College Physics
10th Edition
ISBN: 9781285737027
Author: Raymond A. Serway, Chris Vuille
Publisher: Cengage Learning
expand_more
expand_more
format_list_bulleted
Textbook Question
Chapter 12, Problem 40P
Suppose an ideal (Carnot) heal pump could be constructed, (a) Using Equation 12.15, obtain an expression for the coefficient of performance for such a heat pump in terms of Th and Tc. (b) Would such a heal pump work better If the difference in the operating temperatures were greater or smaller? (c) Compute the coefficient of performance for such a heat pump if the cold reservoir is 50.0°C and indoor temperature is 70.0°C.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
A heat pump has a coefficient of performance of 3.75 and operates with a power consumption of 715 W.
(a) How much energy does it deliver into a home during 2 h of continuous operation?
(b) How much energy does it extract from the outside air in 2 h?
Need Help?
Read It
A Carnot heat engine operates between thermal reservoirs at Th and Tc. What is the theoretical efficiency, η, of this engine?
-Part (a) Write an expression for thermal efficiency, η.
- Part (b) Solve numerically for the thermal efficiency, η, assuming that Th = 820°C and Tc = 440°C.
A heat pump used to warm a home must employ a cycle that produces a working fluid at temperatures greater than typical indoor temperature so that heat transfer to the inside can take place. Similarly, it must produce a working fluid at temperatures that are colder than the outdoor temperature so that heat transfer occurs from outside. Its hot and cold reservoir temperatures therefore cannot be too close, placing a limit on its COPhp . What is the best coefficient of performance possible for such a heat pump, if it has a hot reservoir temperature of 45.0ºC and a cold reservoir temperature of −15.0ºC ?
Chapter 12 Solutions
College Physics
Ch. 12.1 - By visual inspection, order the PV diagrams shown...Ch. 12.4 - Three engines operate between reservoirs separated...Ch. 12.5 - Which of the following is true for the entropy...Ch. 12.5 - Prob. 12.5QQCh. 12 - Prob. 3CQCh. 12 - Prob. 4CQCh. 12 - For an ideal gas in an isothermal process, there...Ch. 12 - Is it possible to construct a heat engine that...Ch. 12 - When a sealed Thermos bottle full of hot coffee is...Ch. 12 - The first law of thermodynamics says we cant get...
Ch. 12 - Prob. 13CQCh. 12 - Prob. 14CQCh. 12 - An ideal gas is compressed to half its initial...Ch. 12 - A thermodynamic process occurs in which the...Ch. 12 - Prob. 17CQCh. 12 - An ideal gas is enclosed in a cylinder with a...Ch. 12 - Sketch a PV diagram and find the work done by the...Ch. 12 - Gas in a container is at a pressure of 1.5 atm and...Ch. 12 - A 40.0-g projectile is launched by the expansion...Ch. 12 - A gas expands from I to F along the three paths...Ch. 12 - Sketch a PV diagram of the following processes:...Ch. 12 - A sample of helium behaves as an ideal gas as it...Ch. 12 - (a) Find the work done by an ideal gas as it...Ch. 12 - One mole of an ideal gas initially at a...Ch. 12 - (a) Determine the work done on a fluid that...Ch. 12 - Prob. 11PCh. 12 - A cylinder of volume 0.300 m3 contains 10.0 mol of...Ch. 12 - A gas expands from I to F in Figure P12.5. The...Ch. 12 - In a running event, a sprinter does 4.8 105 J of...Ch. 12 - A gas is compressed at a constant pressure of...Ch. 12 - A quantity of a monatomic ideal gas undergoes a...Ch. 12 - A gas is enclosed in a container fitted with a...Ch. 12 - A monatomic ideal gas under-goes the thermodynamic...Ch. 12 - An ideal gas is compressed from a volume of Vi =...Ch. 12 - A system consisting of 0.025 6 moles of a diatomic...Ch. 12 - An ideal monatomic gas expands isothermally from...Ch. 12 - An ideal gas expands at constant pressure. (a)...Ch. 12 - An ideal monatomic gas is contained in a vessel of...Ch. 12 - Consider the cyclic process described by Figure...Ch. 12 - A 5.0-kg block of aluminum is heated from 20C to...Ch. 12 - One mole of gas initially at a pressure of 2.00...Ch. 12 - Consider the Universe to be an adiabatic expansion...Ch. 12 - Suppose the Universe is considered to be an ideal...Ch. 12 - A gas increases in pressure from 2.00 atm to 6.00...Ch. 12 - An ideal gas expands at a constant pressure of...Ch. 12 - A heat engine operates between a reservoir at 25C...Ch. 12 - A heat engine is being designed to have a Carnot...Ch. 12 - The work done by an engine equals one-fourth the...Ch. 12 - In each cycle of its operation, a heat engine...Ch. 12 - One of the most efficient engines ever built is a...Ch. 12 - A gun is a heat engine. In particular, it is an...Ch. 12 - An engine absorbs 1.70 kJ from a hot reservoir at...Ch. 12 - A heat pump has a coefficient of performance of...Ch. 12 - A freezer has a coefficient of performance of...Ch. 12 - Suppose an ideal (Carnot) heal pump could be...Ch. 12 - In one cycle a heat engine absorbs 500 J from a...Ch. 12 - A power plant has been proposed that would make...Ch. 12 - Prob. 43PCh. 12 - A heat engine operates in a Carnot cycle between...Ch. 12 - A Styrofoam cup holding 125 g of hot water at 1.00...Ch. 12 - A 65-g ice cube is initially at 0.0C. (a) Find the...Ch. 12 - A freezer is used to freeze 1.0 L of water...Ch. 12 - What is the change in entropy of 1.00 kg of liquid...Ch. 12 - A 70.0-kg log falls from a height of 25.0 m into a...Ch. 12 - Prob. 50PCh. 12 - Prob. 51PCh. 12 - When an aluminum bar is temporarily connected...Ch. 12 - Prepare a table like Table 12.3 for the following...Ch. 12 - Prob. 54PCh. 12 - Prob. 55PCh. 12 - Prob. 56PCh. 12 - Sweating is one of the main mechanisms with which...Ch. 12 - A Carnot engine operates between the temperatures...Ch. 12 - Prob. 59APCh. 12 - A Carnot engine operates between 100C and 20C. How...Ch. 12 - A substance undergoes the cyclic process shown in...Ch. 12 - When a gas follows path 123 on the PV diagram in...Ch. 12 - Prob. 63APCh. 12 - An ideal gas initially at pressure P0, volume V0,...Ch. 12 - One mole of neon gas is heated from 300. K to 420....Ch. 12 - Every second at Niagara Falls, approximately 5.00 ...Ch. 12 - A cylinder containing 10.0 moles of a monatomic...Ch. 12 - Prob. 68APCh. 12 - Suppose you spend 30.0 minutes on a stair-climbing...Ch. 12 - Hydrothermal vents deep on the ocean floor spout...Ch. 12 - An electrical power plant has an overall...Ch. 12 - A diatomic ideal gas expands from a volume of VA =...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- Suppose you want to operate an ideal refrigerator with a cold temperature of 10.0C, and you would like it to have a coefficient of performance 7.00. What is the hot reservoir temperature for such a refrigerator?arrow_forwardA Carnot engine has an efficiency of 0.60. When the temperature of its cold reservoir the efficiency drops to 0.55. If initially Tc=27, determine (a) the constant value of Th and (b) the final value of Tc.arrow_forwardShow that the coefficients of performance of refrigerators and heat pumps are related by COPref=COPhp1. Start with the definitions of the COP s and the conservation of energy relationship between Qh, QC, and W.arrow_forward
- How could you design a Carnot engine with 100% efficiency?arrow_forwardSuppose an ideal (Carnot) heat pump could be constructed. (a) Using the equation |Qc| |Qh| = Tc Th obtain an expression for the coefficient of performance for such a heat pump in terms of Th and Tc. (COP)ho,C = (b) Would such a heat pump work better if the difference in the operating temperatures were greater or were smaller? (c) Compute the coefficient of performance for such a heat pump if the cold reservoir is 51.0°C and indoor temperature is 64.6°C.arrow_forwardA heat pump maintains a dwelling at 68°F. When operating steadily, the power input to the heat pump is 7 hp, and the heat pump receives energy by heat transfer from 55°F well water at a rate of 500 Btu/min. (a) Determine the coefficient of performance. (b) Evaluating electricity at $0.08 per kWh, determine the cost of electricity in a month when the heat pump operates for 300 hours.arrow_forward
- A certain coal-fired power plant has a rated power capacity of P = 1350 MW. The output of this plant is W = 0.34QH, where QH is the energy input as heat from the hot reservoir. Part (a) Write an equation for the efficiency of a heat engine in terms of QH and the heat QC exhausted to a low temperature reservoir. Part (b) Which would increase the efficiency more, doubling QH or reducing QC by half? Part (c) Calculate the maximum thermal efficiency of the power plant. Part (d) Calculate the absolute value of the exhausted heat (QC) each second in MJ for the power plant. Part (e) If the power plant operates for a full day at its rated capacity, how much energy QH in MJ is needed? Part (f) If, on average, one ton of coal contains Q = 25 GJ of energy, how many tons nH of coal would the plant need to operate for a day at its rated capacity? Part (g) How many tons nC of this coal is exhausted as wasted heat to QC in a single day?arrow_forwardAn engineer designs a heat engine using flat-plate solar collectors. The collectors deliver heat at 74°C and the engine releases heat to the surroundings at 32°C. What is the maximum possible efficiency of this engine? (Round the final answer to four decimal places.) The maximum efficiency of the engine is __%arrow_forwardA reversible heat pump can be utilized for heating in Winter and cooling in Summer. The Coefficient of Performance in heating mode is calculated as: COPheating = ΔQhot / W = Thot / (Thot – Tcold) How would you calculate then the COP in cooling mode?arrow_forward
- (a) What is the best coefficient of performance for a heat pump that has a hot reservoir temperature of 59.3°C and a cold reservoir temperature of -12.7°C? (b) How much heat in kilocalories would it pump into the warm environment if 3.60 x 10' ) of work (10.0 kw · h) is put into it? kcal (c) Assume the cost of this work input is 10c/kW · h. Also assume that the cost of direct production of heat by burning natural gas is 85.0c per therm (a common unit of energy for natural gas), wher a therm equals 1.055 x 108 J. Compare the cost of producing the same amount of heat by each method. cost of heat pump cost of natural gas Additional Materials OReadingarrow_forwardA heat pump moves heat from the chilly 8°C air outside a house to the toastier 21°C air inside. The actual coefficient of performance of the system is 3.2, a typical value. How much energy would it take to add 11 kJ each second if the heat pump ran at the maximum theoretical efficiency?arrow_forward1. (a) What is the hot reservoir temperature of a Carnot engine that has an efficiency of 43% and a cold reservoir temperature of 29 deg C? Th= °C (b) What must the hot reservoir temperature be for a real heat engine that achieves 0.65 of the maximum efficiency, but still has an efficiency of 43% (and a cold reservoir at 29 deg C)? Th=2886 °C Something to think about: Does your answer imply practical limits to the efficiency of car gasoline engines?arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- College PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax College
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
College Physics
Physics
ISBN:9781285737027
Author:Raymond A. Serway, Chris Vuille
Publisher:Cengage Learning
College Physics
Physics
ISBN:9781938168000
Author:Paul Peter Urone, Roger Hinrichs
Publisher:OpenStax College
Principles of Physics: A Calculus-Based Text
Physics
ISBN:9781133104261
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning
The Second Law of Thermodynamics: Heat Flow, Entropy, and Microstates; Author: Professor Dave Explains;https://www.youtube.com/watch?v=MrwW4w2nAMc;License: Standard YouTube License, CC-BY