Soln_Fall2008_HW6

# Soln_Fall2008_HW6 - SOLUTIONS HW6 1 In a steam power plant...

This preview shows pages 1–3. Sign up to view the full content.

SOLUTIONS- HW6 1. In a steam power plant 2 MW is added in the boiler, 1.2 MW is taken out in the condenser and the pump work is 0.1 MW. Find the plant thermal efficiency. If everything could be reversed find the coefficient of performance as a refrigerator. Solution: CV. Total plant: Energy Eq.: Q . H + W . P,in = W . T + Q . L W . T = 2 + 0.1 – 1.2 = 0.9 MW η TH = (W . T – W . P,in )/ Q . H = (900– 100)/2000 = 0.4 β = Q . L ( W . T – W . P,in ) = 1200/(900 – 100) = 1.5 2. R-410a at 50°C, x = 0.2 flowing at 3 kg/s is brought to saturated vapor in a constant- pressure heat exchanger. The energy is supplied by a heat pump with a coefficient of performance of β′ = 3. Find the required power to drive the heat pump. Solution: C.V. Heat exchanger m . 1 = m . 2 ; m . 1h1 + Q . H = m . 1h2 Given coefficient of performance β′ = Q . H / W . = 3 Table B.4.1: h 1 = h f + x 1 h fg = 143.65 + 0.2 × 135.73 = 170.836 kJ/kg, h 2 = h g = 279.58 kJ/kg Energy equation for line 1-2: Q . H = m . R-12 (h 2 - h 1 ) = 326.232 kW W . = Q . H / β′ = 326.232/3 = 108.743 kW

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

View Full Document
4 A certain solar-energy collector produces a maximum temperature of 50°C. The energy is used in a cyclic heat engine that operates in a 20°C environment. What is the
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern