What is Carnot refrigerator: Definition and 18 Discussions

Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. A heat pump is a mechanical system that allows for the transmission of heat from one location (the "source") at a lower temperature to another location (the "sink" or "heat sink") at a higher temperature. Thus a heat pump may be thought of as a "heater" if the objective is to warm the heat sink (as when warming the inside of a home on a cold day), or a "refrigerator" or “cooler” if the objective is to cool the heat source (as in the normal operation of a freezer). In either case, the operating principles are close. Heat is moved from a cold place to a warm place.

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  1. bardia sepehrnia

    Engineering Carnot Cycle and Coefficient of Performance

    I think I calculated part a correctly by extracting the cp (specific heat) of water from the table which is 4.188 Then calculated Q_dot by simply using the equation Q=m*c*deltaT=10.47kW But I am stuck at part b, I know that the heat extracted from the water is the same as Q_L (rate of heat...
  2. Mohammed Alqadhi

    Carnot Refrigerator Work Input: 230 J Extracts 346 J Heat

    If a Carnot refrigerator requires a work input of only 230 J to extract 346 J of heat from the cold reservoir. Doesn’t this discrepancy imply a violation of the law of conservation of energy?
  3. Nemo's

    Determine the coefficient of performance of this cycle

    Homework Statement In an ideal refrigeration cycle, the temperature of the condensing vapour is 40oC and the temperature during evaporation is -20oC. Determine the coefficient of performance of this cycle for the working fluids; R12 and ammonia. Homework Equations C.O.Pc = TL/(TH-TL) The...
  4. N

    Refrigeration: Coefficient of Performance (Carnot & Lorenz)

    Homework Statement Cooling of a food from 293K (20 ⁰C), freezing it at 272K (-1⁰C), and further cooling to 253K (-20 ⁰C); using cooling water rising in temperature from 293K (20 ⁰C) to 303K (30 ⁰C) to accept heat. The specific heat of the unfrozen food is taken as 3.2 kJ/kg K, that of the...
  5. duran9987

    Compute work in Carnot Refrigerator

    Homework Statement The temperature inside the room ##T_I= 25 C ## and the temperature outside the house is ##T_O = 32C##. The temperature difference causes energy to flow into the room (by conduction through the walls and window glass) at the rate 3,000 J/s. To return this energy to the...
  6. Soumalya

    COP of Reversible Refrigeration Cycles

    Considering two thermal energy reservoirs, one at a higher temperature of TH compared to the other at TL, if we operate a reversible refrigeration cycle between the reservoirs then its coefficient of performance is given by, COPR,rev=TL/TH-TL This is the basically the maximum COP a...
  7. L

    Carnot Refrigerator Efficiency and Energy Calculations | Homework Help

    Homework Statement An ideal refrigerator utilizes a carnot cycle operating between 0 and 25 degrees celsius. To turn 10 kg of water at 0 degrees celsius into 10 kg of ice at 0 degrees celsius, a) how much heat is exhausted into the room? b) how much energy must be supplied to the...
  8. K

    Carnot engine efficiency * Carnot refrigerator efficiency

    Carnot engine efficiency is: \eta_{work} = 1 - \frac{T_c}{T_h} Carnot refrigeration efficiency is: \eta_{cool} = \frac{ T_c }{T_h-T_c} \eta_{cool} = \frac{ 1 }{\frac{T_h}{T_c} - 1} Simple multiplication should give me the efficiency where both the engine and the refrigeration share the...
  9. S

    Carnot refrigerator and II law of Thermodynamics

    As per II law of thermodynamics you it is NOT possible that a hotter body becomes hotter and colder body becomes colder when in contact. But in a Carnot refrigerator, the heat is taken from a cold reservoir and pushed to a hotter one. It sort of opposite the II law. Help me over this paradoxical...
  10. R

    What is the minimum work needed to cool an object using a carnot refrigerator?

    Homework Statement 433J of heat is extracted from a massive object at 0\circC while rejecting heat to a hot reservoir at 19\circC. What minimum amount of work will accomplish this? Answer in units of J. Homework Equations COP= Qc/(Qh-Qc) = Tc/(Th-Tc) The Attempt at a Solution...
  11. R

    Carnot refrigerator cost problem

    Homework Statement Three kilograms of liquid water at 0° C is put into the freezer compartment of a Carnot refrigerator. The temperature of the compartment is -13.5° C, and the temperature of the kitchen is 24.5° C. If the cost of electrical energy is ten cents per kilowatt · hour, how much...
  12. S

    Carnot Refrigerator at Phase Boundry

    Hi All, My textbook mentions that the coefficient of refrigeration for a Carnot refrigerator acting between a hot reservoir T_{H} and a cold reservoir T_{C} is K_{Carnot} = \frac{T_C}{T_H - T_C} This got me wondering - Suppose you had 1 kg of ice at it's melting point, and 1 kg of water...
  13. I

    How Much Energy is Needed for a Carnot Refrigerator to Convert Water to Ice?

    Homework Statement can you please help me solve this problem? A carnot refrigerator takes heat from water @ 0 degrees celsius and rejects heat to a room at 27 degrees celsius. If 50 kg of water @ 0 degrees celsius is converted to ice @ 0 degrees celsius, how much energy must be supplied...
  14. D

    Carnot Refrigerator Homework: Coeff of Performance, Work & Heat

    Homework Statement A Carnot refrigerator operating between -30.0 ^ C and + 20.0 ^ C extracts heat from the cold reservoir at the rate 300 J/s. What are (a) the coefficient of performance of this refrigerator, (b) the rate at which work is done on the refrigerator and (c) the rate at which heat...
  15. V

    Carnot refrigerator and energy

    Homework Statement a carnot refrigerator takes heat from water at 0 degree celsius and rejects heat to a room at 27 degree celsius. if 50kg of water at 0 degree celsius is converted to ice at 0 degree celsius. how much energy must be supplied to the refrigerator? Homework Equations Sorry, i...
  16. K

    Carnot Refrigerator coefficient of performance

    A Carnot refrigerator operating between -10.0 C and 40.0 C extracts heat from the cold reservoir at the rate 300 J/s. What are (a) the coefficient of performance of this refrigerator, (b) the rate at which work is done on the refrigerator and (c) the rate at which heat is exhausted to the hot...
  17. S

    Carnot refrigerator and work done

    The question reads... A heat pump is essentially a refrigerator engine that uses the inside of a building as a hot reservoir in the winter and the outside of the building as the hot reservoir in the summer. A) For a carnot refrigerator engine operating between 25 C and 40 C in the summer, what...
  18. S

    Carnot Engine - Carnot Refrigerator

    This is just a common problem solving question, which I cannot make, I suspect because I'm bad at maths. Anyway, I want to see it done, hopefully to grasp it. I am doing physics, so, it's an exercise from one of my books. 18-11. Show that the efficiency e of a Carnot engine and the...