part 3 - A cylinder contains a gas at temperature 200°C (T1), volume 5 litres (V1) and a pressure of 2.2MPa (P1). The polytropic process index value (n) of the gas in its initial state is 1.1.
Assume the gas constant for the gas is 188 Jkg-1K-1.
Calculate the initial mass of the gas.
The gas is then cooled to a temperature of T2. At this temperature the pressure is P2. Find the polytropic process index value (n) for the gas after it has been cooled.

Part 4 - A gas is stored in a cylinder that has a volume of V1 litres. The gas is stored at temperature T1 and pressure P1. The gas is then released into the air at sea level. Calculate the final temperature of the gas and the polytropic process index value (n) of the gas.

You need to then produce an evaluation of these polytropic processes, explaining the relationships between parameters and what the results of the calculations show in terms of the impact and operation of the thermodynamic system.

Attachment:- Thermodynamic.rar