Chapter 15: Q19P (page 412)
Question:(I) What is the maximum efficiency of a heat engine whose operating temperatures are 560°C and 345°C?
The maximum efficiency of the heat engine is \(25.81\% \).
Over 30 million students worldwide already upgrade their learning with Vaia!
All the tools & learning materials you need for study success - in one app.
Get started for free
A “Carnot” refrigerator (the reverse of a Carnot engine) absorbs heat from the freezer compartment at a temperature of -17°C and exhausts it into the room at 25°C.
(a) How much work would the refrigerator do to change 0.65 kg of water at 25°C into ice at -17°C.
(b) If the compressor output is 105 W and runs 25% of the time, how long will this take?
(II) When\({\bf{5}}{\bf{.80 \times 1}}{{\bf{0}}{\bf{5}}}\;{\bf{J}}\)of heat is added to a gas enclosed in a cylinder fitted with a light frictionless piston maintained at atmospheric pressure, the volume is observed to increase from\({\bf{1}}{\bf{.9}}\;{{\bf{m}}{\bf{3}}}\)to\({\bf{4}}{\bf{.1}}\;{{\bf{m}}{\bf{3}}}\). Calculate
(a) the work done by the gas, and
(b) the change in internal energy of the gas.
(c) Graph this process on a PV diagram.
An aluminum rod conducts 8.40 cal/s from a heat source maintained at 225°C to a large body of water at 22°C. Calculate the rate at which entropy increases in this process.
Question: (II) A heat pump is used to keep a house warm at 22°C. How much work is required of the pump to deliver 3100 J of heat into the house if the outdoor temperature is (a) 0°C, (b) \({\bf{ - 15^\circ C}}\)? Assume a COP of 3.0. (c) Redo for both temperatures, assuming an ideal (Carnot) coefficient of performance \({\bf{COP = }}{{\bf{T}}_{\bf{L}}}{\bf{/}}\left( {{{\bf{T}}_{\bf{H}}}{\bf{ - }}{{\bf{T}}_{\bf{L}}}} \right)\).
Question:(I) The exhaust temperature of a heat engine is 230°C. What is the high temperature if the Carnot efficiency is 34%?
What do you think about this solution?
We value your feedback to improve our textbook solutions.
