Lec31

# Lec31 - Refrigerant 22 From CV around Expansion valve...

This preview shows pages 1–8. Sign up to view the full content.

ME 200: Thermodynamics I Lecture 31: Applications of rate balance to open systems Sections 6.10.2 Problems: SP31; 6.99, 6.103, 6.109 Professor Hukam Mongia Office Hours: MWF 2:30 to 3:30 pm in ME 83 (Other times email for appointment) Email: [email protected] Phone: 765-494-5640 Course Website: https://engineering.purdue.edu/ME200 Course Secretaries: Diana Akers (ME 84) and Marilyn Morrison (ME 100) See Kul Inn (ME 189) about grading Homework Assignments 1

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2 Applications of rate balance to open systems Example 6.6: Steam Turbine Specific change in entropy: s 2 -s 1 ? h1=3230.9 kJ/kg s1 = 6.9212 kJ/kg.K h2=2676.1 kJ/kg s1 = 6.9212 kJ/kg.K KE and q can’t be neglected? 1 st Law
3

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
4 Example 6.7: Verify the invention; Claims: W cv = 0, Q cv =0 0.6 lb 1.0 lb 0.4 lb Air: Ideal gas w/ c p = 0.24 Btu/lb. o R Is the 1 st Law of Thermo satisfied? c p [(T1-Tref)-0.4(T2-Tref)-0.6(T3-Tref)] =c p (70-0.4x175-0)=c p (70-70)=0 Yes.
5 What is s 3 -s 1 ? Inventor’s claims are verified by the 1 st and 2 nd laws of thermodynamics.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
6 Example 6.8 Entropy Production in Heat Pump Components

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Refrigerant 22 From CV around Expansion valve Refrigerant 22 Tables A-7 thru A-9 Liquid Condition 1 Condition 2 Condition 3 Condition 4 T, o C p, bar T, o C p, bar T, o C p, bar T, o C p, bar x?-5 3.5 75 14 28 14-10.39 3.5 0.216 249.75 0.9572 294.175 0.98225 79.05 0.2936 79.079 0.3078 h, kJ/kg s, kJ/kg K h, kJ/kg s, kJ/kg K h, kJ/kg s, kJ/kg K h, kJ/kg s, kJ/kg K Approximations made at #3 for h & s-Ignored effect of pressure on h & s h 3 =h 4 Adiabatic 7 Entropy production, kW/K for compressor, condenser and expansion valve? Recommend performance improvements to reduce energy consumption. Apply 1 st law steady-state to condenser to calculate the refrigerant flow rate: Assume ideal gas for air to calculate air flow rate. Calculate : s 6-s 5 : 8 Apply 2 nd Law to compressor: Apply 2 nd Law to expansion valve: Which components we should improve from thermal point of view? Any other considerations?...
View Full Document

{[ snackBarMessage ]}

### Page1 / 8

Lec31 - Refrigerant 22 From CV around Expansion valve...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online