Learning Materials
Features
Discover
Chapter 4: 4.7 (page 129)
Why must you put an air conditioner in the window of a building, rather than in the middle of a room?
We must put t an air conditioner in the window to cool the room effectively.
Over 30 million students worldwide already upgrade their learning with 91影视!
All the tools & learning materials you need for study success - in one app.
Get started for free
A small scale steam engine might operate between the temperatures and , with a maximum steam pressure of bars. Calculate the efficiency of a Rankine cycle with these parameters.
A power plant producesof electricity, at an efficiency of (typical of today's coal-fired plants).
(a) At what rate does this plant expel waste heat into its environment?
(b) Assume first that the cold reservoir for this plant is a river whose flow rate is .By how much will the temperature of the river increase?
(c) To avoid this "thermal pollution" of the river, the plant could instead be cooled by evaporation of river water. (This is more expensive, but in some areas it is environmentally preferable.) At what rate must the water evaporate? What fraction of the river must be evaporated?
At a power plant that produces 1 GW109 watts) of electricity, the steam turbines take in steam at a temperature of 500o, and the waste heat is expelled into the environment at 20o
(a) What is the maximum possible efficiency of this plant?
(b) Suppose you develop a new material for making pipes and turbines, which allows the maximum steam temperature to be raised to 600o. Roughly how much money can you make in a year by installing your improved hardware, if you sell the additional electricity for 5 cents per kilowatt-hour? (Assume that the amount of fuel consumed at the plant is unchanged.)
Prove directly (by calculating the heat taken in and the heat expelled) that a Carnot engine using an ideal gas as the working substance has an efficiency of
A common (but imprecise) way of stating the third law of thermodynamics is "You can't reach absolute zero." Discuss how the third law, as stated in Section 3.2, puts limits on how low a temperature can be attained by various refrigeration techniques.
What do you think about this solution?
We value your feedback to improve our textbook solutions.
Explanations 
Textbooks 
Flashcards 
91影视 AI 
Notes 
Study Plans 
Study Sets 
Find a degree 
Magazine